feat(docs): reorganize docs (#7136)

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Victor Wheeler
2024-10-23 12:53:33 -06:00
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.. _coord:
============================
Positions, Sizes and Layouts
============================
Overview
********
Similar to many other parts of LVGL, the concept of setting the
coordinates was inspired by CSS. LVGL has by no means a complete
implementation of CSS but a comparable subset is implemented (sometimes
with minor adjustments).
In short this means:
- Explicitly set coordinates are stored in styles (position, size, layouts, etc.)
- support min-width, max-width, min-height, max-height
- have pixel, percentage, and "content" units
- x=0; y=0 coordinate means the top-left corner of the parent plus the left/top padding plus border width
- width/height means the full size, the "content area" is smaller with padding and border width
- a subset of flexbox and grid layouts are supported
.. _coord_units:
Units
*****
- pixel: Simply a position in pixels. An integer always means pixels.
E.g. :cpp:expr:`lv_obj_set_x(btn, 10)`
- percentage: The percentage of the size of the Widget or its parent
(depending on the property). :cpp:expr:`lv_pct(value)` converts a value to
percentage. E.g. :cpp:expr:`lv_obj_set_width(btn, lv_pct(50))`
- :c:macro:`LV_SIZE_CONTENT`: Special value to set the width/height of an
Widget to involve all the children. It's similar to ``auto`` in CSS.
E.g. :cpp:expr:`lv_obj_set_width(btn, LV_SIZE_CONTENT)`.
.. _coord_boxing_model:
Boxing model
************
LVGL follows CSS's `border-box <https://developer.mozilla.org/en-US/docs/Web/CSS/box-sizing>`__
model. A Widget's "box" is built from the following parts:
- bounding box: the width/height of the elements.
- border width: the width of the border.
- padding: space between the sides of the Widget and its children.
- margin: space outside of the Widget (considered only by some layouts)
- content: the content area which is the size of the bounding box reduced by the border width and padding.
.. image:: /misc/boxmodel.png
:alt: The box models of LVGL: The content area is smaller than the bounding box with the padding and border width
The border is drawn inside the bounding box. Inside the border LVGL
keeps a "padding margin" when placing a Widget's children.
The outline is drawn outside the bounding box.
.. _coord_notes:
Important Notes
***************
This section describes special cases in which LVGL's behavior might be
unexpected.
.. _coord_postponed_coordinate_calculation:
Postponed coordinate calculation
--------------------------------
LVGL doesn't recalculate all the coordinate changes immediately. This is
done to improve performance. Instead, the Widgets are marked as "dirty"
and before redrawing the screen LVGL checks if there are any "dirty"
Widgets. If so it refreshes their position, size and layout.
In other words, if you need to get the coordinate of a Widget and the
coordinates were just changed, LVGL needs to be forced to recalculate
the coordinates. To do this call :cpp:func:`lv_obj_update_layout`.
The size and position might depend on the parent or layout. Therefore
:cpp:func:`lv_obj_update_layout` recalculates the coordinates of all Widgets on
the screen of ``obj``.
.. _coord_removing styles:
Removing styles
---------------
As it's described in the :ref:`coord_using_styles` section,
coordinates can also be set via style properties. To be more precise,
under the hood every style coordinate related property is stored as a
style property. If you use :cpp:expr:`lv_obj_set_x(widget, 20)` LVGL saves ``x=20``
in the local style of the Widget.
This is an internal mechanism and doesn't matter much as you use LVGL.
However, there is one case in which you need to be aware of the
implementation. If the style(s) of a Widget are removed by
.. code-block:: c
lv_obj_remove_style_all(widget)
or
.. code-block:: c
lv_obj_remove_style(widget, NULL, LV_PART_MAIN);
the earlier set coordinates will be removed as well.
For example:
.. code-block:: c
/* The size of obj1 will be set back to the default in the end */
lv_obj_set_size(widget1, 200, 100); /* Now obj1 has 200;100 size */
lv_obj_remove_style_all(widget1); /* It removes the set sizes */
/* widget2 will have 200;100 size in the end */
lv_obj_remove_style_all(widget2);
lv_obj_set_size(widget2, 200, 100);
.. _positioning_widgets:
Positioning Widgets
*******************
Direct
------
To simply set the x and y coordinates of a Widget use:
.. code-block:: c
lv_obj_set_x(widget, 10); /* Separate... */
lv_obj_set_y(widget, 20);
lv_obj_set_pos(widget, 10, 20); /* Or in one function */
By default, the x and y coordinates are measured from the top left
corner of the parent's content area. For example if the parent has five
pixels of padding on every side the above code will place ``obj`` at
(15, 25) because the content area starts after the padding.
Percentage values are calculated from the parent's content area size.
.. code-block:: c
lv_obj_set_x(btn, lv_pct(10)); //x = 10 % of parent content area width
Alignment
---------
Inside parent widget
~~~~~~~~~~~~~~~~~~~~
In many cases it is more convenient to tell LVGL to align your object relative to
an "anchor point" in its parent *other* than its upper left corner. To establish
that "anchor point", call :cpp:expr:`lv_obj_set_align(widget, LV_ALIGN_...)`. After
that call, that "anchor point" will be remembered until another one is established.
In other words, every futire x and y setting for that Widget will be relative to the
that "anchor point".
Example: Position Widget (10,20) px relative to the center of its parent:
.. code-block:: c
lv_obj_set_align(widget, LV_ALIGN_CENTER);
lv_obj_set_pos(widget, 10, 20);
/* Or combine the above in one function... */
lv_obj_align(widget, LV_ALIGN_CENTER, 10, 20);
9 convenient "anchor points" can be used with these functions:
- :cpp:enumerator:`LV_ALIGN_TOP_LEFT`
- :cpp:enumerator:`LV_ALIGN_TOP_MID`
- :cpp:enumerator:`LV_ALIGN_TOP_RIGHT`
- :cpp:enumerator:`LV_ALIGN_BOTTOM_LEFT`
- :cpp:enumerator:`LV_ALIGN_BOTTOM_MID`
- :cpp:enumerator:`LV_ALIGN_BOTTOM_RIGHT`
- :cpp:enumerator:`LV_ALIGN_LEFT_MID`
- :cpp:enumerator:`LV_ALIGN_RIGHT_MID`
- :cpp:enumerator:`LV_ALIGN_CENTER`
See illustration below to visualize what these mean.
It's quite common to align a child to the center of its parent,
therefore a dedicated function exists:
.. code-block:: c
lv_obj_center(widget);
//Has the same effect
lv_obj_align(widget, LV_ALIGN_CENTER, 0, 0);
If the parent's size changes, the set alignment and position of the
children is updated automatically.
Relative to another Widget
~~~~~~~~~~~~~~~~~~~~~~~~~~
Alternately, you can choose an "anchor point" on another Widget.
.. code-block:: c
lv_obj_align_to(widget, reference_widget, align, x, y);
where ``align`` can be done of the following:
- :cpp:enumerator:`LV_ALIGN_OUT_TOP_LEFT`
- :cpp:enumerator:`LV_ALIGN_OUT_TOP_MID`
- :cpp:enumerator:`LV_ALIGN_OUT_TOP_RIGHT`
- :cpp:enumerator:`LV_ALIGN_OUT_BOTTOM_LEFT`
- :cpp:enumerator:`LV_ALIGN_OUT_BOTTOM_MID`
- :cpp:enumerator:`LV_ALIGN_OUT_BOTTOM_RIGHT`
- :cpp:enumerator:`LV_ALIGN_OUT_LEFT_TOP`
- :cpp:enumerator:`LV_ALIGN_OUT_LEFT_MID`
- :cpp:enumerator:`LV_ALIGN_OUT_LEFT_BOTTOM`
- :cpp:enumerator:`LV_ALIGN_OUT_RIGHT_TOP`
- :cpp:enumerator:`LV_ALIGN_OUT_RIGHT_MID`
- :cpp:enumerator:`LV_ALIGN_OUT_RIGHT_BOTTOM`
Example: to horizontally center a label 10 pixels above a button:
.. code-block:: c
lv_obj_align_to(label, btn, LV_ALIGN_OUT_TOP_MID, 0, -10);
Note that, unlike with :cpp:func:`lv_obj_align`, :cpp:func:`lv_obj_align_to`
does not remember the "anchor point" used, and so will not automatically reposition
the aligned widget if the reference widget later moves.
The following illustration shows the meaning of each "anchor point" mentioned above.
.. image:: /misc/align.png
.. _coord_size:
Size
****
Sizing the simple way
---------------------
The width and the height of a Widget can be set easily as well:
.. code-block:: c
lv_obj_set_width(widget, 200); /* Separate... */
lv_obj_set_height(widget, 100);
lv_obj_set_size(widget, 200, 100); /* Or in one function */
Percentage values are calculated based on the parent's content area
size. For example to set the Widget's height to the screen height:
.. code-block:: c
lv_obj_set_height(widget, lv_pct(100));
The size settings support a special value: :c:macro:`LV_SIZE_CONTENT`. It means
the Widget's size in the respective direction will be set to the size of
its children. Note that only children on the right and bottom sides will
be considered and children on the top and left remain cropped. This
limitation makes the behavior more predictable.
Widgets with :cpp:enumerator:`LV_OBJ_FLAG_HIDDEN` or :cpp:enumerator:`LV_OBJ_FLAG_FLOATING` will be
ignored by the :c:macro:`LV_SIZE_CONTENT` calculation.
The above functions set the size of a Widget's bounding box but the
size of the content area can be set as well. This means a Widget's
bounding box will be enlarged with the addition of padding.
.. code-block:: c
lv_obj_set_content_width(widget, 50); /* The actual width: padding left + 50 + padding right */
lv_obj_set_content_height(widget, 30); /* The actual width: padding top + 30 + padding bottom */
The size of the bounding box and the content area can be retrieved with
the following functions:
.. code-block:: c
int32_t w = lv_obj_get_width(widget);
int32_t h = lv_obj_get_height(widget);
int32_t content_w = lv_obj_get_content_width(widget);
int32_t content_h = lv_obj_get_content_height(widget);
.. _extending_click_area:
Extending the click area
------------------------
By default, Widgets can be clicked only within their bounding area. However,
especially with small Widgets, it can be helpful to make a Widget's "clickable" area
larger. You can do this with :cpp:expr:`lv_obj_set_ext_click_area(widget, size)`.
.. _coord_using_styles:
Using styles
************
Under the hood the position, size and alignment properties are style
properties. The above described "simple functions" hide the style
related code for the sake of simplicity and set the position, size, and
alignment properties in the local styles of the Widget.
However, using styles to set the coordinates has some great advantages:
- It makes it easy to set the width/height/etc. for several Widgets
together. E.g. make all the sliders 100x10 pixels sized.
- It also makes possible to modify the values in one place.
- The values can be partially overwritten by other styles. For example
``style_btn`` makes the Widget ``100x50`` by default but adding
``style_full_width`` overwrites only the width of the Widget.
- The Widget can have different position or size depending on state.
E.g. 100 px wide in :cpp:enumerator:`LV_STATE_DEFAULT` but 120 px
in :cpp:enumerator:`LV_STATE_PRESSED`.
- Style transitions can be used to make the coordinate changes smooth.
Here are some examples to set a Widget's size using a style:
.. code-block:: c
static lv_style_t style;
lv_style_init(&style);
lv_style_set_width(&style, 100);
lv_obj_t * btn = lv_button_create(lv_screen_active());
lv_obj_add_style(btn, &style, LV_PART_MAIN);
As you will see below there are some other great features of size and
position setting. However, to keep the LVGL API lean, only the most
common coordinate setting features have a "simple" version and the more
complex features can be used via styles.
.. _coord_translation:
Translation
***********
Let's say the there are 3 buttons next to each other. Their position is
set as described above. Now you want to move a button up a little when
it's pressed.
One way to achieve this is by setting a new Y coordinate for the pressed
state:
.. code-block:: c
static lv_style_t style_normal;
lv_style_init(&style_normal);
lv_style_set_y(&style_normal, 100);
static lv_style_t style_pressed;
lv_style_init(&style_pressed);
lv_style_set_y(&style_pressed, 80);
lv_obj_add_style(btn1, &style_normal, LV_STATE_DEFAULT);
lv_obj_add_style(btn1, &style_pressed, LV_STATE_PRESSED);
lv_obj_add_style(btn2, &style_normal, LV_STATE_DEFAULT);
lv_obj_add_style(btn2, &style_pressed, LV_STATE_PRESSED);
lv_obj_add_style(btn3, &style_normal, LV_STATE_DEFAULT);
lv_obj_add_style(btn3, &style_pressed, LV_STATE_PRESSED);
This works, but it's not really flexible because the pressed coordinate
is hard-coded. If the buttons are not at y=100, ``style_pressed`` won't
work as expected. Translations can be used to solve this:
.. code-block:: c
static lv_style_t style_normal;
lv_style_init(&style_normal);
lv_style_set_y(&style_normal, 100);
static lv_style_t style_pressed;
lv_style_init(&style_pressed);
lv_style_set_translate_y(&style_pressed, -20);
lv_obj_add_style(btn1, &style_normal, LV_STATE_DEFAULT);
lv_obj_add_style(btn1, &style_pressed, LV_STATE_PRESSED);
lv_obj_add_style(btn2, &style_normal, LV_STATE_DEFAULT);
lv_obj_add_style(btn2, &style_pressed, LV_STATE_PRESSED);
lv_obj_add_style(btn3, &style_normal, LV_STATE_DEFAULT);
lv_obj_add_style(btn3, &style_pressed, LV_STATE_PRESSED);
Translation is applied from the current position of the Widget.
Percentage values can be used in translations as well. The percentage is
relative to the size of the Widget (and not to the size of the parent).
For example :cpp:expr:`lv_pct(50)` will move the Widget with half of its
width/height.
The translation is applied after the layouts are calculated. Therefore,
even laid out Widgets' position can be translated.
The translation actually moves the Widget. That means it makes the
scrollbars and :c:macro:`LV_SIZE_CONTENT` sized Widgets react to the position
change.
.. _coord_transformation:
Transformation
**************
Similarly to position, a Widget's size can be changed relative to the
current size as well. The transformed width and height are added on both
sides of the Widget. This means a 10 px transformed width makes the
Widget 2x10 pixels wider.
Unlike position translation, the size transformation doesn't make the
Widget "really" larger. In other words scrollbars, layouts, and
:c:macro:`LV_SIZE_CONTENT` will not react to the transformed size. Hence, size
transformation is "only" a visual effect.
This code enlarges a button when it's pressed:
.. code-block:: c
static lv_style_t style_pressed;
lv_style_init(&style_pressed);
lv_style_set_transform_width(&style_pressed, 10);
lv_style_set_transform_height(&style_pressed, 10);
lv_obj_add_style(btn, &style_pressed, LV_STATE_PRESSED);
.. _coord_min_max_size:
Min and Max size
----------------
Similarly to CSS, LVGL also supports ``min-width``, ``max-width``,
``min-height`` and ``max-height``. These are limits preventing a
Widget's size from becoming smaller/larger than these values. They are
especially useful if the size is set by percentage or
:c:macro:`LV_SIZE_CONTENT`.
.. code-block:: c
static lv_style_t style_max_height;
lv_style_init(&style_max_height);
lv_style_set_y(&style_max_height, 200);
lv_obj_set_height(widget, lv_pct(100));
lv_obj_add_style(widget, &style_max_height, LV_STATE_DEFAULT); //Limit the height to 200 px
Percentage values can be used as well which are relative to the size of
the parent's content area.
.. code-block:: c
static lv_style_t style_max_height;
lv_style_init(&style_max_height);
lv_style_set_y(&style_max_height, lv_pct(50));
lv_obj_set_height(widget, lv_pct(100));
lv_obj_add_style(widget, &style_max_height, LV_STATE_DEFAULT); //Limit the height to half parent height
.. _coord_layout:
Layout
******
Layout overview
---------------
Layouts can update the position and size of a Widget's children. They
can be used to automatically arrange the children into a line or column,
or in much more complicated forms.
The position and size set by the layout overwrites the "normal" x, y,
width, and height settings.
There is only one function that is the same for every layout:
:cpp:func:`lv_obj_set_layout` ``(widget, <LAYOUT_NAME>)`` sets the layout on a Widget.
For further settings of the parent and children see the documentation of
the given layout.
Built-in layouts
----------------
LVGL comes with two very powerful layouts:
* Flexbox: arrange Widgets into rows or columns, with support for wrapping and expanding items.
* Grid: arrange Widgets into fixed positions in 2D table.
Both are heavily inspired by the CSS layouts with the same name.
Layouts are described in detail in their own section of documentation.
Flags
-----
There are some flags that can be used on Widgets to affect how they
behave with layouts:
- :cpp:enumerator:`LV_OBJ_FLAG_HIDDEN` Hidden Widgets are ignored in layout calculations.
- :cpp:enumerator:`LV_OBJ_FLAG_IGNORE_LAYOUT` The Widget is simply ignored by the layouts. Its coordinates can be set as usual.
- :cpp:enumerator:`LV_OBJ_FLAG_FLOATING` Same as :cpp:enumerator:`LV_OBJ_FLAG_IGNORE_LAYOUT` but the Widget with :cpp:enumerator:`LV_OBJ_FLAG_FLOATING` will be ignored in :c:macro:`LV_SIZE_CONTENT` calculations.
These flags can be added/removed with :cpp:expr:`lv_obj_add_flag(widget, FLAG)` and :cpp:expr:`lv_obj_remove_flag(widget, FLAG)`
Adding new layouts
------------------
LVGL can be freely extended by a custom layout like this:
.. code-block:: c
uint32_t MY_LAYOUT;
...
MY_LAYOUT = lv_layout_register(my_layout_update, &user_data);
...
void my_layout_update(lv_obj_t * widget, void * user_data)
{
/* Will be called automatically if it's required to reposition/resize the children of "obj" */
}
Custom style properties can be added which can be retrieved and used in
the update callback. For example:
.. code-block:: c
uint32_t MY_PROP;
...
LV_STYLE_MY_PROP = lv_style_register_prop();
...
static inline void lv_style_set_my_prop(lv_style_t * style, uint32_t value)
{
lv_style_value_t v = {
.num = (int32_t)value
};
lv_style_set_prop(style, LV_STYLE_MY_PROP, v);
}
.. _coord_example:
Examples
********
.. _coord_api:
API
***

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.. _events:
======
Events
======
Events are triggered in LVGL when something happens which might be
interesting to the user, e.g. when a Widget:
- is clicked
- is scrolled
- has its value changed
- is redrawn, etc.
Besides Widgets, events can registered from displays and input devices as well.
It is not detailed below, but you can do this by changing the prefix of the functions
from ``lv_obj_`` to ``lv_display_`` or ``lv_indev_``.
.. _adding_events_to_a_widget:
Adding Events to a Widget
*************************
The user can assign callback functions to a widget to process events.
In practice, it looks like this:
.. code-block:: c
lv_obj_t * btn = lv_button_create(lv_screen_active());
lv_obj_add_event_cb(btn, my_event_cb, LV_EVENT_CLICKED, user_data); /* Assign an event callback */
...
static void my_event_cb(lv_event_t * event)
{
printf("Clicked\n");
}
In the example :cpp:enumerator:`LV_EVENT_CLICKED` means that only the click event will
call ``my_event_cb``. See the :ref:`list of event codes <events_codes>` for
all the options. :cpp:enumerator:`LV_EVENT_ALL` can be used to receive all events.
The last parameter of :cpp:func:`lv_obj_add_event` is a pointer to any custom
data that will be available in the event. NULL may be passed for this argument if
there is no need to use that data when the event is processed. You can retrieve the
pointer passed when setting the callback function like this:
.. code-block:: c
my_user_data_t * user_data;
...
user_data = lv_event_get_user_data(e);
More events can be added to a Widget, like this:
.. code-block:: c
lv_obj_add_event_cb(widget, my_event_cb_1, LV_EVENT_CLICKED, NULL);
lv_obj_add_event_cb(widget, my_event_cb_2, LV_EVENT_PRESSED, NULL);
lv_obj_add_event_cb(widget, my_event_cb_3, LV_EVENT_ALL, NULL); /* No filtering, receive all events */
Even the same event callback can be used on a Widget with different
``user_data``. For example:
.. code-block:: c
lv_obj_add_event_cb(widget, increment_on_click, LV_EVENT_CLICKED, &num1);
lv_obj_add_event_cb(widget, increment_on_click, LV_EVENT_CLICKED, &num2);
The events will be called in the order as they were added.
Other Widgets can use the same *event callback*.
In the very same way, events can be attached to input devices and displays like this:
.. code-block:: c
lv_display_add_event_cb(disp, event_cb, LV_EVENT_RESOLUTION_CHANGED, NULL);
lv_indev_add_event_cb(indev, event_cb, LV_EVENT_CLICKED, NULL);
Removing Event(s) from Widgets
******************************
.. code-block:: c
uint32_t i;
uint32_t event_cnt = lv_obj_get_event_count(widget);
for(i = 0; i < event_cnt; i++) {
lv_event_dsc_t * event_dsc = lv_obj_get_event_dsc(widget, i);
if(lv_event_dsc_get_cb(event_dsc) == some_event_cb) {
lv_obj_remove_event(widget, i);
break;
}
}
.. _events_codes:
Event Codes
***********
The event codes can be grouped into these categories: - Input device
events - Drawing events - Other events - Special events - Custom events
All Widgets (such as Buttons/Labels/Sliders etc.) regardless their type
receive the *Input device*, *Drawing* and *Other* events.
However, the *Special events* are specific to a particular widget type.
See the :ref:`widgets' documentation <widgets>` to learn when they
are sent,
*Custom events* are added by the user and are never sent by LVGL.
The following event codes exist:
Input Device Events
-------------------
- :cpp:enumerator:`LV_EVENT_PRESSED`: Widget has been pressed
- :cpp:enumerator:`LV_EVENT_PRESSING`: Widget is being pressed (called continuously while pressing)
- :cpp:enumerator:`LV_EVENT_PRESS_LOST`: Widget is still being pressed but slid cursor/finger off Widget
- :cpp:enumerator:`LV_EVENT_SHORT_CLICKED`: Widget was pressed for a short period of time, and then released without scrolling.
- :cpp:enumerator:`LV_EVENT_SINGLE_CLICKED`: Widget was pressed for a short period of time, and then released without scrolling, for the first time in a click streak. A click streak refers to multiple short clicks within a short period of time and a small distance.
- :cpp:enumerator:`LV_EVENT_DOUBLE_CLICKED`: Widget was pressed for a short period of time, and then released without scrolling, for the second time in a click streak.
- :cpp:enumerator:`LV_EVENT_TRIPLE_CLICKED`: Widget was pressed for a short period of time, and then released without scrolling, for the third time in a click streak.
- :cpp:enumerator:`LV_EVENT_LONG_PRESSED`: Widget has been pressed for at least `long_press_time`. Not called if scrolled.
- :cpp:enumerator:`LV_EVENT_LONG_PRESSED_REPEAT`: Called after `long_press_time` in every `long_press_repeat_time` ms. Not called if scrolled.
- :cpp:enumerator:`LV_EVENT_CLICKED`: Called on release if not scrolled (regardless of long press)
- :cpp:enumerator:`LV_EVENT_RELEASED`: Called in every cases when Widget has been released
- :cpp:enumerator:`LV_EVENT_SCROLL_BEGIN`: Scrolling begins. The event parameter is a pointer to the animation of the scroll. Can be modified
- :cpp:enumerator:`LV_EVENT_SCROLL_THROW_BEGIN`:
- :cpp:enumerator:`LV_EVENT_SCROLL_END`: Scrolling ends
- :cpp:enumerator:`LV_EVENT_SCROLL`: Scrolling
- :cpp:enumerator:`LV_EVENT_GESTURE`: A gesture is detected. Get the gesture with :cpp:expr:`lv_indev_get_gesture_dir(lv_indev_active())`
- :cpp:enumerator:`LV_EVENT_KEY`: A key is sent to Widget. Get the key with :cpp:expr:`lv_indev_get_key(lv_indev_active())`
- :cpp:enumerator:`LV_EVENT_FOCUSED`: Widget received focus
- :cpp:enumerator:`LV_EVENT_DEFOCUSED`: Widget is defocused
- :cpp:enumerator:`LV_EVENT_LEAVE`: Widget is defocused but still selected
- :cpp:enumerator:`LV_EVENT_HIT_TEST`: Perform advanced hit-testing
- :cpp:enumerator:`LV_EVENT_INDEV_RESET`: Indev has been reset
- :cpp:enumerator:`LV_EVENT_HOVER_OVER`: Indev hover over Widget
- :cpp:enumerator:`LV_EVENT_HOVER_LEAVE`: Indev hover leave Widget
Drawing Events
--------------
- :cpp:enumerator:`LV_EVENT_COVER_CHECK`: Check if Widget fully covers an area. The event parameter is :cpp:type:`lv_cover_check_info_t` ``*``.
- :cpp:enumerator:`LV_EVENT_REFR_EXT_DRAW_SIZE`: Get the required extra draw area around Widget (e.g. for shadow). The event parameter is :cpp:type:`int32_t` ``*`` to store the size.
- :cpp:enumerator:`LV_EVENT_DRAW_MAIN_BEGIN`: Starting the main drawing phase
- :cpp:enumerator:`LV_EVENT_DRAW_MAIN`: Perform the main drawing
- :cpp:enumerator:`LV_EVENT_DRAW_MAIN_END`: Finishing the main drawing phase
- :cpp:enumerator:`LV_EVENT_DRAW_POST_BEGIN`: Starting the post draw phase (when all children are drawn)
- :cpp:enumerator:`LV_EVENT_DRAW_POST`: Perform the post draw phase (when all children are drawn)
- :cpp:enumerator:`LV_EVENT_DRAW_POST_END`: Finishing the post draw phase (when all children are drawn)
- :cpp:enumerator:`LV_EVENT_DRAW_TASK_ADDED`: Adding a draw task
Special Events
--------------
- :cpp:enumerator:`LV_EVENT_VALUE_CHANGED`: Widget's value has changed (i.e. slider moved)
- :cpp:enumerator:`LV_EVENT_INSERT`: A text is inserted to Widget. The event data is ``char `*`` being inserted.
- :cpp:enumerator:`LV_EVENT_REFRESH`: Notify Widget to refresh something on it (for the user)
- :cpp:enumerator:`LV_EVENT_READY`: A process has finished
- :cpp:enumerator:`LV_EVENT_CANCEL`: A process has been cancelled
Other Events
------------
- :cpp:enumerator:`LV_EVENT_CREATE`: Widget is being created
- :cpp:enumerator:`LV_EVENT_DELETE`: Widget is being deleted
- :cpp:enumerator:`LV_EVENT_CHILD_CHANGED`: Child was removed, added, or its size, position were changed
- :cpp:enumerator:`LV_EVENT_CHILD_CREATED`: Child was created, always bubbles up to all parents
- :cpp:enumerator:`LV_EVENT_CHILD_DELETED`: Child was deleted, always bubbles up to all parents
- :cpp:enumerator:`LV_EVENT_SCREEN_UNLOAD_START`: A screen unload started, fired immediately when scr_load is called
- :cpp:enumerator:`LV_EVENT_SCREEN_LOAD_START`: A screen load started, fired when the screen change delay is expired
- :cpp:enumerator:`LV_EVENT_SCREEN_LOADED`: A screen was loaded
- :cpp:enumerator:`LV_EVENT_SCREEN_UNLOADED`: A screen was unloaded
- :cpp:enumerator:`LV_EVENT_SIZE_CHANGED`: Widget coordinates/size have changed
- :cpp:enumerator:`LV_EVENT_STYLE_CHANGED`: Widget's style has changed
- :cpp:enumerator:`LV_EVENT_LAYOUT_CHANGED`: The children position has changed due to a layout recalculation
- :cpp:enumerator:`LV_EVENT_GET_SELF_SIZE`: Get the internal size of a widget
Display Events
--------------
- :cpp:enumerator:`LV_EVENT_INVALIDATE_AREA`
- :cpp:enumerator:`LV_EVENT_RESOLUTION_CHANGED`
- :cpp:enumerator:`LV_EVENT_COLOR_FORMAT_CHANGED`
- :cpp:enumerator:`LV_EVENT_REFR_REQUEST`
- :cpp:enumerator:`LV_EVENT_REFR_START`
- :cpp:enumerator:`LV_EVENT_REFR_READY`
- :cpp:enumerator:`LV_EVENT_RENDER_START`
- :cpp:enumerator:`LV_EVENT_RENDER_READY`
- :cpp:enumerator:`LV_EVENT_FLUSH_START`
- :cpp:enumerator:`LV_EVENT_FLUSH_FINISH`
Custom Events
-------------
Any number of custom event codes can be registered by
``uint32_t MY_EVENT_1 =`` :cpp:func:`lv_event_register_id`
They can be sent to any Widget with
:cpp:expr:`lv_obj_send_event(widget, MY_EVENT_1, &some_data)`
Refresh Event
-------------
:cpp:enumerator:`LV_EVENT_REFRESH` is a special event because it's designed to let the
user notify a Widget to refresh itself. Some examples:
- notify a label to refresh its text according to one or more variables (e.g. current time)
- refresh a label when the language changes
- enable a button if some conditions are met (e.g. the correct PIN is entered)
- add/remove styles to/from a Widget if a limit is exceeded, etc
Sending Events Manually
***********************
To manually send events to a Widget, use
``lv_obj_send_event(widget, <EVENT_CODE>, &some_data)``.
For example, this can be used to manually close a message box by
simulating a button press (although there are simpler ways to do this):
.. code-block:: c
/* Simulate the press of the first button (indexes start from zero) */
uint32_t btn_id = 0;
lv_obj_send_event(mbox, LV_EVENT_VALUE_CHANGED, &btn_id);
The same works for display and input devices with
``lv_display_send_event(widget, <EVENT_CODE>, &some_data)`` and
``lv_indev_send_event(widget, <EVENT_CODE>, &some_data)``.
Fields of lv_event_t
********************
:cpp:type:`lv_event_t` is the only parameter passed to the event callback and it
contains all data about the event. The following values can be gotten from it:
- :cpp:expr:`lv_event_get_code(e)`: get the event code
- :cpp:expr:`lv_event_get_current_target(e)`: get Widget to which an event was sent. I.e. the Widget whose event handler is being called.
- :cpp:expr:`lv_event_get_target(e)`: get Widget that originally triggered the event (different from :cpp:func:`lv_event_get_target` if :ref:`event bubbling <event_bubbling>` is enabled)
- :cpp:expr:`lv_event_get_user_data(e)`: get the pointer passed as the last parameter of :cpp:func:`lv_obj_add_event`.
- :cpp:expr:`lv_event_get_param(e)`: get the parameter passed as the last parameter of :cpp:func:`lv_obj_send_event`
.. _event_bubbling:
Event Bubbling
**************
If :cpp:expr:`lv_obj_add_flag(widget, LV_OBJ_FLAG_EVENT_BUBBLE)` is enabled all
events will be sent to a Widget's parent as well. If the parent also has
:cpp:enumerator:`LV_OBJ_FLAG_EVENT_BUBBLE` enabled the event will be sent to its
parent, and so on.
The *target* parameter of the event is always the current target Widget,
not the original Widget. To get the original target call
:cpp:expr:`lv_event_get_target_obj(e)` in the event handler.
.. _events_examples:
Examples
********
.. include:: ../../examples/event/index.rst
.. _events_api:
API
***

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.. _base_widget_overview:
===========
Base Widget
===========
The following details apply to all types of Widgets.
.. toctree::
:maxdepth: 3
obj
coord
layer
styles/index
event
layouts/index
scroll

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.. _layers:
======
Layers
======
When the term "layer" is used in LVGL documentation, it may refer to one of several
things:
1. for Widgets, the :ref:`layers_creation` creates a natural layering of Widgets;
2. in the context of pixel rendering (drawing), there are :ref:`draw_layers`;
3. permanent :ref:`screen_layers` are part of each :ref:`display` object, and
are covered :ref:`here <screen_layers>`
#1 and #2 are covered below.
.. _layers_creation:
Order of Creation
*****************
By default, LVGL draws new Widgets on top of old Widgets.
For example, assume we add a button to a parent Widget named button1 and
then another button named button2. Then button1 (along with its child
Widget(s)) will be in the background and can be covered by button2 and
its children.
.. image:: /misc/layers.png
.. code-block:: c
/* Create a screen */
lv_obj_t * scr = lv_obj_create(NULL, NULL);
lv_screen_load(scr); /* Load the screen */
/* Create 2 buttons */
lv_obj_t * btn1 = lv_button_create(scr, NULL); /* Create a button on the screen */
lv_button_set_fit(btn1, true, true); /* Enable automatically setting the size according to content */
lv_obj_set_pos(btn1, 60, 40); /* Set the position of the button */
lv_obj_t * btn2 = lv_button_create(scr, btn1); /* Copy the first button */
lv_obj_set_pos(btn2, 180, 80); /* Set the position of the button */
/* Add labels to the buttons */
lv_obj_t * label1 = lv_label_create(btn1, NULL); /* Create a label on the first button */
lv_label_set_text(label1, "Button 1"); /* Set the text of the label */
lv_obj_t * label2 = lv_label_create(btn2, NULL); /* Create a label on the second button */
lv_label_set_text(label2, "Button 2"); /* Set the text of the label */
/* Delete the second label */
lv_obj_delete(label2);
.. _layers_order:
Changing Order
--------------
There are four explicit ways to bring a Widget to the foreground:
- Use :cpp:expr:`lv_obj_move_foreground(widget)` to bring a Widget to the foreground.
Similarly, use :cpp:expr:`lv_obj_move_background(widget)` to move it to the background.
- Use :cpp:expr:`lv_obj_move_to_index(widget, idx)` to move a Widget to a given index in the order of children.
- ``0``: background
- ``child_num - 1``: foreground
- ``< 0``: count from the top, to move forward (up): :cpp:expr:`lv_obj_move_to_index(widget, lv_obj_get_index(widget) - 1)`
- Use :cpp:expr:`lv_obj_swap(widget1, widget2)` to swap the relative layer position of two Widgets.
- When :cpp:expr:`lv_obj_set_parent(widget, new_parent)` is used, ``widget`` will be on the foreground of ``new_parent``.
.. _draw_layers:
Draw Layers
***********
Some style properties cause LVGL to allocate a buffer and render a Widget and its
children there first. Later that layer will be merged to the screen or its parent
layer after applying some transformations or other modifications.
Simple Layer
------------
The following style properties trigger the creation of a "Simple Layer":
- ``opa_layered``
- ``bitmap_mask_src``
- ``blend_mode``
In this case the Widget will be sliced into ``LV_DRAW_SW_LAYER_SIMPLE_BUF_SIZE``
sized chunks.
If there is no memory for a new chunk, LVGL will try allocating the layer after
another chunk is rendered and freed.
Transformed Layer
-----------------
When the widget is transformed a larger part of the Widget needs to rendered to
provide enough data for transformation. LVGL tries to render as small area of the
widget as possible, but due to the nature of transformations no slicing is possible
in this case.
The following style properties trigger the creation of a "Transform Layer":
- ``transform_scale_x``
- ``transform_scale_y``
- ``transform_skew_x``
- ``transform_skew_y``
- ``transform_rotate``
Clip corner
-----------
The ``clip_corner`` style property also causes LVGL to create a 2 layers with radius
height for the top and bottom parts of the Widget.
.. _layers_api:
API
***

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.. _flex:
====
Flex
====
Overview
********
The Flexbox (or Flex for short) is a subset of `CSS Flexbox <https://css-tricks.com/snippets/css/a-guide-to-flexbox/>`__.
It can arrange items into rows or columns (tracks), handle wrapping,
adjust the spacing between the items and tracks, handle *grow* to make
the item(s) fill the remaining space with respect to min/max width and
height.
To make a Widget flex container call
:cpp:expr:`lv_obj_set_layout(widget, LV_LAYOUT_FLEX)`.
Note that the flex layout feature of LVGL needs to be globally enabled
with :c:macro:`LV_USE_FLEX` in ``lv_conf.h``.
Terms
*****
- **tracks**: the rows or columns
- **main direction**: row or column, the direction in which the items are
placed
- **cross direction**: perpendicular to the main direction
- **wrap**: if there is no more space in the track a new track is started
- **grow**: if set on an item it will grow to fill the remaining space on
the track. The available space will be distributed among items
respective to their grow value (larger value means more space)
- **gap**: the space between the rows and columns or the items on a track
Simple interface
****************
With the following functions you can set a Flex layout on any parent.
.. _flex_flow:
Flex flow
---------
:cpp:expr:`lv_obj_set_flex_flow(widget, flex_flow)`
The possible values for ``flex_flow`` are:
- :cpp:enumerator:`LV_FLEX_FLOW_ROW`: Place the children in a row without wrapping
- :cpp:enumerator:`LV_FLEX_FLOW_COLUMN`: Place the children in a column without wrapping
- :cpp:enumerator:`LV_FLEX_FLOW_ROW_WRAP`: Place the children in a row with wrapping
- :cpp:enumerator:`LV_FLEX_FLOW_COLUMN_WRAP`: Place the children in a column with wrapping
- :cpp:enumerator:`LV_FLEX_FLOW_ROW_REVERSE`: Place the children in a row without wrapping but in reversed order
- :cpp:enumerator:`LV_FLEX_FLOW_COLUMN_REVERSE`: Place the children in a column without wrapping but in reversed order
- :cpp:enumerator:`LV_FLEX_FLOW_ROW_WRAP_REVERSE`: Place the children in a row with wrapping but in reversed order
- :cpp:enumerator:`LV_FLEX_FLOW_COLUMN_WRAP_REVERSE`: Place the children in a column with wrapping but in reversed order
.. _flex_align:
Flex align
----------
To manage the placement of the children use
:cpp:expr:`lv_obj_set_flex_align(widget, main_place, cross_place, track_cross_place)`
- ``main_place`` determines how to distribute the items in their track
on the main axis. E.g. flush the items to the right on :cpp:enumerator:`LV_FLEX_FLOW_ROW_WRAP`. (It's called
``justify-content`` in CSS)
- ``cross_place`` determines how to distribute the items in their track
on the cross axis. E.g. if the items have different height place them
to the bottom of the track. (It's called ``align-items`` in CSS)
- ``track_cross_place`` determines how to distribute the tracks (It's
called ``align-content`` in CSS)
The possible values are:
- :cpp:enumerator:`LV_FLEX_ALIGN_START`: means left on a horizontally and top vertically (default)
- :cpp:enumerator:`LV_FLEX_ALIGN_END`: means right on a horizontally and bottom vertically
- :cpp:enumerator:`LV_FLEX_ALIGN_CENTER`: simply center
- :cpp:enumerator:`LV_FLEX_ALIGN_SPACE_EVENLY`: items are distributed so
that the spacing between any two items (and the space to the edges) is
equal. Does not apply to ``track_cross_place``.
- :cpp:enumerator:`LV_FLEX_ALIGN_SPACE_AROUND`: items are evenly
distributed in the track with equal space around them. Note that
visually the spaces aren't equal, since all the items have equal space
on both sides. The first item will have one unit of space against the
container edge, but two units of space between the next item because
that next item has its own spacing that applies. Not applies to
``track_cross_place``.
- :cpp:enumerator:`LV_FLEX_ALIGN_SPACE_BETWEEN`: items are evenly distributed in
the track: first item is on the start line, last item on the end line. Not applies to ``track_cross_place``.
.. _flex_grow:
Flex grow
---------
Flex grow can be used to make one or more children fill the available
space on the track. When more children have grow parameters, the
available space will be distributed proportionally to the grow values.
For example, there is 400 px remaining space and 4 Widgets with grow:
- ``A`` with grow = 1
- ``B`` with grow = 1
- ``C`` with grow = 2
``A`` and ``B`` will have 100 px size, and ``C`` will have 200 px size.
Flex grow can be set on a child with
:cpp:expr:`lv_obj_set_flex_grow(child, value)`. ``value`` needs to be >
1 or 0 to disable grow on the child.
.. _flex_style:
Style interface
***************
All the Flex-related values are style properties under the hood and you
can use them similarly to any other style property.
The following flex related style properties exist:
- :cpp:enumerator:`FLEX_FLOW`
- :cpp:enumerator:`FLEX_MAIN_PLACE`
- :cpp:enumerator:`FLEX_CROSS_PLACE`
- :cpp:enumerator:`FLEX_TRACK_PLACE`
- :cpp:enumerator:`FLEX_GROW`
.. _flex_padding:
Internal padding
----------------
To modify the minimum space flexbox inserts between Widgets, the
following properties can be set on the flex container style:
- ``pad_row`` Sets the padding between the rows.
- ``pad_column`` Sets the padding between the columns.
These can for example be used if you don't want any padding between your
Widgets: :cpp:expr:`lv_style_set_pad_column(&row_container_style,0)`
.. _flex_other:
Other features
**************
RTL
---
If the base direction of the container is set the
:cpp:enumerator:`LV_BASE_DIR_RTL` the meaning of
:cpp:enumerator:`LV_FLEX_ALIGN_START` and
:cpp:enumerator:`LV_FLEX_ALIGN_END` is swapped on ``ROW`` layouts. I.e.
``START`` will mean right.
The items on ``ROW`` layouts, and tracks of ``COLUMN`` layouts will be
placed from right to left.
New track
---------
You can force Flex to put an item into a new line with
:cpp:expr:`lv_obj_add_flag(child, LV_OBJ_FLAG_FLEX_IN_NEW_TRACK)`.
.. _flex_example:
Example
*******
.. include:: ../../../examples/layouts/flex/index.rst
.. _flex_api:
API
***

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.. _grid:
====
Grid
====
Overview
********
The Grid layout is a subset of `CSS Grid <https://css-tricks.com/snippets/css/complete-guide-grid/>`__.
It can arrange items into a 2D "table" that has rows or columns
(tracks). The item can span through multiple columns or rows. The
track's size can be set in pixel, to the largest item
(:c:macro:`LV_GRID_CONTENT`) or in "Free unit" (FR) to distribute the free
space proportionally.
To make a Widget a grid container call :cpp:expr:`lv_obj_set_layout(widget, LV_LAYOUT_GRID)`.
Note that the grid layout feature of LVGL needs to be globally enabled
with :c:macro:`LV_USE_GRID` in ``lv_conf.h``.
Terms
*****
- **tracks**: the rows or columns
- **free unit (FR)**: if set on track's size is set in ``FR`` it will grow
to fill the remaining space on the parent.
- **gap**: the space between the rows and columns or the items on a track
Simple interface
****************
With the following functions you can easily set a Grid layout on any
parent.
.. _grid_descriptors:
Grid descriptors
----------------
First you need to describe the size of rows and columns. It can be done
by declaring 2 arrays and the track sizes in them. The last element must
be :c:macro:`LV_GRID_TEMPLATE_LAST`.
For example:
.. code-block:: c
static int32_t column_dsc[] = {100, 400, LV_GRID_TEMPLATE_LAST}; /* 2 columns with 100 and 400 ps width */
static int32_t row_dsc[] = {100, 100, 100, LV_GRID_TEMPLATE_LAST}; /* 3 100 px tall rows */
To set the descriptors on a parent use
:cpp:expr:`lv_obj_set_grid_dsc_array(widget, col_dsc, row_dsc)`.
Besides simple settings the size in pixel you can use two special
values:
- :c:macro:`LV_GRID_CONTENT` set the size to fit the largest child on this track
- :cpp:expr:`LV_GRID_FR(X)` tell what portion of the remaining space
should be used by this track. Larger value means larger space.
.. _grid_items:
Grid items
----------
By default, the children are not added to the grid. They need to be
added manually to a cell.
To do this call
:cpp:expr:`lv_obj_set_grid_cell(child, column_align, column_pos, column_span, row_align, row_pos, row_span)`.
``column_align`` and ``row_align`` determine how to align the children
in its cell. The possible values are:
- :cpp:enumerator:`LV_GRID_ALIGN_START`: means left on a horizontally and top vertically (default)
- :cpp:enumerator:`LV_GRID_ALIGN_END`: means right on a horizontally and bottom vertically
- :cpp:enumerator:`LV_GRID_ALIGN_CENTER`: simply center ``column_pos`` and ``row_pos``
means the zero based index of the cell into the item should be placed.
``column_span`` and ``row_span`` means how many tracks should the item
involve from the start cell. Must be ``>= 1``.
.. _grid_align:
Grid align
----------
If there are some empty space the track can be aligned several ways:
- :cpp:enumerator:`LV_GRID_ALIGN_START`: means left on a horizontally and top vertically. (default)
- :cpp:enumerator:`LV_GRID_ALIGN_END`: means right on a horizontally and bottom vertically
- :cpp:enumerator:`LV_GRID_ALIGN_CENTER`: simply center
- :cpp:enumerator:`LV_GRID_ALIGN_SPACE_EVENLY`: items are distributed so that the spacing
between any two items (and the space to the edges) is equal. Not applies to ``track_cross_place``.
- :cpp:enumerator:`LV_GRID_ALIGN_SPACE_AROUND`: items are
evenly distributed in the track with equal space around them. Note that
visually the spaces aren't equal, since all the items have equal space
on both sides. The first item will have one unit of space against the
container edge, but two units of space between the next item because
that next item has its own spacing that applies. Not applies to ``track_cross_place``.
- :cpp:enumerator:`LV_GRID_ALIGN_SPACE_BETWEEN`: items are
evenly distributed in the track: first item is on the start line, last
item on the end line. Not applies to ``track_cross_place``.
To set the track's alignment use
:cpp:expr:`lv_obj_set_grid_align(widget, column_align, row_align)`.
.. _grid_subgrid:
Sub grid
--------
If you set the column and/or row grid descriptors of a widget to ``NULL`` it will use the grid descriptor(s) from it's parent.
For example if you create a grid item on 2..6 columns and 1..3 rows of the parent,
the grid item will see 5 columns and 4 rows with the corresponding track size from the parent.
This way even if a wrapper item is used on the grid and can be made "transparent" from the grid's point of view.
Limitations:
- The sub grid is resolved only in one level depth. That is a grid can have a sub grid children, but a sub grid can't have another sub grid.
- ``LV_GRID_CONTENT`` tracks on the are not handled in the sub grid, only in the its own grid.
The sub grid feature works the same as in CSS. For further reference see `this description <https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_grid_layout/Subgrid>`__.
.. _grid_style:
Style interface
***************
All the Grid related values are style properties under the hood and you
can use them similarly to any other style properties.
The following Grid related style properties exist:
- :cpp:enumerator:`GRID_COLUMN_DSC_ARRAY`
- :cpp:enumerator:`GRID_ROW_DSC_ARRAY`
- :cpp:enumerator:`GRID_COLUMN_ALIGN`
- :cpp:enumerator:`GRID_ROW_ALIGN`
- :cpp:enumerator:`GRID_CELL_X_ALIGN`
- :cpp:enumerator:`GRID_CELL_COLUMN_POS`
- :cpp:enumerator:`GRID_CELL_COLUMN_SPAN`
- :cpp:enumerator:`GRID_CELL_Y_ALIGN`
- :cpp:enumerator:`GRID_CELL_ROW_POS`
- :cpp:enumerator:`GRID_CELL_ROW_SPAN`
.. _grid_padding:
Internal padding
----------------
To modify the minimum space Grid inserts between Widgets, the following
properties can be set on the Grid container style:
- ``pad_row`` Sets the padding between the rows.
- ``pad_column`` Sets the padding between the columns.
.. _grid_other:
Other features
**************
RTL
---
If the base direction of the container is set to :cpp:enumerator:`LV_BASE_DIR_RTL`,
the meaning of :cpp:enumerator:`LV_GRID_ALIGN_START` and :cpp:enumerator:`LV_GRID_ALIGN_END` is
swapped. I.e. ``START`` will mean right-most.
The columns will be placed from right to left.
.. _grid_examples:
Example
*******
.. include:: ../../../examples/layouts/grid/index.rst
.. _grid_api:
API
***

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.. _layouts:
=======
Layouts
=======
.. toctree::
:maxdepth: 2
flex
grid

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.. _widget_basics:
=============
Widget Basics
=============
What is a Widget?
*****************
A Widget is the **basic building block** of the LVGL user interface.
Examples of Widgets: :ref:`Base Widget (and Screen) <base_widget>`,
:ref:`Button <lv_button>`, :ref:`Label <lv_label>`,
:ref:`Image <lv_image>`, :ref:`List <lv_list>`,
:ref:`Chart <lv_chart>` and :ref:`Text Area <lv_textarea>`.
See :ref:`widgets` to see all Widget types.
All Widgets are referenced using an :cpp:type:`lv_obj_t` pointer as a handle.
This pointer can later be used to read or change the Widget's attributes.
.. _base_widget:
Base Widget
***********
The most fundamental of all Widgets is the Base Widget, on which all other widgets
are based. From an Object-Oriented perspective, think of the Base Widget as the
Widget class from which all other Widgets inherit.
The functions and functionalities of the Base Widget can be used with
other widgets as well. For example :cpp:expr:`lv_obj_set_width(slider, 100)`.
The Base Widget can be used directly as a simple widget. While it is a simple
rectangle, it has a large number of features shared with all Widgets, detailed
below and in subsequent pages. In HTML terms, think of it as a ``<div>``.
.. _widget_attributes:
Attributes
**********
Basic attributes
----------------
All Widget types share some basic attributes:
- Position
- Size
- Parent
- Styles
- Events it emits
- Flags like *Clickable*, *Scollable*, etc.
- Etc.
You can set/get these attributes with ``lv_obj_set_...`` and
``lv_obj_get_...`` functions. For example:
.. code-block:: c
/* Set basic Widget attributes */
lv_obj_set_size(btn1, 100, 50); /* Set a button's size */
lv_obj_set_pos(btn1, 20,30); /* Set a button's position */
For complete details on position, size, coordinates and layouts, see :ref:`coord`.
Widget-specific attributes
--------------------------
The Widget types have special attributes as well. For example, a slider has
- Minimum and maximum values
- Current value
For these special attributes, every Widget type may have unique API
functions. For example for a slider:
.. code-block:: c
/* Set slider specific attributes */
lv_slider_set_range(slider1, 0, 100); /* Set the min. and max. values */
lv_slider_set_value(slider1, 40, LV_ANIM_ON); /* Set the current value (position) */
The API of the widgets is described in their
:ref:`Documentation <widgets>` but you can also check the respective
header files (e.g. *widgets/lv_slider.h*)
.. _lv_obj_parents_and_children:
Parents and children
--------------------
A Widget's parent is set when the widget is created --- the parent is passed to the
creation function.
To get a Widget's current parent, use :cpp:expr:`lv_obj_get_parent(widget)`.
You can move the Widget to a new parent with :cpp:expr:`lv_obj_set_parent(widget, new_parent)`.
To get a specific child of a parent use :cpp:expr:`lv_obj_get_child(parent, idx)`.
Some examples for ``idx``:
- ``0`` get the child created first
- ``1`` get the child created second
- ``-1`` get the child created last
You can iterate through a parent Widget's children like this:
.. code-block:: c
uint32_t i;
for(i = 0; i < lv_obj_get_child_count(parent); i++) {
lv_obj_t * child = lv_obj_get_child(parent, i);
/* Do something with child. */
}
:cpp:expr:`lv_obj_get_index(widget)` returns the index of the Widget in its parent.
It is equivalent to the number of older children in the parent.
You can bring a Widget to the foreground or send it to the background with
:cpp:expr:`lv_obj_move_foreground(widget)` and :cpp:expr:`lv_obj_move_background(widget)`.
You can change the index of a Widget in its parent using :cpp:expr:`lv_obj_move_to_index(widget, index)`.
You can swap the position of two Widgets with :cpp:expr:`lv_obj_swap(widget1, widget2)`.
To get a Widget's Screen (highest-level parent) use :cpp:expr:`lv_obj_get_screen(widget)`.
.. _widget_working_mechanisms:
Working Mechanisms
******************
Parent-child structure
----------------------
A parent Widget can be considered as the container of its children. Every Widget has
exactly one parent Widget (except Screens), but a parent Widget can have any number
of children. There is no limitation for the type of the parent but there are Widgets
which are typically a parent (e.g. button) or a child (e.g. label).
Moving together
---------------
If the position of a parent changes, the children will move along with
it. Therefore, all positions are relative to the parent.
.. image:: /misc/par_child1.png
.. code-block:: c
lv_obj_t * parent = lv_obj_create(lv_screen_active()); /* Create a parent Widget on current screen */
lv_obj_set_size(parent, 100, 80); /* Set size of parent */
lv_obj_t * obj1 = lv_obj_create(parent); /* Create a Widget on previously created parent Widget */
lv_obj_set_pos(widget1, 10, 10); /* Set position of new Widget */
Modify the position of the parent:
.. image:: /misc/par_child2.png
.. code-block:: c
lv_obj_set_pos(parent, 50, 50); /* Move the parent. The child will move with it. */
(For simplicity the adjusting of colors of the Widgets is not shown in
the example.)
Visibility only on the parent
-----------------------------
If a child is partially or fully outside its parent then the parts
outside will not be visible.
.. image:: /misc/par_child3.png
.. code-block:: c
lv_obj_set_x(widget1, -30); /* Move the child a little bit off the parent */
This behavior can be overwritten with
:cpp:expr:`lv_obj_add_flag(widget, LV_OBJ_FLAG_OVERFLOW_VISIBLE)` which allow the
children to be drawn out of the parent.
Create and delete Widgets
-------------------------
In LVGL, Widgets can be created and deleted dynamically at run time. It
means only the currently created (existing) Widgets consume RAM.
This allows for the creation of a screen just when a button is clicked
to open it, and for deletion of screens when a new screen is loaded.
UIs can be created based on the current environment of the device. For
example one can create meters, charts, bars and sliders based on the
currently attached sensors.
Every widget has its own **create** function with a prototype like this:
.. code-block:: c
lv_obj_t * lv_<widget>_create(lv_obj_t * parent, <other parameters if any>);
Typically, the create functions only have a ``parent`` parameter telling
them on which Widget to create the new Widget.
The return value is a pointer to the created Widget with :cpp:type:`lv_obj_t` ``*``
type.
There is a common **delete** function for all Widget types. It deletes
the Widget and all of its children.
.. code-block:: c
void lv_obj_delete(lv_obj_t * widget);
:cpp:func:`lv_obj_delete` will delete the Widget immediately. If for any reason you
can't delete the Widget immediately you can use
:cpp:expr:`lv_obj_delete_async(widget)` which will perform the deletion on the next
call of :cpp:func:`lv_timer_handler`. This is useful e.g. if you want to
delete the parent of a Widget in the child's :cpp:enumerator:`LV_EVENT_DELETE`
handler.
You can remove all the children of a Widget (but not the Widget itself)
using :cpp:expr:`lv_obj_clean(widget)`.
You can use :cpp:expr:`lv_obj_delete_delayed(widget, 1000)` to delete a Widget after
some time. The delay is expressed in milliseconds.
Sometimes you're not sure whether a Widget was deleted and you need some way to
check if it's still "alive". Anytime before the Widget is deleted, you can use
cpp:expr:`lv_obj_null_on_delete(&widget)` to cause your Widget pointer to be set to ``NULL``
when the Widget is deleted.
Make sure the pointer variable itself stays valid until the Widget is deleted. Here
is an example:
.. code:: c
void some_timer_callback(lv_timer_t * t)
{
static lv_obj_t * my_label;
if(my_label == NULL) {
my_label = lv_label_create(lv_screen_active());
lv_obj_delete_delayed(my_label, 1000);
lv_obj_null_on_delete(&my_label);
}
else {
lv_obj_set_x(my_label, lv_obj_get_x(my_label) + 1);
}
}
.. _screens:
Screens
*******
What are Screens?
-----------------
Not to be confused with a :ref:`display`, Screens are simply any Widget created
without a parent (i.e. passing NULL for the ``parent`` argument during creation). As
such, they form the "root" of a Widget Tree.
Normally the Base Widget is used for this purpose since it has all the features most
Screens need. But an :ref:`lv_image` Widget can also be used to create a wallpaper
background for the Widget Tree.
All Screens:
- are automatically attached to the :ref:`default_display` current when the Screen
was created;
- automatically occupy the full area of the associated display;
- cannot be moved, i.e. functions such as :cpp:func:`lv_obj_set_pos` and
:cpp:func:`lv_obj_set_size` cannot be used on screens.
Each :ref:`display` object can have multiple screens associated with it, but not vice
versa. Thus the relationship::
Display
|
--- (one or more)
/|\
Screen Widgets (root of a Widget Tree)
|
O (zero or more)
/|\
Child Widgets
Creating Screens
----------------
Screens are created like this:
.. code-block:: c
lv_obj_t * scr1 = lv_obj_create(NULL);
Screens can be deleted with :cpp:expr:`lv_obj_delete(scr)`, but be sure you do not
delete the :ref:`active_screen`.
.. _active_screen:
Active Screen
-------------
While each :ref:`display` object can have any number of Screens Widgets associated
with it, only one of those Screens is considered "Active" at any given time. That
Screen is referred to as the Display's "Active Screen". For this reason, only one
Screen and its child Widgets will ever be shown on a display at one time.
When each :ref:`display` object was created, a default screen was created with it and
set as its "Active Screen".
To get a pointer to the "Active Screen", call :cpp:func:`lv_screen_active`.
To set a Screen to be the "Active Screen", call :cpp:func:`lv_screen_load` or
:cpp:func:`lv_screen_load_anim`.
.. _loading_screens:
Loading Screens
---------------
To load a new screen, use :cpp:expr:`lv_screen_load(scr1)`. This sets ``scr1`` as
the Active Screen.
Load Screen with Animation
^^^^^^^^^^^^^^^^^^^^^^^^^^
A new screen can be loaded with animation by using
:cpp:expr:`lv_screen_load_anim(scr, transition_type, time, delay, auto_del)`. The
following transition types exist:
- :cpp:enumerator:`LV_SCR_LOAD_ANIM_NONE`: Switch immediately after ``delay`` milliseconds
- :cpp:enumerator:`LV_SCR_LOAD_ANIM_OVER_LEFT`, :cpp:enumerator:`LV_SCR_LOAD_ANIM_OVER_RIGHT`, :cpp:enumerator:`LV_SCR_LOAD_ANIM_OVER_TOP` and :cpp:enumerator:`LV_SCR_LOAD_ANIM_OVER_BOTTOM`: Move the new screen over the current towards the given direction
- :cpp:enumerator:`LV_SCR_LOAD_ANIM_OUT_LEFT`, :cpp:enumerator:`LV_SCR_LOAD_ANIM_OUT_RIGHT`, :cpp:enumerator:`LV_SCR_LOAD_ANIM_OUT_TOP` and :cpp:enumerator:`LV_SCR_LOAD_ANIM_OUT_BOTTOM`: Move out the old screen over the current towards the given direction
- :cpp:enumerator:`LV_SCR_LOAD_ANIM_MOVE_LEFT`, :cpp:enumerator:`LV_SCR_LOAD_ANIM_MOVE_RIGHT`, :cpp:enumerator:`LV_SCR_LOAD_ANIM_MOVE_TOP` and :cpp:enumerator:`LV_SCR_LOAD_ANIM_MOVE_BOTTOM`: Move both the current and new screens towards the given direction
- :cpp:enumerator:`LV_SCR_LOAD_ANIM_FADE_IN` and :cpp:enumerator:`LV_SCR_LOAD_ANIM_FADE_OUT`: Fade the new screen over the old screen, or vice versa
Setting ``auto_del`` to ``true`` will automatically delete the old
screen when the animation is finished.
The new screen will become active (returned by :cpp:func:`lv_screen_active`) when
the animation starts after ``delay`` time. All inputs are disabled
during the screen animation.
.. _layers_overview:
Layers
------
When an ``lv_display_t`` object is created, 4 Screens (layers) are created and
attached to it.
1. Bottom Layer
2. Active Screen
3. Top Layer
4. System Layer
1, 3 and 4 are independent of the :ref:`active_screen` and they will be shown (if
they contain anything that is visible) regardless of which screen is the Active
Screen. See :ref:`screen_layers` for more information.
.. _transparent_screens:
Transparent Screens
-------------------
Usually, the opacity of the Screen is :cpp:enumerator:`LV_OPA_COVER` to provide a
solid background for its children. If this is not the case (opacity <
100%) the display's ``bottom_layer`` will be visible. If the bottom layer's
opacity is also not :cpp:enumerator:`LV_OPA_COVER` LVGL will have no solid background
to draw.
This configuration (transparent Screen) could be useful to create, for example,
on-screen display (OSD) menus where a video is played on a different hardware layer
of the display panel, and a menu is overlaid on a higher layer.
To properly render a UI on a transparent Screen the Display's color format needs to
be set to one with an alpha channel (for example LV_COLOR_FORMAT_ARGB8888).
In summary, to enable transparent screens and displays for OSD menu-like UIs:
- Set the screen's ``bg_opa`` to transparent:
:cpp:expr:`lv_obj_set_style_bg_opa(lv_screen_active(), LV_OPA_TRANSP, LV_PART_MAIN)`
- Set the bottom layer's ``bg_opa`` to transparent:
:cpp:expr:`lv_obj_set_style_bg_opa(lv_layer_bottom(), LV_OPA_TRANSP, LV_PART_MAIN)`
- Set a color format with alpha channel. E.g.
:cpp:expr:`lv_display_set_color_format(disp, LV_COLOR_FORMAT_ARGB8888)`
.. _widget_parts:
Parts
*****
The widgets are built from multiple parts. For example a
:ref:`Base Widget <base_widget>` uses the main and scrollbar parts but a
:ref:`Slider <lv_slider>` uses the main, indicator and knob parts.
Parts are similar to *pseudo-elements* in CSS.
The following predefined parts exist in LVGL:
- :cpp:enumerator:`LV_PART_MAIN`: A background like rectangle
- :cpp:enumerator:`LV_PART_SCROLLBAR`: The scrollbar(s)
- :cpp:enumerator:`LV_PART_INDICATOR`: Indicator, e.g. for slider, bar, switch, or the tick box of the checkbox
- :cpp:enumerator:`LV_PART_KNOB`: Like a handle to grab to adjust the value
- :cpp:enumerator:`LV_PART_SELECTED`: Indicate the currently selected option or section
- :cpp:enumerator:`LV_PART_ITEMS`: Used if the widget has multiple similar elements (e.g. table cells)
- :cpp:enumerator:`LV_PART_CURSOR`: Mark a specific place e.g. text area's or chart's cursor
- :cpp:enumerator:`LV_PART_CUSTOM_FIRST`: Custom parts can be added from here.
The main purpose of parts is to allow styling the "components" of the
widgets. They are described in more detail in the
:ref:`Style overview <styles>` section.
.. _widget_states:
States
******
The Widget can be in a combination of the following states:
- :cpp:enumerator:`LV_STATE_DEFAULT`: Normal, released state
- :cpp:enumerator:`LV_STATE_CHECKED`: Toggled or checked state
- :cpp:enumerator:`LV_STATE_FOCUSED`: Focused via keypad or encoder or clicked via touchpad/mouse
- :cpp:enumerator:`LV_STATE_FOCUS_KEY`: Focused via keypad or encoder but not via touchpad/mouse
- :cpp:enumerator:`LV_STATE_EDITED`: Edit by an encoder
- :cpp:enumerator:`LV_STATE_HOVERED`: Hovered by mouse (not supported now)
- :cpp:enumerator:`LV_STATE_PRESSED`: Being pressed
- :cpp:enumerator:`LV_STATE_SCROLLED`: Being scrolled
- :cpp:enumerator:`LV_STATE_DISABLED`: Disabled state
- :cpp:enumerator:`LV_STATE_USER_1`: Custom state
- :cpp:enumerator:`LV_STATE_USER_2`: Custom state
- :cpp:enumerator:`LV_STATE_USER_3`: Custom state
- :cpp:enumerator:`LV_STATE_USER_4`: Custom state
The states are usually automatically changed by the library as the user
interacts with a Widget (presses, releases, focuses, etc.). However,
the states can be changed manually as well. To set or clear given state (but
leave the other states untouched) use
:cpp:expr:`lv_obj_add_state(widget, LV_STATE_...)` and
:cpp:expr:`lv_obj_remove_state(widget, LV_STATE_...)`. In both cases OR-ed state
values can be used as well. E.g.
:cpp:expr:`lv_obj_add_state(widget, part, LV_STATE_PRESSED | LV_PRESSED_CHECKED)`.
To learn more about the states read the related section of the
:ref:`Style overview <styles>`.
.. _lv_obj_flags:
Flags
*****
There are some Widget attributes which can be enabled/disabled by
:cpp:expr:`lv_obj_add_flag(widget, LV_OBJ_FLAG_...)` and
:cpp:expr:`lv_obj_remove_flag(widget, LV_OBJ_FLAG_...)`.
- :cpp:enumerator:`LV_OBJ_FLAG_HIDDEN` Make the Widget hidden. (Like it wasn't there at all)
- :cpp:enumerator:`LV_OBJ_FLAG_CLICKABLE` Make the Widget clickable by input devices
- :cpp:enumerator:`LV_OBJ_FLAG_CLICK_FOCUSABLE` Add focused state to the Widget when clicked
- :cpp:enumerator:`LV_OBJ_FLAG_CHECKABLE` Toggle checked state when the Widget is clicked
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLLABLE` Make the Widget scrollable
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_ELASTIC` Allow scrolling inside but with slower speed
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_MOMENTUM` Make the Widget scroll further when "thrown"
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_ONE` Allow scrolling only one snappable children
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_CHAIN_HOR` Allow propagating the horizontal scroll to a parent
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_CHAIN_VER` Allow propagating the vertical scroll to a parent
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_CHAIN` Simple packaging for (:cpp:expr:`LV_OBJ_FLAG_SCROLL_CHAIN_HOR | LV_OBJ_FLAG_SCROLL_CHAIN_VER`)
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_ON_FOCUS` Automatically scroll Widget to make it visible when focused
- :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_WITH_ARROW` Allow scrolling the focused Widget with arrow keys
- :cpp:enumerator:`LV_OBJ_FLAG_SNAPPABLE` If scroll snap is enabled on the parent it can snap to this Widget
- :cpp:enumerator:`LV_OBJ_FLAG_PRESS_LOCK` Keep the Widget pressed even if the press slid from the Widget
- :cpp:enumerator:`LV_OBJ_FLAG_EVENT_BUBBLE` Propagate the events to the parent as well
- :cpp:enumerator:`LV_OBJ_FLAG_GESTURE_BUBBLE` Propagate the gestures to the parent
- :cpp:enumerator:`LV_OBJ_FLAG_ADV_HITTEST` Allow performing more accurate hit (click) test. E.g. accounting for rounded corners
- :cpp:enumerator:`LV_OBJ_FLAG_IGNORE_LAYOUT` Make the Widget not positioned by the layouts
- :cpp:enumerator:`LV_OBJ_FLAG_FLOATING` Do not scroll the Widget when the parent scrolls and ignore layout
- :cpp:enumerator:`LV_OBJ_FLAG_SEND_DRAW_TASK_EVENTS` Enable sending ``LV_EVENT_DRAW_TASK_ADDED`` events
- :cpp:enumerator:`LV_OBJ_FLAG_OVERFLOW_VISIBLE` Do not clip the children's content to the parent's boundary
- :cpp:enumerator:`LV_OBJ_FLAG_FLEX_IN_NEW_TRACK` Start a new flex track on this item
- :cpp:enumerator:`LV_OBJ_FLAG_LAYOUT_1` Custom flag, free to use by layouts
- :cpp:enumerator:`LV_OBJ_FLAG_LAYOUT_2` Custom flag, free to use by layouts
- :cpp:enumerator:`LV_OBJ_FLAG_WIDGET_1` Custom flag, free to use by widget
- :cpp:enumerator:`LV_OBJ_FLAG_WIDGET_2` Custom flag, free to use by widget
- :cpp:enumerator:`LV_OBJ_FLAG_USER_1` Custom flag, free to use by user
- :cpp:enumerator:`LV_OBJ_FLAG_USER_2` Custom flag, free to use by user
- :cpp:enumerator:`LV_OBJ_FLAG_USER_3` Custom flag, free to use by user
- :cpp:enumerator:`LV_OBJ_FLAG_USER_4` Custom flag, free to use by user
Some examples:
.. code-block:: c
/* Hide on Widget */
lv_obj_add_flag(widget, LV_OBJ_FLAG_HIDDEN);
/* Make a Widget non-clickable */
lv_obj_remove_flag(widget, LV_OBJ_FLAG_CLICKABLE);
.. _lv_obj_events:
Base-Widget Events
******************
.. _widget_events:
Events from Input Devices
-------------------------
- :cpp:enumerator:`LV_EVENT_PRESSED` Widget has been pressed.
- :cpp:enumerator:`LV_EVENT_PRESSING` Widget is being pressed (sent continuously while pressing).
- :cpp:enumerator:`LV_EVENT_PRESS_LOST` Widget is still being pressed but slid cursor/finger off Widget.
- :cpp:enumerator:`LV_EVENT_SHORT_CLICKED` Widget was pressed for a short period of time, then released. Not sent if scrolled.
- :cpp:enumerator:`LV_EVENT_SINGLE_CLICKED` Sent for first short click within a small distance and short time.
- :cpp:enumerator:`LV_EVENT_DOUBLE_CLICKED` Sent for second short click within small distance and short time.
- :cpp:enumerator:`LV_EVENT_TRIPLE_CLICKED` Sent for third short click within small distance and short time.
- :cpp:enumerator:`LV_EVENT_LONG_PRESSED` Object has been pressed for at least `long_press_time`. Not sent if scrolled.
- :cpp:enumerator:`LV_EVENT_LONG_PRESSED_REPEAT` Sent after `long_press_time` in every `long_press_repeat_time` ms. Not sent if scrolled.
- :cpp:enumerator:`LV_EVENT_CLICKED` Sent on release if not scrolled (regardless to long press).
- :cpp:enumerator:`LV_EVENT_RELEASED` Sent in every cases when Widget has been released.
- :cpp:enumerator:`LV_EVENT_SCROLL_BEGIN` Scrolling begins. The event parameter is a pointer to the animation of the scroll. Can be modified.
- :cpp:enumerator:`LV_EVENT_SCROLL_THROW_BEGIN` Received when scrolling begins.
- :cpp:enumerator:`LV_EVENT_SCROLL_END` Scrolling ended.
- :cpp:enumerator:`LV_EVENT_SCROLL` Scrolling
- :cpp:enumerator:`LV_EVENT_GESTURE` A gesture is detected. Get gesture with `lv_indev_get_gesture_dir(lv_indev_active());`
- :cpp:enumerator:`LV_EVENT_KEY` A key is sent to Widget. Get key with `lv_indev_get_key(lv_indev_active());`
- :cpp:enumerator:`LV_EVENT_FOCUSED` Widget received focus,
- :cpp:enumerator:`LV_EVENT_DEFOCUSED` Widget's focus has been lost.
- :cpp:enumerator:`LV_EVENT_LEAVE` Widget's focus has been lost but is still selected.
- :cpp:enumerator:`LV_EVENT_HIT_TEST` Perform advanced hit-testing.
Special Events
--------------
- :cpp:enumerator:`LV_EVENT_VALUE_CHANGED` when the :cpp:enumerator:`LV_OBJ_FLAG_CHECKABLE` flag is
enabled and the Widget was clicked (on transition to/from the checked state)
Drawing Events
--------------
- :cpp:enumerator:`LV_EVENT_DRAW_MAIN` Performing drawing of main part
- :cpp:enumerator:`LV_EVENT_DRAW_MAIN_BEGIN` Starting drawing of main part
- :cpp:enumerator:`LV_EVENT_DRAW_MAIN_END` Finishing drawing of main part
- :cpp:enumerator:`LV_EVENT_DRAW_POST` Perform the post draw phase (when all children are drawn)
- :cpp:enumerator:`LV_EVENT_DRAW_POST_BEGIN` Starting the post draw phase (when all children are drawn)
- :cpp:enumerator:`LV_EVENT_DRAW_POST_END` Finishing the post draw phase (when all children are drawn)
Other Events
------------
- :cpp:enumerator:`LV_EVENT_DELETE` Object is being deleted
- :cpp:enumerator:`LV_EVENT_CHILD_CHANGED` Child was removed, added, or its size, position were changed
- :cpp:enumerator:`LV_EVENT_CHILD_CREATED` Child was created, always bubbles up to all parents
- :cpp:enumerator:`LV_EVENT_CHILD_DELETED` Child was deleted, always bubbles up to all parents
- :cpp:enumerator:`LV_EVENT_SIZE_CHANGED` Object coordinates/size have changed
- :cpp:enumerator:`LV_EVENT_STYLE_CHANGED` Object's style has changed
- :cpp:enumerator:`LV_EVENT_LAYOUT_CHANGED` A child's position has changed due to a layout recalculation (when container has flex or grid layout style)
- :cpp:enumerator:`LV_EVENT_GET_SELF_SIZE` Get internal size of a widget
.. admonition:: Further Reading
Learn more about :ref:`events`.
.. _lv_obj_keys:
Keys
****
If :cpp:enumerator:`LV_OBJ_FLAG_CHECKABLE` is enabled, :cpp:enumerator:`LV_KEY_RIGHT` and
:cpp:enumerator:`LV_KEY_UP` make the Widget checked, and :cpp:enumerator:`LV_KEY_LEFT` and
:cpp:enumerator:`LV_KEY_DOWN` make it unchecked.
If :cpp:enumerator:`LV_OBJ_FLAG_SCROLLABLE` is enabled, but the Widget is not editable
(as declared by the widget class), the arrow keys (:cpp:enumerator:`LV_KEY_UP`,
:cpp:enumerator:`LV_KEY_DOWN`, :cpp:enumerator:`LV_KEY_LEFT`, :cpp:enumerator:`LV_KEY_RIGHT`) scroll the Widget.
If the Widget can only scroll vertically, :cpp:enumerator:`LV_KEY_LEFT` and
:cpp:enumerator:`LV_KEY_RIGHT` will scroll up/down instead, making it compatible with
an encoder input device. See :ref:`Input devices overview <indev>` for
more on encoder behaviors and the edit mode.
.. admonition:: Further Reading
Learn more about :ref:`indev_keys`.
.. _widget_snapshot:
Snapshot
********
A snapshot image can be generated for a Widget together with its
children. Check details in :ref:`snapshot`.
Example
*******
.. include:: ../../examples/widgets/obj/index.rst
.. _lv_obj_api:
API
***

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@@ -0,0 +1,294 @@
.. _scrolling:
=========
Scrolling
=========
Overview
********
In LVGL scrolling works very intuitively: if a Widget is outside its
parent content area (the size without padding), the parent becomes
scrollable and scrollbar(s) will appear. That's it.
Any Widget can be scrollable including :ref:`base_widget`, ``lv_image``,
``lv_button``, ``lv_meter``, etc
The Widget can either be scrolled horizontally or vertically in one
stroke; diagonal scrolling is not possible.
Scrollbar
---------
Mode
^^^^
Scrollbars are displayed according to a configured ``mode``. The
following ``mode``\ (s) exist:
- :cpp:enumerator:`LV_SCROLLBAR_MODE_OFF`: Never show the scrollbars
- :cpp:enumerator:`LV_SCROLLBAR_MODE_ON`: Always show the scrollbars
- :cpp:enumerator:`LV_SCROLLBAR_MODE_ACTIVE`: Show scroll bars while a Widget is being scrolled
- :cpp:enumerator:`LV_SCROLLBAR_MODE_AUTO`: Show scroll bars when the content is large enough to be scrolled
:cpp:expr:`lv_obj_set_scrollbar_mode(widget, LV_SCROLLBAR_MODE_...)` sets the scrollbar mode on a Widget.
Styling
^^^^^^^
The scrollbars have their own dedicated part, called
:cpp:enumerator:`LV_PART_SCROLLBAR`. For example a scrollbar can turn to red like
this:
.. code-block:: c
static lv_style_t style_red;
lv_style_init(&style_red);
lv_style_set_bg_color(&style_red, lv_color_red());
...
lv_obj_add_style(widget, &style_red, LV_PART_SCROLLBAR);
A Widget goes to the :cpp:enumerator:`LV_STATE_SCROLLED` state while it's being
scrolled. This allows adding different styles to the scrollbar or the
Widget itself when scrolled. This code makes the scrollbar blue when the
Widget is scrolled:
.. code-block:: c
static lv_style_t style_blue;
lv_style_init(&style_blue);
lv_style_set_bg_color(&style_blue, lv_color_blue());
...
lv_obj_add_style(widget, &style_blue, LV_STATE_SCROLLED | LV_PART_SCROLLBAR);
If the base direction of the :cpp:enumerator:`LV_PART_SCROLLBAR` is RTL
(:c:macro:`LV_BASE_DIR_RTL`) the vertical scrollbar will be placed on the left.
Note that, the ``base_dir`` style property is inherited. Therefore, it
can be set directly on the :cpp:enumerator:`LV_PART_SCROLLBAR` part of a Widget or on
the Widget's or any parent's main part to make a scrollbar inherit the
base direction.
``pad_left/right/top/bottom`` sets the spacing around the scrollbars and
``width`` sets the scrollbar's width.
.. _scroll_events:
Scrolling Events
----------------
The following events are related to scrolling:
- :cpp:enumerator:`LV_EVENT_SCROLL_BEGIN`: Scrolling begins. The event parameter is
``NULL`` or an ``lv_anim_t *`` with a scroll animation descriptor that can be modified if required.
- :cpp:enumerator:`LV_EVENT_SCROLL_END`: Scrolling ends.
- :cpp:enumerator:`LV_EVENT_SCROLL`: Scroll happened. Triggered on every position change. Scroll events
Features of scrolling
*********************
Besides, managing "normal" scrolling there are many interesting and
useful additional features.
Scrollable
----------
It's possible to make a Widget non-scrollable with
:cpp:expr:`lv_obj_remove_flag(widget, LV_OBJ_FLAG_SCROLLABLE)`.
Non-scrollable Widgets can still propagate the scrolling (chain) to
their parents.
The direction in which scrolling happens can be controlled by
:cpp:expr:`lv_obj_set_scroll_dir(widget, LV_DIR_...)`.
The following values are possible for the direction:
- :cpp:enumerator:`LV_DIR_TOP`: only scroll up
- :cpp:enumerator:`LV_DIR_LEFT`: only scroll left
- :cpp:enumerator:`LV_DIR_BOTTOM`: only scroll down
- :cpp:enumerator:`LV_DIR_RIGHT`: only scroll right
- :cpp:enumerator:`LV_DIR_HOR`: only scroll horizontally
- :cpp:enumerator:`LV_DIR_VER`: only scroll vertically
- :cpp:enumerator:`LV_DIR_ALL`: scroll any directions
OR-ed values are also possible. E.g. :cpp:expr:`LV_DIR_TOP | LV_DIR_LEFT`.
Scroll chain
------------
If a Widget can't be scrolled further (e.g. its content has reached the
bottom-most position) additional scrolling is propagated to its parent.
If the parent can be scrolled in that direction than it will be scrolled
instead. It continues propagating to the grandparent and
grand-grandparents as well.
The propagation on scrolling is called "scroll chaining" and it can be
enabled/disabled with ``LV_OBJ_FLAG_SCROLL_CHAIN_HOR/VER`` flag. If
chaining is disabled the propagation stops on the Widget and the
parent(s) won't be scrolled.
Scroll momentum
---------------
When the user scrolls a Widget and releases it, LVGL can emulate
inertial momentum for the scrolling. It's like the Widget was thrown and
scrolling slows down smoothly.
The scroll momentum can be enabled/disabled with the
:cpp:enumerator:`LV_OBJ_FLAG_SCROLL_MOMENTUM` flag.
Elastic scroll
--------------
Normally a Widget can't be scrolled past the extremities of its
content. That is the top side of the content can't be below the top side
of the Widget.
However, with :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_ELASTIC` a fancy effect is added
when the user "over-scrolls" the content. The scrolling slows down, and
the content can be scrolled inside the Widget. When the Widget is
released the content scrolled in it will be animated back to the valid
position.
Snapping
--------
The children of a Widget can be snapped according to specific rules
when scrolling ends. Children can be made snappable individually with
the :cpp:enumerator:`LV_OBJ_FLAG_SNAPPABLE` flag.
A Widget can align snapped children in four ways:
- :cpp:enumerator:`LV_SCROLL_SNAP_NONE`: Snapping is disabled. (default)
- :cpp:enumerator:`LV_SCROLL_SNAP_START`: Align the children to the left/top side of a scrolled Widget
- :cpp:enumerator:`LV_SCROLL_SNAP_END`: Align the children to the right/bottom side of a scrolled Widget
- :cpp:enumerator:`LV_SCROLL_SNAP_CENTER`: Align the children to the center of a scrolled Widget
Snap alignment is set with
:cpp:expr:`lv_obj_set_scroll_snap_x(widget, LV_SCROLL_SNAP_...)` and
:cpp:expr:`lv_obj_set_scroll_snap_y(widget, LV_SCROLL_SNAP_...)`.
Under the hood the following happens:
1. User scrolls a Widget and releases the screen
2. LVGL calculates where the scroll would end considering scroll momentum
3. LVGL finds the nearest scroll point
4. LVGL scrolls to the snap point with an animation
Scroll one
----------
The "scroll one" feature tells LVGL to allow scrolling only one
snappable child at a time. This requires making the children snappable
and setting a scroll snap alignment different from
:cpp:enumerator:`LV_SCROLL_SNAP_NONE`.
This feature can be enabled by the :cpp:enumerator:`LV_OBJ_FLAG_SCROLL_ONE` flag.
Scroll on focus
---------------
Imagine that there a lot of Widgets in a group that are on a scrollable
Widget. Pressing the "Tab" button focuses the next Widget but it might
be outside the visible area of the scrollable Widget. If the "scroll on
focus" feature is enabled LVGL will automatically scroll Widgets to
bring their children into view. The scrolling happens recursively
therefore even nested scrollable Widgets are handled properly. The
Widget will be scrolled into view even if it's on a different page of a
tabview.
Scroll manually
***************
The following API functions allow manual scrolling of Widgets:
- ``lv_obj_scroll_by(widget, x, y, LV_ANIM_ON/OFF)`` scroll by ``x`` and ``y`` values
- ``lv_obj_scroll_to(widget, x, y, LV_ANIM_ON/OFF)`` scroll to bring the given coordinate to the top left corner
- ``lv_obj_scroll_to_x(widget, x, LV_ANIM_ON/OFF)`` scroll to bring the given coordinate to the left side
- ``lv_obj_scroll_to_y(widget, y, LV_ANIM_ON/OFF)`` scroll to bring the given coordinate to the top side
From time to time you may need to retrieve the scroll position of an
element, either to restore it later, or to display dynamically some
elements according to the current scroll. Here is an example to see how
to combine scroll event and store the scroll top position.
.. code-block:: c
static int scroll_value = 0;
static void store_scroll_value_event_cb(lv_event_t* e) {
lv_obj_t* screen = lv_event_get_target(e);
scroll_value = lv_obj_get_scroll_top(screen);
printf("%d pixels are scrolled out on the top\n", scroll_value);
}
lv_obj_t* container = lv_obj_create(NULL);
lv_obj_add_event_cb(container, store_scroll_value_event_cb, LV_EVENT_SCROLL, NULL);
Scroll coordinates can be retrieved from different axes with these
functions:
- ``lv_obj_get_scroll_x(widget)`` Get the ``x`` coordinate of Widget
- ``lv_obj_get_scroll_y(widget)`` Get the ``y`` coordinate of Widget
- ``lv_obj_get_scroll_top(widget)`` Get the scroll coordinate from the top
- ``lv_obj_get_scroll_bottom(widget)`` Get the scroll coordinate from the bottom
- ``lv_obj_get_scroll_left(widget)`` Get the scroll coordinate from the left
- ``lv_obj_get_scroll_right(widget)`` Get the scroll coordinate from the right
Self size
*********
Self size is a property of a Widget. Normally, the user shouldn't use
this parameter but if a custom widget is created it might be useful.
In short, self size establishes the size of a Widget's content. To
understand it better take the example of a table. Let's say it has 10
rows each with 50 px height. So the total height of the content is 500
px. In other words the "self height" is 500 px. If the user sets only
200 px height for the table LVGL will see that the self size is larger
and make the table scrollable.
This means not only the children can make a Widget scrollable but a
larger self size will as well.
LVGL uses the :cpp:enumerator:`LV_EVENT_GET_SELF_SIZE` event to get the self size of
a Widget. Here is an example to see how to handle the event:
.. code-block:: c
if(event_code == LV_EVENT_GET_SELF_SIZE) {
lv_point_t * p = lv_event_get_param(e);
//If x or y < 0 then it doesn't need to be calculated now
if(p->x >= 0) {
p->x = 200; //Set or calculate the self width
}
if(p->y >= 0) {
p->y = 50; //Set or calculate the self height
}
}
.. _scroll_example:
Examples
********
.. include:: ../../examples/scroll/index.rst
.. _scroll_api:
API
***

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.. _styles:
======
Styles
======
.. toctree::
:maxdepth: 2
style
style-properties

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.. _style_details:
=============
Style Details
=============
*Styles* are used to set the appearance of Widgets. Styles in lvgl are
heavily inspired by CSS. The concept in a nutshell is that a
style is an :cpp:type:`lv_style_t` variable which can hold properties like
border width, font, text color and so on. It's similar to a ``class`` in CSS.
- Styles can be assigned to Widgets to change their appearance. Upon
assignment, the target part (*pseudo-element* in CSS) and target state
(*pseudo class*) can be specified. For example one can add
``style_blue`` to the knob of a slider when it's in pressed state.
- The same style can be used by any number of Widgets.
- Styles can be cascaded which means multiple styles may be assigned to a Widget and
each style can have different properties. Therefore, not all properties
have to be specified in a style. LVGL will search for a property until a
style defines it or use a default if it's not specified by any of the
styles. For example ``style_btn`` can result in a default gray button
and ``style_btn_red`` can add only a ``background-color=red`` to
overwrite the background color.
- The most recently added style has higher precedence. This means if a property
is specified in two styles the newest style in the Widget will be used.
- Some properties (e.g. text color) can be inherited from a parent(s) if it's not specified in a Widget.
- Widgets can also have local styles with higher precedence than "normal" styles.
- Unlike CSS (where pseudo-classes describe different states, e.g. ``:focus``),
in LVGL a property is assigned to a given state.
- Transitions can be applied when the Widget changes state.
.. _styles_states:
States
******
The Widgets can be in the combination of the following states:
- :cpp:enumerator:`LV_STATE_DEFAULT`: (0x0000) Normal, released state
- :cpp:enumerator:`LV_STATE_CHECKED`: (0x0001) Toggled or checked state
- :cpp:enumerator:`LV_STATE_FOCUSED`: (0x0002) Focused via keypad or encoder or clicked via touchpad/mouse
- :cpp:enumerator:`LV_STATE_FOCUS_KEY`: (0x0004) Focused via keypad or encoder but not via touchpad/mouse
- :cpp:enumerator:`LV_STATE_EDITED`: (0x0008) Edit by an encoder
- :cpp:enumerator:`LV_STATE_HOVERED`: (0x0010) Hovered by mouse
- :cpp:enumerator:`LV_STATE_PRESSED`: (0x0020) Being pressed
- :cpp:enumerator:`LV_STATE_SCROLLED`: (0x0040) Being scrolled
- :cpp:enumerator:`LV_STATE_DISABLED`: (0x0080) Disabled state
- :cpp:enumerator:`LV_STATE_USER_1`: (0x1000) Custom state
- :cpp:enumerator:`LV_STATE_USER_2`: (0x2000) Custom state
- :cpp:enumerator:`LV_STATE_USER_3`: (0x4000) Custom state
- :cpp:enumerator:`LV_STATE_USER_4`: (0x8000) Custom state
A Widget can be in a combination of states such as being focused and
pressed at the same time. This is represented as :cpp:expr:`LV_STATE_FOCUSED | LV_STATE_PRESSED`.
A style can be added to any state or state combination. For example,
setting a different background color for the default and pressed states.
If a property is not defined in a state the best matching state's
property will be used. Typically this means the property with
:cpp:enumerator:`LV_STATE_DEFAULT` is used.˛ If the property is not set even for the
default state the default value will be used. (See later)
But what does the "best matching state's property" really mean? States
have a precedence which is shown by their value (see in the above list).
A higher value means higher precedence. To determine which state's
property to use let's take an example. Imagine the background color is
defined like this:
- :cpp:enumerator:`LV_STATE_DEFAULT`: white
- :cpp:enumerator:`LV_STATE_PRESSED`: gray
- :cpp:enumerator:`LV_STATE_FOCUSED`: red
1. Initially the Widget is in the default state, so it's a simple case:
the property is perfectly defined in the Widget's current state as
white.
2. When the Widget is pressed there are 2 related properties: default
with white (default is related to every state) and pressed with gray.
The pressed state has 0x0020 precedence which is higher than the
default state's 0x0000 precedence, so gray color will be used.
3. When the Widget has focus the same thing happens as in pressed state
and red color will be used. (Focused state has higher precedence than
default state).
4. When the Widget has focus and pressed both gray and red would work,
but the pressed state has higher precedence than focused so gray
color will be used.
5. It's possible to set e.g. rose color for :cpp:expr:`LV_STATE_PRESSED | LV_STATE_FOCUSED`.
In this case, this combined state has 0x0020 + 0x0002 = 0x0022 precedence, which is higher than
the pressed state's precedence so rose color would be used.
6. When the Widget is in the checked state there is no property to set
the background color for this state. So for lack of a better option,
the Widget remains white from the default state's property.
Some practical notes:
- The precedence (value) of states is quite intuitive, and it's something the
user would expect naturally. E.g. if a Widget has focus the user will still
want to see if it's pressed, therefore the pressed state has a higher
precedence. If the focused state had a higher precedence it would overwrite
the pressed color.
- If you want to set a property for all states (e.g. red background color)
just set it for the default state. If the Widget can't find a property
for its current state it will fall back to the default state's property.
- Use ORed states to describe the properties for complex cases. (E.g.
pressed + checked + focused)
- It might be a good idea to use different
style elements for different states. For example, finding background
colors for released, pressed, checked + pressed, focused, focused +
pressed, focused + pressed + checked, etc. states is quite difficult.
Instead, for example, use the background color for pressed and checked
states and indicate the focused state with a different border color.
.. _styles_cascading:
Cascading styles
****************
It's not required to set all the properties in one style. It's possible
to add more styles to a Widget and have the latter added style modify
or extend appearance. For example, create a general gray button style
and create a new one for red buttons where only the new background color
is set.
This is much like in CSS when used classes are listed like
``<div class=".btn .btn-red">``.
Styles added later have precedence over ones set earlier. So in the
gray/red button example above, the normal button style should be added
first and the red style second. However, the precedence of the states
are still taken into account. So let's examine the following case:
- the basic button style defines dark-gray color for the default state and
light-gray color for the pressed state
- the red button style defines the background color as red only in the default state
In this case, when the button is released (it's in default state) it
will be red because a perfect match is found in the most recently added
style (red). When the button is pressed the light-gray color is a better
match because it describes the current state perfectly, so the button
will be light-gray.
.. _styles_inheritance:
Inheritance
***********
Some properties (typically those related to text) can be inherited from
the parent Widget's styles. Inheritance is applied only if the given
property is not set in the Widget's styles (even in default state). In
this case, if the property is inheritable, the property's value will be
searched in the parents until a Widget specifies a value for the
property. The parents will use their own state to determine the value.
So if a button is pressed, and the text color comes from here, the
pressed text color will be used.
.. _styles_parts:
Parts
*****
Widgets can be composed of *parts* which may each have their own styles.
The following predefined parts exist in LVGL:
- :cpp:enumerator:`LV_PART_MAIN`: A background like rectangle
- :cpp:enumerator:`LV_PART_SCROLLBAR`: The scrollbar(s)
- :cpp:enumerator:`LV_PART_INDICATOR`: Indicator, e.g. for slider, bar, switch, or the tick box of the checkbox
- :cpp:enumerator:`LV_PART_KNOB`: Like a handle to grab to adjust a value
- :cpp:enumerator:`LV_PART_SELECTED`: Indicate the currently selected option or section
- :cpp:enumerator:`LV_PART_ITEMS`: Used if the widget has multiple similar elements (e.g. table cells)
- :cpp:enumerator:`LV_PART_CURSOR`: Mark a specific place e.g. text area's or chart's cursor
- :cpp:enumerator:`LV_PART_CUSTOM_FIRST`: Custom part identifiers can be added starting from here.
For example a :ref:`Slider <lv_slider>` has three parts:
- Background
- Indicator
- Knob
This means all three parts of the slider can have their own styles. See
later how to add styles to Widgets and parts.
.. _styles_initialize:
Initialize styles and set/get properties
****************************************
Styles are stored in :cpp:type:`lv_style_t` variables. Style variables should be
``static``, global or dynamically allocated. In other words they cannot
be local variables in functions which are destroyed when the function
exits. Before using a style it should be initialized with
:cpp:expr:`lv_style_init(&my_style)`. After initializing a style, properties can
be added or changed.
Property set functions looks like this:
``lv_style_set_<property_name>(&style, <value>);`` For example:
.. code-block:: c
static lv_style_t style_btn;
lv_style_init(&style_btn);
lv_style_set_bg_color(&style_btn, lv_color_hex(0x115588));
lv_style_set_bg_opa(&style_btn, LV_OPA_50);
lv_style_set_border_width(&style_btn, 2);
lv_style_set_border_color(&style_btn, lv_color_black());
static lv_style_t style_btn_red;
lv_style_init(&style_btn_red);
lv_style_set_bg_color(&style_btn_red, lv_palette_main(LV_PALETTE_RED));
lv_style_set_bg_opa(&style_btn_red, LV_OPA_COVER);
To remove a property use:
.. code-block:: c
lv_style_remove_prop(&style, LV_STYLE_BG_COLOR);
To get a property's value from a style:
.. code-block:: c
lv_style_value_t v;
lv_result_t res = lv_style_get_prop(&style, LV_STYLE_BG_COLOR, &v);
if(res == LV_RESULT_OK) { /* Found */
do_something(v.color);
}
:cpp:union:`lv_style_value_t` has 3 fields:
- :cpp:member:`num`: for integer, boolean and opacity properties
- :cpp:member:`color`: for color properties
- :cpp:member:`ptr`: for pointer properties
To reset a style (free all its data) use:
.. code-block:: c
lv_style_reset(&style);
Styles can be built as ``const`` as well to save RAM:
.. code-block:: c
const lv_style_const_prop_t style1_props[] = {
LV_STYLE_CONST_WIDTH(50),
LV_STYLE_CONST_HEIGHT(50),
LV_STYLE_CONST_PROPS_END
};
LV_STYLE_CONST_INIT(style1, style1_props);
Later ``const`` style can be used like any other style but (obviously)
new properties cannot be added.
.. _styles_add_remove:
Add and remove styles to a widget
*********************************
A style on its own is not that useful. It must be assigned to a Widget
to take effect.
Add styles
----------
To add a style to a Widget use
``lv_obj_add_style(widget, &style, <selector>)``. ``<selector>`` is an
OR-ed value of parts and state to which the style should be added. Some
examples:
- :cpp:expr:`LV_PART_MAIN | LV_STATE_DEFAULT`
- :cpp:enumerator:`LV_STATE_PRESSED`: The main part in pressed state. :cpp:enumerator:`LV_PART_MAIN` can be omitted
- :cpp:enumerator:`LV_PART_SCROLLBAR`: The scrollbar part in the default state. :cpp:enumerator:`LV_STATE_DEFAULT` can be omitted.
- :cpp:expr:`LV_PART_SCROLLBAR | LV_STATE_SCROLLED`: The scrollbar part when the Widget is being scrolled
- :cpp:expr:`LV_PART_INDICATOR | LV_STATE_PRESSED | LV_STATE_CHECKED` The indicator part when the Widget is pressed and checked at the same time.
Using :cpp:func:`lv_obj_add_style`:
.. code-block:: c
lv_obj_add_style(btn, &style_btn, 0); /* Default button style */
lv_obj_add_style(btn, &btn_red, LV_STATE_PRESSED); /* Overwrite only some colors to red when pressed */
Replace styles
--------------
To replace a specific style of a Widget use
:cpp:expr:`lv_obj_replace_style(widget, old_style, new_style, selector)`. This
function will only replace ``old_style`` with ``new_style`` if the
``selector`` matches the ``selector`` used in ``lv_obj_add_style``. Both
styles, i.e. ``old_style`` and ``new_style``, must not be ``NULL`` (for
adding and removing separate functions exist). If the combination of
``old_style`` and ``selector`` exists multiple times in ``obj``\ 's
styles, all occurrences will be replaced. The return value of the
function indicates whether at least one successful replacement took
place.
Using :cpp:func:`lv_obj_replace_style`:
.. code-block:: c
lv_obj_add_style(btn, &style_btn, 0); /* Add a button style */
lv_obj_replace_style(btn, &style_btn, &new_style_btn, 0); /* Replace the button style with a different one */
Remove styles
-------------
To remove all styles from a Widget use :cpp:expr:`lv_obj_remove_style_all(widget)`.
To remove specific styles use
:cpp:expr:`lv_obj_remove_style(widget, style, selector)`. This function will remove
``style`` only if the ``selector`` matches with the ``selector`` used in
:cpp:func:`lv_obj_add_style`. ``style`` can be ``NULL`` to check only the
``selector`` and remove all matching styles. The ``selector`` can use
the :cpp:enumerator:`LV_STATE_ANY` and :cpp:enumerator:`LV_PART_ANY` values to remove the style from
any state or part.
Report style changes
--------------------
If a style which is already assigned to a Widget changes (i.e. a
property is added or changed), the Widgets using that style should be
notified. There are 3 options to do this:
1. If you know that the changed properties can be applied by a simple redraw
(e.g. color or opacity changes) just call :cpp:expr:`lv_obj_invalidate(widget)`
or :cpp:expr:`lv_obj_invalidate(lv_screen_active())`.
2. If more complex style properties were changed or added, and you know which
Widget(s) are affected by that style call :cpp:expr:`lv_obj_refresh_style(widget, part, property)`.
To refresh all parts and properties use :cpp:expr:`lv_obj_refresh_style(widget, LV_PART_ANY, LV_STYLE_PROP_ANY)`.
3. To make LVGL check all Widgets to see if they use a style and refresh them
when needed, call :cpp:expr:`lv_obj_report_style_change(&style)`. If ``style``
is ``NULL`` all Widgets will be notified about a style change.
Get a property's value on a Widget
-----------------------------------
To get a final value of property
- considering cascading, inheritance, local styles and transitions (see below)
- property get functions like this can be used: ``lv_obj_get_style_<property_name>(widget, <part>)``.
These functions use the Widget's current state and if no better candidate exists they return a default value.
For example:
.. code-block:: c
lv_color_t color = lv_obj_get_style_bg_color(btn, LV_PART_MAIN);
.. _styles_local:
Local styles
************
In addition to "normal" styles, Widgets can also store local styles.
This concept is similar to inline styles in CSS
(e.g. ``<div style="color:red">``) with some modification.
Local styles are like normal styles, but they can't be shared among
other Widgets. If used, local styles are allocated automatically, and
freed when the Widget is deleted. They are useful to add local
customization to a Widget.
Unlike in CSS, LVGL local styles can be assigned to states
(*pseudo-classes*) and parts (*pseudo-elements*).
To set a local property use functions like
``lv_obj_set_style_<property_name>(widget, <value>, <selector>);`` For example:
.. code-block:: c
lv_obj_set_style_bg_color(slider, lv_color_red(), LV_PART_INDICATOR | LV_STATE_FOCUSED);
.. _style_properties_overview:
Style Properties Overview
*************************
For the full list of style properties click :ref:`here <style_properties>`.
Typical background properties
-----------------------------
In the documentation of the widgets you will see sentences like "The
widget uses the typical background properties". These "typical
background properties" are the ones related to:
- Background
- Border
- Outline
- Shadow
- Padding
- Width and height transformation
- X and Y translation
.. _styles_transitions:
Transitions
***********
By default, when a Widget changes state (e.g. it's pressed) the new
properties from the new state are set immediately. However, with
transitions it's possible to play an animation on state change. For
example, on pressing a button its background color can be animated to
the pressed color over 300 ms.
The parameters of the transitions are stored in the styles. It's
possible to set
- the time of the transition
- the delay before starting the transition
- the animation path (also known as the timing or easing function)
- the properties to animate
The transition properties can be defined for each state. For example,
setting a 500 ms transition time in the default state means that when
the Widget goes to the default state a 500 ms transition time is
applied. Setting a 100 ms transition time in the pressed state causes a
100 ms transition when going to the pressed state. This example
configuration results in going to the pressed state quickly and then
going back to default slowly.
To describe a transition an :cpp:struct:`lv_transition_dsc_t` variable needs to be
initialized and added to a style:
.. code-block:: c
/* Only its pointer is saved so must static, global or dynamically allocated */
static const lv_style_prop_t trans_props[] = {
LV_STYLE_BG_OPA, LV_STYLE_BG_COLOR,
0, /* End marker */
};
static lv_style_transition_dsc_t trans1;
lv_style_transition_dsc_init(&trans1, trans_props, lv_anim_path_ease_out, duration_ms, delay_ms);
lv_style_set_transition(&style1, &trans1);
.. _styles_opacity_blend_modes_transformations:
Opacity, Blend modes and Transformations
****************************************
If the ``opa``, ``blend_mode``, ``transform_angle``, or
``transform_zoom`` properties are set to their non-default value LVGL
creates a snapshot about the widget and all its children in order to
blend the whole widget with the set opacity, blend mode and
transformation properties.
These properties have this effect only on the ``MAIN`` part of the
widget.
The created snapshot is called "intermediate layer" or simply "layer".
If only ``opa`` and/or ``blend_mode`` is set to a non-default value LVGL
can build the layer from smaller chunks. The size of these chunks can be
configured by the following properties in ``lv_conf.h``:
- :cpp:enumerator:`LV_LAYER_SIMPLE_BUF_SIZE`: [bytes] the optimal target buffer size. LVGL will try to allocate this size of memory.
- :cpp:enumerator:`LV_LAYER_SIMPLE_FALLBACK_BUF_SIZE`: [bytes] used if :cpp:enumerator:`LV_LAYER_SIMPLE_BUF_SIZE` couldn't be allocated.
If transformation properties were also used the layer cannot be
rendered in chunks, but one larger memory needs to be allocated. The
required memory depends on the angle, zoom and pivot parameters, and the
size of the area to redraw, but it's never larger than the size of the
widget (including the extra draw size used for shadow, outline, etc).
If the widget can fully cover the area to redraw, LVGL creates an RGB
layer (which is faster to render and uses less memory). If the opposite
case ARGB rendering needs to be used. A widget might not cover its area
if it has radius, ``bg_opa != 255``, has shadow, outline, etc.
The click area of the widget is also transformed accordingly.
.. _styles_color_filter:
Color filter
************
TODO
.. _styles_themes:
Themes
******
Themes are a collection of styles. If there is an active theme LVGL
applies it on every created widget. This will give a default appearance
to the UI which can then be modified by adding further styles.
Every display can have a different theme. For example, you could have a
colorful theme on a TFT and monochrome theme on a secondary monochrome
display.
To set a theme for a display, two steps are required:
1. Initialize a theme
2. Assign the initialized theme to a display.
Theme initialization functions can have different prototypes. This
example shows how to set the "default" theme:
.. code-block:: c
lv_theme_t * th = lv_theme_default_init(display, /* Use the DPI, size, etc from this display */
LV_COLOR_PALETTE_BLUE, LV_COLOR_PALETTE_CYAN, /* Primary and secondary palette */
false, /* Light or dark mode */
&lv_font_montserrat_10, &lv_font_montserrat_14, &lv_font_montserrat_18); /* Small, normal, large fonts */
lv_display_set_theme(display, th); /* Assign the theme to the display */
The included themes are enabled in ``lv_conf.h``. If the default theme
is enabled by :c:macro:`LV_USE_THEME_DEFAULT` LVGL automatically initializes
and sets it when a display is created.
Extending themes
----------------
Built-in themes can be extended. If a custom theme is created, a parent
theme can be selected. The parent theme's styles will be added before
the custom theme's styles. Any number of themes can be chained this way.
E.g. default theme -> custom theme -> dark theme.
:cpp:expr:`lv_theme_set_parent(new_theme, base_theme)` extends the
``base_theme`` with the ``new_theme``.
There is an example for it below.
.. _styles_example:
Examples
********
.. include:: ../../../examples/styles/index.rst
.. _styles_api:
API
***

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.. _gdb_plugin:
===========
GDB Plug-In
===========
Debugging LVGL with GDB
-----------------------
To facilitate debugging LVGL with GDB, a GDB plugin is provided. This plugin
can be found in the ``lvgl/scripts/gdb`` directory. The GDB plugin can be used
with any target where GDB is available. For example, you can use it to debug a
device connected to a PC via JLink, which provides a GDB server. Additionally,
if your device crashes and you have a core dump, you can use GDB to analyze the
core dump. To load the LVGL GDB plugin within GDB's command line, type the
following command:
``source lvgl/scripts/gdb/gdbinit.py``
Example of usage:
.. code:: bash
(gdb) source lvgl/scripts/gdb/gdbinit.py
(gdb) dump obj -L 2
obj@0x60700000dd10 (0,0,799,599)
tabview@0x608000204ca0 (0,0,799,599)
obj@0x607000025da0 (0,0,799,69)
obj@0x607000025e80 (0,70,799,599)
obj@0x60700002bd70 (743,543,791,591)
btn@0x60700002c7f0 (747,547,787,587)
keyboard@0x60d0000f7040 (0,300,799,599)
dropdown-list@0x608000205420 (0,0,129,129)
label@0x60d0000f7ba0 (22,22,56,39)
(gdb)
The plugin provides the following commands.
- ``dump obj``: Dump the object tree.
- ``info style``: Show the object's style.
Dump obj tree
-------------
``dump obj``: Dump the object tree.
``dump obj -L 2``: Dump the object tree with a depth of 2.
``dump obj -a 0x60700000dd10``: Dump the object tree starting from the specified address.
Show obj's style
----------------
This command can dump the object's local style, since style value is a union, it's displayed in all possible formats.
``info style address_of_obj``: Show the object's style.
Example:
.. code:: bash
(gdb) info style 0x60700000dd10
32 = {num = 90, ptr = 0x5a, color = {blue = 90 'Z', green = 0 '\000', red = 0 '\000'}}
158 = {num = 32767, ptr = 0x7fff, color = {blue = 255 '\377', green = 127 '\177', red = 0 '\000'}}
(gdb) p lv_global->disp_default->act_scr
$4 = (lv_obj_t *) 0x60700000dd10
(gdb) info style $4
32 = {num = 90, ptr = 0x5a, color = {blue = 90 'Z', green = 0 '\000', red = 0 '\000'}}
158 = {num = 32767, ptr = 0x7fff, color = {blue = 255 '\377', green = 127 '\177', red = 0 '\000'}}
(gdb)

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.. _debugging:
=========
Debugging
=========
.. toctree::
:maxdepth: 2
gdb_plugin
log
profiler
vg_lite_tvg

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.. _logging:
=======
Logging
=======
LVGL has a built-in *Log* module to inform the user about what is
happening in the library.
Log level
*********
To enable logging, set :c:macro:`LV_USE_LOG` in ``lv_conf.h`` and set
:c:macro:`LV_LOG_LEVEL` to one of the following values:
- :c:macro:`LV_LOG_LEVEL_TRACE`: A lot of logs to give detailed information
- :c:macro:`LV_LOG_LEVEL_INFO`: Log important events
- :c:macro:`LV_LOG_LEVEL_WARN`: Log if something unwanted happened but didn't cause a problem
- :c:macro:`LV_LOG_LEVEL_ERROR`: Only critical issues, where the system may fail
- :c:macro:`LV_LOG_LEVEL_USER`: Only user messages
- :c:macro:`LV_LOG_LEVEL_NONE`: Do not log anything
The events which have a higher level than the set log level will be logged
as well. E.g. if you :c:macro:`LV_LOG_LEVEL_WARN`, errors will be also logged.
Printing logs
*************
Logging with printf
-------------------
If your system supports ``printf``, you just need to enable
:c:macro:`LV_LOG_PRINTF` in ``lv_conf.h`` to send the logs with ``printf``.
Custom log function
-------------------
If you can't use ``printf`` or want to use a custom function to log, you
can register a "logger" callback with :cpp:func:`lv_log_register_print_cb`.
For example:
.. code-block:: c
void my_log_cb(lv_log_level_t level, const char * buf)
{
serial_send(buf, strlen(buf));
}
...
lv_log_register_print_cb(my_log_cb);
Add logs
********
You can also use the log module via the
``LV_LOG_TRACE/INFO/WARN/ERROR/USER(text)`` or ``LV_LOG(text)``
functions. Here:
- ``LV_LOG_TRACE/INFO/WARN/ERROR/USER(text)`` append following information to your ``text``
- Log Level
- \__FILE\_\_
- \__LINE\_\_
- \__func\_\_
- ``LV_LOG(text)`` is similar to ``LV_LOG_USER`` but has no extra information attached.
API
***

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.. _profiler:
========
Profiler
========
As the complexity of the application increases, performance issues such as low FPS and frequent cache misses
causing lag may arise. LVGL has internally set up some hooks for performance measurement to help developers
analyze and locate performance issues.
.. _profiler_introduction:
Introduction
************
LVGL has a built-in trace system to track and record the timestamps of important events that occur during runtime,
such as rendering events and user input events. These event timestamps serve as important metrics for performance analysis.
The trace system has a configurable record buffer that stores the names of event functions and their timestamps.
When the buffer is full, the trace system prints the log information through the provided user interface.
The output trace logs are formatted according to Android's `systrace <https://developer.android.com/topic/performance/tracing>`_
format and can be visualized using `Perfetto <https://ui.perfetto.dev>`_.
.. _profiler_usage:
Usage
*****
Configure profiler
^^^^^^^^^^^^^^^^^^
To enable the profiler, set :c:macro:`LV_USE_PROFILER` in ``lv_conf.h`` and configure the following options:
1. Enable the built-in profiler functionality by setting :c:macro:`LV_USE_PROFILER_BUILTIN`.
2. Buffer configuration: Set the value of :c:macro:`LV_PROFILER_BUILTIN_BUF_SIZE` to configure the buffer size. A larger buffer can store more trace event information, reducing interference with rendering. However, it also results in higher memory consumption.
3. Timestamp configuration: LVGL uses the :cpp:func:`lv_tick_get` function with a precision of 1ms by default to obtain timestamps when events occur. Therefore, it cannot accurately measure intervals below 1ms. If your system environment can provide higher precision (e.g., 1us), you can configure the profiler as follows:
- Recommended configuration in **UNIX** environments:
.. code-block:: c
#include <sys/syscall.h>
#include <sys/types.h>
#include <time.h>
static uint32_t my_get_tick_us_cb(void)
{
struct timespec ts;
clock_gettime(CLOCK_MONOTONIC, &ts);
return ts.tv_sec * 1000000 + ts.tv_nsec / 1000;
}
static int my_get_tid_cb(void)
{
return (int)syscall(SYS_gettid);
}
static int my_get_cpu_cb(void)
{
int cpu_id = 0;
syscall(SYS_getcpu, &cpu_id, NULL);
return cpu_id;
}
void my_profiler_init(void)
{
lv_profiler_builtin_config_t config;
lv_profiler_builtin_config_init(&config);
config.tick_per_sec = 1000000; /* One second is equal to 1000000 microseconds */
config.tick_get_cb = my_get_tick_us_cb;
config.tid_get_cb = my_get_tid_cb;
config.cpu_get_cb = my_get_cpu_cb;
lv_profiler_builtin_init(&config);
}
- Recommended configuration in **Arduino** environments:
.. code-block:: c
void my_profiler_init(void)
{
lv_profiler_builtin_config_t config;
lv_profiler_builtin_config_init(&config);
config.tick_per_sec = 1000000; /* One second is equal to 1000000 microseconds */
config.tick_get_cb = micros; /* Use the microsecond time stamp provided by Arduino */
lv_profiler_builtin_init(&config);
}
4. Log output configuration: LVGL uses the :cpp:func:`LV_LOG` interface by default to output trace information. If you want to use another interface to output log information (e.g., file stream), you can redirect the log output using the following code:
.. code-block:: c
static void my_log_print_cb(const char * buf)
{
printf("%s", buf);
}
void my_profiler_init(void)
{
lv_profiler_builtin_config_t config;
lv_profiler_builtin_config_init(&config);
... /* other configurations */
config.flush_cb = my_log_print_cb;
lv_profiler_builtin_init(&config);
}
Run the test scenario
^^^^^^^^^^^^^^^^^^^^^
Run the UI scenario that you want to measure, such as scrolling a scrollable page up and down or entering/exiting an application.
Process the logs
^^^^^^^^^^^^^^^^
Save the output log as `my_trace.txt`, use `trace_filter.py` for filtering and preprocessing:
.. code-block:: bash
./lvgl/scripts/trace_filter.py my_trace.txt
or
.. code-block:: bash
python3 ./lvgl/scripts/trace_filter.py my_trace.txt
You will obtain a processed text file named `trace.systrace`, which roughly contains the following content:
.. code-block:: text
# tracer: nop
#
LVGL-1 [0] 2892.002993: tracing_mark_write: B|1|lv_timer_handler
LVGL-1 [0] 2892.002993: tracing_mark_write: B|1|_lv_display_refr_timer
LVGL-1 [0] 2892.003459: tracing_mark_write: B|1|refr_invalid_areas
LVGL-1 [0] 2892.003461: tracing_mark_write: B|1|lv_draw_rect
LVGL-1 [0] 2892.003550: tracing_mark_write: E|1|lv_draw_rect
LVGL-1 [0] 2892.003552: tracing_mark_write: B|1|lv_draw_rect
LVGL-1 [0] 2892.003556: tracing_mark_write: E|1|lv_draw_rect
LVGL-1 [0] 2892.003560: tracing_mark_write: B|1|lv_draw_rect
LVGL-1 [0] 2892.003573: tracing_mark_write: E|1|lv_draw_rect
...
Import the processed `trace.systrace` file into `Perfetto <https://ui.perfetto.dev>`_ and wait for it to be parsed.
Performance analysis
^^^^^^^^^^^^^^^^^^^^
If the log parsing is successful, you will see the following screen:
.. image:: /misc/perfetto_ui.png
In the Perfetto UI, use the :kbd:`A` or :kbd:`D` keys to pan the timeline horizontally
and the :kbd:`W` or :kbd:`S` keys to zoom in or out on the timeline.
Use the mouse to move the focus and click on functions on the timeline to observe their execution time.
Add Measurement Point
*********************
Users can add their own measured functions:
.. code-block:: c
void my_function_1(void)
{
LV_PROFILER_BEGIN;
do_something();
LV_PROFILER_END;
}
void my_function_2(void)
{
LV_PROFILER_BEGIN_TAG("do_something_1");
do_something_1();
LV_PROFILER_END_TAG("do_something_1");
LV_PROFILER_BEGIN_TAG("do_something_2");
do_something_2();
LV_PROFILER_END_TAG("do_something_2");
}
.. _profiler_custom_implementation:
Custom profiler implementation
******************************
If you wish to use a profiler method provided by your operating system, you can modify the following configurations in ``lv_conf.h``:
- :c:macro:`LV_PROFILER_INCLUDE`: Provides a header file for the profiler function.
- :c:macro:`LV_PROFILER_BEGIN`: Profiler start point function.
- :c:macro:`LV_PROFILER_END`: Profiler end point function.
- :c:macro:`LV_PROFILER_BEGIN_TAG`: Profiler start point function with custom tag.
- :c:macro:`LV_PROFILER_END_TAG`: Profiler end point function with custom tag.
Taking `NuttX <https://github.com/apache/nuttx>`_ RTOS as an example:
.. code-block:: c
#define LV_PROFILER_INCLUDE "nuttx/sched_note.h"
#define LV_PROFILER_BEGIN sched_note_begin(NOTE_TAG_ALWAYS)
#define LV_PROFILER_END sched_note_end(NOTE_TAG_ALWAYS)
#define LV_PROFILER_BEGIN_TAG(str) sched_note_beginex(NOTE_TAG_ALWAYS, str)
#define LV_PROFILER_END_TAG(str) sched_note_endex(NOTE_TAG_ALWAYS, str)
.. _profiler_faq:
FAQ
***
Perfetto log parsing fails
^^^^^^^^^^^^^^^^^^^^^^^^^^
Please check the completeness of the logs. If the logs are incomplete, it may be due to the following reasons:
1. Serial port reception errors caused by a high baud rate. You need to reduce the baud rate.
2. Data corruption caused by other thread logs inserted during the printing of trace logs. You need to disable the log output of other threads or refer to the configuration above to use a separate log output interface.
3. Make sure that the string passed in by :c:macro:`LV_PROFILER_BEGIN_TAG` or :c:macro:`LV_PROFILER_END_TAG` is not a local variable on the stack or a string in shared memory, because currently only the string address is recorded and the content is not copied.
Function execution time displayed as 0s in Perfetto
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If the function execution time is lower than the precision of the timestamps, this situation can occur. You can refer to the configuration instructions above to use a higher precision timestamp.
Significant stuttering occurs during profiling
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
When the buffer used to store trace events becomes full, the profiler will output all the data in the buffer, which can cause UI blocking and stuttering during the output. You can optimize this by taking the following measures:
1. Increase the value of :c:macro:`LV_PROFILER_BUILTIN_BUF_SIZE`. A larger buffer can reduce the frequency of log printing, but it also consumes more memory.
2. Optimize the execution time of log printing functions, such as increasing the serial port baud rate or improving file writing speed.
Trace logs are not being output
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If the trace logs are not automatically printed when the buffer is not full, you can try the following methods to force the log output:
1. Reduce the value of :c:macro:`LV_PROFILER_BUILTIN_BUF_SIZE` to fill the buffer more quickly and trigger automatic printing.
2. Manually call or use a timer to call the :cpp:func:`lv_profiler_builtin_flush` function to force the log output.

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.. _vg_lite_tvg:
=================
VG-Lite Simulator
=================
LVGL integrates a VG-Lite simulator based on ThorVG.
Its purpose is to simplify the debugging of VG-Lite adaptation and reduce the time of debugging and locating problems on hardware devices.
It has been integrated into the CI automated compilation and testing process to ensure that the VG-Lite rendering backend can be fully tested after each PR modification.
How It Works
************
Sort out the APIs in the ``vg_lite.h`` header file provided by the vendor, re-implement the APIs using `ThorVG <https://github.com/thorvg/thorvg>`_,
and simulate the same rendering images as the real hardware on the simulator.
Configuration
*************
1. Enable VG-Lite rendering backend, see :ref:`vglite`.
2. Enable ThorVG and turn on the configuration :c:macro:`LV_USE_THORVG_INTERNAL` or :c:macro:`LV_USE_THORVG_EXTERNAL`.
It is recommended to use the internal ThorVG library to ensure uniform rendering results.
3. Enable :c:macro:`LV_USE_VG_LITE_THORVG` and set :c:macro:`LV_DRAW_BUF_ALIGN` to 64. The rest of the options can remain default.
Make sure :c:macro:`LV_VG_LITE_USE_GPU_INIT` is enabled, because the thorvg drawing context needs to be initialized before it can be used.

17
docs/details/index.rst Normal file
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.. _reference:
=========
Reference
=========
.. toctree::
:maxdepth: 2
base-widget/index
widgets/index
main-components/index
other-components/index
../examples
debugging/index
integration/index
libs/index

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Output API as JSON data
=======================
We have written a script that will read the header files in LVGL and outputs a more friendly JSON format for the API.
This is done so that bindings that generate code automatically will have an easy way to collect the needed information
without having to reinvent the wheel. The JSON data format has already made libraries for reading the format for just
about every programming language out there.
The script in order to run does have some requirements.
- Python >= 3.10
- Pycparser >= 2.21: Python Library for reading the preprocessor ouotput from the C compiler
- PyMSVC >= 0.4.0: Python library is using MSVC Compiler
- C compiler, gcc for Linux, clang for OSX and MSVC for Windows
- Doxygen: used to read the docstrings from the header files.
There are several options when running the script. They are as follows
- `--output-path`: output directory for JSON file. If one is not supplied then it will be output stdout
- `--lvgl-config`: path to lv_conf.h (including file name), if this is not set then a config file will be
generated that has most common things turned on
- `--develop`: leaves the temporary folder in place.
to use the script
.. code-block:: shell
python /scripts/gen_json/gen_json.py --output-path=json/output/directory --lvgl-config=path/to/lv_conf.h
or if you want to run a subprocess from inside of a generation script and read the output from stdout
.. code-block:: shell
python /scripts/gen_json/gen_json.py --lvgl-config=path/to/lv_conf.h
The JSON data is broken apart into a couple of main categories.
- enums
- functions
- function_pointers
- structures
- unions
- variables
- typedefs
- forward_decls
- macros
Those categories are the element names undert the root of the JSON data.
The value for each categry is an array of JSON elements. There is a bit of
nesting with the elements in the arrays and I have created "json_types" that
will allow you to identify exactly what you are dealing with.
The different "json_types" are as follows:
- ``"array"``: The array type is used to identify arrays.
Available JSON fields:
- ``"dim"``: number of items in the array
- ``"quals"``: array of qualifiers, IE "const"
- ``"type"``: This may or may not be available.
- ``"name"``: the name of the data type
- ``"field"``: This type is used to describe fields in structures and unions.
It is used in the ``"fields"`` array of the ``"struct"`` and ``"union"`` JSON types.
Available JSON fields:
- ``"name"``: The name of the field.
- ``"type"``: This contains the type information for the field. Check the
``"json_type"`` to know what type you are dealing with.
- ``"bitsize"``: The number of bits the field has or ``null``
if there is no bit size defined
- ``"docstring"``: you should know what this is.
- ``"arg"``: Used to describe an argument/parameter in a function or a function pointer.
Available JSON fields:
- ``"name"``: The name of the argument/parameter.
- ``"type"``: This contains the type information for the field. Check the
``"json_type"`` to know what type you are dealing with.
- ``"docstring"``: you should know what this is.
- ``"quals"``: array of qualifiers, IE "const"
- ``"forward_decl"``: Describes a forward declaration.There are structures in
LVGL that are considered to be private and that is what these desccribe.
Available JSON fields:
- ``"name"``: The name of the formard declaration.
- ``"type"``: This contains the type information for the field. Check the
``"json_type"`` to know what type you are dealing with.
- ``"docstring"``: you should know what this is.
- ``"quals"``: array of qualifiers, IE "const"
- ``"function_pointer"``: Describes a function pointer. These are used when
registering callback functions in LVGL.
Available JSON fields:
- ``"name"``: The name of the function pointer.
- ``"type"``: This contains the return type information for the function pointer.
- ``"docstring"``: you should know what this is.
- ``"args"``: array of ``"arg"`` Widgets. This describes the fuction arguments/parameters.
- ``"quals"``: array of qualifiers, IE "const"
- ``"variable"``: Describes a global variable.
Available JSON fields:
- ``"name"``: The name of the variable.
- ``"type"``: This contains the type information for the field. Check the
``"json_type"`` to know what type you are dealing with.
- ``"docstring"``: you should know what this is.
- ``"quals"``: array of qualifiers, IE "const"
- ``"storage"``: array of storage classifiers, IE "extern"
- ``"special_type"``: Currently only used to describe an ellipsis argument
for a function.
Available JSON fields:
- ``"name"``: will always be "ellipsis".
- ``"primitive_type"``: This is a base type. There or no other types beneith this.
This tells you that the type is a basic or primitive C type.
IE: struct, union, int, unsigned int, etc...
Available JSON fields:
- ``"name"``: The name of the primitive type.
- ``"enum"``: Describes a grouping of enumeration items/members.
Available JSON fields:
- ``"name"``: The name of the enumeration group/type.
- ``"type"``: This contains the type information for the enumeration group.
This is always going to be an "int" type. Make sure you do not use this
type as the type for the members of this enumeration group. Check the
enumeration members type to get the correct type.
- ``"docstring"``: you should know what this is.
- ``"members"``: array of ``"enum_member"`` Widgets
- ``"enum_member"``: Describes an enumeration item/member. Only found under
the ``"members"`` field of an ``"enum"`` JSON type
Available JSON fields:
- ``"name"``: The name of the enumeration.
- ``"type"``: This contains the type information for the enum member.
This gets a bit tricky because the type specified in here is not always
going to be an "int". It will usually point to an lvgl type and the type
of the lvgl type can be found in the ``"typedefs"`` section.
- ``"docstring"``: you should know what this is.
- ``"value"``: the enumeration member/item's value
- ``"lvgl_type"``: This is a base type. There or no other types beneith this.
This tells you that the type is an LVGL data type.
Available JSON fields:
- ``"name"``: The name of the type.
- ``"quals"``: array of qualifiers, IE "const
- ``"struct"``: Describes a structure
Available JSON fields:
- ``"name"``: The name of the structure.
- ``"type"``: This contains the primitive type information for the structure.
- ``"docstring"``: you should know what this is.
- ``"fields"``: array of ``"field"`` elements.
- ``"quals"``: array of qualifiers, IE "const"
- ``"union"``: Describes a union
Available JSON fields:
- ``"name"``: The name of the union.
- ``"type"``: This contains the primitive type information for the union.
- ``"docstring"``: you should know what this is.
- ``"fields"``: array of ``"field"`` elements.
- ``"quals"``: array of qualifiers, IE "const"
- ``"macro"``: describes a macro. There is limited information that can be
collected about macros and in most cases a binding will need to have these
statically added to a binding. It is more for collecting the docstrings than
anything else.
Available JSON fields:
- ``"name"``: The name of the macro.
- ``"docstring"``: you should know what this is.
- ``"ret_type"``: return type from a function. This is only going to be seen in the ``"type"``
element of a ``"function"`` type.
Available JSON fields:
- ``"type"``: This contains the type information for the field. Check the
``"json_type"`` to know what type you are dealing with.
- ``"docstring"``: you should know what this is.
- ``"function"``: Describes a function.
Available JSON fields:
- ``"name"``: The name of the function.
- ``"type"``: This contains the type information for the return value.
- ``"docstring"``: you should know what this is.
- ``"args"``: array of ``"arg"`` json types. This describes the fuction arguments/parameters.
- ``"stdlib_type"``: This is a base type, meaning that there are no more
type levels beneith this. This tells us that the type is from the C stdlib.
Available JSON fields:
- ``"name"``: The name of the type.
- ``"quals"``: array of qualifiers, IE "const
- ``"unknown_type"``: This should not be seen. If it is then there needs to be
an adjustment made to the script. Please open an issue and let us know if you see this type.
Available JSON fields:
- ``"name"``: The name of the type.
- ``"quals"``: array of qualifiers, IE "const
- ``"pointer"``: This is a wrapper object to let you know that the type you
are dealing with is a pointer
Available JSON fields:
- ``"type"``: This contains the type information for the pointer. Check the
``"json_type"`` to know what type you are dealing with.
- ``"quals"``: array of qualifiers, IE "const", may or may not be available.
- ``"typedef"``: type definitions. I will explain more on this below.
Available JSON fields:
- ``"name"``: The name of the typedef.
- ``"type"``: This contains the type information for the field. Check the
``"json_type"`` to know what type you are dealing with.
- ``"docstring"``: you should know what this is.
- ``"quals"``: array of qualifiers, IE "const"
Here is an example of what the output will look like.
.. code-block:: json
{
"enums":[
{
"name":"_lv_result_t",
"type":{
"name":"int",
"json_type":"primitive_type"
},
"json_type":"enum",
"docstring":"LVGL error codes. ",
"members":[
{
"name":"LV_RESULT_INVALID",
"type":{
"name":"_lv_result_t",
"json_type":"lvgl_type"
},
"json_type":"enum_member",
"docstring":"",
"value":"0x0"
},
{
"name":"LV_RESULT_OK",
"type":{
"name":"_lv_result_t",
"json_type":"lvgl_type"
},
"json_type":"enum_member",
"docstring":"",
"value":"0x1"
}
]
}
],
"functions":[
{
"name":"lv_version_info",
"type":{
"type":{
"type":{
"name":"char",
"json_type":"primitive_type",
"quals":[
"const"
]
},
"json_type":"pointer",
"quals":[]
},
"json_type":"ret_type",
"docstring":""
},
"json_type":"function",
"docstring":"",
"args":[
{
"name":null,
"type":{
"name":"void",
"json_type":"primitive_type",
"quals":[]
},
"json_type":"arg",
"docstring":"",
"quals":[]
}
]
}
],
"function_pointers":[
{
"name":"lv_tlsf_walker",
"type":{
"type":{
"name":"void",
"json_type":"primitive_type",
"quals":[]
},
"json_type":"ret_type",
"docstring":""
},
"json_type":"function_pointer",
"docstring":"",
"args":[
{
"name":"ptr",
"type":{
"type":{
"name":"void",
"json_type":"primitive_type",
"quals":[]
},
"json_type":"pointer",
"quals":[]
},
"json_type":"arg",
"docstring":""
},
{
"name":"size",
"type":{
"name":"size_t",
"json_type":"stdlib_type",
"quals":[]
},
"json_type":"arg",
"docstring":""
},
{
"name":"used",
"type":{
"name":"int",
"json_type":"primitive_type",
"quals":[]
},
"json_type":"arg",
"docstring":""
},
{
"name":"user",
"type":{
"type":{
"name":"void",
"json_type":"primitive_type",
"quals":[]
},
"json_type":"pointer",
"quals":[]
},
"json_type":"arg",
"docstring":""
}
],
"quals":[]
}
],
"structures":[
{
"name":"_lv_gradient_cache_t",
"type":{
"name":"struct",
"json_type":"primitive_type"
},
"json_type":"struct",
"docstring":null,
"fields":[
{
"name":"color_map",
"type":{
"type":{
"name":"lv_color_t",
"json_type":"lvgl_type",
"quals":[]
},
"json_type":"pointer",
"quals":[]
},
"json_type":"field",
"bitsize":null,
"docstring":""
},
{
"name":"opa_map",
"type":{
"type":{
"name":"lv_opa_t",
"json_type":"lvgl_type",
"quals":[]
},
"json_type":"pointer",
"quals":[]
},
"json_type":"field",
"bitsize":null,
"docstring":""
},
{
"name":"size",
"type":{
"name":"uint32_t",
"json_type":"stdlib_type",
"quals":[]
},
"json_type":"field",
"bitsize":null,
"docstring":""
}
]
}
],
"unions":[],
"variables":[
{
"name":"lv_global",
"type":{
"name":"lv_global_t",
"json_type":"lvgl_type",
"quals":[]
},
"json_type":"variable",
"docstring":"",
"quals":[],
"storage":[
"extern"
]
}
],
"typedefs":[
{
"name":"lv_pool_t",
"type":{
"type":{
"name":"void",
"json_type":"primitive_type",
"quals":[]
},
"json_type":"pointer"
},
"json_type":"typedef",
"docstring":"",
"quals":[]
}
],
"forward_decls":[
{
"name":"lv_fragment_managed_states_t",
"type":{
"name":"struct",
"json_type":"primitive_type"
},
"json_type":"forward_decl",
"docstring":"",
"quals":[]
}
],
"macros":[
{
"name":"ZERO_MEM_SENTINEL",
"json_type":"macro",
"docstring":""
}
]
}

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@@ -0,0 +1,5 @@
===
Cpp
===
In progress: https://github.com/lvgl/lv_binding_cpp

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@@ -0,0 +1,13 @@
========
Bindings
========
.. toctree::
:maxdepth: 2
api_json
cpp
javascript
micropython
pikascript

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==========
JavaScript
==========
With `lv_binding_js <https://github.com/lvgl/lv_binding_js>`__ you can write lvgl with JavaScript.
It uses React's virtual DOM concept to manipulate lvgl UI components, providing a familiar React-like
experience to users.
**Code**
**Code Running on Real Device**
Table of Contents
-----------------
- `Features <#features>`__
- `Demo <#demo>`__
- `Building <#building>`__
- `Components <#components>`__
- `Font <#font>`__
- `Animation <#animation>`__
- `Style <#style>`__
- `JSAPI <#jsapi>`__
- `Thanks <#thanks>`__
Features
--------
- Support all lvgl built-in components
- Fully support lvgl flex and grid style
- support most lvgl style, just write like html5 css
- support dynamic load image
- Fully support lvgl animation
Demo
----
See the `demo <https://github.com/lvgl/lv_binding_js/tree/master/demo>`__ folder
Building
--------
The following are developer notes on how to build lvgljs on your native platform. They are not complete guides,
but include notes on the necessary libraries, compile flags, etc.
lvgljs
~~~~~~
- `ubuntu build Notes for sdl simulator <https://github.com/lvgl/lv_binding_js/blob/master/doc/build/build-ubuntu-arm.md>`__
- `macos x86 build Notes for sdl simulator <https://github.com/lvgl/lv_binding_js/blob/master/doc/build/build-macos-x86-simulator.md>`__
- `ubuntu build Notes for platform arm <https://github.com/lvgl/lv_binding_js/blob/master/doc/build/build-ubuntu-x86-simulator.md>`__
JS Bundle
~~~~~~~~~
- `JS Bundle build Notes <https://github.com/lvgl/lv_binding_js/blob/master/doc/build/js-bundle.md>`__
Components
----------
- `View <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/View.md>`__
- `Image <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Image.md>`__
- `Button <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Button.md>`__
- `Text <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Text.md>`__
- `Input <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Input.md>`__
- `Textarea <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Textarea.md>`__
- `Switch <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Switch.md>`__
- `Checkbox <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Checkbox.md>`__
- `Dropdownlist <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Dropdownlist.md>`__
- `ProgressBar <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/ProgressBar.md>`__
- `Line <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Line.md>`__
- `Roller <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Roller.md>`__
- `Keyboard <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Keyboard.md>`__
- `Calendar <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Calendar.md>`__
- `Chart <https://github.com/lvgl/lv_binding_js/blob/master/doc/component/Chart.md>`__
Font
----
- `Builtin-Symbol <https://github.com/lvgl/lv_binding_js/blob/master/doc/Symbol/symbol.md>`__
Animation
---------
- `Animation <https://github.com/lvgl/lv_binding_js/blob/master/doc/animate/animate.md>`__
Style
-----
.. include::https://github.com/lvgl/lv_binding_js/blob/master/doc/style/position-size-layout.md
- `position-size-layout <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/position-size-layout.md>`__
- `boxing-model <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/boxing-model.md>`__
- `color <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/color.md>`__
- `flex <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/flex.md>`__
- `grid <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/grid.md>`__
- `font <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/font.md>`__
- `opacity <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/opacity.md>`__
- `display <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/display.md>`__
- `background <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/background.md>`__
- `scroll <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/scroll.md>`__
- `shadow <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/shadow.md>`__
- `recolor <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/recolor.md>`__
- `line <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/line.md>`__
- `transition <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/transition.md>`__
- `transform <https://github.com/lvgl/lv_binding_js/blob/master/doc/style/transform.md>`__
JSAPI
-----
- `network <https://github.com/lvgl/lv_binding_js/blob/master/doc/jsapi/network.md>`__
- `filesystem <https://github.com/lvgl/lv_binding_js/blob/master/doc/jsapi/fs.md>`__
- `dimension <https://github.com/lvgl/lv_binding_js/blob/master/doc/jsapi/dimension.md>`__
Thanks
------
lvgljs depends on following excellent work
- `lvgl <https://github.com/lvgl/lvgl>`__: Create beautiful UIs for any MCU, MPU and display type
- `QuickJS <https://bellard.org/quickjs/>`__: JavaScript engine
- `libuv <https://github.com/libuv/libuv>`__: platform abstraction layer
- `curl <https://github.com/curl/curl>`__: HTTP client
- `txiki.js <https://github.com/saghul/txiki.js>`__: Tiny JavaScript runtime

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.. _micropython:
===========
MicroPython
===========
What is MicroPython?
--------------------
`MicroPython <http://micropython.org/>`__ is Python for microcontrollers. Using MicroPython, you can write Python3
code and run it even on a bare metal architecture with limited resources.
Highlights of MicroPython
~~~~~~~~~~~~~~~~~~~~~~~~~
- **Compact**: Fits and runs within just 256k of code space and 16k of RAM. No OS is needed, although you
can also run it with an OS, if you want.
- **Compatible**: Strives to be as compatible as possible with normal Python (known as CPython).
- **Versatile**: Supports many architectures (x86, x86-64, ARM, ARM Thumb, Xtensa).
- **Interactive**: No need for the compile-flash-boot cycle. With the REPL (interactive prompt) you can type
commands and execute them immediately, run scripts, etc.
- **Popular**: Many platforms are supported. The user base is growing bigger. Notable forks:
- `MicroPython <https://github.com/micropython/micropython>`__
- `CircuitPython <https://github.com/adafruit/circuitpython>`__
- `MicroPython_ESP32_psRAM_LoBo <https://github.com/loboris/MicroPython_ESP32_psRAM_LoBo>`__
- **Embedded Oriented**: Comes with modules specifically for embedded systems, such as the
`machine module <https://docs.micropython.org/en/latest/library/machine.html#classes>`__
for accessing low-level hardware (I/O pins, ADC, UART, SPI, I2C, RTC, Timers etc.)
--------------
Why MicroPython + LVGL?
-----------------------
MicroPython `does not have a good native high-level GUI library <https://forum.micropython.org/viewtopic.php?f=18&t=5543>`__.
LVGL is an `Object-Oriented Component Based <https://blog.lvgl.io/2018-12-13/extend-lvgl-objects>`__
high-level GUI library, which seems to be a natural candidate to map into a higher level language, such as Python.
LVGL is implemented in C and its APIs are in C.
Here are some advantages of using LVGL in MicroPython:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Develop GUI in Python, a very popular high level language. Use paradigms such as Object-Oriented Programming.
- Usually, GUI development requires multiple iterations to get things right. With C, each iteration consists of
**``Change code`` > ``Build`` > ``Flash`` > ``Run``**. In MicroPython it's just
**``Change code`` > ``Run``** ! You can even run commands interactively using the
`REPL <https://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop>`__ (the interactive prompt)
MicroPython + LVGL could be used for:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Fast prototyping GUI.
- Shortening the cycle of changing and fine-tuning the GUI.
- Modelling the GUI in a more abstract way by defining reusable composite Widgets, taking advantage of Python's language features
such as Inheritance, Closures, List Comprehension, Generators, Exception Handling, Arbitrary Precision Integers and others.
- Make LVGL accessible to a larger audience. No need to know C to create a nice GUI on an embedded system. This goes well with
`CircuitPython vision <https://learn.adafruit.com/welcome-to-circuitpython/what-is-circuitpython>`__.
CircuitPython was designed with education in mind, to make it easier for new or inexperienced users to get started with
embedded development.
- Creating tools to work with LVGL at a higher level (e.g. drag-and-drop designer).
--------------
So what does it look like?
--------------------------
It's very much like the C API, but Object-Oriented for LVGL components.
Let's dive right into an example!
A simple example
~~~~~~~~~~~~~~~~
.. code-block:: python
# Initialize
import display_driver
import lvgl as lv
# Create a button with a label
scr = lv.obj()
btn = lv.button(scr)
btn.align(lv.ALIGN.CENTER, 0, 0)
label = lv.label(btn)
label.set_text('Hello World!')
lv.screen_load(scr)
How can I use it?
-----------------
Online Simulator
~~~~~~~~~~~~~~~~
If you want to experiment with LVGL + MicroPython without downloading anything, you can use our online
simulator! It's a fully functional LVGL + MicroPython that runs entirely in the browser and allows you to
edit a python script and run it.
`Click here to experiment on the online simulator <https://sim.lvgl.io/>`__
Many :ref:`LVGL examples <examples>` are available also for MicroPython. Just click the link!
PC Simulator
~~~~~~~~~~~~
MicroPython is ported to many platforms. One notable port is "unix", which allows you to build and run MicroPython
(+LVGL) on a Linux machine. (On a Windows machine you might need Virtual Box or WSL or MinGW or Cygwin etc.)
`Click here to know more information about building and running the unix port <https://github.com/lvgl/lv_micropython>`__
Embedded Platforms
~~~~~~~~~~~~~~~~~~
In the end, the goal is to run it all on an embedded platform. Both MicroPython and LVGL can be used on many embedded
architectures. `lv_micropython <https://github.com/lvgl/lv_micropython>`__ is a fork of MicroPython+LVGL and currently
supports Linux, ESP32, STM32 and RP2. It can be ported to any other platform supported by MicroPython.
- You would also need display and input drivers. You can either use one of the existing drivers provided with lv_micropython,
or you can create your own input/display drivers for your specific hardware.
- Drivers can be implemented either in C as a MicroPython module, or in pure Python!
lv_micropython already contains these drivers:
- Display drivers:
- SDL on Linux
- X11 on Linux
- ESP32 specific:
- ILI9341
- ILI9488
- GC9A01
- ST7789
- ST7735
- Generic (pure Python):
- ILI9341
- ST7789
- ST7735
- Input drivers:
- SDL
- X11
- XPT2046
- FT6X36
- ESP32 ADC with resistive touch
Where can I find more information?
----------------------------------
- ``lv_micropython`` `README <https://github.com/lvgl/lv_micropython>`__
- ``lv_binding_micropython`` `README <https://github.com/lvgl/lv_binding_micropython>`__
- The `LVGL micropython forum <https://forum.lvgl.io/c/micropython>`__ (Feel free to ask anything!)
- At MicroPython: `docs <http://docs.micropython.org/en/latest/>`__ and `forum <https://forum.micropython.org/>`__
- `Blog Post <https://blog.lvgl.io/2019-02-20/micropython-bindings>`__, a little outdated.
The MicroPython Binding is auto generated!
------------------------------------------
- LVGL is a git submodule inside `lv_micropython <https://github.com/lvgl/lv_micropython>`__
(LVGL is a git submodule of `lv_binding_micropython <https://github.com/lvgl/lv_binding_micropython>`__
which is itself a submodule of `lv_micropython <https://github.com/lvgl/lv_micropython>`__).
- When building lv_micropython, the public LVGL C API is scanned and MicroPython API is auto-generated. That means that
lv_micropython provides LVGL API for **any** LVGL version, and generally does not require code changes as LVGL evolves.
LVGL C API Coding Conventions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For a summary of coding conventions to follow see the :ref:`coding-style`.
.. _memory_management:
Memory Management
~~~~~~~~~~~~~~~~~
- When LVGL runs in MicroPython, all dynamic memory allocations (:cpp:func:`lv_malloc`) are handled by MicroPython's memory
manager which is `garbage-collected <https://en.wikipedia.org/wiki/Garbage_collection_(computer_science)>`__ (GC).
- To prevent GC from collecting memory prematurely, all dynamic allocated RAM must be reachable by GC.
- GC is aware of most allocations, except from pointers on the `Data Segment <https://en.wikipedia.org/wiki/Data_segment>`__:
- Pointers which are global variables
- Pointers which are static global variables
- Pointers which are static local variables
Such pointers need to be defined in a special way to make them reachable by GC
Identify The Problem
^^^^^^^^^^^^^^^^^^^^
Problem happens when an allocated memory's pointer (return value of :cpp:func:`lv_malloc`) is stored only in either **global**,
**static global** or **static local** pointer variable and not as part of a previously allocated ``struct`` or other variable.
Solve The Problem
^^^^^^^^^^^^^^^^^
- Replace the global/static local var with :cpp:expr:`(LV_GLOBAL_DEFAULT()->_var)`
- Include ``lv_global.h`` on files that use ``LV_GLOBAL_DEFAULT``
- Add ``_var`` to ``lv_global_t`` on ``lv_global.h``
Example
^^^^^^^
More Information
^^^^^^^^^^^^^^^^
- `In the README <https://github.com/lvgl/lv_binding_micropython#memory-management>`__
- `In the Blog <https://blog.lvgl.io/2019-02-20/micropython-bindings#i-need-to-allocate-a-littlevgl-struct-such-as-style-color-etc-how-can-i-do-that-how-do-i-allocatedeallocate-memory-for-it>`__
.. _callbacks:
Callbacks
~~~~~~~~~
In C a callback is just a function pointer. But in MicroPython we need to register a *MicroPython callable object* for each
callback. Therefore in the MicroPython binding we need to register both a function pointer and a MicroPython object for every callback.
Therefore we defined a **callback convention** for the LVGL C API that expects lvgl headers to be defined in a certain
way. Callbacks that are declared according to the convention would allow the binding to register a MicroPython object
next to the function pointer when registering a callback, and access that object when the callback is called.
- The basic idea is that we have ``void * user_data`` field that is used automatically by the MicroPython Binding
to save the *MicroPython callable object* for a callback. This field must be provided when registering the function
pointer, and provided to the callback function itself.
- Although called "user_data", the user is not expected to read/write that field. Instead, the MicroPython glue code uses
``user_data`` to automatically keep track of the MicroPython callable object. The glue code updates it when the callback
is registered, and uses it when the callback is called in order to invoke a call to the original callable object.
There are a few options for defining a callback in LVGL C API:
- Option 1: ``user_data`` in a struct
- There's a struct that contains a field called ``void * user_data``
- A pointer to that struct is provided as the **first** argument of a callback registration function
- A pointer to that struct is provided as the **first** argument of the callback itself
- Option 2: ``user_data`` as a function argument
- A parameter called ``void * user_data`` is provided to the registration function as the **last** argument
- The callback itself receives ``void *`` as the **last** argument
- Option 3: both callback and ``user_data`` are struct fields
- The API exposes a struct with both function pointer member and ``user_data`` member
- The function pointer member receives the same struct as its **first** argument
In practice it's also possible to mix these options, for example provide a struct pointer when registering a callback
(option 1) and provide ``user_data`` argument when calling the callback (options 2),
**as long as the same ``user_data`` that was registered is passed to the callback when it's called**.
Examples
^^^^^^^^
- :cpp:type:`lv_anim_t` contains ``user_data`` field. :cpp:func:`lv_anim_set_path_cb` registers `path_cb` callback.
Both ``lv_anim_set_path_cb`` and :cpp:type:`lv_anim_path_cb_t` receive :cpp:type:`lv_anim_t` as their first argument
- ``path_cb`` field can also be assigned directly in the Python code because it's a member of :cpp:type:`lv_anim_t`
which contains ``user_data`` field, and :cpp:type:`lv_anim_path_cb_t` receive :cpp:type:`lv_anim_t` as its first argument.
- :cpp:func:`lv_imgfont_create` registers ``path_cb`` and receives ``user_data`` as the last argument.
The callback :cpp:type:`lv_imgfont_get_path_cb_t` also receives the ``user_data`` as the last argument.
.. _more-information-1:
More Information
^^^^^^^^^^^^^^^^
- In the `Blog <https://blog.lvgl.io/2019-08-05/micropython-pure-display-driver#using-callbacks>`__
and in the `README <https://github.com/lvgl/lv_binding_micropython#callbacks>`__
- `[v6.0] Callback conventions #1036 <https://github.com/lvgl/lvgl/issues/1036>`__
- Various discussions: `here <https://github.com/lvgl/lvgl/pull/3294#issuecomment-1184895335>`__
and `here <https://github.com/lvgl/lvgl/issues/1763#issuecomment-762247629>`__
and`here <https://github.com/lvgl/lvgl/issues/316#issuecomment-467221587>`__

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PikaScript
==========
What is PikaScript ?
--------------------
`PikaScript <https://github.com/pikasTech/pikascript>`__ is a Python interpreter designed specifically for
microcontrollers, and it supports a subset of the common Python3 syntax.
It's lighter, requiring only 32k of code space and 4k of RAM, which means it can run on stm32f103c8 (blue-pill)
or even stm32g030c8, on the other hand, you can leave valuable space for more material or larger buffer areas.
It is simpler, out of the box, runs with no porting and configuration at all, does not depend on OS or file
system, has good support for popular IDEs for Windows platforms like Keil, IAR, RT-Thread-Studio, and of course,
supports linux-gcc development platforms.
It's smarter, with a unique C module mechanism that allows you to generate bindings automatically by simply
writing the API for the C module in Python, and you don't need to deal with the headache of writing any macros
or global tables manually. On the other hand, all C modules have sophisticated smart hints, even hinting at the types
of your arguments .
--------------
Why PikaScript + LVGL ?
-----------------------
- PikaScript now supports the main features of LVGL8, and these APIs are fully compatible with MicroPython!
This means that you can continue to use already written code from MicroPython, and then use less code space and RAM.
- Enjoy detailed code hints down to the parameter type for a better programming experience
- Use a more convenient IDE, such as vs-based simulation projects
So how does it look like?
-------------------------
Here are some examples of lvgl that PikaScript can already run, they are mainly from the lvgl documentation examples
LV_ARC
~~~~~~
.. code-block:: python
import pika_lvgl as lv
import PikaStdLib
mem = PikaStdLib.MemChecker()
# Create an Arc
arc = lv.arc(lv.screen_active())
arc.set_end_angle(200)
arc.set_size(150, 150)
arc.center()
print('mem used max: %0.2f kB' % (mem.getMax()))
print('mem used now: %0.2f kB' % (mem.getNow()))
LV_BAR
~~~~~~
.. code-block:: python
import pika_lvgl as lv
import PikaStdLib
mem = PikaStdLib.MemChecker()
bar1 = lv.bar(lv.screen_active())
bar1.set_size(200, 20)
bar1.center()
bar1.set_value(70, lv.ANIM.OFF)
print('mem used max: %0.2f kB' % (mem.getMax()))
print('mem used now: %0.2f kB' % (mem.getNow()))
LV_BTN
~~~~~~
.. code-block:: python
import pika_lvgl as lv
import PikaStdLib
mem = PikaStdLib.MemChecker()
def event_cb_1(evt):
print('in evt1')
print('mem used now: %0.2f kB' % (mem.getNow()))
def event_cb_2(evt):
print('in evt2')
print('mem used now: %0.2f kB' % (mem.getNow()))
btn1 = lv.btn(lv.screen_active())
btn1.align(lv.ALIGN.TOP_MID, 0, 10)
btn2 = lv.btn(lv.screen_active())
btn2.align(lv.ALIGN.TOP_MID, 0, 50)
btn1.add_event_cb(event_cb_1, lv.EVENT.CLICKED, 0)
btn2.add_event_cb(event_cb_2, lv.EVENT.CLICKED, 0)
print('mem used max: %0.2f kB' % (mem.getMax()))
print('mem used now: %0.2f kB' % (mem.getNow()))
LV_CHECKBOX
~~~~~~~~~~~
.. code-block:: python
import pika_lvgl as lv
import PikaStdLib
mem = PikaStdLib.MemChecker()
cb = lv.checkbox(lv.screen_active())
cb.set_text("Apple")
cb.align(lv.ALIGN.TOP_LEFT, 0 ,0)
cb = lv.checkbox(lv.screen_active())
cb.set_text("Banana")
cb.add_state(lv.STATE.CHECKED)
cb.align(lv.ALIGN.TOP_LEFT, 0 ,30)
cb = lv.checkbox(lv.screen_active())
cb.set_text("Lemon")
cb.add_state(lv.STATE.DISABLED)
cb.align(lv.ALIGN.TOP_LEFT, 0 ,60)
cb = lv.checkbox(lv.screen_active())
cb.add_state(lv.STATE.CHECKED | lv.STATE.DISABLED)
cb.set_text("Melon")
cb.align(lv.ALIGN.TOP_LEFT, 0 ,90)
print('mem used max: %0.2f kB' % (mem.getMax()))
print('mem used now: %0.2f kB' % (mem.getNow()))
--------------
How does it work?
-----------------
PikaScript has a unique C module smart binding tool
Just write the Python interface in pika_lvgl.pyi (.pyi is the python interface file)
.. code-block:: python
# pika_lvgl.pyi
class arc(lv_obj):
def set_end_angle(self, angle: int): ...
def set_bg_angles(self, start: int, end: int): ...
def set_angles(self, start: int, end: int): ...
Then PikaScript's pre-compiler can automatically bind the following C functions, simply by naming the functions
in the module_class_method format, without any additional work, and all binding and registration is done automatically.
.. code-block:: c
/* pika_lvgl_arc.c */
void pika_lvgl_arc_set_end_angle(PikaObj* self, int angle) {
lv_obj_t* lv_obj = obj_getPtr(self, "lv_obj");
lv_arc_set_end_angle(lv_obj, angle);
}
void pika_lvgl_arc_set_bg_angles(PikaObj *self, int start, int end){
lv_obj_t* lv_obj = obj_getPtr(self, "lv_obj");
lv_arc_set_bg_angles(lv_obj, start, end);
}
void pika_lvgl_arc_set_angles(PikaObj *self, int start, int end){
lv_obj_t* lv_obj = obj_getPtr(self, "lv_obj");
lv_arc_set_angles(lv_obj, start, end);
}
To use the module, just ``import pika_lvgl`` and the precompiler will automatically scan main.py and bind the
``pika_lvgl`` module
.. code-block:: shell
$ ./rust-msc-latest-win10.exe
(pikascript) packages installed:
pikascript-core==v1.10.0
PikaStdLib==v1.10.0
PikaStdDevice==v1.10.0
(pikascript) pika compiler:
scanning main.py...
binding pika_lvgl.pyi...
The precompiler is written in Rust, runs on windows and linux, and is completely open source.
In addition to binding C modules, the precompiler compiles Python scripts to bytecode in the PC, reducing the
size of the script and increasing its speed.
--------------
How can I use it?
-----------------
The simulation repo on vs is available on https://github.com/pikasTech/lv_pikascript

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.. _build_cmake:
=====
CMake
=====
Overview
********
This project uses CMakePresets to ensure an easy build.
Find out more on Cmake Presets here: https://cmake.org/cmake/help/latest/manual/cmake-presets.7.html
Prerequisites
-------------
You need to install
- CMake
- Ninja (for Linux builds). Be sure to Add ninja to your PATH!
How to build this project using cmake
-------------------------------------
The recommended way to build this project is to use the provided CMakePresets.json. This file contains 2 configurations
- a windows (msvc) build using Visual Studio
- a linux (gcc) build using Ninja
More configurations will be added once available.
Build with IDE
--------------
The recommend way for consuming CMakePresets is a CMakePresets aware IDE such as
- VS 2022
- VS Code
- CLion
Simply load this project into your IDE and select your desired preset and you are good to go.
Build with CMake GUI
--------------------
Open this project with CMake GUI and select your desired preset. When hitting the generate button,
CMake will create solution files (for VS) or Ninja Files (for Linux Ninja Build)
The following targets are available.
- lvgl (the actual library, required)
- lvgl_thorvg (an vector graphics extension, optional)
- lvgl_examples (example usages, optional)
- lvgl_demos (some demos, optional)
All optional targets can be disabled by setting the proper cache variables.
If you use cmake to install lvgl 3 folders will be created.
- include/lvgl (contains all public headers)
- bin (contains all binaries (\*.dll))
- lib (contains all precompiled source files (\*.lib))
Build with Command line
-----------------------
You can also build your project using the command line. Run the following commands
- ``cmake --preset windows-base``
- ``cmake --build --preset windows-base_dbg``
- ``ctest --preset windows-base_dbg``

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=============
Build systems
=============
.. toctree::
:maxdepth: 2
make
cmake

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.. _build_make:
====
make
====
LVGL can be easily integrated into any Makefile project by adding ``include lvgl/lvgl.mk`` to the main ``Makefile``.

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.. _arm:
===
Arm
===
Arm is a leading semiconductor and software design company, renowned for creating the Cortex-M microcontroller (MCU) cores and Cortex-A/R (MPU) processor cores, which are integral to a wide range of devices. These cores are at the heart of many embedded systems, powering chips from industry giants such as STMicroelectronics, NXP, and Renesas. Arm's energy-efficient designs are used in billions of devices worldwide, from microcontrollers to smartphones and servers. By licensing their processor designs, Arm enables a broad ecosystem of partners to develop customized solutions optimized for performance, power, and size. Arm's architecture is highly compatible with various operating systems and software libraries, including LVGL, making it a versatile choice for developers creating efficient, high-performance graphical user interfaces.
Compile LVGL for Arm
--------------------
No specific action is required. Any compiler that supports the target Arm architecture can be used to compile LVGL's source code, including GCC, LLVM, and AC6.
It is also possible to cross-compile LVGL for an MPU (instead of compiling it on the target hardware) or create a shared library. For more information, check out :ref:`build_cmake`.
Getting Started with AC6
~~~~~~~~~~~~~~~~~~~~~~~~
Since AC6 is a proprietary toolchain, it contains many specific optimizations, so you can expect the best performance when using it.
AC6 is not free, but it offers a community license that can be activated as follows:
1. Download and install the AC6 compiler from `Arm's website <https://developer.arm.com/Tools%20and%20Software/Arm%20Compiler%20for%20Embedded>`__.
2. To register a community license, go to the ``bin`` folder of the compiler and, in a terminal, run ``armlm.exe activate -server https://mdk-preview.keil.arm.com -product KEMDK-COM0`` (On Linux, use ``./armlm``).
IDE Support
-----------
There are no limitations on the supported IDEs. LVGL works in various vendors' IDEs, including Arm's Keil MDK, IAR, Renesas's e2 studio, NXP's MCUXpresso, ST's CubeIDE, as well as custom make or CMake projects.
Arm2D and the Helium instruction set
------------------------------------
Arm Cortex-M55 and Cortex-M85 have the `SIMD Helium <https://www.arm.com/technologies/helium>`__ instruction set.
Among many others, this can effectively speed up UI rendering. :ref:`Arm2D <arm2d>` is a library maintained by Arm that leverages the Helium instruction set.
Note that GCC has some known issues with Helium intrinsics. It is recommended to use AC6 or LLVM when dealing with Helium code.
To add Arm2D to your project, follow these steps:
1. To utilize its power, ensure that ``mcpu`` is set to ``cortex-m85``, ``cortex-m55``, or ``cortex-m52`` and add the ``-fvectorize`` flag. To test without SIMD, use e.g. ``cortex-m85+nomve``.
2. Arm2D can be downloaded from `https://github.com/ARM-software/Arm-2D <https://github.com/ARM-software/Arm-2D>`__. Consider using the ``developing`` branch, which contains the latest updates.
3. Add ``Arm-2D/Library/Include`` to the include paths.
4. Copy ``Arm-2D/Library/Include/template/arm_2d_cfg.h`` to any location you prefer to provide the default configuration for Arm2D. Ensure that the folder containing ``arm_2d_cfg.h`` is added to the include path.
5. The Arm2D repository contains several examples and templates; however, ensure that only ``Arm-2D/Library/Source`` is compiled.
6. The CMSIS DSP library also needs to be added to the project. You can use CMSIS-PACKS or add it manually.
7. For better performance, enable ``LTO`` (Link Time Optimization) and use ``-Omax`` or ``-Ofast``.
8. Arm2D tries to read/write multiple data with a single instruction. Therefore, it's important to use the fastest memory (e.g., ``BSS`` or ``TCM``) for LVGL's buffer to avoid memory bandwidth bottlenecks.
9. Enable ``LV_USE_DRAW_ARM2D_SYNC 1`` and ``LV_USE_DRAW_SW_ASM LV_DRAW_SW_ASM_HELIUM`` in ``lv_conf.h``.
Neon Acceleration
-----------------
Several Cortex-A microprocessors support the `Neon SIMD <https://www.arm.com/technologies/neon>`__ instruction set. LVGL has built-in support to improve the performance of software rendering by utilizing Neon instructions. To enable Neon acceleration, set ``LV_USE_DRAW_SW_ASM`` to ``LV_DRAW_SW_ASM_NEON`` in ``lv_conf.h``.

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=============================
Espressif (ESP32 Chip Series)
=============================
LVGL can be used and configured as standard `ESP-IDF <https://github.com/espressif/esp-idf>`__ component.
If you are new to ESP-IDF, follow the instructions in the `ESP-IDF Programming guide <https://docs.espressif.com/projects/esp-idf/en/stable/esp32/get-started/index.html>`__ to install and set up ESP-IDF on your machine.
LVGL Demo Projects for ESP32
----------------------------
For a quick start with LVGL and ESP32, the following pre-configured demo projects are available for specific development boards:
- `ESP-BOX-3 <https://github.com/lvgl/lv_port_espressif_esp-box-3>`__
- `ESP32-S3-LCD-EV-BOARD <https://github.com/lvgl/lv_port_espressif_esp32-s3-lcd-ev-board>`__
- `M5Stack-CoreS3 <https://github.com/lvgl/lv_port_espressif_M5Stack_CoreS3>`__
Refer to the README.md files in these repositories for build and flash instructions.
These demo projects use Espressif's Board Support Packages (BSPs). Additional BSPs and examples are available in the `esp-bsp <https://github.com/espressif/esp-bsp>`__ repository.
Using LVGL in Your ESP-IDF Project
----------------------------------
The simplest way to integrate LVGL into your ESP-IDF project is via the `esp_lvgl_port <https://components.espressif.com/components/espressif/esp_lvgl_port>`__ component. This component, used in the demo projects mentioned above, provides helper functions for easy installation of LVGL and display drivers. Moreover, it can add support for touch, rotary encoders, button or USB HID inputs. It simplifies power savings, screen rotation and other platform specific nuances.
The esp_lvgl_port supports LVGL versions 8 and 9 and is compatible with ESP-IDF v4.4 and above. To add it to your project, use the following command:
.. code:: sh
idf.py add-dependency "espressif/esp_lvgl_port^2.3.0"
By default, esp_lvgl_port depends on the latest stable version of LVGL, so no additional steps are needed for new projects. If a specific LVGL version is required, specify this in your project to avoid automatic updates. LVGL can also be used without esp_lvgl_port, as described below.
Obtaining LVGL
~~~~~~~~~~~~~~
LVGL is distributed through `ESP Registry <https://components.espressif.com/>`__, where all LVGL releases are uploaded.
In case you do not want to use esp_lvgl_port, you can add `LVGL component <https://components.espressif.com/component/lvgl/lvgl>`__ into your project with following command:
.. code-block:: sh
idf.py add-dependency lvgl/lvgl^9.*
Adjust the ``^9.*`` part to match your LVGL version requirement. More information on version specifications can be found in the `IDF Component Manager documentation <https://docs.espressif.com/projects/idf-component-manager/en/latest/reference/versioning.html#range-specifications>`__. During the next build, the LVGL component will be fetched from the component registry and added to the project.
**Advanced usage: Use LVGL as local component**
For LVGL development and testing, it may be useful to use LVGL as a local component instead of from the ESP Registry, which offers only released versions and does not allow local modifications. To do this, clone LVGL to your project with the following command:
.. code-block:: sh
git submodule add https://github.com/lvgl/lvgl.git components/lvgl
.. note::
All components from ``${project_dir}/components`` are automatically added to build.
Configuration
~~~~~~~~~~~~~
To configure LVGL, launch the configuration menu with ``idf.py menuconfig`` in your project root directory. Navigate to ``Component config`` and then ``LVGL configuration``.
Support for Display and Touch Drivers
-------------------------------------
For successful LVGL project you will need a display driver and optionally a touch driver. Espressif provides these drivers that are built on its `esp_lcd <https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/lcd/index.html>`__ component.
- esp_lcd natively supports for some `basic displays <https://github.com/espressif/esp-idf/tree/master/components/esp_lcd/src>`__
- Other displays are maintained in `esp-bsp repository <https://github.com/espressif/esp-bsp/tree/master/components/lcd>`__ and are uploaded to ESP Registry
- Touch drivers are maintained in `esp-bsp repository <https://github.com/espressif/esp-bsp/tree/master/components/lcd_touch>`__ and are uploaded to ESP Registry
These components share a common public API, making it easy to migrate your projects across different display and touch drivers.
To add a display or touch driver to your project, use a command like:
.. code-block:: sh
idf.py add-dependency "espressif/esp_lcd_gc9a01^2.0.0"
Using the File System under ESP-IDF
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ESP-IDF uses the standard C functions (``fopen``, ``fread``) in all storage related APIs.
This allows seamless interoperability with LVGL when enabling the :c:macro:`LV_USE_FS_STDIO` configuration.
The process is described in details below, using ``SPIFFS`` as demonstration.
- **Decide what storage system you want to use**
ESP-IDF has many, ready-to-use examples like
`SPIFFS <https://github.com/espressif/esp-idf/tree/master/examples/storage/spiffsgen>`__
,
`SD Card <https://github.com/espressif/esp-idf/tree/master/examples/storage/sd_card/sdspi>`__
and
`LittleFS <https://github.com/espressif/esp-idf/tree/master/examples/storage/littlefs>`__
.
- **Re-configure your own project**
The example project should be examined for details, but in general the changes involve:
- Enabling LVGL's STDIO file system in the configuration
You can use ``menuconfig``:
- ``Component config → LVGL configuration → 3rd Party Libraries``: enable ``File system on top of stdio API``
- Then select ``Set an upper cased letter on which the drive will accessible`` and set it to ``65`` (ASCII **A**)
- You can also set ``Default driver letter`` to 65 to skip the prefix in file paths.
- Modifying the partition table
The exact configuration depends on your flash size and existing partitions,
but the new final result should look something like this:
.. csv-table:: Partition Table
nvs, data, nvs, 0x9000, 0x6000
phy_init, data, phy, 0xf000, 0x1000
factory, app, factory, 0x10000, 1400k
storage, data, spiffs, , 400k
.. note::
If you are not using a custom ``partition.csv`` yet, it can be added
via ``menuconfig`` (``Partition Table → Partition Table → Custom partition table CSV``).
- Apply changes to the build system
Some ESP file systems provide automatic generation from a host folder using CMake. The proper line(s) must be copied to ``main/CMakeLists.txt``
.. note::
``LittleFS`` has extra dependencies that should be added to ``main/idf_component.yml``
- **Prepare the image files**
LVGL's ``LVGLImage.py`` Python tool can be used to convert images to binary pixel map files.
It supports various formats and compression.
Meanwhile 3rd party libraries
(like :ref:`LodePNG<lodepng_rst>` and :ref:`Tiny JPEG<tjpgd>`)
allow using image files without conversion.
After preparing the files, they should be moved to the target device:
- If properly activated a **SPIFFS** file system based on the ``spiffs_image`` folder should be automatically generated and later flashed to the target
- Similar mechanism for **LittleFS** uses the ``flash_data`` folder, but it's only available for Linux hosts
- For the **SD Card**, a traditional file browser can be used
- **Invoke proper API calls in the application code**
The core functionality requires only a few lines. The following example draws the image as well.
.. code:: c
#include "esp_spiffs.h"
void lv_example_image_from_esp_fs(void) {
esp_vfs_spiffs_conf_t conf = {
.base_path = "/spiffs",
.partition_label = NULL,
.max_files = 5,
.format_if_mount_failed = false
};
esp_err_t ret = esp_vfs_spiffs_register(&conf);
if (ret != ESP_OK) {
ESP_LOGE(TAG, "Failed to register SPIFF filesystem");
return;
}
lv_obj_t * obj = lv_image_create(lv_screen_active());
lv_image_set_src(widget, "A:/spiffs/logo.bin");
lv_obj_center(widget);
}
- **Build and flash**
After calling ``idf.py build flash`` the picture should be displayed on the screen.
.. note::
Changes made by ``menuconfig`` are not being tracked in the repository if the ``sdkconfig`` file is added to ``.gitignore``, which is the default for many ESP-IDF projects.
To make your configuration permanent, add the following lines to ``sdkconfig.defaults``:
.. code:: c
CONFIG_PARTITION_TABLE_CUSTOM=y
CONFIG_LV_USE_FS_STDIO=y
CONFIG_LV_FS_STDIO_LETTER=65
CONFIG_LV_LV_FS_DEFAULT_DRIVE_LETTER=65

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============
Chip vendors
============
.. toctree::
:maxdepth: 2
arm
espressif
nxp
renesas
stm32

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===
NXP
===
NXP has integrated LVGL into the MCUXpresso SDK packages for several of our
microcontrollers as an optional software component, allowing easy evaluation and
migration into your product design. LVGL is a free and open-source embedded
graphic library with features that enable you to create embedded GUIs with
intuitive graphical elements, beautiful visual effects and a low memory
footprint. The complete graphic framework includes a variety of widgets for you
to use in the creation of your GUI, and supports more advanced functions such as
animations and anti-aliasing.
LVGL enables graphics in our free GUI Guider UI tool. It's available for use
with NXPs general purpose and crossover microcontrollers, providing developers
with a tool for creating complete, high quality GUI applications with LVGL.
Creating new project with LVGL
------------------------------
`Download an SDK for a supported board <https://www.nxp.com/design/software/embedded-software/littlevgl-open-source-graphics-library:LITTLEVGL-OPEN-SOURCE-GRAPHICS-LIBRARY?&tid=vanLITTLEVGL-OPEN-SOURCE-GRAPHICS-LIBRARY>`__
today and get started with your next GUI application. It comes fully configured
with LVGL (and with PXP/VGLite support if the modules are present), no
additional integration work is required.
HW acceleration for NXP iMX RT platforms
----------------------------------------
Depending on the RT platform used, the acceleration can be done by NXP PXP
(PiXel Pipeline) and/or the Verisilicon GPU through an API named VGLite. Each
accelerator has its own context that allows them to be used individually as well
simultaneously (in LVGL multithreading mode).
PXP accelerator
~~~~~~~~~~~~~~~
Basic configuration:
^^^^^^^^^^^^^^^^^^^^
- Select NXP PXP engine in "lv_conf.h": Set :c:macro:`LV_USE_PXP` to `1`.
- In order to use PXP as a draw unit, select in "lv_conf.h": Set :c:macro:`LV_USE_DRAW_PXP` to `1`.
- In order to use PXP to rotate the screen, select in "lv_conf.h": Set :c:macro:`LV_USE_ROTATE_PXP` to `1`.
- Enable PXP asserts in "lv_conf.h": Set :c:macro: `LV_USE_PXP_ASSERT` to `1`.
There are few PXP assertions that can stop the program execution in case the
c:macro:`LV_ASSERT_HANDLER` is set to `while(1);` (Halt by default). Else,
there will be logged just an error message via `LV_LOG_ERROR`.
- If :c:macro:`SDK_OS_FREE_RTOS` symbol is defined, FreeRTOS implementation
will be used, otherwise bare metal code will be included.
Basic initialization:
^^^^^^^^^^^^^^^^^^^^^
PXP draw initialization is done automatically in :cpp:func:`lv_init()` once the
PXP is enabled as a draw unit or to rotate the screen, no user code is required:
.. code-block:: c
#if LV_USE_DRAW_PXP || LV_USE_ROTATE_PXP
lv_draw_pxp_init();
#endif
During PXP initialization, a new draw unit `lv_draw_pxp_unit_t` will be created
with the additional callbacks, if :c:macro:`LV_USE_DRAW_PXP` is set to `1`:
.. code-block:: c
lv_draw_pxp_unit_t * draw_pxp_unit = lv_draw_create_unit(sizeof(lv_draw_pxp_unit_t));
draw_pxp_unit->base_unit.evaluate_cb = _pxp_evaluate;
draw_pxp_unit->base_unit.dispatch_cb = _pxp_dispatch;
draw_pxp_unit->base_unit.delete_cb = _pxp_delete;
and an addition thread `_pxp_render_thread_cb()` will be spawned in order to
handle the supported draw tasks.
.. code-block:: c
#if LV_USE_PXP_DRAW_THREAD
lv_thread_init(&draw_pxp_unit->thread, LV_THREAD_PRIO_HIGH, _pxp_render_thread_cb, 2 * 1024, draw_pxp_unit);
#endif
If `LV_USE_PXP_DRAW_THREAD` is not defined, then no additional draw thread will be created
and the PXP drawing task will get executed on the same LVGL main thread.
`_pxp_evaluate()` will get called after each task is being created and will
analyze if the task is supported by PXP or not. If it is supported, then an
preferred score and the draw unit id will be set to the task. An `score` equal
to `100` is the default CPU score. Smaller score means that PXP is capable of
drawing it faster.
`_pxp_dispatch()` is the PXP dispatcher callback, it will take a ready to draw
task (having the `DRAW_UNIT_ID_PXP` set) and will pass the task to the PXP draw
unit for processing.
`_pxp_delete()` will cleanup the PXP draw unit.
Features supported:
^^^^^^^^^^^^^^^^^^^
Several drawing features in LVGL can be offloaded to the PXP engine. The CPU is
available for other operations while the PXP is running. RTOS is required to
block the LVGL drawing thread and switch to another task or suspend the CPU for
power savings.
Supported draw tasks are available in "src/draw/nxp/pxp/lv_draw_pxp.c":
.. code-block:: c
switch(t->type) {
case LV_DRAW_TASK_TYPE_FILL:
lv_draw_pxp_fill(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_IMAGE:
lv_draw_pxp_img(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_LAYER:
lv_draw_pxp_layer(draw_unit, t->draw_dsc, &t->area);
break;
default:
break;
}
Additional, the screen rotation can be handled by the PXP:
.. code-block::c
void lv_draw_pxp_rotate(const void * src_buf, void * dest_buf, int32_t src_width, int32_t src_height,
int32_t src_stride, int32_t dest_stride, lv_display_rotation_t rotation,
lv_color_format_t cf);
- Fill area with color (w/o radius, w/o gradient) + optional opacity.
- Blit source image RGB565/ARGB888/XRGB8888 over destination.
RGB565/RGB888/ARGB888/XRGB8888 + optional opacity.
- Recolor source image RGB565.
- Scale and rotate (90, 180, 270 degree) source image RGB565.
- Blending layers (w/ same supported formats as blitting).
- Rotate screen (90, 180, 270 degree).
Known limitations:
^^^^^^^^^^^^^^^^^^
- PXP can only rotate at 90x angles.
- Rotation is not supported for images unaligned to blocks of 16x16 pixels. PXP
is set to process 16x16 blocks to optimize the system for memory bandwidth and
image processing time. The output engine essentially truncates any output
pixels after the desired number of pixels has been written. When rotating a
source image and the output is not divisible by the block size, the incorrect
pixels could be truncated and the final output image can look shifted.
- Recolor or transformation for images w/ opacity or alpha channel can't be
obtained in a single PXP pipeline configuration. Two or multiple steps would
be required.
- Buffer address must be aligned to 64 bytes: set :c:macro:`LV_DRAW_BUF_ALIGN`
to `64` in "lv_conf.h".
No stride alignment is required: set :c:macro:`LV_DRAW_BUF_STRIDE_ALIGN` to
`1` in "lv_conf.h".
Project setup:
^^^^^^^^^^^^^^
- Add PXP related source files (and corresponding headers if available) to
project:
- "src/draw/nxp/pxp/lv_draw_buf_pxp.c": draw buffer callbacks
- "src/draw/nxp/pxp/lv_draw_pxp_fill.c": fill area
- "src/draw/nxp/pxp/lv_draw_pxp_img.c": blit image (w/ optional recolor or
transformation)
- "src/draw/nxp/pxp/lv_draw_pxp_layer.c": layer blending
- "src/draw/nxp/pxp/lv_draw_pxp.c": draw unit initialization
- "src/draw/nxp/pxp/lv_pxp_cfg.c": init, deinit, run/wait PXP device
- "src/draw/nxp/pxp/lv_pxp_osa.c": OS abstraction (FreeRTOS or bare metal)
- "src/draw/nxp/pxp/lv_pxp_utils.c": function helpers
- PXP related code depends on two drivers provided by MCU SDK. These drivers
need to be added to project:
- fsl_pxp.c: PXP driver
- fsl_cache.c: CPU cache handling functions
PXP default configuration:
^^^^^^^^^^^^^^^^^^^^^^^^^^
- Implementation depends on multiple OS-specific functions. The struct
:cpp:struct:`pxp_cfg_t` with callback pointers is used as a parameter for the
:cpp:func:`lv_pxp_init()` function. Default implementation for FreeRTOS and
bare metal is provided in lv_pxp_osa.c.
- :cpp:func:`pxp_interrupt_init()`: Initialize PXP interrupt (HW setup,
OS setup)
- :cpp:func:`pxp_interrupt_deinit()`: Deinitialize PXP interrupt (HW setup,
OS setup)
- :cpp:func:`pxp_run()`: Start PXP job. Use OS-specific mechanism to block
drawing thread.
- :cpp:func:`pxp_wait()`: Wait for PXP completion.
VGLite accelerator
~~~~~~~~~~~~~~~~~~
Extra drawing features in LVGL can be handled by the VGLite engine. The
CPU is available for other operations while the VGLite is running. An
RTOS is required to block the LVGL drawing thread and switch to another
task or suspend the CPU for power savings.
Basic configuration:
^^^^^^^^^^^^^^^^^^^^
- Select NXP VGLite engine in "lv_conf.h": Set :c:macro:`LV_USE_DRAW_VGLITE` to
`1`. :c:macro:`SDK_OS_FREE_RTOS` symbol needs to be defined so that FreeRTOS
driver osal implementation will be enabled.
- Enable VGLite asserts in "lv_conf.h": Set :c:macro: `LV_USE_VGLITE_ASSERT` to
`1`.
VGLite assertions will verify the driver API status code and in any error, it
can stop the program execution in case the c:macro: `LV_ASSERT_HANDLER` is set
to `while(1);` (Halt by default). Else, there will be logged just an error
message via `LV_LOG_ERROR`.
Basic initialization:
^^^^^^^^^^^^^^^^^^^^^
Initialize VGLite GPU before calling :cpp:func:`lv_init()` by specifying the
width/height of tessellation window. The default values for tesselation width
and height, and command buffer size are in the SDK file "vglite_support.h".
.. code-block:: c
#if LV_USE_DRAW_VGLITE
#include "vg_lite.h"
#include "vglite_support.h"
#endif
...
#if LV_USE_DRAW_VGLITE
if(vg_lite_init(DEFAULT_VG_LITE_TW_WIDTH, DEFAULT_VG_LITE_TW_HEIGHT) != VG_LITE_SUCCESS)
{
PRINTF("VGLite init error. STOP.");
vg_lite_close();
while (1)
;
}
if (vg_lite_set_command_buffer_size(VG_LITE_COMMAND_BUFFER_SIZE) != VG_LITE_SUCCESS)
{
PRINTF("VGLite set command buffer. STOP.");
vg_lite_close();
while (1)
;
}
#endif
VGLite draw initialization is done automatically in :cpp:func:`lv_init()` once
the VGLite is enabled, no user code is required:
.. code-block:: c
#if LV_USE_DRAW_VGLITE
lv_draw_vglite_init();
#endif
During VGLite initialization, a new draw unit `lv_draw_vglite_unit_t` will be
created with the additional callbacks:
.. code-block:: c
lv_draw_vglite_unit_t * draw_vglite_unit = lv_draw_create_unit(sizeof(lv_draw_vglite_unit_t));
draw_vglite_unit->base_unit.evaluate_cb = _vglite_evaluate;
draw_vglite_unit->base_unit.dispatch_cb = _vglite_dispatch;
draw_vglite_unit->base_unit.delete_cb = _vglite_delete;
and an addition thread `_vglite_render_thread_cb()` will be spawned in order to
handle the supported draw tasks.
.. code-block:: c
#if LV_USE_VGLITE_DRAW_THREAD
lv_thread_init(&draw_vglite_unit->thread, LV_THREAD_PRIO_HIGH, _vglite_render_thread_cb, 2 * 1024, draw_vglite_unit);
#endif
If `LV_USE_VGLITE_DRAW_THREAD` is not defined, then no additional draw thread will be created
and the VGLite drawing task will get executed on the same LVGL main thread.
`_vglite_evaluate()` will get called after each task is being created and will
analyze if the task is supported by VGLite or not. If it is supported, then an
preferred score and the draw unit id will be set to the task. An `score` equal
to `100` is the default CPU score. Smaller score means that VGLite is capable of
drawing it faster.
`_vglite_dispatch()` is the VGLite dispatcher callback, it will take a ready to
draw task (having the `DRAW_UNIT_ID_VGLITE` set) and will pass the task to the
VGLite draw unit for processing.
`_vglite_delete()` will cleanup the VGLite draw unit.
Advanced configuration:
^^^^^^^^^^^^^^^^^^^^^^^
- Enable VGLite blit split in "lv_conf.h":
Set :c:macro: `LV_USE_VGLITE_BLIT_SPLIT` to `1`.
Enabling the blit split workaround will mitigate any quality degradation issue
on screen's dimension > 352 pixels.
.. code-block:: c
#define VGLITE_BLIT_SPLIT_THR 352
- By default, the blit split threshold is set to 352. Blits with width or height
higher than this value will be done in multiple steps. Value must be multiple
of stride alignment in px. For most color formats, the alignment is 16px
(except the index formats). Transformation will not be supported once with
the blit split.
- Enable VGLite draw task synchronously in "lv_conf.h":
Set :c:macro: `LV_USE_VGLITE_DRAW_ASYNC` to `1`.
Multiple draw tasks can be queued and flushed them once to the GPU based on
the GPU idle status. If GPU is busy, the task will be queued, and the VGLite
dispatcher will ask for a new available task. If GPU is idle, the queue with
any pending tasks will be flushed to the GPU. The completion status of draw
task will be sent to the main LVGL thread asynchronously.
Features supported:
^^^^^^^^^^^^^^^^^^^
Several drawing features in LVGL can be offloaded to the VGLite engine. The CPU
is available for other operations while the GPU is running. RTOS is required to
block the LVGL drawing thread and switch to another task or suspend the CPU for
power savings.
Supported draw tasks are available in "src/draw/nxp/pxp/lv_draw_vglite.c":
.. code-block:: c
switch(t->type) {
case LV_DRAW_TASK_TYPE_LABEL:
lv_draw_vglite_label(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_FILL:
lv_draw_vglite_fill(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_BORDER:
lv_draw_vglite_border(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_IMAGE:
lv_draw_vglite_img(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_ARC:
lv_draw_vglite_arc(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_LINE:
lv_draw_vglite_line(draw_unit, t->draw_dsc);
break;
case LV_DRAW_TASK_TYPE_LAYER:
lv_draw_vglite_layer(draw_unit, t->draw_dsc, &t->area);
break;
case LV_DRAW_TASK_TYPE_TRIANGLE:
lv_draw_vglite_triangle(draw_unit, t->draw_dsc);
break;
default:
break;
}
All the below operation can be done in addition with optional opacity.
- Fill area with color (w/ radius or gradient).
- Blit source image (any format from ``_vglite_src_cf_supported()``) over
destination (any format from ``_vglite_dest_cf_supported()``).
- Recolor source image.
- Scale and rotate (any decimal degree) source image.
- Blending layers (w/ same supported formats as blitting).
- Draw letters (blit bitmap letters / raster font).
- Draw full borders (LV_BORDER_SIDE_FULL).
- Draw arcs (w/ rounded edges).
- Draw lines (w/ dash or rounded edges).
- Draw triangles with color (w/ gradient).
Known limitations:
^^^^^^^^^^^^^^^^^^
- Source image alignment: The byte alignment requirement for a pixel depends on
the specific pixel format. Both buffer address and buffer stride must be
aligned. As general rule, the alignment is set to 16 pixels. This makes the
buffer address alignment to be 32 bytes for RGB565 and 64 bytes for ARGB8888.
- For pixel engine (PE) destination, the alignment should be 64 bytes for all
tiled (4x4) buffer layouts. The pixel engine has no additional alignment
requirement for linear buffer layouts (:c:macro:`VG_LITE_LINEAR`).
Project setup:
^^^^^^^^^^^^^^
- Add VGLite related source files (and corresponding headers if available) to
project:
- "src/draw/nxp/vglite/lv_draw_buf_vglite.c": draw buffer callbacks
- "src/draw/nxp/vglite/lv_draw_vglite_arc.c": draw arc
- "src/draw/nxp/vglite/lv_draw_vglite_border.c": draw border
- "src/draw/nxp/vglite/lv_draw_vglite_fill.c": fill area
- "src/draw/nxp/vglite/lv_draw_vglite_img.c": blit image (w/ optional recolor or transformation)
- "src/draw/nxp/vglite/lv_draw_vglite_label.c": draw label
- "src/draw/nxp/vglite/lv_draw_vglite_layer.c": layer blending
- "src/draw/nxp/vglite/lv_draw_vglite_line.c": draw line
- "src/draw/nxp/vglite/lv_draw_vglite_triangle.c": draw triangle
- "src/draw/nxp/vglite/lv_draw_vglite.c": draw unit initialization
- "src/draw/nxp/vglite/lv_vglite_buf.c": init/get vglite buffer
- "src/draw/nxp/vglite/lv_vglite_matrix.c": set vglite matrix
- "src/draw/nxp/vglite/lv_vglite_path.c": create vglite path data
- "src/draw/nxp/vglite/lv_vglite_utils.c": function helpers

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@@ -0,0 +1,224 @@
.. _renesas:
=======
Renesas
=======
`Renesas <https://renesas.com/>`__ is an official partner of LVGL. Therefore, LVGL contains built-in support for
`Dave2D <https://www.renesas.com/document/mas/tes-dave2d-driver-documentation>`__ (the GPU of Renesas) and we also maintain
ready-to-use Renesas projects.
Dave2D
------
Dave2D is capable of accelerating most of the drawing operations of LVGL:
- Rectangle drawing, even with gradients
- Image drawing, scaling, and rotation
- Letter drawing
- Triangle drawing
- Line drawing
As Dave2D works in the background, the CPU is free for other tasks. In practice, during rendering, Dave2D can reduce the CPU usage by
half or to one-third, depending on the application.
GLCDC
-----
GLCDC is a multi-stage graphics output peripheral available in several Renesas MCUs. It is able to drive LCD panels via a highly
configurable RGB interface.
More info can be found at the :ref:`driver's page<renesas_glcdc>`.
Supported boards
----------------
.. list-table::
:widths: 10 30 30 30
* -
- **EK-RA8D1**
- **EK-RA6M3G**
- **RX72N Envision Kit**
* - CPU
- 480MHz, Arm Cortex-M85 core
- 120MHz, Arm Cortex-M4 core
- 240MHz, Renesas RXv3 core
* - Memory
-
| 1MB internal, 64MB external SDRAM
| 2MB internal, 64MB External Octo-SPI Flash
-
| 640kB internal SRAM
| 2MB internal, 32MB external QSPI Flash
-
| 1MB internal SRAM
| 4MB internal, 32MB external QSPI Flash
* - Display
-
| 4.5”
| 480x854
| 2-lane MIPI
-
| 4.3”
| 480x272
| Parallel RGB565
-
| 4.3”
| 480x272
| Parallel RGB565
* - `Board <https://lvgl.io/boards>`__ video
- .. raw:: html
<iframe width="320" height="180" src="https://www.youtube.com/embed/WkJPB8wto_U" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
- .. raw:: html
<iframe width="320" height="180" src="https://www.youtube.com/embed/0kar4Ee3Qic" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
- .. raw:: html
<iframe width="320" height="180" src="https://www.youtube.com/embed/__56v8DsfH0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
* - Links
- `Demo repository for EK-RA8D1 <https://github.com/lvgl/lv_port_renesas_ek-ra8d1>`__
- `Demo repository for EK-RA6M3G <https://github.com/lvgl/lv_port_renesas_ek-ra6m3g>`__
- `Demo repository for RX72N Envision Kit <https://github.com/lvgl/lv_port_renesas_rx72n-envision-kit>`__
Get started with the Renesas ecosystem
--------------------------------------
.. |img_debug_btn| image:: /misc/renesas/debug_btn.png
:alt: Debug button
.. dropdown:: RA Family
- The official IDE of Renesas is called e² studio. As it's Eclipse-based, it runs on Windows, Linux, and Mac as well.
The RA family requires the latest version with FSP 5.3. It can be downloaded `here <https://www.renesas.com/us/en/software-tool/flexible-software-package-fsp>`__.
- JLink is used for debugging, it can be downloaded `here <https://www.segger.com/downloads/jlink/>`__.
- Clone the ready-to-use repository for your selected board:
.. code-block:: shell
git clone https://github.com/lvgl/lv_port_renesas_ek-ra8d1.git --recurse-submodules
Downloading the `.zip` from GitHub doesn't work as it doesn't download the submodules.
- Open e² studio, go to ``File`` -> ``Import project`` and select ``General`` / ``Existing projects into workspace``
- Browse the cloned folder and press ``Finish``.
- Double click on ``configuration.xml``. This will activate the `Configuration Window`.
Renesas' Flexible Software Package (FSP) incudes BSP and HAL layer support extended with multiple RTOS variants and other middleware stacks.
The components will be available via code generation, including the entry point of *"main.c"*.
Press ``Generate Project Content`` in the top right corner.
.. image:: /misc/renesas/generate.png
:alt: Code generation with FSP
- Build the project by pressing ``Ctrl`` + ``Alt`` + ``B``
- Click the Debug button (|img_debug_btn|). If prompted with `Debug Configurations`, on the `Debugger` tab select the ``J-Link ARM`` as `Debug hardware` and the proper IC as `Target Device`:
- ``R7FA8D1BH`` for EK-RA8D1
.. image:: /misc/renesas/debug_ra8.png
:alt: Debugger parameters for RA8
- ``R7FA6M3AH`` for EK-RA6M3G
.. image:: /misc/renesas/debug_ra6.png
:alt: Debugger parameters for RA6
.. note::
On EK-RA8D1 boards, the ``SW1`` DIP switch (middle of the board) 7 should be ON, all others are OFF.
.. dropdown:: RX Family
- The official IDE of Renesas is called e² studio. As it's Eclipse-based, it runs on Windows, Linux, and Mac as well.
It can be downloaded `here <https://www.renesas.com/us/en/software-tool/e-studio>`__.
- Download and install the required driver for the debugger
- for Windows: `64 bit here <https://www.renesas.com/us/en/document/uid/usb-driver-renesas-mcu-tools-v27700-64-bit-version-windows-os?r=488806>`__
and `32 bit here <https://www.renesas.com/us/en/document/uid/usb-driver-renesas-mcu-toolse2e2-liteie850ie850apg-fp5-v27700for-32-bit-version-windows-os?r=488806>`__
- for Linux: `here <https://www.renesas.com/us/en/document/swo/e2-emulator-e2-emulator-lite-linux-driver?r=488806>`__
- RX72 requires an external compiler for the RXv3 core. A free and open-source version is available
`here <https://llvm-gcc-renesas.com/rx-download-toolchains/>`__ after a registration.
The compiler must be activated in e² studio:
- Go to go to ``Help`` -> ``Add Renesas Toolchains``
- Press the ``Add...`` button
- Browse the installation folder of the toolchain
<br/>
.. image:: /misc/renesas/toolchains.png
:alt: Toolchains
- Clone the ready-to-use `lv_port_renesas_rx72n-envision-kit <https://github.com/lvgl/lv_port_renesas_rx72n-envision-kit.git>`__ repository:
.. code-block:: shell
git clone https://github.com/lvgl/lv_port_renesas_rx72n-envision-kit.git --recurse-submodules
Downloading the `.zip` from GitHub doesn't work as it doesn't download the submodules.
- Open e² studio, go to ``File`` -> ``Import project`` and select ``General`` / ``Existing projects into workspace``
- Select the cloned folder and press ``Finish``.
- Double click on ``RX72N_EnVision_LVGL.scfg``. This will activate the `Configuration Window`.
Renesas' Smart Configurator (SMC) incudes BSP and HAL layer support extended with multiple RTOS variants and other middleware stacks.
The components will be available via code generation, including the entry point of the application.
Press ``Generate Code`` in the top right corner.
.. image:: /misc/renesas/generate_smc.png
:alt: Code generation with SMC
- Build the project by pressing ``Ctrl`` + ``Alt`` + ``B``
- Click the Debug button (|img_debug_btn|). If prompted with `Debug Configurations`, on the `Debugger` tab select the ``E2 Lite``
as `Debug hardware` and ``R5F572NN`` as `Target Device`:
.. image:: /misc/renesas/debug_rx72.png
:alt: Debugger parameters for RX72
.. note::
Make sure that both channels of ``SW1`` DIP switch (next to ``ECN1``) are OFF.
Modify the project
------------------
Open a demo
~~~~~~~~~~~
The entry point of the main task is contained in ``src/LVGL_thread_entry.c`` in all 3 projects.
You can disable the LVGL demos (or just comment them out) and call some ``lv_example_...()`` functions, or add your custom code.
Configuration
~~~~~~~~~~~~~
``src/lv_conf.h`` contains the most important settings for LVGL. Namely:
- :c:macro:`LV_COLOR_DEPTH` to set LVGL's default color depth
- :c:macro:`LV_MEM_SIZE` to set the maximum RAM available for LVGL
- :c:macro:`LV_USE_DAVE2D` to enable the GPU
Hardware and software components can be modified in a visual way using the `Configuration Window`.
Support
-------
In case of any problems or questions open an issue in the corresponding repository.

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@@ -0,0 +1,295 @@
=====
STM32
=====
LVGL Can be added to `STM32CubeIDE <https://www.st.com/en/development-tools/stm32cubeide.html>`__
in a similar fashion to any other Eclipse-based IDE.
Including LVGL in a Project
---------------------------
- Create or open a project in STM32CubeIDE.
- Copy the entire LVGL folder to *[project_folder]/Drivers/lvgl*.
- In the STM32CubeIDE **Project Explorer** pane: right click on the
LVGL folder that you copied (you may need to refresh the view first
before it will appear), and select **Add/remove include path…**. If
this doesn't appear, or doesn't work, you can review your project
include paths under the **Project** -> **Properties** menu, and then
navigating to **C/C++ Build** -> **Settings** -> **Include paths**, and
ensuring that the LVGL directory is listed.
Now that the source files are included in your project, follow the instructions to
:ref:`add_lvgl_to_your_project` and to create the ``lv_conf.h`` file, and
initialise the display.
Bare Metal Example
------------------
A minimal example using STM32CubeIDE, and HAL. \* When setting up
**Pinout and Configuration** using the **Device Configuration Tool**,
select **System Core** -> **SYS** and ensure that **Timebase Source** is
set to **SysTick**. \* Configure any other peripherals (including the
LCD panel), and initialise them in *main.c*. \* ``#include "lvgl.h"`` in
the *main.c* file. \* Create some frame buffer(s) as global variables:
.. code-block:: c
/* Frame buffers
* Static or global buffer(s). The second buffer is optional
* TODO: Adjust color format and choose buffer size. DISPLAY_WIDTH * 10 is one suggestion. */
#define BYTES_PER_PIXEL (LV_COLOR_FORMAT_GET_SIZE(LV_COLOR_FORMAT_RGB565)) /* will be 2 for RGB565 */
#define BUFF_SIZE (DISPLAY_WIDTH * 10 * BYTES_PER_PIXEL)
static uint8_t buf_1[BUFF_SIZE];
static uint8_t buf_2[BUFF_SIZE];
- In your ``main()`` function, after initialising your CPU,
peripherals, and LCD panel, call :cpp:func:`lv_init` to initialise LVGL.
You can then create the display driver using
:cpp:func:`lv_display_create`, and register the frame buffers using
:cpp:func:`lv_display_set_buffers`.
.. code-block:: c
//Initialise LVGL UI library
lv_init();
lv_display_t * disp = lv_display_create(WIDTH, HEIGHT); /* Basic initialization with horizontal and vertical resolution in pixels */
lv_display_set_flush_cb(disp, my_flush_cb); /* Set a flush callback to draw to the display */
lv_display_set_buffers(disp, buf_1, buf_2, sizeof(buf_1), LV_DISPLAY_RENDER_MODE_PARTIAL); /* Set an initialized buffer */
- Create some dummy Widgets to test the output:
.. code-block:: c
/* Change Active Screen's background color */
lv_obj_set_style_bg_color(lv_screen_active(), lv_color_hex(0x003a57), LV_PART_MAIN);
lv_obj_set_style_text_color(lv_screen_active(), lv_color_hex(0xffffff), LV_PART_MAIN);
/* Create a spinner */
lv_obj_t * spinner = lv_spinner_create(lv_screen_active(), 1000, 60);
lv_obj_set_size(spinner, 64, 64);
lv_obj_align(spinner, LV_ALIGN_BOTTOM_MID, 0, 0);
- Add a call to :cpp:func:`lv_timer_handler` inside your ``while(1)`` loop:
.. code-block:: c
/* Infinite loop */
while (1)
{
lv_timer_handler();
HAL_Delay(5);
}
- Add a call to :cpp:func:`lv_tick_inc` inside the :cpp:func:`SysTick_Handler` function. Open the *stm32xxxx_it.c*
file (the name will depend on your specific MCU), and update the :cpp:func:`SysTick_Handler` function:
.. code-block:: c
void SysTick_Handler(void)
{
/* USER CODE BEGIN SysTick_IRQn 0 */
HAL_SYSTICK_IRQHandler();
lv_tick_inc(1);
#ifdef USE_RTOS_SYSTICK
osSystickHandler();
#endif
/* USER CODE END SysTick_IRQn 0 */
HAL_IncTick();
/* USER CODE BEGIN SysTick_IRQn 1 */
/* USER CODE END SysTick_IRQn 1 */
}
- Finally, write the callback function, ``my_flush_cb``, which will send the display buffer to your LCD panel. Below is
one example, but it will vary depending on your setup.
.. code-block:: c
void my_flush_cb(lv_display_t * disp, const lv_area_t * area, lv_color_t * color_p)
{
//Set the drawing region
set_draw_window(area->x1, area->y1, area->x2, area->y2);
int height = area->y2 - area->y1 + 1;
int width = area->x2 - area->x1 + 1;
//We will do the SPI write manually here for speed
HAL_GPIO_WritePin(DC_PORT, DC_PIN, GPIO_PIN_SET);
//CS low to begin data
HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_RESET);
//Write colour to each pixel
for (int i = 0; i < width * height; i++) {
uint16_t color_full = (color_p->red << 11) | (color_p->green << 5) | (color_p->blue);
parallel_write(color_full);
color_p++;
}
//Return CS to high
HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_SET);
/* IMPORTANT!!!
* Inform the graphics library that you are ready with the flushing */
lv_display_flush_ready(disp);
}
FreeRTOS Example
----------------
A minimal example using STM32CubeIDE, HAL, and CMSISv1 (FreeRTOS).
*Note that we have not used Mutexes in this example, however LVGL is* **NOT**
*thread safe and so Mutexes should be used*. See: :ref:`threading`
\* ``#include "lvgl.h"`` \* Create your frame buffer(s) as global variables:
.. code-block:: c
/* Frame buffers
* Static or global buffer(s). The second buffer is optional */
#define BYTES_PER_PIXEL (LV_COLOR_FORMAT_GET_SIZE(LV_COLOR_FORMAT_RGB565)) /* will be 2 for RGB565 */
/* TODO: Declare your own BUFF_SIZE appropriate to your system. */
static lv_color_t buf_1[BUFF_SIZE];
#define BUFF_SIZE (DISPLAY_WIDTH * 10 * BYTES_PER_PIXEL)
static uint8_t buf_1[BUFF_SIZE];
static lv_color_t buf_2[BUFF_SIZE];
- In your ``main`` function, after your peripherals (SPI, GPIOs, LCD
etc) have been initialised, initialise LVGL using :cpp:func:`lv_init`,
create a new display driver using :cpp:func:`lv_display_create`, and
register the frame buffers using :cpp:func:`lv_display_set_buffers`.
.. code-block:: c
/* Initialise LVGL UI library */
lv_init();
lv_display_t *display = lv_display_create(WIDTH, HEIGHT); /* Create the display */
lv_display_set_flush_cb(display, my_flush_cb); /* Set a flush callback to draw to the display */
lv_display_set_buffers(disp, buf_1, buf_2, sizeof(buf_1), LV_DISPLAY_RENDER_MODE_PARTIAL); /* Set an initialized buffer */
/* Register the touch controller with LVGL - Not included here for brevity. */
- Create some dummy Widgets to test the output:
.. code-block:: c
/* Change Active Screen's background color */
lv_obj_set_style_bg_color(lv_screen_active(), lv_color_hex(0x003a57), LV_PART_MAIN);
lv_obj_set_style_text_color(lv_screen_active(), lv_color_hex(0xffffff), LV_PART_MAIN);
/* Create a spinner */
lv_obj_t * spinner = lv_spinner_create(lv_screen_active(), 1000, 60);
lv_obj_set_size(spinner, 64, 64);
lv_obj_align(spinner, LV_ALIGN_BOTTOM_MID, 0, 0);
- Create two threads to call :cpp:func:`lv_timer_handler`, and
:cpp:func:`lv_tick_inc`.You will need two ``osThreadId`` handles for
CMSISv1. These don't strictly have to be globally accessible in this
case, however STM32Cube code generation does by default. If you are
using CMSIS and STM32Cube code generation it should look something
like this:
.. code-block:: c
//Thread Handles
osThreadId lvgl_tickHandle;
osThreadId lvgl_timerHandle;
/* definition and creation of lvgl_tick */
osThreadDef(lvgl_tick, LVGLTick, osPriorityNormal, 0, 1024);
lvgl_tickHandle = osThreadCreate(osThread(lvgl_tick), NULL);
//LVGL update timer
osThreadDef(lvgl_timer, LVGLTimer, osPriorityNormal, 0, 1024);
lvgl_timerHandle = osThreadCreate(osThread(lvgl_timer), NULL);
- And create the thread functions:
.. code-block:: c
/* LVGL timer for tasks. */
void LVGLTimer(void const * argument)
{
for(;;)
{
lv_timer_handler();
osDelay(20);
}
}
/* LVGL tick source */
void LVGLTick(void const * argument)
{
for(;;)
{
lv_tick_inc(10);
osDelay(10);
}
}
- Finally, create the ``my_flush_cb`` function to output the frame
buffer to your LCD. The specifics of this function will vary
depending on which MCU features you are using. Below is an example
for a typical MCU interface.
.. code-block:: c
void my_flush_cb(lv_display_t * display, const lv_area_t * area, uint8_t * px_map);
{
uint16_t * color_p = (uint16_t *)px_map;
//Set the drawing region
set_draw_window(area->x1, area->y1, area->x2, area->y2);
int height = area->y2 - area->y1 + 1;
int width = area->x2 - area->x1 + 1;
//Begin SPI Write for DATA
HAL_GPIO_WritePin(DC_PORT, DC_PIN, GPIO_PIN_SET);
HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_RESET);
//Write colour to each pixel
for (int i = 0; i < width * height; i++) {
parallel_write(color_p);
color_p++;
}
//Return CS to high
HAL_GPIO_WritePin(CS_PORT, CS_PIN, GPIO_PIN_SET);
/* IMPORTANT!!!
* Inform the graphics library that you are ready with the flushing */
lv_display_flush_ready(display);
}
.. _dma2d:
DMA2D Support
-------------
LVGL supports DMA2D - a feature of some STM32 MCUs which can improve performance
when blending fills and images. Some STM32 product lines such as STM32F4 STM32F7, STM32L4,
STM32U5, and STM32H7 include models with DMA2D support.
LVGL's integration with DMA2D can be enabled by setting ``LV_USE_DRAW_DMA2D``
to ``1`` in ``lv_conf.h``
With ``LV_USE_DRAW_DMA2D_INTERRUPT`` set to ``0`` and ``LV_USE_OS`` set to ``LV_OS_NONE``,
DMA2D will draw some fills and images concurrently with the software render where
possible. If ``LV_USE_DRAW_DMA2D_INTERRUPT`` is set to ``1`` and ``LV_USE_OS`` set to
``LV_OS_FREERTOS`` (or another OS) the main difference will be that the core will idle
instead of "busywait" while waiting for a DMA2D transfer to complete.
If ``LV_USE_DRAW_DMA2D_INTERRUPT`` is enabled then you are required to call
:cpp:expr:`lv_draw_dma2d_transfer_complete_interrupt_handler` whenever the DMA2D
"transfer complete" global interrupt is received.
If your STM device has a Nema GPU, you can use the :ref:`Nema GFX renderer <stm32_nema_gfx>` instead.

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=========================
X11 Display/Inputs driver
=========================
Overview
--------
| The **X11** display/input `driver <https://github.com/lvgl/lvgl/src/drivers/x11>`__ offers support for simulating the LVGL display and keyboard/mouse inputs in an X11 desktop window.
| It is an alternative to **Wayland**, **XCB**, **SDL** or **Qt**.
The main purpose for this driver is for testing/debugging the LVGL application in a **Linux** simulation window.
Prerequisites
-------------
The X11 driver uses XLib to access the linux window manager.
1. Install XLib: ``sudo apt-get install libx11-6`` (should be installed already)
2. Install XLib development package: ``sudo apt-get install libx11-dev``
Configure X11 driver
--------------------
1. Enable the X11 driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_X11 1
2. Optional configuration options:
- Direct Exit
.. code-block:: c
#define LV_X11_DIRECT_EXIT 1 /* preferred default - ends the application automatically if last window has been closed */
// or
#define LV_X11_DIRECT_EXIT 0 /* application is responsible for ending the application (e.g. by own LV_EVENT_DELETE handler */
- Double buffering
.. code-block:: c
#define LV_X11_DOUBLE_BUFFER 1 /* preferred default */
// or
#define LV_X11_DOUBLE_BUFFER 0 /* not recommended */
- Render mode
.. code-block:: c
#define LV_X11_RENDER_MODE_PARTIAL 1 /* LV_DISPLAY_RENDER_MODE_PARTIAL, preferred default */
// or
#define LV_X11_RENDER_MODE_DIRECT 1 /* LV_DISPLAY_RENDER_MODE_DIRECT, not recommended for X11 driver */
// or
#define LV_X11_RENDER_MODE_DULL 1 /* LV_DISPLAY_RENDER_MODE_FULL, not recommended for X11 driver */
Usage
-----
| The minimal initialisation opening a window and enabling keyboard/mouse support
| (e.g. in main.c, LV_X11_DIRECT_EXIT must be 1):
.. code-block:: c
int main(int argc, char ** argv)
{
...
/* initialize X11 display driver */
lv_display_t * disp = lv_x11_window_create("LVGL X11 Simulation", monitor_hor_res, monitor_ver_res);
/* initialize X11 input drivers (for keyboard, mouse & mousewheel) */
lv_x11_inputs_create(disp, NULL);
...
while(true)
{
...
/* Periodically call the lv_timer handler */
lv_timer_handler();
}
}
| Full initialisation with mouse pointer symbol and own application exit handling
| (dependent on LV_X11_DIRECT_EXIT (can be 1 or 0))
.. code-block:: c
bool terminated = false;
#if !LV_X11_DIRECT_EXIT
static void on_close_cb(lv_event_t * e)
{
...
terminate = true;
}
#endif
int main(int argc, char ** argv)
{
...
/* initialize X11 display driver */
lv_display_t * disp = lv_x11_window_create("LVGL X11 Simulation", monitor_hor_res, monitor_ver_res);
lv_display_add_event_cb(disp, on_close_cb, LV_EVENT_DELETE, disp);
/* initialize X11 input drivers (for keyboard, mouse & mousewheel) */
LV_IMAGE_DECLARE(my_mouse_cursor_icon);
lv_x11_inputs_create(disp, &my_mouse_cursor_icon);
#if !LV_X11_DIRECT_EXIT
/* set optional window close callback to enable application cleanup and exit */
lv_x11_window_set_close_cb(disp, on_close_cb, disp);
#endif
...
while(!terminated)
{
...
/* Periodically call the lv_timer handler */
lv_timer_handler();
}
}

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========================
Linux Framebuffer Driver
========================
Overview
--------
The Linux framebuffer (fbdev) is a linux subsystem used to display graphics. It is a hardware-independent API that gives user space software
access to the framebuffer (the part of a computer's video memory containing a current video frame) using only the Linux kernel's own basic
facilities and its device file system interface, avoiding the need for libraries that implement video drivers in user space.
Prerequisites
-------------
Your system has a framebuffer device configured (usually under ``/dev/fb0``).
Configuring the driver
----------------------
Enable the framebuffer driver support in lv_conf.h, by cmake compiler define or by KConfig. Additionally you may configure the rendering
mode.
.. code-block:: c
#define LV_USE_LINUX_FBDEV 1
#define LV_LINUX_FBDEV_RENDER_MODE LV_DISPLAY_RENDER_MODE_PARTIAL
Usage
-----
To set up a framebuffer-based display, first create a display with ``lv_linux_fbdev_create``. Afterwards set the framebuffer device
node on the display (usually this is ``/dev/fb0``).
.. code-block:: c
lv_display_t *disp = lv_linux_fbdev_create();
lv_linux_fbdev_set_file(disp, "/dev/fb0");
If your screen stays black or only draws partially, you can try enabling direct rendering via ``LV_DISPLAY_RENDER_MODE_DIRECT``. Additionally,
you can activate a force refresh mode with ``lv_linux_fbdev_set_force_refresh(true)``. This usually has a performance impact though and shouldn't
be enabled unless really needed.

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=================================================
Generic MIPI DCS compatible LCD Controller driver
=================================================
Overview
--------
From the `Wikipedia <https://en.wikipedia.org/wiki/MIPI_Alliance>`__:
`MIPI Alliance <https://www.mipi.org/>`__ is a global business alliance that develops technical specifications
for the mobile ecosystem, particularly smart phones but including mobile-influenced industries. MIPI was founded in 2003 by Arm, Intel, Nokia, Samsung,
STMicroelectronics and Texas Instruments.
MIPI Alliance published a series of specifications related to display devices, including DBI (Display Bus Interface), DSI (Display Serial Interface) and DCS
(Display Command Set). Usually when one talks about a MIPI-compatible display, one thinks of a device with a DSI serial interface. However, the Display Bus Interface specification
includes a number of other, legacy interfaces, like SPI serial, or i8080-compatible parallel interface, which are often used to interface LCD displays to lower-end microcontrollers.
Furthermore, the DCS specification contains a standard command set, which is supported by a large number of legacy TFT LCD controllers, including the popular Sitronix
(ST7735, ST7789, ST7796) and Ilitek (ILI9341) SOCs. These commands provide a common interface to configure display orientation, color resolution, various power modes, and provide generic video memory access. On top
of that standard command set each LCD controller chip has a number of vendor-specific commands to configure voltage generator levels, timings, or gamma curves.
.. note::
It is important to understand that this generic MIPI LCD driver is not a hardware driver for displays with the DSI ("MIPI") serial interface. Instead, it implements the MIPI DCS command set used in many LCD controllers with an SPI or i8080 bus, and provides a common framework for chip-specific display controllers.
.. tip::
Although this is a generic driver, it can be used to support compatible chips which do not have a specific driver.
Prerequisites
-------------
There are no prerequisites.
Configuring the driver
----------------------
Enable the generic MIPI LCD driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_GENERIC_MIPI 1
.. note::
:c:macro:`LV_USE_GENERIC_MIPI` is automatically enabled when a compatible driver is enabled.
Usage
-----
You need to implement two platform-dependent functions:
.. code-block:: c
/* Send short command to the LCD. This function shall wait until the transaction finishes. */
int32_t my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
int32_t my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
The only difference between the :cpp:func:`my_lcd_send_cmd()` and :cpp:func:`my_lcd_send_color()` functions is that :cpp:func:`my_lcd_send_cmd()` is used to send short commands and it is expected
complete the transaction when it returns (in other words, it should be blocking), while :cpp:func:`my_lcd_send_color()` is only used to send pixel data, and it is recommended to use
DMA to transmit data in the background. More sophisticated methods can be also implemented, like queuing transfers and scheduling them in the background.
Please note that while display flushing is handled by the driver, it is the user's responsibility to call :cpp:func:`lv_display_flush_ready()`
when the color transfer completes. In case of a DMA transfer this is usually done in a transfer ready callback.
.. note::
While it is acceptable to use a blocking implementation for the pixel transfer as well, performance will suffer.
.. tip::
Care must be taken to avoid sending a command while there is an active transfer going on in the background. It is the user's responsibility to implement this either
by polling the hardware, polling a global variable (which is reset at the end of the transfer), or by using a semaphore or other locking mechanism.
Please also note that the driver does not handle the draw buffer allocation, because this may be platform-dependent, too. Thus you need to allocate the buffers and assign them
to the display object as usual by calling :cpp:func:`lv_display_set_buffers()`.
The driver can be used to create multiple displays. In such a configuration the callbacks must be able to distinguish between the displays. Usually one would
implement a separate set of callbacks for each display. Also note that the user must take care of arbitrating the bus when multiple devices are connected to it.
Example
-------
.. note::
You can find a step-by-step guide and the actual implementation of the callbacks on an STM32F746 using STM32CubeIDE and the ST HAL libraries here: :ref:`lcd_stm32_guide`
.. code-block:: c
#include "src/drivers/display/st7789/lv_st7789.h"
#define LCD_H_RES 240
#define LCD_V_RES 320
#define LCD_BUF_LINES 60
lv_display_t *my_disp;
...
/* Initialize LCD I/O bus, reset LCD */
static int32_t my_lcd_io_init(void)
{
...
return HAL_OK;
}
/* Send command to the LCD controller */
static void my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send pixel data to the LCD controller */
static void my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
int main(int argc, char ** argv)
{
...
/* Initialize LVGL */
lv_init();
/* Initialize LCD bus I/O */
if (my_lcd_io_init() != 0)
return;
/* Create the LVGL display object and the LCD display driver */
my_disp = lv_lcd_generic_mipi_create(LCD_H_RES, LCD_V_RES, LV_LCD_FLAG_NONE, my_lcd_send_cmd, my_lcd_send_color);
/* Set display orientation to landscape */
lv_display_set_rotation(my_disp, LV_DISPLAY_ROTATION_90);
/* Configure draw buffers, etc. */
uint8_t * buf1 = NULL;
uint8_t * buf2 = NULL;
uint32_t buf_size = LCD_H_RES * LCD_BUF_LINES * lv_color_format_get_size(lv_display_get_color_format(my_disp));
buf1 = lv_malloc(buf_size);
if(buf1 == NULL) {
LV_LOG_ERROR("display draw buffer malloc failed");
return;
}
/* Allocate secondary buffer if needed */
...
lv_display_set_buffers(my_disp, buf1, buf2, buf_size, LV_DISPLAY_RENDER_MODE_PARTIAL);
ui_init(my_disp);
while(true) {
...
/* Periodically call the lv_timer handler */
lv_timer_handler();
}
}
Advanced topics
---------------
Create flags
^^^^^^^^^^^^
The third argument of the :cpp:func:`lv_lcd_generic_mipi_create()` function is a flag array. This can be used to configure the orientation and RGB ordering of the panel if the
default settings do not work for you. In particular, the generic MIPI driver accepts the following flags:
.. code-block:: c
LV_LCD_FLAG_NONE
LV_LCD_FLAG_MIRROR_X
LV_LCD_FLAG_MIRROR_Y
LV_LCD_FLAG_BGR
You can pass multiple flags by ORing them together, e.g., :c:macro:`LV_LCD_FLAG_MIRROR_X` ``|`` :c:macro:`LV_LCD_FLAG_BGR`.
Custom command lists
^^^^^^^^^^^^^^^^^^^^
While the chip-specific drivers do their best to initialize the LCD controller correctly, it is possible, that different TFT panels need different configurations.
In particular a correct gamma setup is crucial for good color reproduction. Unfortunately, finding a good set of parameters is not easy. Usually the manufacturer
of the panel provides some example code with recommended register settings.
You can use the ``my_lcd_send_cmd()`` function to send an arbitrary command to the LCD controller. However, to make it easier to send a large number of parameters
the generic MIPI driver supports sending a custom command list to the controller. The commands must be put into a 'uint8_t' array:
.. code-block:: c
static const uint8_t init_cmd_list[] = {
<command 1>, <number of parameters>, <parameter 1>, ... <parameter N>,
<command 2>, <number of parameters>, <parameter 1>, ... <parameter N>,
...
LV_LCD_CMD_DELAY_MS, LV_LCD_CMD_EOF /* terminate list: this is required! */
};
...
lv_lcd_generic_mipi_send_cmd_list(my_disp, init_cmd_list);
You can add a delay between the commands by using the pseudo-command ``LV_LCD_CMD_DELAY_MS``, which must be followed by the delay given in 10ms units.
To terminate the command list you must use a delay with a value of ``LV_LCD_CMD_EOF``, as shown above.
See an actual example of sending a command list `here <https://github.com/lvgl/lvgl/src/drivers/display/st7789/lv_st7789.c>`__.

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=============================
ILI9341 LCD Controller driver
=============================
Overview
--------
The `ILI9341 <https://www.buydisplay.com/download/ic/ILI9341.pdf>`__ is a 262,144-color single-chip SOC driver for a-TFT liquid crystal display with resolution of 240RGBx320
dots, comprising a 720-channel source driver, a 320-channel gate driver, 172,800 bytes GRAM for graphic
display data of 240RGBx320 dots, and power supply circuit.
ILI9341 supports parallel 8-/9-/16-/18-bit data bus MCU interface, 6-/16-/18-bit data bus RGB interface and
3-/4-line serial peripheral interface (SPI).
The ILI9341 LCD controller `driver <https://github.com/lvgl/lvgl/src/drivers/display/ili9341>`__ is a platform-agnostic driver, based on the `generic MIPI driver <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
It implements display initialization, supports display rotation and implements the display flush callback. The user needs to implement only two platform-specific functions to send
a command or pixel data to the controller via SPI or parallel bus. Typically these are implemented by calling the appropriate SDK library functions on the given platform.
Prerequisites
-------------
There are no prerequisites.
Configuring the driver
----------------------
Enable the ILI9341 driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_ILI9341 1
Usage
-----
You need to implement two platform-dependent functions:
.. code-block:: c
/* Send short command to the LCD. This function shall wait until the transaction finishes. */
int32_t my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
int32_t my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
To create an ILI9341-based display use the function
.. code-block:: c
/**
* Create an LCD display with ILI9341 driver
* @param hor_res horizontal resolution
* @param ver_res vertical resolution
* @param flags default configuration settings (mirror, RGB ordering, etc.)
* @param send_cmd platform-dependent function to send a command to the LCD controller (usually uses polling transfer)
* @param send_color platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer: must implement a 'ready' callback)
* @return pointer to the created display
*/
lv_display_t * lv_ili9341_create(uint32_t hor_res, uint32_t ver_res, lv_lcd_flag_t flags,
lv_ili9341_send_cmd_cb_t send_cmd_cb, lv_ili9341_send_color_cb_t send_color_cb);
For additional details and a working example see the `generic MIPI driver documentation <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
.. note::
You can find a step-by-step guide and the actual implementation of the callbacks on an STM32F746 using STM32CubeIDE and the ST HAL libraries here: :ref:`lcd_stm32_guide`

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=======
Display
=======
.. toctree::
:maxdepth: 2
fbdev
gen_mipi
ili9341
lcd_stm32_guide
renesas_glcdc
st_ltdc
st7735
st7789
st7796

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.. _lcd_stm32_guide:
=========================================================================
Step-by-step Guide: How to use the LVGL v9 LCD drivers with STM32 devices
=========================================================================
Introduction
------------
This guide is intended to be a step-by-step instruction of how to configure the STM32Cube HAL with the new TFT-LCD display drivers introduced in LVGL v9.0. The example code has been tested on the STM32F746-based Nucleo-F746ZG board with an ST7789-based LCD panel connected via SPI. The application itself and the hardware configuration code were generated with the STM32CubeIDE 1.14.0 tool.
.. tip::
ST Micro provide their own TFT-LCD drivers in their X-CUBE-DISPLAY Software Extension Package. While these drivers can be used with LVGL as well, the LVGL LCD drivers do not depend on this package.
The LVGL LCD drivers are meant as an alternative, simple to use API to implement LCD support for your LVGL-based project on any platform. Moreover, even in the initial release we support more LCD controllers than X-CUBE-DISPLAY currently provides, and we plan to add support for even more LCD controllers in the future.
Please note however, that unlike X-CUBE-DISPLAY the LVGL LCD drivers do not implement the communication part, whether SPI, parallel i8080 bus or other. It is the user's responsibility to implement and optimize these on their chosen platform. LVGL will only provide examples for the most popular platforms.
By following the steps you will have a fully functional program, which can be used as the foundation of your own LVGL-based project. If you are in a hurry and not interested in the details, you can find the final project `here <https://github.com/lvgl/lv_port_lcd_stm32>`__. You will only need to configure LVGL to use the driver corresponding to your hardware (if it is other than the ST7789), and implement the function ``ui_init()`` to create your widgets.
.. note::
This example is not meant as the best possible implementation, or the recommended solution. It relies solely on the HAL drivers provided by ST Micro, which favor portability over performance. Despite of this the performance is very good, thanks to the efficient, DMA-based implementation of the drivers.
.. note::
Although the example uses FreeRTOS, this is not a strict requirement with the LVGL LCD display drivers.
You can find the source code snippets of this guide in the `lv_port_lcd_stm32_template.c <https://github.com/lvgl/lvgl/examples/porting/lv_port_lcd_stm32_template.c>`__ example.
Hardware configuration
----------------------
In this example we'll use the SPI1 peripheral to connect the microcontroller to the LCD panel. Besides the hardware-controlled SPI pins SCK and MOSI we need some additional output pins for the chip select, command/data select, and LCD reset:
==== ============= ======= ==========
pin configuration LCD user label
==== ============= ======= ==========
PA4 GPIO_Output CS LCD_CS
PA5 SPI1_SCK SCK --
PA7 SPI1_MOSI SDI --
PA15 GPIO_Output RESET LCD_RESET
PB10 GPIO_Output DC LCD_DCX
==== ============= ======= ==========
Step-by-step instructions
-------------------------
#. Create new project in File/New/STM32 Project.
#. Select target processor/board.
#. Set project name and location.
#. Set Targeted Project Type to STM32Cube and press Finish.
#. Say "Yes" to Initialize peripherals with their default Mode? After the project is created, the configuration file (.ioc) is opened automatically.
#. Switch to the Pinout & Configuration tab.
#. In the System Core category switch to RCC.
#. Set High Speed Clock to "BYPASS Clock Source", and Low Speed Clock to "Crystal/Ceramic Resonator".
#. In the System Core category select SYS, and set Timebase Source to other than SysTick (in our example, TIM2).
#. Switch to the Clock Configuration tab.
#. Set the HCLK clock frequency to the maximum value (216 MHz for the STM32F746).
#. Switch back to the Pinout & Configuration tab, and in the Middleware and Software Packs category select FREERTOS.
#. Select Interface: CMSIS_V1.
#. In the Advanced Settings tab enable USE_NEWLIB_REENTRANT. We are finished here.
#. In the Pinout view configure PA5 as SPI1_SCK, PA7 as SPI1_MOSI (right click the pin and select the function).
#. In the Pinout & Configuration/Connectivity category select SPI1.
#. Set Mode to Transmit Only Master, and Hardware NSS Signal to Disable.
#. In the Configuration subwindow switch to Parameter Settings.
#. Set Frame Format to Motorola, Data Size to 8 Bits, First Bit to MSB First.
#. Set the Prescaler to the maximum value according to the LCD controllers datasheet (e.g., 15 MBits/s). Set CPOL/CPHA as required (leave as default).
#. Set NSSP Mode to Disabled and NSS Signal Type to Software.
#. In DMA Settings add a new Request for SPI1_TX (when using SPI1).
#. Set Priority to Medium, Data Width to Half Word.
#. In NVIC Settings enable SPI1 global interrupt.
#. In GPIO Settings set SPI1_SCK to Pull-down and Very High output speed and set the User Label to ``LCD_SCK``.
#. Set SPI1_MOSI to Pull-up and Very High, and name it ``LCD_SDI``.
#. Select System Core/GPIO category. In the Pinout view configure additional pins for chip select, reset and command/data select. Name them ``LCD_CS``, ``LCD_RESET`` and ``LCD_DCX``, respectively. Configure them as GPIO Output. (In this example we will use PA4 for ``LCD_CS``, PA15 for ``LCD_RESET`` and PB10 for ``LCD_DCX``.)
#. Set ``LCD_CS`` to No pull-up and no pull-down, Low level and Very High speed.
#. Set ``LCD_RESET`` to Pull-up and High level.
#. Set ``LCD_DCX`` to No pull-up and no pull-down, High level and Very High speed.
#. Open the Project Manager tab, and select Advanced Settings. On the right hand side there is a Register Callback window. Select SPI and set it to ENABLE.
#. We are ready with the hardware configuration. Save the configuration and let STM32Cube generate the source.
#. In the project tree clone the LVGL repository into the Middlewares/Third_Party folder (this tutorial uses the release/v9.0 branch of LVGL):
.. code-block:: dosbatch
git clone https://github.com/lvgl/lvgl.git -b release/v9.0
#. Cloning should create an 'lvgl' subfolder inside the 'Third_Party' folder. From the 'lvgl' folder copy 'lv_conf_template.h' into the 'Middlewares' folder, and rename it to 'lv_conf.h'. Refresh the project tree.
#. Open 'lv_conf.h', and in line 15 change ``#if 0`` to ``#if 1``.
#. Search for the string ``LV_USE_ST7735``, and enable the appropriate LCD driver by setting its value to 1. This example uses the ST7789 driver:
.. code-block:: c
#define LV_USE_ST7789 1
#. Right click the folder 'Middlewares/Third_Party/lvgl/tests', select Resource Configurations/Exclude from Build..., check both Debug and Release, then press OK.
#. Right click the project name and select "Properties". In the C/C++ Build/Settings panel select MCU GCC Compiler/Include paths. In the Configuration dropdown select [ All configurations ]. Add the following Include path:
.. code-block:: c
../Middlewares/Third_Party/lvgl
#. Open Core/Src/stm32xxx_it.c (the file name depends on the processor variation). Add 'lv_tick.h' to the Private includes section:
.. code-block:: c
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "./src/tick/lv_tick.h"
/* USER CODE END Includes */
#. Find the function ``TIM2_IRQHandler``. Add a call to ``lv_tick_inc()``:
.. code-block:: c
void TIM2_IRQHandler(void)
{
/* USER CODE BEGIN TIM2_IRQn 0 */
/* USER CODE END TIM2_IRQn 0 */
HAL_TIM_IRQHandler(&htim2);
/* USER CODE BEGIN TIM2_IRQn 1 */
lv_tick_inc(1);
/* USER CODE END TIM2_IRQn 1 */
}
#. Save the file, then open Core/Src/main.c. Add the following lines to the Private includes (if your LCD uses other than the ST7789, replace the driver path and header with the appropriate one):
.. code-block:: c
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "lvgl.h"
#include "./src/drivers/display/st7789/lv_st7789.h"
/* USER CODE END Includes */
#. Add the following lines to Private defines (change them according to your LCD specs):
.. code-block:: c
#define LCD_H_RES 240
#define LCD_V_RES 320
#define BUS_SPI1_POLL_TIMEOUT 0x1000U
#. Add the following lines to the Private variables:
.. code-block:: c
osThreadId LvglTaskHandle;
lv_display_t *lcd_disp;
volatile int lcd_bus_busy = 0;
#. Add the following line to the Private function prototypes:
.. code-block:: c
void ui_init(lv_display_t *disp);
void LVGL_Task(void const *argument);
#. Add the following lines after USER CODE BEGIN RTOS_THREADS:
.. code-block:: c
osThreadDef(LvglTask, LVGL_Task, osPriorityIdle, 0, 1024);
LvglTaskHandle = osThreadCreate(osThread(LvglTask), NULL);
#. Copy and paste the hardware initialization and the transfer callback functions from the example code after USER CODE BEGIN 4:
.. code-block:: c
/* USER CODE BEGIN 4 */
void lcd_color_transfer_ready_cb(SPI_HandleTypeDef *hspi)
{
/* CS high */
HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_SET);
lcd_bus_busy = 0;
lv_display_flush_ready(lcd_disp);
}
/* Initialize LCD I/O bus, reset LCD */
static int32_t lcd_io_init(void)
{
/* Register SPI Tx Complete Callback */
HAL_SPI_RegisterCallback(&hspi1, HAL_SPI_TX_COMPLETE_CB_ID, lcd_color_transfer_ready_cb);
/* reset LCD */
HAL_GPIO_WritePin(LCD_RESET_GPIO_Port, LCD_RESET_Pin, GPIO_PIN_RESET);
HAL_Delay(100);
HAL_GPIO_WritePin(LCD_RESET_GPIO_Port, LCD_RESET_Pin, GPIO_PIN_SET);
HAL_Delay(100);
HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_SET);
HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_SET);
return HAL_OK;
}
/* Platform-specific implementation of the LCD send command function. In general this should use polling transfer. */
static void lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
LV_UNUSED(disp);
while (lcd_bus_busy); /* wait until previous transfer is finished */
/* Set the SPI in 8-bit mode */
hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
HAL_SPI_Init(&hspi1);
/* DCX low (command) */
HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_RESET);
/* CS low */
HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_RESET);
/* send command */
if (HAL_SPI_Transmit(&hspi1, cmd, cmd_size, BUS_SPI1_POLL_TIMEOUT) == HAL_OK) {
/* DCX high (data) */
HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_SET);
/* for short data blocks we use polling transfer */
HAL_SPI_Transmit(&hspi1, (uint8_t *)param, (uint16_t)param_size, BUS_SPI1_POLL_TIMEOUT);
/* CS high */
HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_SET);
}
}
/* Platform-specific implementation of the LCD send color function. For better performance this should use DMA transfer.
* In case of a DMA transfer a callback must be installed to notify LVGL about the end of the transfer.
*/
static void lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
LV_UNUSED(disp);
while (lcd_bus_busy); /* wait until previous transfer is finished */
/* Set the SPI in 8-bit mode */
hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
HAL_SPI_Init(&hspi1);
/* DCX low (command) */
HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_RESET);
/* CS low */
HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_RESET);
/* send command */
if (HAL_SPI_Transmit(&hspi1, cmd, cmd_size, BUS_SPI1_POLL_TIMEOUT) == HAL_OK) {
/* DCX high (data) */
HAL_GPIO_WritePin(LCD_DCX_GPIO_Port, LCD_DCX_Pin, GPIO_PIN_SET);
/* for color data use DMA transfer */
/* Set the SPI in 16-bit mode to match endianness */
hspi1.Init.DataSize = SPI_DATASIZE_16BIT;
HAL_SPI_Init(&hspi1);
lcd_bus_busy = 1;
HAL_SPI_Transmit_DMA(&hspi1, param, (uint16_t)param_size / 2);
/* NOTE: CS will be reset in the transfer ready callback */
}
}
#. Add the LVGL_Task() function. Replace the ``lv_st7789_create()`` call with the appropriate driver. You can change the default orientation by adjusting the parameter of ``lv_display_set_rotation()``. You will also need to create the display buffers here. This example uses a double buffering scheme with 1/10th size partial buffers. In most cases this is a good compromise between the required memory size and performance, but you are free to experiment with other settings.
.. code-block:: c
void LVGL_Task(void const *argument)
{
/* Initialize LVGL */
lv_init();
/* Initialize LCD I/O */
if (lcd_io_init() != 0)
return;
/* Create the LVGL display object and the LCD display driver */
lcd_disp = lv_st7789_create(LCD_H_RES, LCD_V_RES, LV_LCD_FLAG_NONE, lcd_send_cmd, lcd_send_color);
lv_display_set_rotation(lcd_disp, LV_DISPLAY_ROTATION_270);
/* Allocate draw buffers on the heap. In this example we use two partial buffers of 1/10th size of the screen */
lv_color_t * buf1 = NULL;
lv_color_t * buf2 = NULL;
uint32_t buf_size = LCD_H_RES * LCD_V_RES / 10 * lv_color_format_get_size(lv_display_get_color_format(lcd_disp));
buf1 = lv_malloc(buf_size);
if(buf1 == NULL) {
LV_LOG_ERROR("display draw buffer malloc failed");
return;
}
buf2 = lv_malloc(buf_size);
if(buf2 == NULL) {
LV_LOG_ERROR("display buffer malloc failed");
lv_free(buf1);
return;
}
lv_display_set_buffers(lcd_disp, buf1, buf2, buf_size, LV_DISPLAY_RENDER_MODE_PARTIAL);
ui_init(lcd_disp);
for(;;) {
/* The task running lv_timer_handler should have lower priority than that running `lv_tick_inc` */
lv_timer_handler();
/* raise the task priority of LVGL and/or reduce the handler period can improve the performance */
osDelay(10);
}
}
#. All that's left is to implement ``ui_init()`` to create the screen. Here's a simple "Hello World" example:
.. code-block:: c
void ui_init(lv_display_t *disp)
{
lv_obj_t *obj;
/* set screen background to white */
lv_obj_t *scr = lv_screen_active();
lv_obj_set_style_bg_color(scr, lv_color_white(), 0);
lv_obj_set_style_bg_opa(scr, LV_OPA_100, 0);
/* create label */
obj = lv_label_create(scr);
lv_obj_set_align(widget, LV_ALIGN_CENTER);
lv_obj_set_height(widget, LV_SIZE_CONTENT);
lv_obj_set_width(widget, LV_SIZE_CONTENT);
lv_obj_set_style_text_font(widget, &lv_font_montserrat_14, 0);
lv_obj_set_style_text_color(widget, lv_color_black(), 0);
lv_label_set_text(widget, "Hello World!");
}

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.. _renesas_glcdc:
=============
Renesas GLCDC
=============
Overview
--------
.. image:: /misc/renesas/glcdc.png
:alt: Architectural overview of Renesas GLCDC
:align: center
<br/>
GLCDC is a multi-stage graphics output peripheral used in Renesas MCUs.
It is designed to automatically generate timing and data signals for different LCD panels.
- Supports LCD panels with RGB interface (up to 24 bits) and sync signals (HSYNC, VSYNC and Data Enable optional)
- Supports various color formats for input graphics planes (RGB888, ARGB8888, RGB565, ARGB1555, ARGB4444, CLUT8, CLUT4, CLUT1)
- Supports the Color Look-Up Table (CLUT) usage for input graphics planes (ARGB8888) with 512 words (32 bits/word)
- Supports various color formats for output (RGB888, RGB666, RGB565, Serial RGB888)
- Can input two graphics planes on top of the background plane and blend them on the screen
- Generates a dot clock to the panel. The clock source is selectable from internal or external (LCD_EXTCLK)
- Supports brightness adjustment, contrast adjustment, and gamma correction
- Supports GLCDC interrupts to handle frame-buffer switching or underflow detection
Setting up a project and further integration with Renesas' ecosystem is described in detail on :ref:`page Renesas <renesas>`.
Check out the following repositories for ready-to-use examples:
- `EK-RA8D1 <https://github.com/lvgl/lv_port_renesas_ek-ra8d1>`__
- `EK-RA6M3G <https://github.com/lvgl/lv_port_renesas_ek-ra6m3g>`__
- `RX72N Envision Kit <https://github.com/lvgl/lv_port_renesas_rx72n-envision-kit>`__
Prerequisites
-------------
- This diver relies on code generated by e² studio. Missing the step while setting up the project will cause a compilation error.
- Activate the diver by setting :c:macro:`LV_USE_RENESAS_GLCDC` to ``1`` in your *"lv_conf.h"*.
Usage
-----
There is no need to implement any platform-specific functions.
The following code demonstrates using the diver in :cpp:enumerator:`LV_DISPLAY_RENDER_MODE_DIRECT` mode.
.. code-block:: c
lv_display_t * disp = lv_renesas_glcdc_direct_create();
lv_display_set_default(disp);
To use the driver in :cpp:enumerator:`LV_DISPLAY_RENDER_MODE_PARTIAL` mode, an extra buffer must be allocated,
preferably in the fastest available memory region.
Buffer swapping can be activated by passing a second buffer of same size instead of the :cpp:expr:`NULL` argument.
.. code-block:: c
static lv_color_t partial_draw_buf[DISPLAY_HSIZE_INPUT0 * DISPLAY_VSIZE_INPUT0 / 10] BSP_PLACE_IN_SECTION(".sdram") BSP_ALIGN_VARIABLE(1024);
lv_display_t * disp = lv_renesas_glcdc_partial_create(partial_draw_buf, NULL, sizeof(partial_draw_buf));
lv_display_set_default(disp);
.. note::
Partial mode can be activated via the macro in ``src/board_init.c`` file of the demo projects.
Screen rotation
"""""""""""""""
Software based screen rotation is supported in partial mode. It uses the common API, no extra configuration is required:
.. code-block:: c
lv_display_set_rotation(lv_display_get_default(), LV_DISP_ROTATION_90);
/* OR */
lv_display_set_rotation(lv_display_get_default(), LV_DISP_ROTATION_180);
/* OR */
lv_display_set_rotation(lv_display_get_default(), LV_DISP_ROTATION_270);
Make sure the heap is large enough, as a buffer with the same size as the partial buffer will be allocated.

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============================
ST7735 LCD Controller driver
============================
Overview
--------
The `ST7735S <https://www.buydisplay.com/download/ic/ST7735S.pdf>`__ is a single-chip controller/driver for 262K-color, graphic type TFT-LCD. It consists of 396
source line and 162 gate line driving circuits. This chip is capable of connecting directly to an external
microprocessor, and accepts Serial Peripheral Interface (SPI), 8-bit/9-bit/16-bit/18-bit parallel interface.
Display data can be stored in the on-chip display data RAM of 132 x 162 x 18 bits. It can perform display data
RAM read/write operation with no external operation clock to minimize power consumption. In addition,
because of the integrated power supply circuits necessary to drive liquid crystal, it is possible to make a
display system with fewer components.
The ST7735 LCD controller `driver <https://github.com/lvgl/lvgl/src/drivers/display/st7735>`__ is a platform-agnostic driver, based on the `generic MIPI driver <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
It implements display initialization, supports display rotation and implements the display flush callback. The user needs to implement only two platform-specific functions to send
a command or pixel data to the controller via SPI or parallel bus. Typically these are implemented by calling the appropriate SDK library functions on the given platform.
Prerequisites
-------------
There are no prerequisites.
Configuring the driver
----------------------
Enable the ST7735 driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_ST7735 1
Usage
-----
You need to implement two platform-dependent functions:
.. code-block:: c
/* Send short command to the LCD. This function shall wait until the transaction finishes. */
int32_t my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
int32_t my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
To create an ST7735-based display use the function
.. code-block:: c
/**
* Create an LCD display with ST7735 driver
* @param hor_res horizontal resolution
* @param ver_res vertical resolution
* @param flags default configuration settings (mirror, RGB ordering, etc.)
* @param send_cmd platform-dependent function to send a command to the LCD controller (usually uses polling transfer)
* @param send_color platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer: must implement a 'ready' callback)
* @return pointer to the created display
*/
lv_display_t * lv_st7735_create(uint32_t hor_res, uint32_t ver_res, lv_lcd_flag_t flags,
lv_st7735_send_cmd_cb_t send_cmd_cb, lv_st7735_send_color_cb_t send_color_cb);
For additional details and a working example see the `generic MIPI driver documentation <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
.. note::
You can find a step-by-step guide and the actual implementation of the callbacks on an STM32F746 using STM32CubeIDE and the ST HAL libraries here: :ref:`lcd_stm32_guide`

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============================
ST7789 LCD Controller driver
============================
Overview
--------
The `ST7789 <https://www.buydisplay.com/download/ic/ST7789.pdf>`__ is a single-chip controller/driver for 262K-color, graphic type TFT-LCD. It consists of 720
source line and 320 gate line driving circuits. This chip is capable of connecting directly to an external
microprocessor, and accepts, 8-bits/9-bits/16-bits/18-bits parallel interface. Display data can be stored in the
on-chip display data RAM of 240x320x18 bits. It can perform display data RAM read/write operation with no
external operation clock to minimize power consumption. In addition, because of the integrated power supply
circuit necessary to drive liquid crystal; it is possible to make a display system with the fewest components.
The ST7789 LCD controller `driver <https://github.com/lvgl/lvgl/src/drivers/display/st7789>`__ is a platform-agnostic driver, based on the `generic MIPI driver <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
It implements display initialization, supports display rotation and implements the display flush callback. The user needs to implement only two platform-specific functions to send
a command or pixel data to the controller via SPI or parallel bus. Typically these are implemented by calling the appropriate SDK library functions on the given platform.
Prerequisites
-------------
There are no prerequisites.
Configuring the driver
----------------------
Enable the ST7789 driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_ST7789 1
Usage
-----
You need to implement two platform-dependent functions:
.. code-block:: c
/* Send short command to the LCD. This function shall wait until the transaction finishes. */
int32_t my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
int32_t my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
To create an ST7789-based display use the function
.. code-block:: c
/**
* Create an LCD display with ST7789 driver
* @param hor_res horizontal resolution
* @param ver_res vertical resolution
* @param flags default configuration settings (mirror, RGB ordering, etc.)
* @param send_cmd platform-dependent function to send a command to the LCD controller (usually uses polling transfer)
* @param send_color platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer: must implement a 'ready' callback)
* @return pointer to the created display
*/
lv_display_t * lv_st7789_create(uint32_t hor_res, uint32_t ver_res, lv_lcd_flag_t flags,
lv_st7789_send_cmd_cb_t send_cmd_cb, lv_st7789_send_color_cb_t send_color_cb);
For additional details and a working example see the `generic MIPI driver documentation <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
.. note::
You can find a step-by-step guide and the actual implementation of the callbacks on an STM32F746 using STM32CubeIDE and the ST HAL libraries here: :ref:`lcd_stm32_guide`

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============================
ST7796 LCD Controller driver
============================
Overview
--------
The `ST7796S <https://www.buydisplay.com/download/ic/ST7796S.pdf>`__ is a single-chip controller/driver for 262K-color, graphic type TFT-LCD. It consists of 960
source lines and 480 gate lines driving circuits. The ST7796S is capable of connecting directly to an external
microprocessor, and accepts 8-bit/9-bit/16-bit/18-bit parallel interface, SPI, and the ST7796S also provides
MIPI interface. Display data can be stored in the on-chip display data RAM of 320x480x18 bits. It can perform
display data RAM read-/write-operation with no external clock to minimize power consumption. In addition,
because of the integrated power supply circuit necessary to drive liquid crystal; it is possible to make a display
system with fewest components.
The ST7796 LCD controller `driver <https://github.com/lvgl/lvgl/src/drivers/display/st7796>`__ is a platform-agnostic driver, based on the `generic MIPI driver <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
It implements display initialization, supports display rotation and implements the display flush callback. The user needs to implement only two platform-specific functions to send
a command or pixel data to the controller via SPI or parallel bus. Typically these are implemented by calling the appropriate SDK library functions on the given platform.
Prerequisites
-------------
There are no prerequisites.
Configuring the driver
----------------------
Enable the ST7796 driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_ST7796 1
Usage
-----
You need to implement two platform-dependent functions:
.. code-block:: c
/* Send short command to the LCD. This function shall wait until the transaction finishes. */
int32_t my_lcd_send_cmd(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, const uint8_t *param, size_t param_size)
{
...
}
/* Send large array of pixel data to the LCD. If necessary, this function has to do the byte-swapping. This function can do the transfer in the background. */
int32_t my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
{
...
}
To create an ST7796-based display use the function
.. code-block:: c
/**
* Create an LCD display with ST7796 driver
* @param hor_res horizontal resolution
* @param ver_res vertical resolution
* @param flags default configuration settings (mirror, RGB ordering, etc.)
* @param send_cmd platform-dependent function to send a command to the LCD controller (usually uses polling transfer)
* @param send_color platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer: must implement a 'ready' callback)
* @return pointer to the created display
*/
lv_display_t * lv_st7796_create(uint32_t hor_res, uint32_t ver_res, lv_lcd_flag_t flags,
lv_st7796_send_cmd_cb_t send_cmd_cb, lv_st7796_send_color_cb_t send_color_cb);
For additional details and a working example see the `generic MIPI driver documentation <https://github.com/lvgl/lvgl/doc/integration/drivers/display/gen_mipi.rst>`__.
.. note::
You can find a step-by-step guide and the actual implementation of the callbacks on an STM32F746 using STM32CubeIDE and the ST HAL libraries here: :ref:`lcd_stm32_guide`

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=================
STM32 LTDC Driver
=================
Some STM32s have a specialized peripheral for driving
displays called LTDC (LCD-TFT display controller).
Usage Modes With LVGL
*********************
The driver within LVGL is designed to work with an
already-configured LTDC peripheral. It relies on the
HAL to detect information about the configuration.
The color format of the created LVGL display will
match the LTDC layer's color format. Use STM32CubeIDE
or STM32CubeMX to generate LTDC initialization code.
There are some different use cases for LVGL's driver.
All permutations of the below options are well supported.
- single or double buffered
- direct or partial render mode
- OS and no OS
- paralellized flushing with DMA2D (only for partial render mode)
If OS is enabled, a synchronization primitive will be used to
give the thread a chance to yield to other threads while blocked,
improving CPU utilization. See :c:macro:`LV_USE_OS` in your lv_conf.h
LTDC Layers
***********
This driver creates an LVGL display
which is only concerned with a specific layer of the LTDC peripheral, meaning
two LVGL LTDC displays can be created and operate independently on the separate
layers.
Direct Render Mode
******************
For direct render mode, invoke :cpp:func:`lv_st_ltdc_create_direct` like this:
.. code-block:: c
void * my_ltdc_framebuffer_address = (void *)0x20000000u;
uint32_t my_ltdc_layer_index = 0; /* typically 0 or 1 */
lv_display_t * disp = lv_st_ltdc_create_direct(my_ltdc_framebuffer_address,
optional_other_full_size_buffer,
my_ltdc_layer_index);
``my_ltdc_framebuffer_address`` is the framebuffer configured for use by
LTDC. ``optional_other_full_size_buffer`` can be another buffer which is the same
size as the default framebuffer for double-buffered
mode, or ``NULL`` otherwise. ``my_ltdc_layer_index`` is the layer index of the
LTDC layer to create the display for.
For the best visial results, ``optional_other_full_size_buffer`` should be used
if enough memory is available. Single-buffered mode is what you should use
if memory is very scarce. If there is almost enough memory for double-buffered
direct mode, but not quite, then use partial render mode.
Partial Render Mode
*******************
For partial render mode, invoke :cpp:func:`lv_st_ltdc_create_partial` like this:
.. code-block:: c
static uint8_t partial_buf1[65536];
static uint8_t optional_partial_buf2[65536];
uint32_t my_ltdc_layer_index = 0; /* typically 0 or 1 */
lv_display_t * disp = lv_st_ltdc_create_partial(partial_buf1,
optional_partial_buf2,
65536,
my_ltdc_layer_index);
The driver will use the information in the LTDC layer configuration to find the
layer's framebuffer and flush to it.
Providing a second partial buffer can improve CPU utilization and increase
performance compared to
a single buffer if :c:macro:`LV_ST_LTDC_USE_DMA2D_FLUSH` is enabled.
DMA2D
*****
:c:macro:`LV_ST_LTDC_USE_DMA2D_FLUSH` can be enabled to use DMA2D to flush
partial buffers in parallel with other LVGL tasks, whether or not OS is
enabled. If the display is not partial, then there is no need to enable this
option.
It must not be enabled at the same time as :c:macro:`LV_USE_DRAW_DMA2D`.
See the :ref:`DMA2D support <dma2d>`.
.. admonition:: Further Reading
You may be interested in enabling the :ref:`Nema GFX renderer <stm32_nema_gfx>`
if your STM32 has a GPU which is supported by Nema GFX.
`lv_port_riverdi_stm32u5 <https://github.com/lvgl/lv_port_riverdi_stm32u5>`__
is a way to quick way to get started with LTDC on LVGL.

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.. _drivers:
=======
Drivers
=======
.. toctree::
:maxdepth: 2
display/index
libinput
opengles
touchpad/index
wayland
windows
X11

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===============
Libinput Driver
===============
Overview
--------
Libinput is an input stack for processes that need to provide events from commonly used input devices. That includes mice, keyboards, touchpads,
touchscreens and graphics tablets. Libinput handles device-specific quirks and provides an easy-to-use API to receive events from devices.
Prerequisites
-------------
You have the development version of libinput installed (usually ``libinput-dev``). If your input device requires quirks, make sure they are
installed as well (usually in ``/usr/share/libinput/*.quirks``). To test if your device is set up correctly for use with libinput, you can
run ``libinput list-devices``.
.. code-block:: console
$ sudo libinput list-devices
...
Device: ETPS/2 Elantech Touchpad
Kernel: /dev/input/event5
Group: 10
Seat: seat0, default
Size: 102x74mm
Capabilities: pointer gesture
Tap-to-click: disabled
Tap-and-drag: enabled
...
If your device doesn't show up, you may have to configure udev and the appropriate udev rules to connect it.
Additionally, if you want full keyboard support, including letters and modifiers, you'll need the development version of libxkbcommon
installed (usually ``libxkbcommon-dev``).
Configuring the driver
----------------------
Enable the libinput driver support in lv_conf.h, by cmake compiler define or by KConfig.
.. code-block:: c
#define LV_USE_LIBINPUT 1
Full keyboard support needs to be enabled separately.
.. code-block:: c
#define LV_LIBINPUT_XKB 1
#define LV_LIBINPUT_XKB_KEY_MAP { .rules = NULL, .model = "pc101", .layout = "us", .variant = NULL, .options = NULL }
To find the right key map values, you may use the ``setxkbmap -query`` command.
Usage
-----
To set up an input device via the libinput driver, all you need to do is call ``lv_libinput_create`` with the respective device type
(``LV_INDEV_TYPE_POINTER`` or ``LV_INDEV_TYPE_KEYPAD``) and device node path (e.g. ``/dev/input/event5``).
.. code-block:: c
lv_indev_t *indev = lv_libinput_create(LV_INDEV_TYPE_POINTER, "/dev/input/event5");
Note that touchscreens are treated as (absolute) pointer devices by the libinput driver and require ``LV_INDEV_TYPE_POINTER``.
Depending on your system, the device node paths might not be stable across reboots. If this is the case, you can use ``lv_libinput_find_dev``
to find the first device that has a specific capability.
.. code-block:: c
char *path = lv_libinput_find_dev(LV_LIBINPUT_CAPABILITY_TOUCH, true);
The second argument controls whether or not all devices are rescanned. If you have many devices connected this can get quite slow.
Therefore, you should only specify ``true`` on the first call when calling this method multiple times in a row. If you want to find
all devices that have a specific capability, use ``lv_libinput_find_devs``.
If you want to connect a keyboard device to a textarea, create a dedicated input group and set it on both the indev and textarea.
.. code-block:: c
lv_obj_t *textarea = lv_textarea_create(...);
...
lv_group_t *keyboard_input_group = lv_group_create();
lv_indev_set_group(indev, keyboard_input_group);
lv_group_add_obj(keyboard_input_group, textarea);

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.. _opengl_es_driver:
===============================
OpenGL ES Display/Inputs Driver
===============================
Overview
--------
| The **OpenGL ES** display/input `driver <https://github.com/lvgl/lvgl/src/drivers/opengles>`__ offers support for simulating the LVGL display and keyboard/mouse inputs in an desktop window created via GLFW.
| It is an alternative to **Wayland**, **XCB**, **SDL** or **Qt**.
The main purpose for this driver is for testing/debugging the LVGL application in an **OpenGL** simulation window.
Prerequisites
-------------
The OpenGL driver uses GLEW GLFW to access the OpenGL window manager.
1. Install GLEW and GLFW: ``sudo apt-get install libglew-dev libglfw3-dev``
Configure OpenGL Driver
-----------------------
1. Required linked libraries: -lGL -lGLEW -lglfw
2. Enable the OpenGL driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_OPENGLES 1
Basic Usage
-----------
.. code-block:: c
#include "lvgl/lvgl.h"
#include "lvgl/examples/lv_examples.h"
#include "lvgl/demos/lv_demos.h"
#define WIDTH 640
#define HEIGHT 480
int main()
{
/* initialize lvgl */
lv_init();
/* create a window and initialize OpenGL */
lv_glfw_window_t * window = lv_glfw_window_create(WIDTH, HEIGHT, true);
/* create a display that flushes to a texture */
lv_display_t * texture = lv_opengles_texture_create(WIDTH, HEIGHT);
lv_display_set_default(texture);
/* add the texture to the window */
unsigned int texture_id = lv_opengles_texture_get_texture_id(texture);
lv_glfw_texture_t * window_texture = lv_glfw_window_add_texture(window, texture_id, WIDTH, HEIGHT);
/* get the mouse indev of the window texture */
lv_indev_t * mouse = lv_glfw_texture_get_mouse_indev(window_texture);
/* add a cursor to the mouse indev */
LV_IMAGE_DECLARE(mouse_cursor_icon);
lv_obj_t * cursor_obj = lv_image_create(lv_screen_active());
lv_image_set_src(cursor_obj, &mouse_cursor_icon);
lv_indev_set_cursor(mouse, cursor_obj);
/* create Widgets on the screen */
lv_demo_widgets();
while (1)
{
uint32_t time_until_next = lv_timer_handler();
lv_delay_ms(time_until_next);
}
return 0;
}
Advanced Usage
--------------
The OpenGL driver can draw textures from the user. A third-party library could be
used to add content to a texture and the driver will draw the texture in the window.
.. code-block:: c
#include "lvgl/lvgl.h"
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#define WIDTH 640
#define HEIGHT 480
void custom_texture_example(void)
{
/*****************
* MAIN WINDOW
*****************/
/* create a window and initialize OpenGL */
/* multiple windows can be created */
lv_glfw_window_t * window = lv_glfw_window_create(WIDTH, HEIGHT, true);
/****************************
* OPTIONAL MAIN TEXTURE
****************************/
/* create a main display that flushes to a texture */
lv_display_t * main_texture = lv_opengles_texture_create(WIDTH, HEIGHT);
lv_display_set_default(main_texture);
/* add the main texture to the window */
unsigned int main_texture_id = lv_opengles_texture_get_texture_id(main_texture);
lv_glfw_texture_t * window_main_texture = lv_glfw_window_add_texture(window, main_texture_id, WIDTH, HEIGHT);
/* get the mouse indev of this main texture */
lv_indev_t * main_texture_mouse = lv_glfw_texture_get_mouse_indev(window_main_texture);
/* add a cursor to the mouse indev */
LV_IMAGE_DECLARE(mouse_cursor_icon);
lv_obj_t * cursor_obj = lv_image_create(lv_screen_active());
lv_image_set_src(cursor_obj, &mouse_cursor_icon);
lv_indev_set_cursor(main_texture_mouse, cursor_obj);
/* create Widgets on the screen of the main texture */
lv_demo_widgets();
/**********************
* ANOTHER TEXTURE
**********************/
/* create a sub display that flushes to a texture */
const int32_t sub_texture_w = 300;
const int32_t sub_texture_h = 300;
lv_display_t * sub_texture = lv_opengles_texture_create(sub_texture_w, sub_texture_h);
/* add the sub texture to the window */
unsigned int sub_texture_id = lv_opengles_texture_get_texture_id(sub_texture);
lv_glfw_texture_t * window_sub_texture = lv_glfw_window_add_texture(window, sub_texture_id, sub_texture_w, sub_texture_h);
/* create Widgets on the screen of the sub texture */
lv_display_set_default(sub_texture);
lv_example_keyboard_2();
lv_display_set_default(main_texture);
/* position the sub texture within the window */
lv_glfw_texture_set_x(window_sub_texture, 250);
lv_glfw_texture_set_y(window_sub_texture, 150);
/* optionally change the opacity of the sub texture */
lv_glfw_texture_set_opa(window_sub_texture, LV_OPA_80);
/*********************************************
* USE AN EXTERNAL OPENGL TEXTURE IN LVGL
*********************************************/
unsigned int external_texture_id;
glGenTextures(1, &external_texture_id);
glBindTexture(GL_TEXTURE_2D, external_texture_id);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
LV_IMAGE_DECLARE(img_cogwheel_argb);
#if LV_COLOR_DEPTH == 8
const int texture_format = GL_R8;
#elif LV_COLOR_DEPTH == 16
const int texture_format = GL_RGB565;
#elif LV_COLOR_DEPTH == 24
const int texture_format = GL_RGB;
#elif LV_COLOR_DEPTH == 32
const int texture_format = GL_RGBA;
#else
#error("Unsupported color format")
#endif
glTexImage2D(GL_TEXTURE_2D, 0, texture_format, img_cogwheel_argb.header.w, img_cogwheel_argb.header.h, 0, GL_BGRA, GL_UNSIGNED_BYTE, img_cogwheel_argb.data);
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, 0);
/* add the external texture to the window */
lv_glfw_texture_t * window_external_texture = lv_glfw_window_add_texture(window, external_texture_id, img_cogwheel_argb.header.w, img_cogwheel_argb.header.h);
/* set the position and opacity of the external texture within the window */
lv_glfw_texture_set_x(window_external_texture, 20);
lv_glfw_texture_set_y(window_external_texture, 20);
lv_glfw_texture_set_opa(window_external_texture, LV_OPA_70);
/*********************************************
* USE AN LVGL TEXTURE IN ANOTHER LIBRARY
*********************************************/
lv_refr_now(sub_texture);
/* the texture is drawn on by LVGL and can be used by anything that uses OpenGL textures */
third_party_lib_use_texture(sub_texture_id);
}
OpenGL Texture Caching Renderer
-------------------------------
There is a renderer in LVGL which caches software-rendered areas as OpenGL textures.
The textures are retrieved from the cache and reused when there is a match.
The performance will be drastically improved in most cases.
.. code-block:: c
#define LV_USE_DRAW_OPENGLES 1
Known Limitations
~~~~~~~~~~~~~~~~~
- Performance will be the same or slightly worse if the drawn areas are never found in the cache
due to Widgets with continuously varying colors or shapes. One example is a label whose color
is set to a random value every frame, as in the "Multiple labels" scene of the benchmark demo.
- Layers with transparent pixels and an overall layer transparency will not blend correctly.
The effect can be observed in the "Containers with opa_layer" scene of the benchmark demo
in the border corners.
- Layers with rotation are not currently supported. Images with rotation are fine.
.. Comment: The above blank line is necessary for Sphinx to not complain,
since it looks for the blank line after a bullet list.

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==================
Linux Evdev Driver
==================
Overview
--------
The Linux event device (evdev) is a hardware-independent API that gives access to input events from,
for example, a mouse or touchscreen. It is exposed via the Linux device file system interface.
Prerequisites
-------------
Your system has an input device configured (usually under ``/dev/input/`` such as ``/dev/input/event0``).
Configuring the driver
----------------------
Enable the Linux LVGL evdev driver support in ``lv_conf.h``.
.. code-block:: c
#define LV_USE_EVDEV 1
Usage
-----
To set up an event input, first create an input device with ``lv_edev_create`` setting it to the correct Linux event device.
Then link this to the LVGL display with ``lv_indev_set_display``.
.. code-block:: c
lv_indev_t *touch = lv_evdev_create(LV_INDEV_TYPE_POINTER, "/dev/input/event0");
lv_indev_set_display(touch, disp);
Ensure that an ``lv_display_t`` object is already created for ``disp``. An example for this is shown below, using the Linux framebuffer driver.
.. code-block:: c
lv_display_t * disp = lv_linux_fbdev
lv_linux_fbdev_set_file(disp, "/dev/fb0");_create();
Locating your input device
--------------------------
If you can't determine your input device, first run
```$cat /proc/bus/input/devices```
This should show input devices and there will be entries with the word ``event`` which give a clue as to the device to use eg. ``event1`` would be ``/dev/input/event1``.
You can use ``evtest`` to show data from that event source to see if it is actually the one you want.
Try:
``$evtest /dev/input/event1`` replacing ``eventX`` with your event device from above.

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======
FT6X36
======
TODO

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========
Touchpad
========
.. toctree::
:maxdepth: 2
evdev
ft6x36

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.. _wayland_driver:
=============================
Wayland Display/Inputs driver
=============================
Overview
--------
| The **Wayland** `driver <https://github.com/lvgl/lvgl/tree/master/src/drivers/wayland>`__ offers support for simulating the LVGL display and keyboard/mouse inputs in a desktop window.
| It is an alternative to **X11** or **SDL2**
The main purpose for this driver is for testing/debugging the LVGL application, it can also be used to run applications in 'kiosk mode'
Dependencies
------------
The wayland driver requires some dependencies.
On Ubuntu
.. code:: bash
sudo apt-get install libwayland-dev libxkbcommon-dev libwayland-bin wayland-protocols
On Fedora
.. code:: bash
sudo dnf install wayland-devel libxkbcommon-devel wayland-utils wayland-protocols-devel
Configuring the wayland driver
------------------------------
1. Enable the wayland driver in ``lv_conf.h``
.. code:: c
#define LV_USE_WAYLAND 1
2. Optional configuration options:
- Enable window decorations, only required on GNOME because out of all the available wayland compositors
**only** Mutter/GNOME enforces the use of client side decorations
.. code:: c
#define LV_WAYLAND_WINDOW_DECORATIONS 1
- Enable support for the deprecated 'wl_shell', Only useful when the BSP on the target has weston ``9.x``
.. code:: c
#define LV_WAYLAND_WL_SHELL 1
Example
-------
An example simulator is available in this `repo <https://github.com/lvgl/lv_port_linux/>`__
Usage
-----
#. In ``main.c`` ``#incude "lv_drivers/wayland/wayland.h"``
#. Enable the Wayland driver in ``lv_conf.h`` with ``LV_USE_WAYLAND 1``
#. ``LV_COLOR_DEPTH`` should be set either to ``32`` or ``16`` in ``lv_conf.h``
#. Add a display using ``lv_wayland_window_create()``,
possibly with a close callback to track the status of each display:
.. code:: c
#define H_RES (800)
#define V_RES (480)
/* Create a display */
lv_disp_t * disp = lv_wayland_create_window(H_RES, V_RES, "Window Title", close_cb);
As part of the above call, the Wayland driver will register four input devices
for each display:
* a KEYPAD connected to Wayland keyboard events
* a POINTER connected to Wayland touch events
* a POINTER connected to Wayland pointer events
* an ENCODER connected to Wayland pointer axis events
Handles for input devices of each display can be obtained using
``lv_wayland_get_indev_keyboard()``, ``lv_wayland_get_indev_touchscreen()``,
``lv_wayland_get_indev_pointer()`` and ``lv_wayland_get_indev_pointeraxis()`` respectively.
Fullscreen mode
^^^^^^^^^^^^^^^
To programmatically fullscreen the window,
use the ``lv_wayland_window_set_fullscreen()`` function respectively with ``true``
or ``false`` for the ``fullscreen`` argument.
Maximized mode
^^^^^^^^^^^^^^
To programmatically maximize the window,
use the ``lv_wayland_window_set_maximized()`` function respectively with ``true``
or ``false`` for the ``maximized`` argument.
Custom timer handler
^^^^^^^^^^^^^^^^^^^^
Always call ``lv_wayland_timer_handler()`` in your timer loop instead of the regular ``lv_timer_handler()``.
**Note:** ``lv_wayland_timer_handler()`` internally calls ``lv_timer_handler()``
This allows the wayland client to work on well on weston, resizing shared memory buffers during
a commit does not work well on weston.
Wrapping the call to ``lv_timer_hander()`` is a necessity to have more control over
when the LVGL flush callback is called.
The custom timer handler returns ``false`` if the frame from previous cycle is not rendered.
When this happens, it usually means that the application is minimized or hidden behind another window.
Causing the driver to wait until the arrival of any message on the wayland socket, the process is in interruptible sleep.
Building the wayland driver
---------------------------
An example simulator is available in this `repo <https://github.com/lvgl/lv_port_linux/>`__
If there is a need to use driver with another build system. The source and header files for the XDG shell
must be generated from the definitions for the XDG shell protocol.
In the example Cmake is used to perform the operation by invoking the ``wayland-scanner`` utility
To achieve this manually,
Make sure the dependencies listed at the start of the article are installed.
The wayland protocol is defined using XML files which are present in ``/usr/share/wayland-protocols``
To generate the required files run the following commands:
.. code-block:: sh
wayland-scanner client-header </usr/share/wayland-protocols/stable/xdg-shell/xdg-shell.xml > wayland_xdg_shell.h
wayland-scanner private-code </usr/share/wayland-protocols/stable/xdg-shell/xdg-shell.xml > wayland_xdg_shell.c
The resulting files can then be integrated into the project, it's better to re-run ``wayland-scanner`` on
each build to ensure that the correct versions are generated, they must match the version of the ``wayland-client``
dynamically linked library installed on the system.
Current state and objectives
----------------------------
* Add direct rendering mode
* Refactor the shell integrations to avoid excessive conditional compilation
* Technically, the wayland driver allows to create multiple windows - but this feature is experimental.
* Eventually add enhanced support for XDG shell to allow the creation of desktop apps on Unix-like platforms,
similar to what the win32 driver does.
* Add a support for Mesa, currently wl_shm is used and it's not the most effective technique.
Bug reports
-----------
The wayland driver is currently under construction, bug reports, contributions and feedback is always welcome.
It is however important to create detailed issues when a problem is encountered, logs and screenshots of the problem are of great help.
Please enable ``LV_USE_LOG`` and launch the simulator executable like so
.. code::
WAYLAND_DEBUG=1 ./path/to/simulator_executable > /tmp/debug 2>&1
This will create a log file called ``debug`` in the ``/tmp`` directory, copy-paste the content of the file in the github issue.
The log file contains LVGL logs and the wayland messages.
Be sure to replicate the problem quickly otherwise the logs become too big

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=============================
Windows Display/Inputs driver
=============================
Overview
--------
The **Windows** display/input `driver <https://github.com/lvgl/lvgl/src/drivers/windows>`__ offers support for simulating the LVGL display and keyboard/mouse inputs in a Windows Win32 window.
The main purpose for this driver is for testing/debugging the LVGL application in a **Windows** simulation window via **simulator mode**, or developing a standard **Windows** desktop application with LVGL via **application mode**.
Here are the **similarity** for simulator mode and application mode.
- Support LVGL pointer, keypad and encoder devices integration.
- Support Windows touch input.
- Support Windows input method integration input.
- Support Per-monitor DPI Aware (both V1 and V2).
Here are the **differences** for simulator mode and application mode.
Simulator Mode
^^^^^^^^^^^^^^
- Designed for LVGL simulation scenario.
- Keep the LVGL display resolution all time for trying best to simulate UI layout which will see in their production devices.
- When Windows DPI scaling setting is changed, Windows backend will stretch the display content.
Application Mode
^^^^^^^^^^^^^^^^
- Designed for Windows desktop application development scenario.
- Have the Window resizing support and LVGL display resolution will be changed.
- When Windows DPI scaling setting is changed, the LVGL display DPI value will also be changed.
Prerequisites
-------------
The minimum Windows OS requirement for this driver is Windows Vista RTM.
If you use Windows API shim libraries like `YY-Thunks <https://github.com/Chuyu-Team/YY-Thunks>`__, the tested minimum Windows OS requirement for this driver is Windows XP RTM.
According to the Windows GDI API this driver used. Maybe the minimum Windows OS requirement limitation for this driver is Windows 2000 RTM.
Configure Windows driver
------------------------
Enable the Windows driver support in lv_conf.h, by cmake compiler define or by KConfig
.. code-block:: c
#define LV_USE_WINDOWS 1
Usage
-----
.. code-block:: c
#include <Windows.h>
#include "lvgl/lvgl.h"
#include "lvgl/examples/lv_examples.h"
#include "lvgl/demos/lv_demos.h"
int main()
{
lv_init();
int32_t zoom_level = 100;
bool allow_dpi_override = false;
bool simulator_mode = false;
lv_display_t* display = lv_windows_create_display(
L"LVGL Display Window",
800,
480,
zoom_level,
allow_dpi_override,
simulator_mode);
if (!display)
{
return -1;
}
lv_lock();
lv_indev_t* pointer_device = lv_windows_acquire_pointer_indev(display);
if (!pointer_device)
{
return -1;
}
lv_indev_t* keypad_device = lv_windows_acquire_keypad_indev(display);
if (!keypad_device)
{
return -1;
}
lv_indev_t* encoder_device = lv_windows_acquire_encoder_indev(display);
if (!encoder_device)
{
return -1;
}
lv_demo_widgets();
lv_unlock();
while (1)
{
uint32_t time_till_next = lv_timer_handler();
lv_delay_ms(time_till_next);
}
return 0;
}

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=======
Arduino
=======
The `LVGL library <https://github.com/lvgl/lvgl>`__ is directly available as Arduino libraries.
Note that you need to choose a board powerful enough to run LVGL and
your GUI. See the :ref:`requirements of LVGL <requirements>`.
For example ESP32 is a good candidate to create UI's with LVGL.
Get the LVGL Arduino library
----------------------------
LVGL can be installed via the Arduino IDE Library Manager or as a .ZIP library.
You can `Download <https://github.com/lvgl/lvgl/archive/refs/heads/master.zip>`__
the latest version of LVGL from GitHub and simply copy it to Arduino's
library folder.
Set up drivers
--------------
To get started it's recommended to use `TFT_eSPI <https://github.com/Bodmer/TFT_eSPI>`__ library as a TFT
driver to simplify testing. To make it work, setup ``TFT_eSPI``
according to your TFT display type via editing either:
- ``User_Setup.h``
- or by selecting a configuration in the ``User_Setup_Select.h``
Both files are located in ``TFT_eSPI`` library's folder.
Configure LVGL
--------------
LVGL has its own configuration file called ``lv_conf.h``. When LVGL is
installed, follow these configuration steps:
1. Go to the directory of the installed Arduino libraries
2. Go to ``lvgl`` and copy ``lv_conf_template.h`` as ``lv_conf.h`` into the Arduino Libraries directory next to the ``lvgl`` library folder.
3. Open ``lv_conf.h`` and change the first ``#if 0`` to ``#if 1`` to enable the content of the file
4. Set the color depth of you display in :c:macro:`LV_COLOR_DEPTH`
Finally the layout with ``lv_conf.h`` should look like this:
::
arduino
|-libraries
|-lvgl
|-other_lib_1
|-other_lib_2
|-lv_conf.h
Initialize and run LVGL
-----------------------
Take a look at `LVGL_Arduino.ino <https://github.com/lvgl/lvgl/blob/master/examples/arduino/LVGL_Arduino/LVGL_Arduino.ino>`__
to see how to initialize LVGL. ``TFT_eSPI`` is used as the display driver.
In the INO file you can see how to register a display and a touchpad for
LVGL and call an example.
Use the examples and demos
--------------------------
Note that, there is no dedicated INO file for every example. Instead,
you can load an example by calling an ``lv_example_...`` function. For
example :cpp:func:`lv_example_btn_1`.
:important: Due to some the limitations of Arduino's build system you
need to copy ``lvgl/examples`` to ``lvgl/src/examples``. Similarly for
the demos ``lvgl/demos`` to ``lvgl/src/demos``.
Debugging and logging
---------------------
LVGL can display debug information in case of trouble. In the
``LVGL_Arduino.ino`` example there is a ``my_print`` method, which sends
this debug information to the serial interface. To enable this feature
you have to edit the ``lv_conf.h`` file and enable logging in the
section ``log settings``:
.. code-block:: c
/* Log settings */
#define USE_LV_LOG 1 /* Enable/disable the log module */
#if LV_USE_LOG
/* How important log should be added:
* LV_LOG_LEVEL_TRACE A lot of logs to give detailed information
* LV_LOG_LEVEL_INFO Log important events
* LV_LOG_LEVEL_WARN Log if something unwanted happened but didn't cause a problem
* LV_LOG_LEVEL_ERROR Only critical issue, when the system may fail
* LV_LOG_LEVEL_NONE Do not log anything
*/
# define LV_LOG_LEVEL LV_LOG_LEVEL_WARN
After enabling the log module and setting :c:macro:`LV_LOG_LEVEL` accordingly, the
output log is sent to the ``Serial`` port @ 115200 bps.

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==========
Frameworks
==========
.. toctree::
:maxdepth: 2
arduino
platformio
tasmota-berry

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==========
PlatformIO
==========
TODO

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=================
Tasmota and berry
=================
What is Tasmota?
----------------
`Tasmota <https://github.com/arendst/Tasmota>`__ is a widely used
open-source firmware for ESP8266 and EPS32 based devices. It supports a
wide variety of devices, sensors and integrations to Home Automation and
Cloud services. Tasmota firmware is downloaded more than 200,000 times
each month, and has an active and growing community.
Tasmota provides access to hundreds of supported devices, full support
of MQTT, HTTP(S), integration with major Home Automation systems, myriad
of sensors, IR, RF, Zigbee, Bluetooth, AWS IoT, Azure IoT, Alexa and
many more.
What is Berry?
--------------
`Berry <https://github.com/berry-lang/berry>`__ is a ultra-lightweight
dynamically typed embedded scripting language. It is designed for
lower-performance embedded devices. The interpreter of Berry include a
one-pass compiler and register-based VM, all the code is written in ANSI
C99. Berry offers a syntax very similar to Python, and is inspired from
LUA VM. It is fully integrated in Tasmota
Highlights of Berry
~~~~~~~~~~~~~~~~~~~
Berry has the following advantages:
- Lightweight: A well-optimized interpreter with very little resources. Ideal for use in microprocessors.
- Fast: optimized one-pass bytecode compiler and register-based virtual machine.
- Powerful: supports imperative programming, object-oriented programming, functional programming.
- Flexible: Berry is a dynamic type script, and it's intended for embedding in applications.
It can provide good dynamic scalability for the host system.
- Simple: simple and natural syntax, support garbage collection, and easy to use FFI (foreign function interface).
- RAM saving: With compile-time object construction, most of the constant objects are stored
in read-only code data segments, so the RAM usage of the interpreter is very low when it starts.
All features are detailed in the `Berry Reference Manual <https://github.com/berry-lang/berry/wiki/Reference>`__
--------------
Why LVGL + Tasmota + Berry?
---------------------------
In 2021, Tasmota added full support of LVGL for ESP32 based devices. It
also introduced the Berry scripting language, a small-footprint language
similar to Python and fully integrated in Tasmota.
A comprehensive mapping of LVGL in Berry language is now available,
similar to the mapping of MicroPython. It allows to use +98% of all LVGL
features. It is also possible to write custom widgets in Berry.
Versions supported: LVGL v8.0.2, LodePNG v20201017, Freetype 2.10.4
Tasmota + Berry + LVGL could be used for:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Fast prototyping GUI.
- Shortening the cycle of changing and fine-tuning the GUI.
- Modelling the GUI in a more abstract way by defining reusable composite Widgets, taking
advantage of Berry's language features such as Inheritance, Closures, Exception Handling…
- Make LVGL accessible to a larger audience. No need to know C to create a nice GUI on an embedded system.
A higher level interface compatible with
`OpenHASP <https://github.com/HASwitchPlate/openHASP>`__
is also under development.
--------------
So what does it look like?
--------------------------
TL;DR: Similar to MicroPython, it's very much like the C API, but Object-Oriented for LVGL components.
Let's dive right into an example!
A simple example
~~~~~~~~~~~~~~~~
.. code-block:: python
lv.start() # start LVGL
scr = lv.screen_active() # get default screen
btn = lv.btn(scr) # create button
btn.center()
label = lv.label(btn) # create a label in the button
label.set_text("Button") # set a label to the button
How can I use it?
-----------------
You can start in less than 10 minutes on a M5Stack or equivalent device
in less than 10 minutes in this `short tutorial <https://tasmota.github.io/docs/LVGL_in_10_minutes/>`__
Where can I find more information?
----------------------------------
- `Tasmota Documentation <https://tasmota.github.io/docs/>`__
- `Berry Documentation <https://github.com/berry-lang/berry/wiki/Reference>`__
- `Tasmota LVGL Berry documentation <https://tasmota.github.io/docs/LVGL/>`__

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====
IDEs
====
.. toctree::
:maxdepth: 2
mdk
pc-simulator

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===
MDK
===
TODO

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.. _simulator:
===============
Simulator on PC
===============
You can try out LVGL **using only your PC** (i.e. without any
development boards). LVGL will run on a simulator environment on the PC
where anyone can write and experiment with real LVGL applications.
Using the simulator on a PC has the following advantages:
- Hardware independent: Write code, run it on the PC and see the result on a monitor.
- Cross-platform: Any Windows, Linux or macOS system can run the PC simulator.
- Portability: The written code is portable, which means you can simply copy it when migrating to embedded hardware.
- Easy Validation: The simulator is also very useful to report bugs because it
provides a common platform for every user.
- Better developer experience: On PC Debuggers are usually faster and better, you can log to files,
add a lot of ``printf`` s, do profiling, and so on.
Select an IDE
-------------
The simulator is ported to various IDEs (Integrated Development Environments).
Choose your favorite IDE, read its README on GitHub, download the project, and load it to the IDE.
- `Eclipse with SDL driver <https://github.com/lvgl/lv_sim_eclipse_sdl>`__: Recommended on Linux and Mac, supports CMake as well
- `VisualStudio <https://github.com/lvgl/lv_port_pc_visual_studio>`__: Recommended on Windows
- `VSCode with SDL driver <https://github.com/lvgl/lv_port_pc_vscode>`__: Recommended on Linux (SDL) and Mac (SDL)
- `CodeBlocks <https://github.com/lvgl/lv_sim_codeblocks_win>`__: Recommended on Windows
- `PlatformIO with SDL driver <https://github.com/lvgl/lv_platformio>`__: Recommended on Linux and Mac but has an STM32 environment as well
- `Generic Linux <https://github.com/lvgl/lv_port_linux>`__: CMake based project where you can easily switch between fbdev, DRM, and SDL.
- `MDK with FastModel <https://github.com/lvgl/lv_port_an547_cm55_sim>`__: For Windows
External project not maintained by the LVGL organization:
- `QT Creator <https://github.com/Varanda-Labs/lvgl-qt-sim>`__: Cross platform
Built-in drivers
----------------
LVGL comes with several :ref:`built-in drivers <drivers>`.
Even if a simulator project comes with e.g. SDL, you can easily replace it by enabling
another driver in ``lv_conf.h`` and calling its ``create`` function.
For example to use the Linux frame buffer device instead of SDL just enable ``LV_USE_LINUX_FBDEV``
and call
.. code-block:: c
lv_display_t *display = lv_linux_fbdev_create();
lv_linux_fbdev_set_file(display, "/dev/fb0")

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.. _integration_index:
=======================
Integration and Drivers
=======================
.. toctree::
:maxdepth: 2
bindings/index
building/index
chip/index
driver/index
renderers/index
framework/index
ide/index
os/index

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========
FreeRTOS
========
TODO

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======
(RT)OS
======
.. toctree:: :maxdepth: 2
freertos
mqx
nuttx
px5
qnx
rt-thread
yocto/index
zephyr

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.. _mqx:
========
MQX RTOS
========
See `MQX RTOS's homepage <https://www.nxp.com/design/design-center/software/embedded-software/mqx-software-solutions/mqx-real-time-operating-system-rtos:MQXRTOS>`__
TODO

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==========
NuttX RTOS
==========
What is NuttX?
--------------
`NuttX <https://nuttx.apache.org/>`__ is a mature and secure real-time
operating system (RTOS) with an emphasis on technical standards
compliance and small size. It is scalable from 8-bit to 64-bit
microcontrollers and microprocessors and compliant with the Portable
Operating System Interface (POSIX) and the American National Standards
Institute (ANSI) standards and with many Linux-like subsystems. The best
way to think about NuttX is to think of it as a small Unix/Linux for
microcontrollers.
Highlights of NuttX
~~~~~~~~~~~~~~~~~~~
- **Small** - Fits and runs in microcontrollers as small as 32 kB Flash
and 8 kB of RAM.
- **Compliant** - Strives to be as compatible as possible with POSIX
and Linux.
- **Versatile** - Supports many architectures (ARM, ARM Thumb, AVR,
MIPS, OpenRISC, RISC-V 32-bit and 64-bit, RX65N, x86-64, Xtensa,
Z80/Z180, etc.).
- **Modular** - Its modular design allows developers to select only
what really matters and use modules to include new features.
- **Popular** - NuttX is used by many companies around the world.
Probably you already used a product with NuttX without knowing it was
running NuttX.
- **Predictable** - NuttX is a preemptible Realtime kernel, so you can
use it to create predictable applications for realtime control.
--------------
Why NuttX + LVGL?
-----------------
Although NuttX has its own graphic library called
`NX <https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=139629474>`__,
LVGL is a good alternative because users could find more eye-candy demos
and they can reuse code from previous projects. LVGL is an
`Object-Oriented Component
Based <https://blog.lvgl.io/2018-12-13/extend-lvgl-objects>`__
high-level GUI library, that could fit very well for a RTOS with
advanced features like NuttX. LVGL is implemented in C and its APIs are
in C.
Here are some advantages of using LVGL in NuttX
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Develop GUI in Linux first and when it is done just compile it for
NuttX. Nothing more, no wasting of time.
- Usually, GUI development for low level RTOS requires multiple
iterations to get things right, where each iteration consists of
**``Change code`` > ``Build`` > ``Flash`` > ``Run``**. Using LVGL,
Linux and NuttX you can reduce this process and just test everything
on your computer and when it is done, compile it on NuttX and that is
it.
NuttX + LVGL could be used for
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- GUI demos to demonstrate your board graphics capacities.
- Fast prototyping GUI for MVP (Minimum Viable Product) presentation.
- visualize sensor data directly and easily on the board without using
a computer.
- Final products with a GUI without a touchscreen (i.e. 3D Printer
Interface using Rotary Encoder to Input data).
- Final products with a touchscreen (and all sorts of bells and
whistles).
--------------
How to get started with NuttX and LVGL?
---------------------------------------
There are many boards in the `NuttX
mainline <https://github.com/apache/incubator-nuttx>`__ with support for
LVGL. Let's use the
`STM32F429IDISCOVERY <https://www.st.com/en/evaluation-tools/32f429idiscovery.html>`__
as an example because it is a very popular board.
First you need to install the pre-requisites on your system
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Let's use the `Windows Subsystem for
Linux <https://acassis.wordpress.com/2018/01/10/how-to-build-nuttx-on-windows-10/>`__
.. code-block:: shell
$ sudo apt-get install automake bison build-essential flex gcc-arm-none-eabi gperf git libncurses5-dev libtool libusb-dev libusb-1.0.0-dev pkg-config kconfig-frontends openocd
Now let's create a workspace to save our files
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: shell
$ mkdir ~/nuttxspace
$ cd ~/nuttxspace
Clone the NuttX and Apps repositories:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: shell
$ git clone https://github.com/apache/incubator-nuttx nuttx
$ git clone https://github.com/apache/incubator-nuttx-apps apps
Configure NuttX to use the stm32f429i-disco board and the LVGL Demo
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: shell
$ ./tools/configure.sh stm32f429i-disco:lvgl
$ make
If everything went fine you should have now the file ``nuttx.bin`` to
flash on your board:
.. code-block:: shell
$ ls -l nuttx.bin
-rwxrwxr-x 1 alan alan 287144 Jun 27 09:26 nuttx.bin
Flashing the firmware in the board using OpenOCD:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: shell
$ sudo openocd -f interface/stlink-v2.cfg -f target/stm32f4x.cfg -c init -c "reset halt" -c "flash write_image erase nuttx.bin 0x08000000"
Reset the board and using the 'NSH>' terminal start the LVGL demo:
.. code-block:: shell
nsh> lvgldemo
Configurations
--------------
Here are some configurations that you can use to customize your NuttX and LVGL setup:
- **LV_USE_NUTTX_INDEPENDENT_IMAGE_HEAP** - You can enable or disable the
LVGL image heap in NuttX. By default, it is disabled. If you enable
it, LVGL will use the NuttX heap instead.
Where can I find more information?
----------------------------------
- This blog post: `LVGL on
LPCXpresso54628 <https://acassis.wordpress.com/2018/07/19/running-nuttx-on-lpcxpresso54628-om13098/>`__
- NuttX mailing list: `Apache NuttX Mailing
List <http://nuttx.incubator.apache.org/community/>`__
.. Comment: The above blank line is necessary for Sphinx to not complain,
since it looks for the blank line after a bullet list.

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========
PX5 RTOS
========
See `PX5 RTOS's homepage <https://px5rtos.com/>`__
TODO

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.. _qnx:
===
QNX
===
What is QNX?
************
QNX is a commercial operating system first released in 1980. The operating
system is based on a micro-kernel design, with the file system(s), network
stack, and various other drivers each running in its own process with a separate
address space.
See www.qnx.com for more details.
Highlight of QNX
----------------
- 64-bit only, runs on x86_64 and ARMv8
- Requires an MMU as the design mandates separation among processes
- Support for thousands of processes and millions of threads
- Up to 64 cores, up to 16TB of RAM
- Virtualization support (as host and guest)
- Full POSIX compatibility
- Safety certification to various automotive, industrial and medical standards
How to run LVGL on QNX?
***********************
There are two ways to use LVGL in your QNX project. The first is similar to how
LVGL is used on other systems. The second is to build LVGL as either a shared or
a static library.
Include LVGL in Your Project
----------------------------
Follow the generic instructions for getting started with LVGL. After copying
`lv_conf_template.h` to `lv_conf.h` make the following changes to the latter:
1. Enable QNX support:
.. code-block:: c
#define LV_USE_QNX 1
2. Set colour depth to 32:
.. code-block:: c
#define LV_COLOR_DEPTH 32
3. (Optional) Enable double-buffering:
.. code-block:: c
#define LV_QNX_BUF_COUNT 2
Build LVGL as a Library
-----------------------
**Note that this method is an alternative to including LVGL in your project. If
you choose to build a library then you do not need to follow the instructions in
the previous section.**
The top-level `qnx` directory includes a recursive make file for building LVGL,
both as a shared library and as a static library for the supported
architectures. To build all libraries, simply invoke `make` in this directory:
.. code-block:: shell
# cd $(LVGL_ROOT)/env_support/qnx
# make
If you prefer to build for a specific architecture and variant, go to the
appropriate directory and run `make` there. For example, to build a shared
library for ARMv8:
.. code-block:: shell
# cd $(LVGL_ROOT)/env_support/qnx/aarch64/so.le
# make
As a general rule, if you only want to have one LVGL application in your system
then it is better to use a static library. If you have more than one, and
especially if they run concurrently, it is better to use the shared library.
Before building the library, you may wish to edit
`$(LVGL_ROOT)/env_support/qnx/lv_conf.h`, e.g. to add fonts or disable
double-buffering.
Writing a LVGL Application
--------------------------
To create a LVGL application for QNX, follow these steps in your code:
1. Initialize the library.
2. Create a window.
3. Add the input devices.
4. Create the UI.
5. Run the event loop.
Steps 2, 3 and 5 use QNX-specific calls, but the rest of the code should be
identical to that of a LVGL application written for any other platform.
The following code shows how to create a "Hello World" application:
.. code-block:: c
#include <lvgl.h>
int
main(int argc, char **argv)
{
/* Initialize the library. */
lv_init();
/* Create a 800x480 window. */
lv_display_t *disp = lv_qnx_window_create(800, 480);
lv_qnx_window_set_title(disp, "LVGL Example");
/* Add keyboard and mouse devices. */
lv_qnx_add_keyboard_device(disp);
lv_qnx_add_pointer_device(disp);
/* Generate the UI. */
lv_obj_set_style_bg_color(lv_screen_active(), lv_color_hex(0x003a57), LV_PART_MAIN);
lv_obj_t * label = lv_label_create(lv_screen_active());
lv_label_set_text(label, "Hello world");
lv_obj_set_style_text_color(lv_screen_active(), lv_color_hex(0xffffff), LV_PART_MAIN);
lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
/* Run the event loop until it exits. */
return lv_qnx_event_loop(disp);
}
Build the Application
---------------------
Building the application consists of compiling the source with the LVGL headers,
and then linking against the library. This can be done in many ways, using
different build systems. The following is a simple make file for the example
above, which builds for ARMv8 with the shared library:
.. code-block:: makefile
CC=qcc -Vgcc_ntoaarch64le
LVGL_ROOT=$(HOME)/src/lvgl
CCFLAGS=-I$(LVGL_ROOT)/env_support/qnx -I$(LVGL_ROOT)
LDFLAGS=-lscreen -llvgl -L$(LVGL_ROOT)/env_support/qnx/aarch64/so.le
lvgl_example: lvgl_example.c
$(CC) $(CCFLAGS) -Wall -o $@ $< $(LDFLAGS)
clean:
rm -f *.o *~ lvgl_example

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==============
RT-Thread RTOS
==============
What is RT-Thread?
------------------
`RT-Thread <https://www.rt-thread.io/>`__ is an `open
source <https://github.com/RT-Thread/rt-thread>`__, neutral, and
community-based real-time operating system (RTOS). RT-Thread has
**Standard version** and **Nano version**. For resource-constrained
microcontroller (MCU) systems, the Nano version that requires only 3 KB
Flash and 1.2 KB RAM memory resources can be tailored with easy-to-use
tools. For resource-rich IoT devices, RT-Thread can use the **online
software package** management tool, together with system configuration
tools, to achieve intuitive and rapid modular cutting, seamlessly import
rich software packages; thus, achieving complex functions like Android's
graphical interface and touch sliding effects, smart voice interaction
effects, and so on.
Key features
~~~~~~~~~~~~
- Designed for resource-constrained devices, the minimum kernel
requires only 1.2KB of RAM and 3 KB of Flash.
- A variety of standard interfaces, such as POSIX, CMSIS, C++
application environment.
- Has rich components and a prosperous and fast growing `package ecosystem <https://packages.rt-thread.org/en/>`__
- Elegant code style, easy to use, read and master.
- High Scalability. RT-Thread has high-quality scalable software
architecture, loose coupling, modularity, is easy to tailor and
expand.
- Supports high-performance applications.
- Supports all mainstream compiling tools such as GCC, Keil and IAR.
- Supports a wide range of `architectures and chips <https://www.rt-thread.io/board.html>`__
How to run LVGL on RT-Thread?
-----------------------------
`中文文档 <https://www.rt-thread.org/document/site/#/rt-thread-version/rt-thread-standard/packages-manual/lvgl-docs/introduction>`__
LVGL has registered as a
`softwarepackage <https://packages.rt-thread.org/en/detail.html?package=LVGL>`__
of RT-Thread. By using
`Env tool <https://www.rt-thread.io/download.html?download=Env>`__ or
`RT-Thread Studio IDE <https://www.rt-thread.io/download.html?download=Studio>`__,
RT-Thread users can easily download LVGL source code and combine with
RT-Thread project.
RT-Thread community has port LVGL to several BSPs:
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| BSP | BSP |
+======================================================================================================================================+======================================================================================================================================================+
| `QEMU simulator <https://github.com/RT-Thread/rt-thread/tree/master/bsp/qemu-vexpress-a9/applications/lvgl>`__ | `Infineon psoc6-evaluationkit-062S2 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/Infineon/psoc6-evaluationkit-062S2/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Visual Studio simulator <https://github.com/RT-Thread/rt-thread/tree/master/bsp/simulator/applications/lvgl>`__ | `Renesas ra6m3-ek <https://github.com/RT-Thread/rt-thread/tree/master/bsp/renesas/ra6m3-ek/board/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton numaker-iot-m487 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/numaker-iot-m487/applications/lvgl>`__ | `Renesas ra6m4-cpk <https://github.com/RT-Thread/rt-thread/tree/master/bsp/renesas/ra6m4-cpk/board/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton numaker-pfm-m487 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/numaker-pfm-m487/applications/lvgl>`__ | `Renesas ra6m3-hmi <https://github.com/RT-Thread/rt-thread/tree/master/bsp/renesas/ra6m3-hmi-board/board/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton nk-980iot <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/nk-980iot/applications/lvgl>`__ | `STM32H750 ART-Pi <https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32h750-artpi/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton numaker-m2354 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/numaker-m2354/applications/lvgl>`__ | `STM32F469 Discovery <https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32f469-st-disco/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton nk-n9h30 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/nk-n9h30/applications/lvgl>`__ | `STM32F407 explorer <https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32f407-atk-explorer/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton numaker-m032ki <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/numaker-m032ki/applications/lvgl>`__ | `STM32L475 pandora <https://github.com/RT-Thread/rt-thread/tree/master/bsp/stm32/stm32l475-atk-pandora/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton numaker-hmi-ma35d1 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/numaker-hmi-ma35d1/applications/lvgl>`__ | `NXP imxrt1060-evk <https://github.com/RT-Thread/rt-thread/tree/master/bsp/imxrt/imxrt1060-nxp-evk/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton numaker-iot-m467 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/numaker-iot-m467/applications/lvgl>`__ | `Raspberry PICO <https://github.com/RT-Thread/rt-thread/tree/master/bsp/raspberry-pico/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `Nuvoton numaker-m467hj <https://github.com/RT-Thread/rt-thread/tree/master/bsp/nuvoton/numaker-m467hj/applications/lvgl>`__ | `NXP LPC55S69 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/lpc55sxx/lpc55s69_nxp_evk/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
| `synwit swm341 <https://github.com/RT-Thread/rt-thread/tree/master/bsp/synwit/swm341/applications/lvgl>`__ |
+--------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------------+
Tutorials
~~~~~~~~~
- `Introduce about RT-Thread and how to run LVGL on RT-Thread in simulators <https://www.youtube.com/watch?v=k7QYk6hSwnc>`__
- `How to import a BSP project with latest code into RT-Thread Studio <https://www.youtube.com/watch?v=fREPLuh-h8k>`__
- `How to Use LVGL with RT-Thread Studio in STM32F469 Discovery Board <https://www.youtube.com/watch?v=O_QA99BxnOE>`__
- `RT-Thread Youtube Channel <https://www.youtube.com/channel/UCdDHtIfSYPq4002r27ffqPw>`__
- `RT-Thread documentation center <https://www.rt-thread.io/document/site/>`__

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.. _yocto_project_core_components:
=============================
Yocto Project Core Components
=============================
The BitBake task executor together with various types of configuration files
form the OpenEmbedded-Core (OE-Core). This section overviews these components
by describing their use and how they interact.
BitBake handles the parsing and execution of the data files. The data
itself is of various types:
- *Recipes:* Provides details about particular pieces of software.
- *Class Data:* Abstracts common build information (e.g. how to build a
Linux kernel).
- *Configuration Data:* Defines machine-specific settings, policy
decisions, and so forth. Configuration data acts as the glue to bind
everything together.
BitBake knows how to combine multiple data sources together and refers
to each data source as a layer.
Here are some brief details on these core components.
.. _bitbake_section:
BitBake
*******
BitBake is the tool at the heart of the OpenEmbedded Build System and is
responsible for parsing the Metadata, generating a list of tasks from it, and
then executing those tasks.
This section briefly introduces BitBake. If you want more information on
BitBake, see the `BitBake User Manual <https://docs.yoctoproject.org/bitbake/2.
8/index.html>`_.
To see a list of the options BitBake supports, use either of the
following commands::
$ bitbake -h
$ bitbake --help
The most common usage for BitBake is ``bitbake recipename``, where
``recipename`` is the name of the recipe you want to build (referred
to as the "target"). The target often equates to the first part of a
recipe's filename (e.g. "foo" for a recipe named ``foo_1.3.0-r0.bb``).
So, to process the ``matchbox-desktop_1.2.3.bb`` recipe file, you might
type the following::
$ bitbake matchbox-desktop
Several different versions of ``matchbox-desktop`` might exist. BitBake chooses
the one selected by the distribution configuration. You can get more details
about how BitBake chooses between different target versions and providers in the
"`Preferences <https://docs.yoctoproject.org/bitbake/2.8/bitbake-user-manual/
bitbake-user-manual-execution.html#preferences>`_" section of the BitBake User
Manual.
BitBake also tries to execute any dependent tasks first. So for example,
before building ``matchbox-desktop``, BitBake would build a cross
compiler and ``glibc`` if they had not already been built.
A useful BitBake option to consider is the ``-k`` or ``--continue``
option. This option instructs BitBake to try and continue processing the
job as long as possible even after encountering an error. When an error
occurs, the target that failed and those that depend on it cannot be
remade. However, when you use this option other dependencies can still
be processed.
.. _recipes_section:
Recipes
*******
Files that have the ``.bb`` suffix are "recipes" files. In general, a
recipe contains information about a single piece of software. This
information includes the location from which to download the unaltered
source, any source patches to be applied to that source (if needed),
which special configuration options to apply, how to compile the source
files, and how to package the compiled output.
The term "package" is sometimes used to refer to recipes. However, since
the word "package" is used for the packaged output from the OpenEmbedded
build system (i.e. ``.ipk`` or ``.deb`` files), this document avoids
using the term "package" when referring to recipes.
.. _classes_section:
Classes
*******
Class files (``.bbclass``) contain information that is useful to share
between recipes files. An example is the autotools* class,
which contains common settings for any application that is built with
the `GNU Autotools <https://en.wikipedia.org/wiki/GNU_Autotools>`.
The "`Classes <https://docs.yoctoproject.org/ref-manual/classes.
html#classes>`_" chapter in the Yocto Project
Reference Manual provides details about classes and how to use them.
.. _configurations_section:
Configurations
**************
The configuration files (``.conf``) define various configuration
variables that govern the OpenEmbedded build process. These files fall
into several areas that define machine configuration options,
distribution configuration options, compiler tuning options, general
common configuration options, and user configuration options in
``conf/local.conf``, which is found in the `Build Directory <https://docs.
yoctoproject.org/ref-manual/terms.html#term-Build-Directory>`_.
.. _layers_section:
Layers
******
Layers are repositories that contain related metadata (i.e. sets of
instructions) that tell the OpenEmbedded build system how to build a
target. `The yocto project layer model <https://docs.yoctoproject.org/
overview-manual/yp-intro.html#the-yocto-project-layer-model>`_
facilitates collaboration, sharing, customization, and reuse within the
Yocto Project development environment. Layers logically separate
information for your project. For example, you can use a layer to hold
all the configurations for a particular piece of hardware. Isolating
hardware-specific configurations allows you to share other metadata by
using a different layer where that metadata might be common across
several pieces of hardware.
There are many layers working in the Yocto Project development environment. The
`Yocto Project Compatible Layer Index <https://www.yoctoproject.org/development/
yocto-project-compatible-layers/>`_ and `OpenEmbedded Layer Index <https://
layers.openembedded.org/layerindex/branch/master/layers/>`_ both contain layers
from
which you can use or leverage.
By convention, layers in the Yocto Project follow a specific form. Conforming
to a known structure allows BitBake to make assumptions during builds on where
to find types of metadata. You can find procedures and learn about tools (i.e.
``bitbake-layers``) for creating layers suitable for the Yocto Project in the
"`understanding and creating layers <https://docs.yoctoproject.org/dev-manual/
layers.html#understanding-and-creating-layers>`_" section of the
Yocto Project Development Tasks Manual.

View File

@@ -0,0 +1,28 @@
.. _yocto:
=====
Yocto
=====
The Yocto Project (YP) is an open source collaboration project that helps
developers create custom Linux-based systems regardless of the hardware
architecture.
The project provides a flexible set of tools and a space where embedded
developers worldwide can share technologies, software stacks, configurations,
and best practices that can be used to create tailored Linux images for
embedded and IOT devices, or anywhere a customized Linux OS is needed.
This section objective is to ease to process of understanding the basic
concepts of Yocto and to help beginners to start with Yocto.
.. toctree::
:titlesonly:
:maxdepth: 1
core_components
lvgl_recipe
terms_and_variables

View File

@@ -0,0 +1,916 @@
.. _yocto_lvgl_recipe:
=============
LVGL in Yocto
=============
This chapter serves as a guide to help you create a recipe for an application
using LVGL. While the process will be demonstrated for the Raspberry Pi 3
(64-bit), it can be applied to any board in a similar way.
Build Host Packages
*******************
You must install essential host packages on your build host. The following
command installs the host packages based on an Ubuntu distribution
.. code-block::
sudo apt install gawk wget git diffstat unzip texinfo gcc build-essential \
chrpath socat cpio python3 python3-pip python3-pexpect xz-utils \
debianutils iputils-ping python3-git python3-jinja2 python3-subunit zstd \
liblz4-tool file locales libacl1
.. note::
For host package requirements on all supported Linux distributions, see the
`Required Packages for the Build Host <https://docs.yoctoproject.org/
ref-manual/system-requirements.html#required-packages-for-the-build-host>`_
section in the Yocto Project Reference Manual.
Use Git to clone the required repositories
******************************************
After this section the folder tree will be like this
.. code-block:: none
lvgl_yocto_guide/
├── build/
│ ├── cache/
│ ├── conf/
│ ├── downloads/
│ └── ...
└── sources/
├── meta-openembedded
├── meta-raspberrypi
└── poky
Start creating the folder architecture
.. code-block::
mkdir -p lvgl_yocto_guide/sources
Clone Poky, meta-openembedded and meta-raspberrypi in the sources
.. code-block::
cd lvgl_yocto_guide/sources
git clone --branch scarthgap https://git.yoctoproject.org/poky.git
git clone --branch scarthgap https://git.openembedded.org/meta-openembedded
git clone --branch scarthgap git://git.yoctoproject.org/meta-raspberrypi
Build a base image
******************
To understand better what is going on, let's build the image like it is
prepared for us
.. code-block:: none
cd ../ # go back to the root folder
source sources/poky/oe-init-build-env
Now you should have a folder named ``build`` next to ``sources``. The last
command
also sets the current directory to the build directory.
In the build directory, there is a ``conf`` folder with some files in it
.. code-block:: none
└── build/
└── conf/
├── bblayers.conf
├── conf-notes.txt
├── conf-summary.txt
├── local.conf
└── templateconf.cfg
The important files for us are ``local.conf`` and ``bblayers.conf``
To add layers to the project there are 2 options:
**Bitbake commands (Option 1)**
You need to be in the same terminal you did the ``source`` command. Add the
layers with the Bitbake command like this
.. code-block::
bitbake-layers add-layer ../sources/meta-openembedded
bitbake-layers add-layer ../sources/meta-raspberrypi
**Modify conf file (Option 2)**
Open ``conf/bblayers.conf`` file and add manually the paths:
.. code-block:: bash
# POKY_BBLAYERS_CONF_VERSION is increased each time build/conf/bblayers.conf
# changes incompatibly
POKY_BBLAYERS_CONF_VERSION = "2"
BBPATH = "${TOPDIR}"
BBFILES ?= ""
BBLAYERS ?= " \
${TOPDIR}/../sources/poky/meta \
${TOPDIR}/../sources/poky/meta-poky \
${TOPDIR}/../sources/poky/meta-yocto-bsp \
${TOPDIR}/../sources/meta-raspberrypi \
${TOPDIR}/../sources/meta-openembedded/meta-oe \
${TOPDIR}/../sources/meta-openembedded/meta-multimedia \
${TOPDIR}/../sources/meta-openembedded/meta-networking \
${TOPDIR}/../sources/meta-openembedded/meta-python \
"
To ensure the layers were added as expected, run the Bitbake command to show
all the layers::
bitbake-layers show-layers
The following layers should be listed:
- core
- yocto
- yoctobsp
- raspberrypi
- openembedded-layer
- multimedia-layer
- networking-layer
- meta-python
Build for RaspberryPi3 64
=========================
The available machine configurations for Raspberrypi can be listed like this
.. code-block::
ls ../sources/meta-raspberrypi/conf/machine/*.conf
To build an image for Raspberrypi3 64 bits, modify the file ``local.conf`` file
replacing the ``MACHINE ??=`` default value like this
.. code-block:: bash
MACHINE ??= "raspberrypi3-64"
To build the image we will target, it is also needed to add this to the file:
.. code-block:: bash
LICENSE_FLAGS_ACCEPTED = "synaptics-killswitch"
.. note::
You can find more information about this variable `here <https://meta-raspberrypi.readthedocs.io/en/latest/ipcompliance.html#linux-firmware-rpidistro>`_.
Everything is setup, time to build the image::
bitbake core-image-base
Overview of the build
=====================
Let's go through the build folders to understand what happened.
Downloads
---------
The folder location can be changed with the ``DL_DIR`` variable.
The Downloads folder is a fundamental part of the Yocto build environment,
serving as a local cache for all external sources and dependencies. This
caching mechanism is essential for efficient builds, ensuring that repeated
builds do not waste time downloading the same files again.
tmp/deploy
----------
This folder contains the final output artifacts that are ready for deployment.
These artifacts include kernel images, root filesystems, packages, SDKs,
bootloader files, and other components that are generated during the Yocto
build process.
There are some key folders:
- **images**: it contains the images that can be flashed or deployed to
the target device. Files like the Linux kernel, root filesystem (e.g., .
ext4, .tar.gz, .squashfs), bootloaders (e.g., U-Boot), and other
bootable images for the device are found here. ts organized by the
machine (or target board) for which the image was built.
- **rmp/deb/ipk**: These folders contain the individual software packages
generated during the build, in the specified package format (RPM, DEB,
or IPK). These packages are typically created when youre building your
Yocto project with package management support enabled. These can later
be installed on the target device using package management tools
- **sdk**: This subdirectory contains Software Development Kits (SDKs)
that you can use to cross-compile applications for your target system.
The SDKs are generated when you use the ``bitbake -c populate_sdk``
command.
tmp/sysroots-components
-----------------------
This folder is a modular approach introduced in Yocto to handle sysroots. It
divides the sysroot into individual components, which can be thought of as the
building blocks or packages that make up the entire sysroot environment.
Each component corresponds to a specific package or dependency that is staged
into the sysroot. This approach allows for more efficient reuse of sysroots
across multiple packages or builds, and it helps with dependency tracking and
management during the build process.
The sysroot-components directory helps optimize the build process because if
one package changes, Yocto only needs to update the corresponding component
rather than rebuilding or copying the entire sysroot.
If you followed the previous steps, here are the folders you will find:
- ``all``: Architecture-independent files.
- ``cortexa53``: Files for the Cortex-A53 (ARMv8-A) architecture.
- ``manifests``: Track files installed in the sysroot by package.
- ``raspberrypi3_64``: Files specific to the Raspberry Pi 3 (64-bit).
- ``x86_64``: Files for the x86_64 (PC) architecture, typically for
cross-compilation tools.
- ``x86_64-nativesdk``: Files related to the SDK for cross-compilation on
an x86_64 host.
Each folder corresponds to components relevant to the specific architecture,
and they collectively form the complete environment needed to compile and run
software for the target and host systems.
tmp/sysroots-uninative
----------------------
The sysroots-uninative directory in Yocto is used to support the "uninative"
feature, which allows for more reproducible builds by ensuring that the build
environment remains consistent across different host systems. It essentially
provides a way to use the same native build tools across different Linux
distributions.
tmp/work
--------
The ``work`` folder in Yocto is a key directory in the ``tmp`` folder that
holds all the temporary build artifacts for each package during the build
process. It is where the actual building and compiling of individual packages
or recipes takes place. Each package (or "recipe") that BitBake processes
generates temporary files and directories inside this ``work`` folder.
The ``work`` folder is typically structured by machine architecture and
package. Here's how it generally works:
.. code-block:: none
work/
└── <architecture>/
└── <package>/
└── <version>/
├── temp/
├── work/
├── sysroot-destdir/
└── image/
This folder is very important and helps a lot during debug phases. The ``temp``
subfolder contains important logs that can help you diagnose build issues. This
is where you'll look when a build fails to figure out what went wrong.
LVGL recipe
***********
Find more information about recipes in :ref:`recipes_section` section.
There is a recipe in ``meta-openembedded`` since ``honister``.
.. list-table:: lvgl recipe version
:widths: 200 100
:header-rows: 1
* - Branch
- Recipe
* - scarthgap (Yocto Project 5.0)
- lvgl 9.1.0
* - nanbield (Yocto Project 4.3)
- lvgl 8.3.10
* - mickledore (Yocto Project 4.2)
- lvgl 8.1.0
* - langdale (Yocto Project 4.1)
- lvgl 8.1.0
* - langdale (Yocto Project 4.1)
- lvgl 8.1.0
* - kirkstone (Yocto Project 4.0)
- lvgl 8.0.3
In this guide, we are on the ``scarthgap`` branch, so we are using lvgl 9.1.0.
Let's dive into this recipe to understand what is done. The objective is to add
this library as a shared object in the target rootfs, and also to generate a
SDK with lvgl.
This is the path of lvgl recipes: ``lvgl_yocto_guide/sources/meta-openembedded/
meta-oe/recipes-graphics/lvgl``
Here is the architecture of lvgl recipes folder:
.. code-block:: bash
lvgl
├── files
│ ├── 0002-fix-sdl-handle-both-LV_IMAGE_SRC_FILE-and-LV_IMAGE_S.patch
│ ├── 0003-Make-fbdev-device-node-runtime-configurable-via-envi.patch
│ ├── 0004-Factor-out-fbdev-initialization-code.patch
│ ├── 0005-Add-DRM-KMS-example-support.patch
│ ├── 0006-Add-SDL2-example-support.patch
│ ├── 0007-fix-cmake-generate-versioned-shared-libraries.patch
│ └── 0008-fix-fbdev-set-resolution-prior-to-buffer.patch
├── lv-conf.inc
├── lvgl_9.1.0.bb
└── lvgl-demo-fb_9.1.0.bb
- ``file`` folder contains all the patches that can be applied when
building the recipe.
- ``lv_conf.inc`` is an include file, usually containing common configuration
settings for LVGL that can be shared between multiple recipes.
- ``lvgl_9.1.0.bb`` is the recipe to build lvgl library.
- ``lvgl-demo-fb_9.1.0.bb`` is a recipe to build an application using lvgl.
For now let's understand the recipe of lvgl library.
.. code-block:: bash
# SPDX-FileCopyrightText: Huawei Inc.
#
# SPDX-License-Identifier: MIT
HOMEPAGE = "https://lvgl.io/"
DESCRIPTION = "LVGL is an OSS graphics library to create embedded GUI"
SUMMARY = "Light and Versatile Graphics Library"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://LICENCE.txt;md5=bf1198c89ae87f043108cea62460b03a"
SRC_URI = "\
git://github.com/lvgl/lvgl;protocol=https;branch=master \
file://0002-fix-sdl-handle-both-LV_IMAGE_SRC_FILE-and-LV_IMAGE_S.patch \
file://0007-fix-cmake-generate-versioned-shared-libraries.patch \
file://0008-fix-fbdev-set-resolution-prior-to-buffer.patch \
"
SRCREV = "e1c0b21b2723d391b885de4b2ee5cc997eccca91"
inherit cmake
EXTRA_OECMAKE = "-DLIB_INSTALL_DIR=${baselib} -DBUILD_SHARED_LIBS=ON"
S = "${WORKDIR}/git"
require lv-conf.inc
do_install:append() {
install -d "${D}${includedir}/${PN}"
install -m 0644 "${S}/lv_conf.h" "${D}${includedir}/${PN}/lv_conf.h"
}
FILES:${PN}-dev += "\
${includedir}/${PN}/ \
"
**LICENSE**: Indicates the licensing of the software, stating that it is
distributed under the MIT License.
**LIC_FILES_CHKSUM**: This variable contains a checksum (in this case, an MD5 hash)
for the license file (here assumed to be LICENCE.txt). This helps to ensure the
integrity of the license file included in the package. In LVGL repository,
there is a LICENSE.txt. To get the value of the hash of the file, you can do
this command: ``md5sum LICENSE.txt``
SRC_URI: Specifies the locations of the source code and patches for the recipe:
- The main source repository for LVGL specifying the master branch.
- The following arguments are the local patch files that will be applied to
the source code during the build process.
**SRCREV**: Defines the specific commit (in this case, a Git SHA hash) from
which the source code will be fetched. This ensures that the build uses a
consistent version of the code.
**inherit**: This line indicates that the recipe uses the ``cmake`` class,
which provides functionality for building projects that use CMake as
their build system.
**EXTRA_OECMAKE**: Additional options passed to CMake during the
configuration step.
**S**: This variable defines the source directory where the unpacked source
code will be located after fetching. ``${WORKDIR}`` is a standard
variable in BitBake that points to the working directory for the recipe.
require: This line includes another configuration file, ``lv-conf.inc``,
which likely contains additional configuration options or variables
specific to the LVGL library.
**FILES**: This is a BitBake variable used to specify the files that should
be included in a particular package. In this case, the variable is
specifying files for a package related to development (i.e., header
files).
Recipe Tasks
************
When a recipe is compiled, it will run multiple tasks. You can run each task
manually to understand what is generated each step, or you can run ``bitbake
lvgl`` to run all the tasks.
Fetch (do_fetch)
.. code-block:: bash
bitbake lvgl -c fetch
Fetch task fetches the package source from the local or remote repository.
The fetch Repo address has to be stored in **SRC_URI** variable. In
**SRCREV** Variable the commit hash of github repo is defined.
When the fetch task has been completed, you can find the fetched sources in
``build/downloads``.
For this recipe, you will find a new folder here: ``lvgl_yocto_guide
build/downloads/git2/github.com.lvgl.lvgl``.
You can also find the folder architecture created in ``lvgl_yocto_guide/
build/tmp/work/cortexa53-poky-linux/lvgl`` but these folders are empty since
only the fetch was done.
Unpack (do_upack)
.. code-block:: bash
bitbake lvgl -c unpack
Unpack task unpacks the package that has been downloaded with Fetch task.
In the ``lvgl_yocto_guide/build/tmp/work/cortexa53-poky-linux/lvgl/9.1.0``
folder, you can now find the source code in ``git`` (as it was defined in
the recipe). You will also see the patches that will be applied on the next
step. So for now, the sources are unmodified and the same than the commit
that was specified.
Patch (do_patch)
.. code-block:: bash
bitbake lvgl -c patch
Patch task locates the patch files and applies the patches to the sources
if any patch is available. This is optional task, executes if patch is
available.
Patch file is also defined in **SRC_URI** variable. By default it runs in
current source directory **${S}**.
Configure (do_configure)
.. code-block:: bash
bitbake lvgl -c configure
The Configuration task configures the source by enabling and disabling any
build-time and configuration options for the software being built before
compilation if any configuration is available.
This is a optional steps, executes if configuration is available.
In this case, it creates a build directory, It invokes CMake to configure
the project, specifying build options and paths based on variables in your
recipe. It generates Makefiles or project files needed for the build. Also,
there are operations added in the task in ``lv-conf.inc``.
So at the end of the task, in the ``lvgl_yocto_guide/build/tmp/work/
cortexa53-poky-linux/lvgl/9.1.0``, you will find a ``build`` folder that was
generated running the CMake command, but nothing is built yet. Also, the
sysroots have everything required to build lvgl library.
Compile (do_compile)
.. code-block:: bash
bitbake lvgl -c compile
The Compilation task compiles the source code if any compilation steps are
available and generates a binary file.
This is a optional steps, executes if compilation is available.
If there are any compilation steps, then these steps are define in
do_compile() funtion of bitbake.
Like in the previous task, this is handle by ``inherit cmake``.
In the build folder, you can now see the built library. The ``.so`` files
are available in ``lvgl_yocto_guide/build/tmp/work/ cortexa53-poky-linux/lvgl/9.1.0/build/lib``.
After this task has been completed, everything is ready to be installed.
Install (do_install)
.. code-block:: bash
bitbake lvgl -c install
The Install task copies files that are to be packaged into the holding area
**${D}**. This task runs with the current working directory **${S}** which
is the compilation directory.
It creates the necessary directory for the header files in the destination
installation directory.
It installs the ``lv_conf.h`` header file from the source directory into the
appropriate include directory in the destination path, ensuring it has the
correct permissions.
The lvgl library (``.so`` files) are also ready to be installed in the final
image. A new folder ``image`` was created.
.. important::
In the file ``build/conf/local.conf``, add these 2 lines at the end of the
file:
.. code-block:: bash
IMAGE_INSTALL:append = " lvgl"
TOOLCHAIN_HOST_TASK:append = " lvgl"
This will add the lvgl library in the generated image, and it will also add
the library to the host SDK we will generate later on.
With these modifications, you can now run the image recipe again::
bitbake core-image-base
This will execute all the previous described tasks.
If everything went well, you should now found this file ``build/tmp/deploy/
rpm/cortexa53/lvgl-9.1.0-r0.cortexa53.rpm`` and other rpm files related to
lvgl.
SDK generation
**************
Generating a Software Development Kit (SDK) in Yocto serves several important
purposes, particularly in embedded development:
- **Development Environment**: The SDK provides developers with a
ready-to-use development environment tailored for a specific target
hardware platform.
This includes the necessary tools, libraries, and headers to build
applications that run on the target device.
- **Cross-Compilation**: The SDK allows developers to cross-compile
applications from a host machine (typically x86 or x86_64 architecture)
for a different architecture (e.g., ARM). This is essential for embedded
systems, where development often occurs on more powerful machines.
- **Simplified Development**: By packaging all required components, the SDK
simplifies the process of setting up a development environment.
Developers don't need to manually install and configure tools and
libraries; everything needed is included in the SDK.
- **Consistent Build Environment**: The SDK ensures that developers are
working with the same versions of and tools used in the Yocto
build, which helps to avoid compatibility issues and ensures that
applications will behave as expected on the target device.
To generate an SDK of the environment, run the following command:
.. code-block:: bash
bitbake core-image-base -c populate_sdk
This will create a sript ``build/tmp/deploy/sdk/
poky-glibc-x86_64-core-image-base-cortexa53-raspberrypi3-64-toolchain-5.0.4.
sh``. This script allows you to install the SDK where you prefer. Here is the
execution output of the scrips
.. code-block:: bash
$ ./sdk/poky-glibc-x86_64-core-image-base-cortexa53-raspberrypi3-64-toolchain-5.0.4.sh
Poky (Yocto Project Reference Distro) SDK installer version 5.0.4
=================================================================
Enter target directory for SDK (default: /opt/poky/5.0.4): /opt/poky/sdk-with-lvgl
You are about to install the SDK to "/opt/poky/sdk-with-lvgl". Proceed [Y/n]? y
If you want to ensure the SDK was generated with lvgl being installed, go to
the path you extracted the SDK and find all lvgl files:
.. code-block:: bash
cd /opt/poky/5.0.4/sysroots/cortexa53-poky-linux
find . -name "*lvgl*"
The ``.so`` files you will find will depend on the LVGL configuration you used.
Now to use the SDK environment and cross-compile an application:
.. code-block:: bash
source /opt/poke/5.0.4/environment-setup-cortexa53-poky-linux
.. note::
The tools available in LVGL library will depend on the build configuration
the recipe was done with.
Custom recipe
*************
Until this section, everything was already done for you. We used existing
recipes. The objective here is to create a recipe from scratch and to add the
generated binary in the image.
Create a layer
==============
First, create a layer and add it to the configuration file
.. code-block::
bitbake-layers create-layer ../sources/meta-mylvgl
bitbake-layers add-layer ../sources/meta-mylvgl
In the ``sources`` folder, a new folder was created: ``meta-mylvgl`` and the
directory tree should look like the following
.. code-block:: none
├── conf
│ └── layer.conf
├── COPYING.MIT
├── README
└── recipes-example
└── example
└── example_0.1.bb
Create a recipe
===============
Following this structure, create a folder containing the recipies to build 1
or multiple applications using lvgl
.. code-block::
cd ../sources/meta-mylvgl
mkdir -p recipes-lvglapp/lvgl-fbdev-benchmark/files
touch recipes-lvglapp/lvgl-fbdev-benchmark/lvglbenchmarkfbdev_2.4.bb
We will focus on 1 application that will clone an lvgl git repository and patch
it for our needs.
The content of ``recipes-lvglapp/lvgl-fbdev-benchmark/lvglbenchmarkfbdev_2.4.
bb``
.. code-block:: none
DESCRIPTION = "My C++ lvgl app with CMake"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
# Update SRC_URI to point to the GitHub repository
SRC_URI = "gitsm://github.com/lvgl/lv_port_linux.git;branch=master;protocol=https \
file://0001-change-config-file-to-run-fbdev-with-2-threads.patch \
file://0002-adapt-CMakeLists-file-to-compile-and-link-fbdev.patch \
"
S = "${WORKDIR}/git"
inherit cmake
CMAKE_PROJECT_NAME = "lvgl_app"
CMAKE_PROJECT_VERSION = "2.0"
do_install() {
install -d ${D}${bindir}
install -m 0755 ${S}/bin/lvglbenchmark ${D}${bindir}
}
The sources come from ``lv_port_linux`` repository. We apply 2 patches to modify the ``CMakeLists.txt`` and ``lv_conf.h``.
Patch 1
-------
Create the first patch file
.. code-block::
touch 0001-change-config-file-to-run-fbdev-with-2-threads.patch
Content of ``0001-change-config-file-to-run-fbdev-with-2-threads.patch``
.. code-block:: none
From d49d475d57f69d6172a6b38095ebf3b887f0e731 Mon Sep 17 00:00:00 2001
From: Gabriel Catel Torres <gabriel.catel@edgemtech.ch>
Date: Tue, 1 Oct 2024 10:28:55 +0200
Subject: [PATCH] change config file to run fbdev with 2 threads
---
lv_conf.h | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)
diff --git a/lv_conf.h b/lv_conf.h
index 62a834f..58fbe7a 100644
--- a/lv_conf.h
+++ b/lv_conf.h
@@ -39,9 +39,9 @@
* - LV_STDLIB_RTTHREAD: RT-Thread implementation
* - LV_STDLIB_CUSTOM: Implement the functions externally
*/
-#define LV_USE_STDLIB_MALLOC LV_STDLIB_BUILTIN
-#define LV_USE_STDLIB_STRING LV_STDLIB_BUILTIN
-#define LV_USE_STDLIB_SPRINTF LV_STDLIB_BUILTIN
+#define LV_USE_STDLIB_MALLOC LV_STDLIB_CLIB
+#define LV_USE_STDLIB_STRING LV_STDLIB_CLIB
+#define LV_USE_STDLIB_SPRINTF LV_STDLIB_CLIB
#define LV_STDINT_INCLUDE <stdint.h>
#define LV_STDDEF_INCLUDE <stddef.h>
@@ -89,7 +89,7 @@
* - LV_OS_WINDOWS
* - LV_OS_MQX
* - LV_OS_CUSTOM */
-#define LV_USE_OS LV_OS_NONE
+#define LV_USE_OS LV_OS_PTHREAD
#if LV_USE_OS == LV_OS_CUSTOM
#define LV_OS_CUSTOM_INCLUDE <stdint.h>
@@ -117,12 +117,12 @@
* and can't be drawn in chunks. */
/* The target buffer size for simple layer chunks. */
-#define LV_DRAW_LAYER_SIMPLE_BUF_SIZE (24 * 1024) /* [bytes] */
+#define LV_DRAW_LAYER_SIMPLE_BUF_SIZE (512 * 1024) /* [bytes] */
/* The stack size of the drawing thread.
* NOTE: If FreeType or ThorVG is enabled, it is recommended to set it to 32KB or more.
*/
-#define LV_DRAW_THREAD_STACK_SIZE (8 * 1024) /* [bytes] */
+#define LV_DRAW_THREAD_STACK_SIZE (32 * 1024) /* [bytes] */
#define LV_USE_DRAW_SW 1
#if LV_USE_DRAW_SW == 1
@@ -147,7 +147,7 @@
/* Set the number of draw unit.
* > 1 requires an operating system enabled in `LV_USE_OS`
* > 1 means multiple threads will render the screen in parallel */
- #define LV_DRAW_SW_DRAW_UNIT_CNT 1
+ #define LV_DRAW_SW_DRAW_UNIT_CNT 2
/* Use Arm-2D to accelerate the sw render */
#define LV_USE_DRAW_ARM2D_SYNC 0
@@ -979,8 +979,8 @@
#define LV_USE_LINUX_FBDEV 1
#if LV_USE_LINUX_FBDEV
#define LV_LINUX_FBDEV_BSD 0
- #define LV_LINUX_FBDEV_RENDER_MODE LV_DISPLAY_RENDER_MODE_PARTIAL
- #define LV_LINUX_FBDEV_BUFFER_COUNT 0
+ #define LV_LINUX_FBDEV_RENDER_MODE LV_DISPLAY_RENDER_MODE_DIRECT
+ #define LV_LINUX_FBDEV_BUFFER_COUNT 2
#define LV_LINUX_FBDEV_BUFFER_SIZE 60
#endif
@@ -1069,19 +1069,19 @@
#define LV_USE_DEMO_WIDGETS 1
/* Demonstrate the usage of encoder and keyboard */
-#define LV_USE_DEMO_KEYPAD_AND_ENCODER 1
+#define LV_USE_DEMO_KEYPAD_AND_ENCODER 0
/* Benchmark your system */
#define LV_USE_DEMO_BENCHMARK 1
/* Render test for each primitives. Requires at least 480x272 display */
-#define LV_USE_DEMO_RENDER 1
+#define LV_USE_DEMO_RENDER 0
/* Stress test for LVGL */
-#define LV_USE_DEMO_STRESS 1
+#define LV_USE_DEMO_STRESS 0
/* Music player demo */
-#define LV_USE_DEMO_MUSIC 1
+#define LV_USE_DEMO_MUSIC 0
#if LV_USE_DEMO_MUSIC
#define LV_DEMO_MUSIC_SQUARE 0
#define LV_DEMO_MUSIC_LANDSCAPE 0
@@ -1091,16 +1091,16 @@
#endif
/* Flex layout demo */
-#define LV_USE_DEMO_FLEX_LAYOUT 1
+#define LV_USE_DEMO_FLEX_LAYOUT 0
/* Smart-phone like multi-language demo */
-#define LV_USE_DEMO_MULTILANG 1
+#define LV_USE_DEMO_MULTILANG 0
/* Widget transformation demo */
-#define LV_USE_DEMO_TRANSFORM 1
+#define LV_USE_DEMO_TRANSFORM 0
/* Demonstrate scroll settings */
-#define LV_USE_DEMO_SCROLL 1
+#define LV_USE_DEMO_SCROLL 0
/* Vector graphic demo */
#define LV_USE_DEMO_VECTOR_GRAPHIC 0
--
2.34.1
Patch 2
-------
Create the first patch file
.. code-block::
touch 0002-adapt-CMakeLists-file-to-compile-and-link-fbdev.patch
Content of ``0002-adapt-CMakeLists-file-to-compile-and-link-fbdev.patch``
.. code-block:: none
From ad464e0683aced74085fb89895b8d040ecad0206 Mon Sep 17 00:00:00 2001
From: Gabriel Catel Torres <gabriel.catel@edgemtech.ch>
Date: Tue, 1 Oct 2024 10:31:29 +0200
Subject: [PATCH] adapt CMakeLists file to compile and link only for fbdev
---
CMakeLists.txt | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 658193f..ad56cc2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,8 @@
cmake_minimum_required(VERSION 3.10)
project(lvgl)
-set(CMAKE_C_STANDARD 99)#C99 # lvgl officially support C99 and above
-set(CMAKE_CXX_STANDARD 17)#C17
+set(CMAKE_C_STANDARD 99)
+set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)
@@ -10,15 +10,8 @@ set(EXECUTABLE_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/bin)
add_subdirectory(lvgl)
target_include_directories(lvgl PUBLIC ${PROJECT_SOURCE_DIR})
-add_executable(main main.c mouse_cursor_icon.c)
+add_executable(lvglbenchmark main.c mouse_cursor_icon.c)
-include(${CMAKE_CURRENT_LIST_DIR}/lvgl/tests/FindLibDRM.cmake)
-include_directories(${Libdrm_INCLUDE_DIRS})
-
-find_package(SDL2)
-find_package(SDL2_image)
-include_directories(${SDL2_INCLUDE_DIRS} ${SDL2_IMAGE_INCLUDE_DIRS})
-
-target_link_libraries(main lvgl lvgl::examples lvgl::demos lvgl::thorvg ${SDL2_LIBRARIES} ${SDL2_IMAGE_LIBRARIES} ${Libdrm_LIBRARIES} m pthread)
-add_custom_target (run COMMAND ${EXECUTABLE_OUTPUT_PATH}/main DEPENDS main)
+target_link_libraries(lvglbenchmark lvgl lvgl::examples lvgl::demos lvgl::thorvg m pthread)
+add_custom_target (run COMMAND ${EXECUTABLE_OUTPUT_PATH}/lvglbenchmark DEPENDS main)
--
2.34.1
Build the recipe
================
You should now be able to see the recipe listing the existing recipes
.. code-block::
bitbake-layers show-recipes | grep lvglbenchmarkfbdev
Now add the recipe to the project. Modify ``build/conf/local.conf`` file adding
this line
.. code-block::
IMAGE_INSTALL:append = " lvglbenchmarkfbdev"
Now build the image
.. code-block::
bitbake core-image-base
Run this command to ensure the binary was generated and was installed in the
rootfs
.. code-block::
# Run this command in build/tmp folder
find . -wholename "*bin/lvglbench*"

View File

@@ -0,0 +1,196 @@
.. _yocto_project_terms:
===================
Yocto Project Terms
===================
Getting started in Yocto can be overwheming. There are many terms used that are
specific to Yocto and Bitbake environment.
A list of terms and definitions users new to the Yocto Project
development environment might find helpful can be found `here <https://docs.
yoctoproject.org/ref-manual/terms.html>`_.
Yocto Variables Glossary
************************
This chapter lists basic variables used in the LVGL Yocto guide and gives an
overview of their function and contents.
A More complete variable glossary can be found in `Yocto Variable Glossary
<https://docs.yoctoproject.org/ref-manual/variables.html>`_. This section
covers a lot of variables used in the OpenEmbedded build system.
.. _S:
S
-
The location in the Build Directory where unpacked recipe source code resides.
By default, this directory is ${WORKDIR}/${BPN}-${PV}, where ${BPN} is the
base recipe name and ${PV} is the recipe version. If the source tarball
extracts the code to a directory named anything other than ${BPN}-${PV}, or if
the source code is fetched from an SCM such as Git or Subversion, then you
must set S in the recipe so that the OpenEmbedded build system knows where to
find the unpacked source.
As an example, assume a Source Directory top-level folder named poky and a
default Build Directory at poky/build. In this case, the work directory the
build system uses to keep the unpacked recipe for db is the following:
.. code-block:: bash
poky/build/tmp/work/qemux86-poky-linux/db/5.1.19-r3/db-5.1.19
The unpacked source code resides in the db-5.1.19 folder.
This next example assumes a Git repository. By default, Git repositories are
cloned to ${WORKDIR}/git during do_fetch. Since this path is different from the
default value of S, you must set it specifically so the source can be located:
.. code-block:: bash
SRC_URI = "git://path/to/repo.git;branch=main"
S = "${WORKDIR}/git"
.. _D:
D
-
The destination directory. The location in the Build Directory where components
are installed by the do_install task. This location defaults to:
.. code-block:: bash
${WORKDIR}/image
.. note::
Tasks that read from or write to this directory should run under fakeroot.
.. _B:
B
-
The directory within the Build Directory in which the OpenEmbedded build system
places generated objects during a recipe's build process. By default, this
directory is the same as the S directory, which is defined as:
.. code-block:: bash
S = "${WORKDIR}/${BP}"
You can separate the (S) directory and the directory pointed to by the B
variable. Most Autotools-based recipes support separating these directories.
The build system defaults to using separate directories for gcc and some kernel
recipes.
.. _WORKDIR:
WORKDIR
-------
The pathname of the work directory in which the OpenEmbedded build system
builds a recipe. This directory is located within the TMPDIR directory
structure and is specific to the recipe being built and the system for which it
is being built.
The WORKDIR directory is defined as follows:
.. code-block:: bash
${TMPDIR}/work/${MULTIMACH_TARGET_SYS}/${PN}/${EXTENDPE}${PV}-${PR}
The actual directory depends on several things:
- **TMPDIR**: The top-level build output directory
- **MULTIMACH_TARGET_SYS**: The target system identifier
- **PN**: The recipe name
- **EXTENDPE**: The epoch — if PE is not specified, which is usually the
case for most recipes, then EXTENDPE is blank.
- **PV**: The recipe version
- **PR**: The recipe revision
As an example, assume a Source Directory top-level folder name poky, a default
Build Directory at poky/build, and a qemux86-poky-linux machine target system.
Furthermore, suppose your recipe is named foo_1.3.0-r0.bb. In this case, the
work directory the build system uses to build the package would be as follows:
.. code-block:: bash
poky/build/tmp/work/qemux86-poky-linux/foo/1.3.0-r0
.. _PN:
PN
--
This variable can have two separate functions depending on the context: a
recipe name or a resulting package name.
PN refers to a recipe name in the context of a file used by the OpenEmbedded
build system as input to create a package. The name is normally extracted from
the recipe file name. For example, if the recipe is named expat_2.0.1.bb, then
the default value of PN will be “expat”.
The variable refers to a package name in the context of a file created or
produced by the OpenEmbedded build system.
If applicable, the PN variable also contains any special suffix or prefix. For
example, using bash to build packages for the native machine, PN is
bash-native. Using bash to build packages for the target and for Multilib, PN
would be bash and lib64-bash, respectively.
.. _PR:
PR
--
The revision of the recipe. The default value for this variable is
"r0". Subsequent revisions of the recipe conventionally have the
values "r1", "r2", and so forth. When PV increases,
PR is conventionally reset to "r0".
.. note::
The OpenEmbedded build system does not need the aid of PR to know when to
rebuild a recipe. The build system uses the task input checksums along with
the stamp and shared state cache mechanisms.
The PR variable primarily becomes significant when a package
manager dynamically installs packages on an already built image. In
this case, PR, which is the default value of
PKGR, helps the package manager distinguish which
package is the most recent one in cases where many packages have the
same PV (i.e. PKGV). A component having many packages with
the same PV usually means that the packages all install the same
upstream version, but with later (PR) version packages including
packaging fixes.
.. note::
PR does not need to be increased for changes that do not change the
package contents or metadata.
Because manually managing PR can be cumbersome and error-prone,
an automated solution exists. See the
"`working with a pr service <https://docs.yoctoproject.org/dev-manual/packages.
html#working-with-a-pr-service>`_" section in the Yocto Project Development
Tasks Manual for more information.
.. _PV:
PV
--
The version of the recipe. The version is normally extracted from the recipe
filename. For example, if the recipe is named expat_2.0.1.bb, then the default
value of PV will be “2.0.1”. PV is generally not overridden within a recipe
unless it is building an unstable (i.e. development) version from a source code
repository (e.g. Git or Subversion).
PV is the default value of the PKGV variable.

View File

@@ -0,0 +1,194 @@
======
Zephyr
======
What is Zephyr?
---------------
`Zephyr <https://zephyrproject.org/>`__ is an `open
source <https://github.com/zephyrproject-rtos/zephyr>`__ real-time operating
system (RTOS) that is easy to deploy, secure, connect and manage.
It has a growing set of software libraries that can be used
across various applications and industry sectors such as
Industrial IoT, wearables, machine learning and more.
Zephyr is built with an emphasis on broad chipset support,
security, dependability, longterm support releases and a
growing open source ecosystem.
Highlights of Zephyr
~~~~~~~~~~~~~~~~~~~~
- **Small** - Runs on microcontrollers as small as 8 kB Flash
and 5 kB of RAM.
- **Scalable** - Usable for complex multicore systems.
- **Customizable** - Out-of-the-box support for 500+ boards
and high portability.
- **Secure** - Built with safety and security in mind,
offers Long-term support.
- **Ecosystem** - Zephyr not only provides the RTOS kernel but
also developer tooling, device drivers, connectivity, logging,
tracing, power management and much more.
- **Decoupling** - Leverages devicetree to describe and
configure the target system.
- **Compliant** - Apps are runnable as native Linux applications,
which simplifies debugging and profiling.
How to run LVGL on Zephyr?
--------------------------
To setup your development environment refer to the
`getting started guide <https://docs.zephyrproject.org/latest/develop/getting_started/index.html>`__.
After you completed the setup above you can check out all of the `provided samples <https://docs.zephyrproject.org/latest/samples/>`__ for various boards.
You can check the list of available boards using:
.. code-block:: shell
$ west boards
After you chose a board you can build one of the LVGL demos for it. Here we are using the :code:`native_posix`
board, which allows for running the application on your posix compliant host system:
.. code-block:: shell
$ west build -b native_posix samples/modules/lvgl/demos
To run the application on your host:
.. code-block:: shell
$ west build -t run
In case you chose any of the other supported boards you can flash to the device with:
.. code-block:: shell
$ west flash
If you want to build any of the other demo applications check out the samples
`README <https://docs.zephyrproject.org/latest/samples/modules/lvgl/demos/README.html>`__.
Leveraging Zephyr Features
--------------------------
Shell
~~~~~
Zephyr includes a powerful shell implementation that can be enabled with the Kconfig symbols
:code:`CONFIG_SHELL` and :code:`CONFIG_LV_Z_SHELL` (the demos from above have it enabled by default).
The shell offers enabling/disabling of LVGL monkeys:
.. code-block:: shell
# Create a new monkey with the given indev type
uart$ lvgl monkey create [pointer|keypad|button|encoder]
# Enable/Disable a monkey
uart$ lvgl monkey set <index> <inactive/active>
This is useful for checking your application for memory leaks and other bugs.
Speaking of memory leaks, you can also acquire stats of the memory used by LVGL
.. code-block:: shell
uart$ lvgl stats memory
For more details refer to the `shell documentation <https://docs.zephyrproject.org/latest/services/shell/index.html>`__.
Devicetree
~~~~~~~~~~
Zephyr uses the devicetree description language to create and manage LVGL input devices.
The pseudo device binding descriptions can be found at:
- `button input <https://docs.zephyrproject.org/latest/build/dts/api/bindings/input/zephyr,lvgl-button-input.html>`__
- `pointer input <https://docs.zephyrproject.org/latest/build/dts/api/bindings/input/zephyr,lvgl-pointer-input.html>`__
- `encoder input <https://docs.zephyrproject.org/latest/build/dts/api/bindings/input/zephyr,lvgl-encoder-input.html>`__
- `keypad input <https://docs.zephyrproject.org/latest/build/dts/api/bindings/input/zephyr,lvgl-keypad-input.html>`__
Essentially those buffer the :code:`input_event` generated by the device pointed to by the :code:`input` phandle or if left
empty the binding captures all events regardless of the source. You do not have to instantiate or manage the devices yourself,
they are created at application start up before :code:`main()` is executed.
Most boards or shields that have a display or display connector have the pointer input device already declared:
.. code-block::
lvgl_pointer {
compatible = "zephyr,lvgl-pointer-input";
input = <&ft5336_touch>;
};
You can access the underlying lvgl :code:`lv_indev_t` for configuration.
Example with the encoder device to assign a :code:`lv_group_t`:
.. code-block:: c
const struct device *lvgl_encoder = DEVICE_DT_GET(DT_COMPAT_GET_ANY_STATUS_OKAY(zephyr_lvgl_encoder_input));
lv_obj_t *arc;
lv_group_t *arc_group;
arc = lv_arc_create(lv_screen_active());
lv_obj_align(arc, LV_ALIGN_CENTER, 0, 0);
lv_obj_set_size(arc, 150, 150);
arc_group = lv_group_create();
lv_group_add_obj(arc_group, arc);
lv_indev_set_group(lvgl_input_get_indev(lvgl_encoder), arc_group);
Kconfig
~~~~~~~~
Aside from enabling the shell you can also use Kconfig to finetune
the footprint of your application.
.. code-block::
# Size of the memory region from which lvgl memory is allocated
CONFIG_LV_Z_MEM_POOL_SIZE=8192
# Do not include every widget/theme by default, enable them as needed.
CONFIG_LV_CONF_MINIMAL=y
Overlays can be used to enable/disable features for specific boards or build
targets. For more information refer to the
`application development guide <https://docs.zephyrproject.org/latest/develop/application/index.html#application-configuration>`__.
Performance Tuning in LVGL
~~~~~~~~~~~~~~~~~~~~~~~~~~
To optimize LVGL's performance, several `kconfig` options can be configured:
- **CONFIG_LV_Z_VDB_SIZE**: Sets the rendering buffer size as a percentage of the display area, adjustable from 1% to 100%. Larger buffers can enhance performance, especially when used with **CONFIG_LV_Z_FULL_REFRESH**.
- **CONFIG_LV_Z_DOUBLE_VDB**: Enables the use of two rendering buffers, allowing for parallel rendering and data flushing, thus improving responsiveness and reducing latency.
- **CONFIG_LV_Z_VDB_ALIGN**: Ensures that the rendering buffer is properly aligned, which is critical for efficient memory access based on the color depth.
- **CONFIG_LV_Z_VBD_CUSTOM_SECTION**: Allows rendering buffers to be placed in a custom memory section (e.g., `.lvgl_buf`), useful for leveraging specific memory types like tightly coupled or external memory to enhance performance.
Zephyr ≤ 3.7.0 Specific Options
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For Zephyr versions 3.7.0 and below, additional options are available to manage LVGL's frame flushing:
- **CONFIG_LV_Z_FLUSH_THREAD**: Enables flushing LVGL frames in a separate thread, allowing the main thread to continue rendering the next frame simultaneously. This option can be disabled if the performance gain is not needed.
- **CONFIG_LV_Z_FLUSH_THREAD_STACK_SIZE**: Specifies the stack size for the flush thread, with a default of 1024 bytes.
- **CONFIG_LV_Z_FLUSH_THREAD_PRIO**: Sets the priority of the flush thread, with a default priority of 0, indicating cooperative priority.
For newer versions of Zephyr, the OSAL (Operating System Abstraction Layer) can be utilized, which takes care of the flushing.
Where can I find more information?
----------------------------------
- Zephyr Documentation: `Zephyr Documentation <https://docs.zephyrproject.org/latest/index.html>`__
- Zephyr mailing list: `Zepyhr Mailing
List <https://lists.zephyrproject.org/g/main>`__
- Zephyr Discord server: `Zepyhr Discord
server <https://chat.zephyrproject.org/>`__

View File

@@ -0,0 +1,70 @@
.. _arm2d:
==========
Arm-2D GPU
==========
Arm-2D is not a GPU but **an abstraction layer for 2D GPUs dedicated to
Microcontrollers**. It supports all Cortex-M processors ranging from
Cortex-M0 to the latest Cortex-M85.
Arm-2D accelerates LVGL9 with two modes: **Synchronous Mode** and
**Asynchronous Mode**.
- When **Helium** and **ACI (Arm Custom Instruction)** are available, it is recommend
to use **Synchronous Mode** to accelerate LVGL.
- When Arm-2D backed 2D-GPUs are available, for example, **DMAC-350 based 2D
GPUs**, it is recommend to use **Asynchronous Mode** to accelerate LVGL.
Arm-2D is an open-source project on GitHub. For more, please refer to:
https://github.com/ARM-software/Arm-2D.
How to Use
**********
In general:
- you can set the macro :c:macro:`LV_USE_DRAW_ARM2D_SYNC` to ``1`` and
:c:macro:`LV_DRAW_SW_ASM` to ``LV_DRAW_SW_ASM_HELIUM`` in ``lv_conf.h`` to
enable Arm-2D synchronous acceleration for LVGL.
- You can set
the macro :c:macro:`LV_USE_DRAW_ARM2D_ASYNC` to ``1`` in ``lv_conf.h`` to enable
Arm-2D Asynchronous acceleration for LVGL.
If you are using
`CMSIS-Pack <https://github.com/lvgl/lvgl/tree/master/env_support/cmsis-pack>`__
to deploy the LVGL. You don't have to define the macro
:c:macro:`LV_USE_DRAW_ARM2D_SYNC` manually, instead the lv_conf_cmsis.h will
check the environment and set the :c:macro:`LV_USE_DRAW_ARM2D_SYNC` accordingly.
Design Considerations
*********************
As mentioned before, Arm-2D is an abstraction layer for 2D GPU; hence if
there is no accelerator or dedicated instruction set (such as Helium or
ACI) available for Arm-2D, it provides negligible performance boost for
LVGL (sometimes worse) for regular Cortex-M processors.
**We highly recommend you enable Arm-2D acceleration for LVGL** when:
- The target processors are **Cortex-M55**, **Cortex-M52** and **Cortex-M85**
- The target processors support
`Helium <https://developer.arm.com/documentation/102102/0103/?lang=en>`__.
- The device vendor provides an arm-2d compliant driver for their
proprietary 2D accelerators and/or ACI (Arm Customized Instruction).
- The target device contains
`DMAC-350 <https://community.arm.com/arm-community-blogs/b/internet-of-things-blog/posts/arm-corelink-dma-350-next-generation-direct-memory-access-for-endpoint-ai>`__
Examples
********
- `A Cortex-M55 (supports Helium) based MDK Project, PC emulation is
available. <https://github.com/lvgl/lv_port_an547_cm55_sim>`__
API
***
:ref:`lv_draw_sw_arm2d_h`
:ref:`lv_blend_arm2d_h`

View File

@@ -0,0 +1,14 @@
==================
Renderers and GPUs
==================
.. toctree::
:maxdepth: 2
sw
arm2d
nema_gfx
nxp_pxp
nxp_vglite
sdl
stm32_dma2d

View File

@@ -0,0 +1,94 @@
.. _stm32_nema_gfx:
===================================
NemaGFX Acceleration (AKA NeoChrom)
===================================
Some of the more powerful STM32 MCUs such as the
STM32U5 feature a 2.5D GPU which can natively draw most
LVGL primitives.
Get Started with the Riverdi STM32U5 5-inch Display
***************************************************
`lv_port_riverdi_stm32u5 <https://github.com/lvgl/lv_port_riverdi_stm32u5>`__
is a ready-to-use port for the Riverdi STM32 5.0" Embedded Display
(STM32U599NJH6Q or STM32U5A9NJH6Q) which has Nema enabled.
Follow the instructions in the readme to get started.
Usage and Configuration
***********************
Enable the renderer by setting :c:macro:`LV_USE_NEMA_GFX` to ``1`` in
lv_conf.h. If using :c:macro:`LV_USE_NEMA_VG`,
set :c:macro:`LV_NEMA_GFX_MAX_RESX` and :c:macro:`LV_NEMA_GFX_MAX_RESY`
to the size of the display you will be using so that enough static
memory will be reserved for VG. Without VG, more task types will be
performed by the software renderer.
"libs/nema_gfx" contains pre-compiled binaries for the Nema GPU
drivers. In `lv_port_riverdi_stm32u5 <https://github.com/lvgl/lv_port_riverdi_stm32u5>`__
the project is already configured to link the binaries when building.
With a different STM32CubeIDE project, you can configure the libraries to be linked
by right-clicking the project in the "Project Explorer" sidebar, clicking
"Properties", navigating to "C/C++ Build", "Settings", "MCU G++ Linker", and then
"Libraries". Add an entry under "Libraries (-l)" that is "nemagfx-float-abi-hard".
Add an entry under "Library search path (-L)" which is a path to
"libs/nema_gfx/lib/core/cortex_m33/gcc" e.g.
"${workspace_loc:/${ProjName}/Middlewares/LVGL/lvgl/libs/nema_gfx/lib/core/cortex_m33/gcc}".
You will also want to add the "libs/nema_gfx/include" directory to your include
search paths. Under "MCU GCC Compiler", "Include paths", add an entry to "Include paths (-I)"
which is a path to "libs/nema_gfx/include" e.g.
"${workspace_loc:/${ProjName}/Middlewares/LVGL/lvgl/libs/nema_gfx/include}".
Click "Apply and Close".
32 and 16 bit :c:macro:`LV_COLOR_DEPTH` is supported.
At the time of writing, :c:macro:`LV_USE_OS` support is experimental
and not yet working in
`lv_port_riverdi_stm32u5 <https://github.com/lvgl/lv_port_riverdi_stm32u5>`__
"src/draw/nema_gfx/lv_draw_nema_gfx_hal.c" implements the HAL functionality
required by Nema to allocate memory and lock resources (in this implementation,
no locking is done). It may conflict with existing definitions
if you have an existing Nema HAL implementation. You may
simply be able to remove yours.
TSC Images
**********
TSC (ThinkSillicon Compression) images can be drawn by this renderer. The
TSC 4/6/6A/12/12A color formats are part of :cpp:type:`lv_color_format_t`.
All other renderers will ignore images with these color formats.
Define an image descriptor variable with the corresponding
TSC color format and the GPU will be able to draw it directly.
Stride does not need to be specified because it will be computed by the
renderer.
.. code-block:: c
const lv_image_dsc_t img_demo_widgets_avatar_tsc6a = {
.header.cf = LV_COLOR_FORMAT_NEMA_TSC6A,
.header.w = 144,
.header.h = 144,
.data = img_demo_widgets_avatar_tsc6a_map,
.data_size = sizeof(img_demo_widgets_avatar_tsc6a_map),
};
DMA2D
*****
The Nema renderer uses DMA2D to flush in parallel with rendering in
`lv_port_riverdi_stm32u5 <https://github.com/lvgl/lv_port_riverdi_stm32u5>`__.
If your STM does not have the Nema GPU, it may still support
DMA2D. DMA2D is a simple peripheral which can draw fills
and images independently of the CPU.
See the LVGL :ref:`DMA2D support <dma2d>`.
API
***
:ref:`lv_draw_nema_gfx_h`
:ref:`lv_draw_nema_gfx_utils_h`

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===========
NXP PXP GPU
===========
API
***
:ref:`lv_draw_pxp_h`
:ref:`lv_pxp_cfg_h`
:ref:`lv_pxp_osa_h`
:ref:`lv_pxp_utils_h`

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.. _vglite:
===============
NXP VG-Lite GPU
===============
This is a generic VG-Lite rendering backend implementation that is designed to utilize
`VeriSilicon <https://verisilicon.com/>`_'s generic API to operate GPU hardware as much as possible.
Even with different chip manufacturers, as long as they use the same version of VG-Lite API as the rendering backend,
LVGL rendering acceleration can be supported without the need for LVGL adaptation work.
Configuration
*************
1. Set :c:macro:`LV_USE_DRAW_VG_LITE` to 1 in ``lv_conf.h`` to enabled the VG-Lite rendering backend.
Make sure that your hardware has been adapted to the VG-Lite API and that the absolute path to ``vg_lite.h``, which can be directly referenced by lvgl, has been exposed.
2. Confirm the GPU initialization method, there are two ways:
- The SDK calls the GPU initialization function on its own during system startup, and the GPU is available when LVGL starts; set :c:macro:`LV_VG_LITE_USE_GPU_INIT` to 0.
- LVGL actively calls the GPU initialization function, and the SDK needs to implement the public function `gpu_init()`.
LVGL will call it to complete the GPU hardware initialization during startup; set :c:macro:`LV_VG_LITE_USE_GPU_INIT` to 1.
3. Set the :c:macro:`LV_VG_LITE_USE_ASSERT` configuration to enable GPU call parameter checking.
Due to the complexity of the parameters used in GPU calls, incorrect parameters can result in abnormal GPU hardware operation, such as forgetting to add an end symbol
to the path or not meeting the alignment requirements for buffer stride.
To quickly resolve such issues, strict parameter checking has been added before each VG-Lite call, including buffer stride validation and matrix invertibility check.
When an error parameter is detected, an assertion will occur to print out the error parameter, allowing the user to promptly make corrections and reduce the time wasted on hardware simulation.
Please note that enabling this check will decrease runtime performance. It is recommended to enable it in Debug mode and disable it in the Release version.
4. Set the :c:macro:`LV_VG_LITE_FLUSH_MAX_COUNT` configuration to specify the flush method.
VG-Lite uses two sets of command buffer buffers to render instructions, and utilizing this mechanism well can greatly improve drawing efficiency.
Currently, two buffering methods are supported:
- Set :c:macro:`LV_VG_LITE_FLUSH_MAX_COUNT` to zero (recommended). The rendering backend will obtain the GPU's working status every time it writes rendering instructions to the command buffer.
When the GPU is idle, it will immediately call ``vg_lite_flush`` to notify the GPU to start rendering and swap the command buffer. When the GPU is busy, it will continue to fill the command buffer cache with rendering instructions.
The underlying driver will automatically determine if the command buffer has been filled. When it is about to be filled, it will forcibly wait for the unfinished drawing tasks to end and swap the command buffer.
This method can effectively improve GPU utilization, especially in scenarios where rendering text, as the GPU's drawing time and the CPU's data preparation time are very close, allowing the CPU and GPU to run in parallel.
- Set :c:macro:`LV_VG_LITE_FLUSH_MAX_COUNT` to a value greater than zero, such as 8. After writing 8 rendering instructions to the command buffer, the rendering backend
will call ``vg_lite_flush`` to notify the GPU to start rendering and swap the command buffer.
5. Set the :c:macro:`LV_VG_LITE_USE_BOX_SHADOW` configuration to use GPU rendering for shadows.
In fact, GPU hardware does not actually support shadow rendering. However, through experimentation, it has been found that a similar shadow effect
can be achieved by using multiple layers of borders with different levels of transparency.
It is recommended to enable this configuration in scenarios where the shadow quality requirements are not high, as it can significantly improve rendering efficiency.
6. Set the :c:macro:`LV_VG_LITE_GRAD_CACHE_CNT` configuration to specify the number of gradient cache entries.
Gradient drawing includes linear gradients and radial gradients. Using a cache can effectively reduce the number of times the gradient image is created and improve drawing efficiency.
Each individual gradient consumes around 4K of GPU memory pool. If there are many gradients used in the interface, you can try increasing the number of gradient cache entries.
If the VG-Lite API returns the :c:macro:`VG_LITE_OUT_OF_RESOURCES` error, you can try increasing the size of the GPU memory pool or reducing the number of gradient cache entries.
7. Set the :c:macro:`LV_VG_LITE_STROKE_CACHE_CNT` configuration to specify the number of stroke path caches.
When the stroke parameters do not change, the previously generated stroke parameters are automatically retrieved from the cache to improve rendering performance.
The memory occupied by the stroke is strongly related to the path length. If the VG-Lite API returns the :c:macro:`VG_LITE_OUT_OF_RESOURCES` error,
you can try increasing the size of the GPU memory pool or reducing the number of stroke cache entries.
NOTE: VG-Lite rendering backend does not support multi-threaded calls, please make sure :c:macro:`LV_USE_OS` is always configured as :c:macro:`LV_OS_NONE`.
VG-Lite Simulator
*****************
LVGL integrates a VG-Lite simulator based on ThorVG.
Its purpose is to simplify the debugging of VG-Lite adaptation and reduce the time of debugging and locating problems on hardware devices.
For detailed instructions, see :ref:`vg_lite_tvg`.
API
***
:ref:`lv_draw_vglite_h`
:ref:`lv_vglite_buf_h`
:ref:`lv_vglite_matrix_h`
:ref:`lv_vglite_path_h`
:ref:`lv_vglite_utils_h`

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============
SDL Renderer
============
API
***
:ref:`lv_draw_sdl_h`

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===============
STM32 DMA2D GPU
===============
API
***
:ref:`lv_draw_dma2d_h`

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=================
Software Renderer
=================
API
***
:ref:`lv_draw_sw_h`
:ref:`lv_draw_sw_blend_h`
:ref:`lv_draw_sw_gradient_h`

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.. _arduino_esp_littlefs:
====================
Arduino ESP littlefs
====================
LittleFS is a little fail-safe filesystem designed for microcontrollers and integrated in the Arduino framework
when used with ESP32 and ESP8266.
Detailed introduction:
- https://github.com/esp8266/Arduino
- https://github.com/espressif/arduino-esp32
Usage
-----
Enable :c:macro:`LV_USE_FS_ARDUINO_ESP_LITTLEFS` and define a :c:macro:`LV_FS_ARDUINO_ESP_LITTLEFS_LETTER` in ``lv_conf.h``.
API
---

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.. _arduino_sd:
==========
Arduino SD
==========
Enables reading and writing on SD cards.
Once an SD memory card is connected to the SPI interface of the Arduino or Genuino board you can create files
and read/write on them. You can also move through directories on the SD card..
Detailed introduction:
- https://www.arduino.cc/reference/en/libraries/sd/
Usage
-----
Enable :c:macro:`LV_USE_FS_ARDUINO_SD` and define a :c:macro:`LV_FS_ARDUINO_SD_LETTER` in ``lv_conf.h``.
You will need to initialize the SD card before LVGL can use it (i.e. :cpp:expr:`SD.begin(0, SPI, 40000000)`).
API
---

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.. _barcode:
=======
Barcode
=======
Barcode generation with LVGL. Uses
`code128 <https://github.com/fhunleth/code128>`__ by
`fhunleth <https://github.com/fhunleth>`__.
.. _barcode_usage:
Usage
-----
Enable :c:macro:`LV_USE_BARCODE` in ``lv_conf.h``.
Use :cpp:func:`lv_barcode_create` to create a barcode object, and use
:cpp:func:`lv_barcode_update` to generate a barcode.
Call :cpp:func:`lv_barcode_set_scale` to adjust scaling,
call :cpp:func:`lv_barcode_set_dark_color` and :cpp:func:`lv_barcode_set_light_color`
adjust color, call :cpp:func:`lv_barcode_set_direction` will set
direction to display, and call :cpp:func:`lv_barcode_update` again to regenerate
the barcode.
Notes
-----
- It is best not to manually set the width of the barcode, because when
the width of the Widget is lower than the width of the barcode, the
display will be incomplete due to truncation.
- The scale adjustment can only be an integer multiple, for example,
:cpp:expr:`lv_barcode_set_scale(barcode, 2)` means 2x scaling.
- The direction adjustment can be :cpp:enumerator:`LV_DIR_HOR` or :cpp:enumerator:`LV_DIR_VER`
.. _barcode_example:
Example
-------
.. include:: ../../examples/libs/barcode/index.rst
.. _barcode_api:
API
---
:ref:`code128_h`

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.. _bmp:
===========
BMP decoder
===========
This extension allows the use of BMP images in LVGL.
Library source: https://github.com/caj-johnson/bmp-decoder
The pixels are read on demand (not the whole image is loaded)
so using BMP images requires very little RAM.
If enabled in ``lv_conf.h`` by :c:macro:`LV_USE_BMP` LVGL will register a new
image decoder automatically so BMP files can be directly used as image
sources. For example:
.. code-block:: c
lv_image_set_src(my_img, "S:path/to/picture.bmp");
Note that, a file system driver needs to registered to open images from
files. Read more about it :ref:`overview_file_system` or just
enable one in ``lv_conf.h`` with ``LV_USE_FS_...``
.. _bmp_limitations:
Limitations
-----------
- Only BMP files are supported and BMP images as C array
(:c:struct:`lv_image_dsc_t`) are not. It's because there is no practical
differences between how the BMP files and LVGL's image format stores
the image data.
- BMP files can be loaded only from file. If you want to store them in
flash it's better to convert them to C array with `LVGL's image converter <https://lvgl.io/tools/imageconverter>`__.
- The BMP files color format needs to match with :c:macro:`LV_COLOR_DEPTH`.
Use GIMP to save the image in the required format. Both RGB888 and
ARGB888 works with :c:macro:`LV_COLOR_DEPTH` ``32``
- Palette is not supported.
- Because not the whole image is read in cannot be zoomed or rotated.
.. _bmp_example:
Example
-------
.. include:: ../../examples/libs/bmp/index.rst
.. _bmp_api:
API
---

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.. _ffmpeg:
==============
FFmpeg support
==============
A complete, cross-platform solution to record, convert and stream audio and video.
Detailed introduction: https://www.ffmpeg.org
Install FFmpeg
--------------
Download first FFmpeg from `here <https://www.ffmpeg.org/download.html>`__, then install it:
.. code-block:: shell
./configure --disable-all --disable-autodetect --disable-podpages --disable-asm --enable-avcodec --enable-avformat --enable-decoders --enable-encoders --enable-demuxers --enable-parsers --enable-protocol='file' --enable-swscale --enable-zlib
make
sudo make install
Add FFmpeg to your project
--------------------------
- Add library: ``FFmpeg`` (for GCC: ``-lavformat -lavcodec -lavutil -lswscale -lm -lz -lpthread``)
.. _ffmpeg_usage:
Usage
-----
Enable :c:macro:`LV_USE_FFMPEG` in ``lv_conf.h``.
See the examples below.
:note: FFmpeg extension doesn't use LVGL's file system. You can
simply pass the path to the image or video as usual on your operating
system or platform.
.. _ffmpeg_example:
Example
-------
.. include:: ../../examples/libs/ffmpeg/index.rst
.. _ffmpeg_api:
API
---

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.. _freetype:
================
FreeType support
================
Interface to FreeType library to generate font bitmap at run time.
Detailed introduction: https://www.freetype.org
Add FreeType to your project
----------------------------
First, Download FreeType from `here <https://sourceforge.net/projects/freetype/files/>`__.
There are two ways to use FreeType:
For UNIX
~~~~~~~~
For UNIX systems, it is recommended to use the way of compiling and installing libraries.
- Enter the FreeType source code directory
- ``make``
- ``sudo make install``
- Add include path: ``/usr/include/freetype2`` (for GCC: ``-I/usr/include/freetype2 -L/usr/local/lib``)
- Link library: ``freetype`` (for GCC: ``-L/usr/local/lib -lfreetype``)
For Embedded Devices
~~~~~~~~~~~~~~~~~~~~
For embedded devices, it is more recommended to use the FreeType
configuration file provided by LVGL, which only includes the most
commonly used functions, which is very meaningful for saving limited
FLASH space.
- Copy the FreeType source code to your project directory.
- Refer to the following ``Makefile`` for configuration:
.. code-block:: make
# FreeType custom configuration header file
CFLAGS += -DFT2_BUILD_LIBRARY
CFLAGS += -DFT_CONFIG_MODULES_H=<lvgl/src/libs/freetype/ftmodule.h>
CFLAGS += -DFT_CONFIG_OPTIONS_H=<lvgl/src/libs/freetype/ftoption.h>
# FreeType include path
CFLAGS += -Ifreetype/include
# FreeType C source file
FT_CSRCS += freetype/src/base/ftbase.c
FT_CSRCS += freetype/src/base/ftbitmap.c
FT_CSRCS += freetype/src/base/ftdebug.c
FT_CSRCS += freetype/src/base/ftglyph.c
FT_CSRCS += freetype/src/base/ftinit.c
FT_CSRCS += freetype/src/cache/ftcache.c
FT_CSRCS += freetype/src/gzip/ftgzip.c
FT_CSRCS += freetype/src/sfnt/sfnt.c
FT_CSRCS += freetype/src/smooth/smooth.c
FT_CSRCS += freetype/src/truetype/truetype.c
CSRCS += $(FT_CSRCS)
.. _freetype_usage:
Usage
-----
Enable :c:macro:`LV_USE_FREETYPE` in ``lv_conf.h``.
Cache configuration:
- :c:macro:`LV_FREETYPE_CACHE_FT_GLYPH_CNT` Maximum number of cached glyphs., etc.
By default, the FreeType extension doesn't use LVGL's file system. You
can simply pass the path to the font as usual on your operating system
or platform.
If you want FreeType to use lvgl's memory allocation and file system
interface, you can enable :c:macro:`LV_FREETYPE_USE_LVGL_PORT` in
``lv_conf.h``, convenient for unified management.
The font style supports *Italic* and **Bold** fonts processed by
software, and can be set with reference to the following values:
- :cpp:enumerator:`LV_FREETYPE_FONT_STYLE_NORMAL`: Default style.
- :cpp:enumerator:`LV_FREETYPE_FONT_STYLE_ITALIC`: Italic style.
- :cpp:enumerator:`LV_FREETYPE_FONT_STYLE_BOLD`: Bold style.
They can be combined.eg:
:cpp:expr:`LV_FREETYPE_FONT_STYLE_BOLD | LV_FREETYPE_FONT_STYLE_ITALIC`.
The FreeType extension also supports colored bitmap glyphs such as emojis. Note
that only bitmaps are supported at this time. Colored vector graphics cannot be
rendered. An example on how to draw a colored bitmap glyph is shown below.
Use the :cpp:func:`lv_freetype_font_create` function to create a font. To
delete a font, use :cpp:func:`lv_freetype_font_delete`. For more detailed usage,
please refer to example code.
.. _freetype_example:
Examples
--------
.. include:: ../../examples/libs/freetype/index.rst
Learn more
----------
- FreeType`tutorial <https://www.freetype.org/freetype2/docs/tutorial/step1.html>`__
- LVGL's :ref:`add_font`
.. _freetype_api:
API
---
:ref:`ftoption_h`
:ref:`ftmodule_h`

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.. _libs_filesystem:
======================
File System Interfaces
======================
LVGL has a :ref:`overview_file_system` module
to provide an abstraction layer for various file system drivers.
LVG has built in support for:
- `FATFS <http://elm-chan.org/fsw/ff/00index_e.html>`__
- STDIO (Linux and Windows using C standard function .e.g ``fopen``, ``fread``)
- POSIX (Linux and Windows using POSIX function .e.g ``open``, ``read``)
- WIN32 (Windows using Win32 API function .e.g ``CreateFileA``, ``ReadFile``)
- MEMFS (read a file from a memory buffer)
- LITTLEFS (a little fail-safe filesystem designed for microcontrollers)
- Arduino ESP LITTLEFS (a little fail-safe filesystem designed for Arduino ESP)
- Arduino SD (allows for reading from and writing to SD cards)
You still need to provide the drivers and libraries, this extension
provides only the bridge between FATFS, STDIO, POSIX, WIN32 and LVGL.
.. _libs_filesystem_usage:
Usage
*****
In ``lv_conf.h`` enable ``LV_USE_FS_...`` and assign an upper cased
letter to ``LV_FS_..._LETTER`` (e.g. ``'S'``). After that you can access
files using that driver letter. E.g. ``"S:path/to/file.txt"``.
Working with common prefixes
""""""""""""""""""""""""""""
A **default driver letter** can be set by ``LV_FS_DEFAULT_DRIVE_LETTER``,
which allows skipping the drive prefix in file paths.
For example if ``LV_FS_DEFAULT_DRIVE_LETTER`` is set the ``'S'`` *"path/to/file.txt"* will mean *"S:path/to/file.txt"*.
This feature is useful if you have only a single driver and don't want to bother with LVGL's driver layer in the file paths.
It also helps to use a unified path with LVGL's file system and normal file systems.
The original mechanism is not affected, so a path starting with drive letter will still work.
The **working directory** can be set with ``LV_FS_..._PATH``. E.g.
``"/home/joe/projects/"`` The actual file/directory paths will be
appended to it, allowing to skip the common part.
Caching
"""""""
:ref:`Cached reading <overview_file_system_cache>` is also supported if ``LV_FS_..._CACHE_SIZE`` is set to
not ``0`` value. :cpp:func:`lv_fs_read` caches this size of data to lower the
number of actual reads from the storage.
To use the memory-mapped file emulation an ``lv_fs_path_ex_t`` object must be
created and initialized. This object can be passed to :cpp:func:`lv_fs_open` as
the file name:
.. code-block:: c
lv_fs_path_ex_t mempath;
lv_fs_file_t file;
uint8_t *buffer;
uint32_t size;
/* Initialize buffer */
...
lv_fs_make_path_from_buffer(&mempath, LV_FS_MEMFS_LETTER, (void*)buffer, size);
lv_fs_res_t res = lv_fs_open(&file, (const char *)&mempath, LV_FS_MODE_RD);
.. _libs_filesystem_api:
API
***

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.. _gif:
===========
GIF decoder
===========
Allow using GIF images in LVGL.
Detailed introduction: https://github.com/lecram/gifdec
When enabled in ``lv_conf.h`` with :c:macro:`LV_USE_GIF`
:cpp:expr:`lv_gif_create(parent)` can be used to create a gif widget.
:cpp:expr:`lv_gif_set_src(widget, src)` works very similarly to :cpp:func:`lv_image_set_src`.
As source, it also accepts images as variables (:c:struct:`lv_image_dsc_t`) or
files.
Convert GIF files to C array
----------------------------
To convert a GIF file to byte values array use `LVGL's online
converter <https://lvgl.io/tools/imageconverter>`__. Select "Raw" color
format and "C array" Output format.
Use GIF images from file
------------------------
For example:
.. code-block:: c
lv_gif_set_src(widget, "S:path/to/example.gif");
Note that, a file system driver needs to be registered to open images
from files. Read more about it :ref:`overview_file_system` or just
enable one in ``lv_conf.h`` with ``LV_USE_FS_...``
Memory requirements
-------------------
To decode and display a GIF animation the following amount of RAM is
required:
- :c:macro:`LV_COLOR_DEPTH` ``8``: 3 x image width x image height
- :c:macro:`LV_COLOR_DEPTH` ``16``: 4 x image width x image height
- :c:macro:`LV_COLOR_DEPTH` ``32``: 5 x image width x image height
.. _gif_example:
Example
-------
.. include:: ../../examples/libs/gif/index.rst
.. _gif_api:
API
---
:ref:`gifdec_h`

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.. _3rd_party_libraries:
===================
3rd-Party Libraries
===================
.. toctree::
:maxdepth: 1
arduino_esp_littlefs
arduino_sd
barcode
bmp
ffmpeg
freetype
fs
gif
lfs
libjpeg_turbo
libpng
lodepng
qrcode
rle
rlottie
svg
tiny_ttf
tjpgd

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.. _lfs:
==============
littlefs
==============
littlefs is a little fail-safe filesystem designed for microcontrollers.
Detailed introduction: https://github.com/littlefs-project/littlefs
Usage
-----
Enable :c:macro:`LV_USE_FS_LITTLEFS` and define a :c:macro:`LV_FS_LITTLEFS_LETTER` in ``lv_conf.h``.
When enabled :c:macro:`lv_littlefs_set_handler` can be used to set up a mount point.
Example
-------
.. code-block:: c
#include "lfs.h"
// configuration of the filesystem is provided by this struct
const struct lfs_config cfg = {
// block device operations
.read = user_provided_block_device_read,
.prog = user_provided_block_device_prog,
.erase = user_provided_block_device_erase,
.sync = user_provided_block_device_sync,
// block device configuration
.read_size = 16,
.prog_size = 16,
.block_size = 4096,
.block_count = 128,
.cache_size = 16,
.lookahead_size = 16,
.block_cycles = 500,
};
// mount the filesystem
int err = lfs_mount(&lfs, &cfg);
// reformat if we can't mount the filesystem
// this should only happen on the first boot
if (err) {
lfs_format(&lfs, &cfg);
lfs_mount(&lfs, &cfg);
}
lv_littlefs_set_handler(&lfs);
API
---

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.. _libjpeg:
=====================
libjpeg-turbo decoder
=====================
**libjpeg-turbo** is a JPEG image codec that uses SIMD instructions to accelerate baseline JPEG compression and decompression on x86,
x86-64, Arm, PowerPC, and MIPS systems, as well as progressive JPEG compression on x86, x86-64, and Arm systems.
Detailed introduction: https://libjpeg-turbo.org
Library source: https://github.com/libjpeg-turbo/libjpeg-turbo
.. _libjpeg_install:
Install
-------
.. code-block:: bash
sudo apt install libjpeg-turbo8-dev
Add libjpeg-turbo to your project
---------------------------------
.. code-block:: cmake
find_package(JPEG REQUIRED)
include_directories(${JPEG_INCLUDE_DIR})
target_link_libraries(${PROJECT_NAME} PRIVATE ${JPEG_LIBRARIES})
.. _libjpeg_usage:
Usage
-----
Enable :c:macro:`LV_USE_LIBJPEG_TURBO` in ``lv_conf.h``.
See the examples below.
It should be noted that each image of this decoder needs to consume ``image width x image height x 3`` bytes of RAM,
and it needs to be combined with the :ref:`overview_image_caching` feature to ensure that the memory usage is within a reasonable range.
.. _libjpeg_example:
Example
-------
.. include:: ../../examples/libs/libjpeg_turbo/index.rst
.. _libjpeg_api:
API
---
:ref:`lv_libjpeg_turbo_h`

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.. _libpng:
==============
libpng decoder
==============
libpng is the official PNG reference library. It supports almost all PNG features, is extensible, and has been extensively tested for over 28 years.
Detailed introduction: http://www.libpng.org/pub/png/libpng.html
Install
-------
.. code-block:: bash
sudo apt install libpng-dev
Add libpng to your project
--------------------------
.. code-block:: cmake
find_package(PNG REQUIRED)
include_directories(${PNG_INCLUDE_DIR})
target_link_libraries(${PROJECT_NAME} PRIVATE ${PNG_LIBRARIES})
.. _libpng_usage:
Usage
-----
Enable :c:macro:`LV_USE_LIBPNG` in ``lv_conf.h``.
See the examples below.
It should be noted that each image of this decoder needs to consume ``width x height x 4`` bytes of RAM,
and it needs to be combined with the :ref:`overview_image_caching` feature to ensure that the memory usage is within a reasonable range.
The decoded image is stored in RGBA pixel format.
.. _libpng_example:
Example
-------
.. include:: ../../examples/libs/libpng/index.rst
.. _libpng_api:
API
---
:ref:`libpng`

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.. _lodepng_rst:
===============
LodePNG decoder
===============
Allow the use of PNG images in LVGL.
Detailed introduction: https://github.com/lvandeve/lodepng
If enabled in ``lv_conf.h`` by :c:macro:`LV_USE_LODEPNG` LVGL will register a new
image decoder automatically so PNG files can be directly used as any
other image sources.
:note: a file system driver needs to be registered to open images from
files. Read more about it :ref:`overview_file_system` or just
enable one in ``lv_conf.h`` with ``LV_USE_FS_...``
The whole PNG image is decoded, so ``width x height x 4`` bytes free RAM space is required.
The decoded image is stored in RGBA pixel format.
As it might take significant time to decode PNG images LVGL's :ref:`overview_image_caching` feature can be useful.
Compress PNG files
------------------
PNG file format supports True color (24/32 bit), and 8-bit palette colors.
Usually cliparts, drawings, icons and simple graphics are stored in PNG format,
that do not use the whole color space, so it is possible to compress further
the image by using 8-bit palette colors, instead of 24/32 bit True color format.
Because embedded devices have limited (flash) storage, it is recommended
to compress images.
One option is to use a free online PNG compressor site,
for example Compress PNG: https://compresspng.com/
.. _lodepng_example:
Example
-------
.. include:: ../../examples/libs/lodepng/index.rst
.. _lodepng_api:
API
---
:ref:`lodepng_h`

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.. _qrcode:
=======
QR code
=======
QR code generation with LVGL. Uses
`QR-Code-generator <https://github.com/nayuki/QR-Code-generator>`__ by
`nayuki <https://github.com/nayuki>`__.
.. _qrcode_usage:
Usage
-----
Enable :c:macro:`LV_USE_QRCODE` in ``lv_conf.h``.
Use :cpp:func:`lv_qrcode_create` to create a qrcode object, and use
:cpp:func:`lv_qrcode_update` to generate a QR code.
If you need to re-modify the size and color, use
:cpp:func:`lv_qrcode_set_size` and :cpp:func:`lv_qrcode_set_dark_color` or
:cpp:func:`lv_qrcode_set_light_color`, and
call :cpp:func:`lv_qrcode_update` again to regenerate the QR code.
Notes
-----
- QR codes with less data are smaller, but they scaled by an integer
number to best fit to the given size.
.. _qrcode_example:
Example
-------
.. include:: ../../examples/libs/qrcode/index.rst
.. _qrcode_api:
API
---
:ref:`qrcodegen_h`

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.. _rle:
============
RLE Compress
============
LVGL provides a custom RLE compression method. It can be used to reduce binary
image size. The RLE compression is a lossless compression method.
The LVGL's built-in binary image decoder supports RLE compressed images.
The decoder supports both variable and file as image sources. The original
binary data is directly decoded to RAM
Benefits
--------
Based on test result from a watch project. Most of the images can be compressed
to save more than 70% space as show in below statistic. It shows the file count
of every compress level. For rare conditions, RLE compress may increase the file
size if there's no large repetition in data.
.. image:: rle-compress-statistics.png
:alt: RLE compress statistics from a watch project
:align: center
Theory
------
The RLE algorithm is a simple compression algorithm that is based on the fact that
the for many pixels, the color is the same. The algorithm simply counts how many
repeated data are there and store the count value and the color value.
If the coming pixels are not repeated, it stores the non-repeat count value and
original color value. For more details, the script used to compress the image
can be found from ``lvgl/script/LVGLImage.py``.
.. code-block:: python
def rle_compress(self, data: bytearray, blksize: int, threshold=16):
index = 0
data_len = len(data)
compressed_data = []
while index < data_len:
memview = memoryview(data)
repeat_cnt = self.get_repeat_count(
memview[index:], blksize)
if repeat_cnt == 0:
# done
break
elif repeat_cnt < threshold:
nonrepeat_cnt = self.get_nonrepeat_count(
memview[index:], blksize, threshold)
ctrl_byte = uint8_t(nonrepeat_cnt | 0x80)
compressed_data.append(ctrl_byte)
compressed_data.append(
memview[index: index + nonrepeat_cnt * blksize])
index += nonrepeat_cnt * blksize
else:
ctrl_byte = uint8_t(repeat_cnt)
compressed_data.append(ctrl_byte)
compressed_data.append(memview[index: index + blksize])
index += repeat_cnt * blksize
return b"".join(compressed_data)
.. _rle_usage:
Usage
-----
To use the RLE Decoder, enable it in ``lv_conf.h`` configuration file by setting :c:macro:`LV_USE_RLE` to `1`.
The RLE image can be used same as other images.
.. code-block:: c
lv_image_set_src(img, "path/to/image.rle");
Generate RLE compressed binary images
-------------------------------------
The image can be directly generated using script ``lvgl/script/LVGLImage.py``
.. code-block:: bash
./script/LVGLImage.py --ofmt BIN --cf I8 --compress RLE cogwheel.png

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.. _rlottie:
==============
Rlottie player
==============
.. warning::
Rlottie is deprecated. Consider using :ref:`lv_lottie` instead.
Allows playing Lottie animations in LVGL. Taken from `lv_rlottie <https://github.com/ValentiWorkLearning/lv_rlottie>`__.
LVGL provides the interface to `Samsung/rlottie <https://github.com/Samsung/rlottie>`__ library's C
API. That is the actual Lottie player is not part of LVGL, it needs to
be built separately.
Build Rlottie
-------------
To build Samsung's Rlottie C++14 compatible compiler and optionally
CMake 3.14 or higher is required.
To build on desktop you can follow the instructions from Rlottie's
`README <https://github.com/Samsung/rlottie/blob/master/README.md>`__.
In the most basic case it looks like this:
.. code-block:: shell
mkdir rlottie_workdir
cd rlottie_workdir
git clone https://github.com/Samsung/rlottie.git
mkdir build
cd build
cmake ../rlottie
make -j
sudo make install
And finally add the ``-lrlottie`` flag to your linker.
On embedded systems you need to take care of integrating Rlottie to the
given build system.
ESP-IDF example at bottom
~~~~~~~~~~~~~~~~~~~~~~~~~
.. _rlottie_usage:
Usage
-----
You can use animation from files or raw data (text). In either case
first you need to enable :c:macro:`LV_USE_RLOTTIE` in ``lv_conf.h``.
The ``width`` and ``height`` of the Widget be set in the *create*
function and the animation will be scaled accordingly.
Use Rlottie from file
~~~~~~~~~~~~~~~~~~~~~
To create a Lottie animation from file use:
.. code-block:: c
lv_obj_t * lottie = lv_rlottie_create_from_file(parent, width, height, "path/to/lottie.json");
Note that, Rlottie uses the standard STDIO C file API, so you can use
the path "normally" and no LVGL specific driver letter is required.
Use Rlottie from raw string data
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
``lv_example_rlottie_approve.c`` contains an example animation in raw
format. Instead storing the JSON string, a hex array is stored for the
following reasons:
- avoid escaping ``"`` character in the JSON file
- some compilers don't support very long strings
``lvgl/scripts/filetohex.py`` can be used to convert a Lottie file a hex
array. E.g.:
.. code-block:: shell
./filetohex.py path/to/lottie.json > out.txt
To create an animation from raw data:
.. code-block:: c
extern const uint8_t lottie_data[];
lv_obj_t* lottie = lv_rlottie_create_from_raw(parent, width, height, (const char *)lottie_data);
Getting animations
------------------
Lottie is standard and popular format so you can find many animation
files on the web. For example: https://lottiefiles.com/
You can also create your own animations with Adobe After Effects or
similar software.
Controlling animations
----------------------
LVGL provides two functions to control the animation mode:
:cpp:func:`lv_rlottie_set_play_mode` and :cpp:func:`lv_rlottie_set_current_frame`.
You'll combine your intentions when calling the first method, like in
these examples:
.. code-block:: c
lv_obj_t * lottie = lv_rlottie_create_from_file(scr, 128, 128, "test.json");
lv_obj_center(lottie);
// Pause to a specific frame
lv_rlottie_set_current_frame(lottie, 50);
lv_rlottie_set_play_mode(lottie, LV_RLOTTIE_CTRL_PAUSE); // The specified frame will be displayed and then the animation will pause
// Play backward and loop
lv_rlottie_set_play_mode(lottie, LV_RLOTTIE_CTRL_PLAY | LV_RLOTTIE_CTRL_BACKWARD | LV_RLOTTIE_CTRL_LOOP);
// Play forward once (no looping)
lv_rlottie_set_play_mode(lottie, LV_RLOTTIE_CTRL_PLAY | LV_RLOTTIE_CTRL_FORWARD);
The default animation mode is **play forward with loop**.
If you don't enable looping, a :cpp:enumerator:`LV_EVENT_READY` is sent when the
animation cannot make more progress without looping.
To get the number of frames in an animation or the current frame index,
you can cast the :c:struct:`lv_obj_t` instance to a :c:struct:`lv_rlottie_t` instance
and inspect the ``current_frame`` and ``total_frames`` members.
ESP-IDF Example
---------------
Background
~~~~~~~~~~
Rlottie can be expensive to render on embedded hardware. Lottie
animations tend to use a large amount of CPU time and can use large
portions of RAM. This will vary from lottie to lottie but in general for
best performance:
- Limit total # of frames in the animation
- Where possible, try to avoid bezier type animations
- Limit animation render size
If your ESP32 chip does not have SPIRAM you will face severe limitations
in render size.
To give a better idea on this, lets assume you want to render a 240x320
lottie animation.
In order to pass initialization of the lv_rlottie_t object, you need
240x320x32/8 (307k) available memory. The latest ESP32-S3 has 256kb RAM
available for this (before freeRtos and any other initialization starts
taking chunks out). So while you can probably start to render a 50x50
animation without SPIRAM, PSRAM is highly recommended.
Additionally, while you might be able to pass initialization of the
lv_rlottie_t object, as rlottie renders frame to frame, this consumes
additional memory. A 30 frame animation that plays over 1 second
probably has minimal issues, but a 300 frame animation playing over 10
seconds could very easily crash due to lack of memory as rlottie
renders, depending on the complexity of the animation.
Rlottie will not compile for the IDF using the ``-02`` compiler option at
this time.
For stability in lottie animations, I found that they run best in the
IDF when enabling :c:macro:`LV_MEM_CUSTOM` (using ``stdlib.h``)
For all its faults, when running right-sized animations, they provide a
wonderful utility to LVGL on embedded LCDs and can look really good when
done properly.
When picking/designing a lottie animation consider the following
limitations:
- Build the lottie animation to be sized for the intended size
- it can scale/resize, but performance will be best when the base lottie size is as intended
- Limit total number of frames, the longer the lottie animation is,
the more memory it will consume for rendering (rlottie consumes IRAM for rendering)
- Build the lottie animation for the intended frame rate
- default lottie is 60fps, embedded LCDs likely won't go above 30fps
IDF Setup
~~~~~~~~~
Where the LVGL simulator uses the installed rlottie lib, the IDF works
best when using rlottie as a submodule under the components directory.
.. code-block:: shell
cd 'your/project/directory'
git add submodule
git add submodule https://github.com/Samsung/rlottie.git ./components/rlottie/rlottie
git submodule update --init --recursive
Now, Rlottie is available as a component in the IDF, but it requires
some additional changes and a CMakeLists file to tell the IDF how to
compile.
Rlottie patch file
~~~~~~~~~~~~~~~~~~
Rlottie relies on a dynamic linking for an image loader lib. This needs
to be disabled as the IDF doesn't play nice with dynamic linking.
A patch file is available in lvgl under:
``/env_support/esp/rlottie/0001-changes-to-compile-with-esp-idf.patch``
Apply the patch file to your rlottie submodule.
CMakeLists for IDF
~~~~~~~~~~~~~~~~~~
An example CMakeLists file has been provided at
``/env_support/esp/rlottie/CMakeLists.txt``
Copy this CMakeLists file to
``'your-project-directory'/components/rlottie/``
In addition to the component CMakeLists file, you'll also need to tell
your project level CMakeLists in your IDF project to require rlottie:
.. code-block:: console
REQUIRES "lvgl" "rlottie"
From here, you should be able to use lv_rlottie objects in your ESP-IDF
project as any other widget in LVGL ESP examples. Please remember that
these animations can be highly resource constrained and this does not
guarantee that every animation will work.
Additional Rlottie considerations in ESP-IDF
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
While unnecessary, removing the ``rlottie/rlottie/example`` folder can remove
many un-needed files for this embedded LVGL application
From here, you can use the relevant LVGL lv_rlottie functions to create
lottie animations in LVGL on embedded hardware!
Please note, that while lottie animations are capable of running on many
ESP chips, below is recommended for best performance.
- ESP32-S3-WROOM-1-N16R8
- 16mb quad spi flash
- 8mb octal spi PSRAM
- IDF4.4 or higher
The Esp-box devkit meets this spec and
https://github.com/espressif/esp-box is a great starting point to adding
lottie animations.
You will need to enable :c:macro:`LV_USE_RLOTTIE` through **idf.py** menuconfig under
LVGL component settings.
Additional changes to make use of SPIRAM
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:cpp:expr:`lv_alloc/realloc` do not make use of SPIRAM. Given the high memory usage
of lottie animations, it is recommended to shift as much out of internal
DRAM into SPIRAM as possible. In order to do so, SPIRAM will need to be
enabled in the menuconfig options for your given espressif chip.
There may be a better solution for this, but for the moment the
recommendation is to make local modifications to the lvgl component in
your espressif project. This is as simple as swapping
:cpp:expr:`lv_alloc/lv_realloc` calls in `lv_rlottie.c`` with :cpp:expr:`heap_caps_malloc` (for
IDF) with the appropriate :cpp:expr:`MALLOC_CAP` call - for SPIRAM usage this is
:cpp:expr:`MALLOC_CAP_SPIRAM`.
.. code-block:: c
rlottie->allocated_buf = heap_caps_malloc(allocated_buf_size+1, MALLOC_CAP_SPIRAM);
.. _rlottie_example:
Example
-------
.. include:: ../../examples/libs/rlottie/index.rst
.. _rlottie_api:
API
---

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.. _svg:
==============
SVG support
==============
Scalable Vector Graphics (SVG) Tiny 1.2 support in LVGL.
Detailed introduction: https://www.w3.org/TR/SVGTiny12/
Usage
*****
Enable :c:macro:`LV_USE_SVG` in ``lv_conf.h``.
See the examples below.
If you need support SVG animation attribute parsing,
you can enable :c:macro:`LV_USE_SVG_ANIMATION` in ``lv_conf.h``.
.. _svg_example:
Example
*******
.. code:: c
lv_svg_node_t * svg_doc;
const char* svg_data = "<svg><rect x=\"0\" y=\"0\" width=\"100\" height=\"100\"/></svg>";
/* Create an SVG DOM tree*/
svg_doc = lv_svg_load_data(svg_data, svg_len);
...
/* Draw SVG image*/
lv_draw_svg(layer, svg_doc);
...
/* Release the DOM tree*/
lv_svg_node_delete(svg_doc);
.. _svg_api:
API
***

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.. _tiny_ttf:
====================
Tiny TTF font engine
====================
.. _tiny_ttf_usage:
Usage
-----
Allow using TrueType fonts in LVGL.
Detailed introduction: https://github.com/nothings/stb
When enabled in ``lv_conf.h`` with :c:macro:`LV_USE_TINY_TTF`
:cpp:expr:`lv_tiny_ttf_create_data(data, data_size, font_size)` can be used to
create a TTF font instance at the specified line height. You can then
use that font anywhere :c:struct:`lv_font_t` is accepted.
By default, the TTF or OTF file must be embedded as an array, either in
a header, or loaded into RAM in order to function.
However, if :c:macro:`LV_TINY_TTF_FILE_SUPPORT` is enabled,
:cpp:expr:`lv_tiny_ttf_create_file(path, font_size)` will also be available,
allowing tiny_ttf to stream from a file. The file must remain open the
entire time the font is being used.
After a font is created, you can change the font size in pixels by using
:cpp:expr:`lv_tiny_ttf_set_size(font, font_size)`.
By default, a font will cache data for upto 256 glyphs elements to speed up rendering.
This maximum can be changed by using
:cpp:expr:`lv_tiny_ttf_create_data_ex(data, data_size, font_size, kerning, cache_size)`
or :cpp:expr:`lv_tiny_ttf_create_file_ex(path, font_size, kerning, cache_size)` (when
available). The cache size is indicated in number of entries. Kerning is whether to allow
if supported, or disable.
.. _tiny_ttf_example:
Example
-------
.. include:: ../../examples/libs/tiny_ttf/index.rst
.. _tiny_ttf_api:
API
---
:ref:`stb_rect_pack_h`
:ref:`stb_truetype_htcw_h`

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.. _tjpgd:
================================
Tiny JPEG Decompressor (TJpgDec)
================================
Allow the use of JPEG (JPG) images in LVGL.
Detailed introduction: `TJpgDec <http://elm-chan.org/fsw/tjpgd/>`__
.. _tjpgd_overview:
Overview
--------
- JPEG is decoded in 8x8 tiles.
- Only baseline JPEG files are supported (no progressive JPEG support).
- Read from file and C array are implemented.
- Only the required portions of the JPEG images are decoded,
therefore they can't be zoomed or rotated.
.. _tjpgd_usage:
Usage
-----
If enabled in ``lv_conf.h`` by :c:macro:`LV_USE_TJPGD` LVGL will register a new
image decoder automatically so JPEG files can be used directly
as image sources.
For example:
.. code-block:: c
lv_image_set_src(my_img, "S:path/to/picture.jpg");
:note: a file system driver needs to be registered to open images from
files. Read more about :ref:`overview_file_system` or just
enable one in ``lv_conf.h`` with ``LV_USE_FS_...`` config.
Converter
---------
Converting JPEG to C array
~~~~~~~~~~~~~~~~~~~~~~~~~~
- Use lvgl online tool https://lvgl.io/tools/imageconverter
- Color format = RAW, output format = C Array
.. _tjpgd_example:
Example
-------
.. include:: ../../examples/libs/tjpgd/index.rst
.. _tjpgd_api:
API
---
:ref:`lv_tjpgd_h`
:ref:`tjpgd_h`
:ref:`tjpgdcnf_h`

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