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docs add style props

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Gabor Kiss-Vamosi
2021-05-14 15:37:35 +02:00
parent 9b647dc919
commit abe04e98d3
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196
docs/get-started/quick-overview.md
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@@ -12,38 +12,45 @@ You should read it first to get a general impression and read the detailed [Port
Instead of porting LVGL to an embedded hardware, it's highly recommended to get started in a simulator first.
LVGL is ported to many IDEs to be sure you will find your faviourite one. Go to [Simulators](/get-started/pc-simulator) to get ready-to-use projects which can be run on your PC. This way you can save the porting for now and make some experience with LVGL immediately.
LVGL is ported to many IDEs to be sure you will find your favorite one.
Go to the [Simulators](/get-started/pc-simulator) section to get ready-to-use projects that can be run on your PC.
This way you can save the time of porting for now and make some experience with LVGL immediately.
## Add LVGL into your project
If you rather want to try LVGL on your own project follow these steps:
The following steps show how to setup LVGL on an embedded system with a display and a touchpad.
- [Download](https://github.com/lvgl/lvgl/archive/master.zip) or Clone the library from GitHub with `git clone https://github.com/lvgl/lvgl.git`
- Copy the `lvgl` folder into your project
- Copy `lvgl/lv_conf_template.h` as `lv_conf.h` next to the `lvgl` folder, change the first `#if 0` to `1` to enable the file's content and set at least `LV_HOR_RES_MAX`, `LV_VER_RES_MAX` and `LV_COLOR_DEPTH` defines.
- Include `lvgl/lvgl.h` where you need to use LVGL related functions.
- Call `lv_tick_inc(x)` every `x` milliseconds **in a Timer or Task** (`x` should be between 1 and 10). It is required for the internal timing of LVGL. Alternatively, configure `LV_TICK_CUSTOM` (see `lv_conf.h`) so that LVGL can retrieve the current time directly.
- [Download](https://github.com/lvgl/lvgl/archive/master.zip) or Clone the library from GitHub with `git clone https://github.com/lvgl/lvgl.git`.
- Copy the `lvgl` folder into your project.
- Copy `lvgl/lv_conf_template.h` as `lv_conf.h` next to the `lvgl` folder, change the first `#if 0` to `1` to enable the file's content and set the `LV_COLOR_DEPTH` defines.
- Include `lvgl/lvgl.h` in files where you need to use LVGL related functions.
- Call `lv_tick_inc(x)` every `x` milliseconds in a Timer or Task (`x` should be between 1 and 10). It is required for the internal timing of LVGL.
Alternatively, configure `LV_TICK_CUSTOM` (see `lv_conf.h`) so that LVGL can retrieve the current time directly.
- Call `lv_init()`
- Create a display buffer for LVGL. LVGL will render the graphics here first, and seed the rendered image to the display. The buffer size can be set freely but 1/10 screen size is a good starting point.
- Create a draw buffer: LVGL will render the graphics here first, and seed the rendered image to the display.
The buffer size can be set freely but 1/10 screen size is a good starting point.
```c
static lv_disp_buf_t disp_buf;
static lv_color_t buf[LV_HOR_RES_MAX * LV_VER_RES_MAX / 10]; /*Declare a buffer for 1/10 screen size*/
lv_disp_buf_init(&disp_buf, buf, NULL, LV_HOR_RES_MAX * LV_VER_RES_MAX / 10); /*Initialize the display buffer*/
static lv_disp_darw_buf_t draw_buf;
static lv_color_t buf1[DISP_HOR_RES * DISP_VER_RES / 10]; /*Declare a buffer for 1/10 screen size*/
lv_disp_draw_buf_init(&draw_buf, buf1, NULL, MY_DISP_HOR_RES * MY_DISP_VER_SER / 10); /*Initialize the display buffer.*/
```
- Implement and register a function which can **copy the rendered image** to an area of your display:
- Implement and register a function which can copy the rendered image to an area of your display:
```c
lv_disp_drv_t disp_drv; /*Descriptor of a display driver*/
lv_disp_drv_init(&disp_drv); /*Basic initialization*/
disp_drv.flush_cb = my_disp_flush; /*Set your driver function*/
disp_drv.buffer = &disp_buf; /*Assign the buffer to the display*/
disp_drv.buffer = &draw_buf; /*Assign the buffer to the display*/
disp_drv.hor_res = MY_DISP_HOR_RES; /*Set the horizontal resolution of the display*/
disp_drv.hor_res = MY_DISP_VER_RES; /*Set the verizontal resolution of the display*/
lv_disp_drv_register(&disp_drv); /*Finally register the driver*/
void my_disp_flush(lv_disp_drv_t * disp, const lv_area_t * area, lv_color_t * color_p)
{
int32_t x, y;
/*It's a very slow but simple implementation.
*`set_pixel` needs to be written by you to a set pixel on the screen*/
for(y = area->y1; y <= area->y2; y++) {
for(x = area->x1; x <= area->x2; x++) {
set_pixel(x, y, *color_p); /* Put a pixel to the display.*/
set_pixel(x, y, *color_p);
color_p++;
}
}
@@ -52,7 +59,7 @@ void my_disp_flush(lv_disp_drv_t * disp, const lv_area_t * area, lv_color_t * co
}
```
- Implement and register a function which can **read an input device**. E.g. for a touch pad:
- Implement and register a function which can read an input device. E.g. for a touch pad:
```c
lv_indev_drv_t indev_drv; /*Descriptor of a input device driver*/
lv_indev_drv_init(&indev_drv); /*Basic initialization*/
@@ -62,35 +69,42 @@ lv_indev_drv_register(&indev_drv); /*Finally register the driver*/
bool my_touchpad_read(lv_indev_t * indev, lv_indev_data_t * data)
{
data->state = touchpad_is_pressed() ? LV_INDEV_STATE_PR : LV_INDEV_STATE_REL;
if(data->state == LV_INDEV_STATE_PR) touchpad_get_xy(&data->point.x, &data->point.y);
return false; /*Return `false` because we are not buffering and no more data to read*/
/*`touchpad_is_pressed` and `touchpad_get_xy` needs to be implemented by you*/
if(touchpad_is_pressed()) {
data->state = LV_INDEV_STATE_PRESSED;
touchpad_get_xy(&data->point.x, &data->point.y);
} else {
data->state = LV_INDEV_STATE_RELEASED;
}
}
```
- Call `lv_task_handler()` periodically every few milliseconds in the main `while(1)` loop, in Timer interrupt or in an Operation system task.
It will redraw the screen if required, handle input devices etc.
- Call `lv_timer_handler()` periodically every few milliseconds in the main `while(1)` loop or in an Operation system task.
It will redraw the screen if required, handle input devices, animation etc.
For a more detailed guide go to the [Porting](https://docs.lvgl.io/v7/en/html/porting/index.html) section.
For a more detailed guide go to the [Porting](/porting/index.html) section.
## Learn the basics
### Widgets
The graphical elements like Buttons, Labels, Sliders, Charts etc are called objects or widgets in LVGL. Go to [Widgets](/widgets/index) to see the full list of available widgets.
The graphical elements like Buttons, Labels, Sliders, Charts etc. are called objects or widgets. Go to [Widgets](/widgets/index) to see the full list of available widgets.
Every object has a parent object where it is create. For example if a label is created on a button, the button is the parent of label.
The child object moves with the parent and if the parent is deleted the children will be deleted too.
Children can be visible only on their parent. It other words, the parts of the children out of the parent are clipped.
A *screen* is the "root" parent. You can have any number of screens. To get the current screen call `lv_scr_act()`, and to load a screen use `lv_scr_load(scr1)`.
A Screen is the "root" parent. You can have any number of screens.
To get the current screen call `lv_scr_act()`, and to load a screen use `lv_scr_load(scr1)`.
You can create a new object with `lv_<type>_create(parent)`. It will return an `lv_obj_t *` variable that can be used as a reference to the object to set its parameters.
You can create a new object with `lv_<type>_create(parent, obj_to_copy)`. It will return an `lv_obj_t *` variable which should be used as a reference to the object to set its parameters.
The first parameter is the desired *parent*, the second parameters can be an object to copy (`NULL` if unused).
For example:
```c
lv_obj_t * slider1 = lv_slider_create(lv_scr_act(), NULL);
lv_obj_t * slider1 = lv_slider_create(lv_scr_act());
```
To set some basic attribute `lv_obj_set_<paramters_name>(obj, <value>)` function can be used. For example:
@@ -100,69 +114,132 @@ lv_obj_set_y(btn1, 10);
lv_obj_set_size(btn1, 200, 50);
```
The objects has type specific parameters too which can be set by `lv_<type>_set_<paramters_name>(obj, <value>)` functions. For example:
The widgets have type specific parameters too which can be set by `lv_<widget_type>_set_<paramters_name>(obj, <value>)` functions. For example:
```c
lv_slider_set_value(slider1, 70, LV_ANIM_ON);
```
To see the full API visit the documentation of the widgets or the related header file (e.g. [lvgl/src/lv_widgets/lv_slider.h](https://github.com/lvgl/lvgl/blob/master/src/lv_widgets/lv_slider.h)).
To see the full API visit the documentation of the widgets or the related header file (e.g. [lvgl/src/widgets/lv_slider.h](https://github.com/lvgl/lvgl/blob/master/src/widgets/lv_slider.h)).
### Events
Events are used to inform the user if something has happened with an object. You can assign a callback to an object which will be called if the object is clicked, released, dragged, being deleted etc. It should look like this:
Events are used to inform the user if something has happened with an object.
You can assign one or more callbacks to an object which will be called if the object is clicked, released, dragged, being deleted etc.
It should look like this:
```c
lv_obj_set_event_cb(btn, btn_event_cb); /*Assign a callback to the button*/
lv_obj_add_event_cb(btn, btn_event_cb, LV_EVENT_CLICKED, NULL); /*Assign a callback to the button*/
...
void btn_event_cb(lv_obj_t * btn, lv_event_t event)
void btn_event_cb(lv_event_t * e)
{
if(code == LV_EVENT_CLICKED) {
printf("Clicked\n");
}
printf("Clicked\n");
}
```
Learn more about the events in the [Event overview](/overview/event) section.
Instead of `LV_EVENT_CLICKED` `LV_EVENT_ALL` can be used too to call the callback for any event.
From `lv_event_t * e` the current event code can be get with
```c
lv_event_code_t code = lv_event_get_code(e);
```
The object that triggered the event can be retrieved with
```c
lv_obj_t * obj = lv_event_get_target(e);
```
To learn all features of the events go to the [Event overview](/overview/event) section.
### Parts
Widgets might be built from one or more parts. For example a button has only one part called `LV_BTN_PART_MAIN`.
However, a [Page](/widgets/page) has `LV_PAGE_PART_BG`, `LV_PAGE_PART_SCROLLABLE`, `LV_PAGE_PART_SCROLLBAR` and `LV_PAGE_PART_EDGE_FLASG`.
Widgets might be built from one or more *parts*. For example a button has only one part called `LV_PART_MAIN`.
However, a [Slider](/widgets/core/slider) has `LV_PART_MAIN`, `LV_PART_INDICATOR` and `LV_PART_KNOB`.
Some parts are *virtual* (they are not real object, just drawn on the fly, such as the scrollbar of a page) but other parts are *real* (they are real object, such as the scrollable part of the page).
By using parts you can apply different styles to different parts. (See below)
Parts come into play when you want to set the styles and states of a given part of an object. (See below)
To learn which parts are used by which object read the widgets' documentation.
### States
The objects can be in a combination of the following states:
- **LV_STATE_DEFAULT** Normal, released
- **LV_STATE_CHECKED** Toggled or checked
- **LV_STATE_FOCUSED** Focused via keypad or encoder or clicked via touchpad/mouse
- **LV_STATE_EDITED** Edit by an encoder
- **LV_STATE_HOVERED** Hovered by mouse (not supported now)
- **LV_STATE_PRESSED** Pressed
- **LV_STATE_DISABLED** Disabled or inactive
- `LV_STATE_DEFAULT` Normal, released state
- `LV_STATE_CHECKED` Toggled or checked state
- `LV_STATE_FOCUSED` Focused via keypad or encoder or clicked via touchpad/mouse
- `LV_STATE_FOCUS_KEY` Focused via keypad or encoder but not via touchpad/mouse
- `LV_STATE_EDITED` Edit by an encoder
- `LV_STATE_HOVERED` Hovered by mouse (not supported now)
- `LV_STATE_PRESSED` eing pressed
- `LV_STATE_SCROLLED` Being scrolled
- `LV_STATE_DISABLED` Disabled
For example, if you press an object it will automatically get the `LV_STATE_PRESSED` state and when you release it, the state will be removed.
For example, if you press an object it will automatically goes to `LV_STATE_FOCUSED` and `LV_STATE_PRESSED` state and when you release it, the `LV_STATE_PRESSED` state will be removed.
To get the current state use `lv_obj_get_state(obj, part)`. It will return the `OR`ed states.
For example, this is a valid state for a checkbox: `LV_STATE_CHECKED | LV_STATE_PRESSED | LV_STATE_FOCUSED`
To check if an object is in a geven state use `lv_obj_has_state(obj, LV_STATE_...)`. It will return `true` if the object "has" the given state at that moment.
To manually add remove the states use
```c
lv_obj_add_state(obj, LV_STATE_...);
lv_obj_clear_state(obj, LV_STATE_...);
```
### Styles
Styles can be assigned to the parts of an object to change their appearance.
A style can describe for example the background color, border width, text font and so on. See the full list [here](https://docs.lvgl.io/v7/en/html/overview/style.html#properties).
Styles contains properties such as background color, border width, font, etc to describe the appearance of the objects.
The styles are `lv_style_t` variables. Only their pointer is saved in the objects so they need to be static or global.
Before using a style it needs to be initialized with `lv_style_init(&style1)`. After that properties can be added. For example:
```
static lv_style_t style1;
lv_style_init(&style1);
lv_style_set_bg_color(&style1, lv_color_hex(0xa03080))
lv_style_set_border_width(&style1, 2))
```
See the full list of properties go [here](/overview/style.html#properties).
The styles are assigned to an object's part and state. For example to *"Use this style on the slider's indicator when the slider is pressed"*:
```c
lv_obj_add_style(slider1, &style1, LV_PART_INDICATOR | LV_STATE_PRESSED);
```
If the *part* is `LV_PART_MAIN` it can be omitted:
```c
lv_obj_add_style(btn1, &style1, LV_STATE_PRESSED); /*Equal to LV_PART_MAIN | LV_STATE_PRESSED*/
```
Similarly, `LV_STATE_DEFAULT` can be omitted too:
```c
lv_obj_add_style(slider1, &style1, LV_PART_INDICATOR); /*Equal to LV_PART_INDICATOR | LV_STATE_DEFAULT*/
```
For `LV_STATE_DEFAULT` and `LV_PART_MAIN` simply write `0`:
```c
lv_obj_add_style(btn1, &style1, 0); /*Equal to LV_PART_MAIN | LV_STATE_DEFAULT*/
```
The styles can be cascaded (similarly to CSS). It means you can add more styles to a part of an object.
For example `style_btn` can set a default button appearance, and `style_btn_red` can overwrite some properties to make the button red-
For example `style_btn` can set a default button appearance, and `style_btn_red` can overwrite the background color to make the button red:
```c
lv_obj_add_style(btn1, &style_btn, 0);
lv_obj_add_style(btn1, &style1_btn_red, 0);
```
Every style property you set is specific to a state. For example, you can set a different background color for `LV_STATE_DEFAULT` and `LV_STATE_PRESSED`.
The library finds the best match between the state of the given part and the available style properties. For example if the object is in pressed state and the border width is specified for pressed state, then it will be used.
However, if it's not specified for pressed state, the `LV_STATE_DEFAULT`'s border width will be used. If the border width not defined for `LV_STATE_DEFAULT` either, a default value will be used.
If a property is not set on for the current state the style with `LV_STATE_DEFAULT` will be used. If the property is not defined even in the default state a default value is used.
Some properties (typically the text-related ones) can be inherited. It means if a property is not set in an object it will be searched in its parents too.
For example you can set the font once in the screen's style and every text will inherit it by default.
For example, you can set the font once in the screen's style and every text will inherit it by default.
Local style properties also can be added to the objects. It creates a style is inside the object that is used only by the object:
```c
lv_obj_set_style_bg_color(slider1, lv_color_hex(0x2080bb), LV_PART_INDICATOR | LV_STATE_PRESSED);
```
To learn all the features of styles see the [Style overview](/overview/style) section
Local style properties also can be added to the objects.
### Themes
Themes are the default styles of the objects.
@@ -190,3 +267,4 @@ label.set_text("Button")
# Load the screen
lv.scr_load(scr)
```

1
docs/overview/index.md
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@@ -14,6 +14,7 @@
object
coords
style
style-props
scroll
layer
event

8
docs/overview/style.md
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@@ -109,7 +109,7 @@ For example a [Slider](/widgets/slider) has three parts:
- Indiactor
- Knob
It means the all three parts of teh slider can have their own styles. See later how to add style styles to objects and parts.
It means the all three parts of the slider can have their own styles. See later how to add style styles to objects and parts.
## Initialize styles and set/get properties
@@ -212,12 +212,8 @@ For example:
```c
lv_obj_set_style_local_bg_color(slider, lv_color_red(), LV_PART_INDICATOR | LV_STATE_FOCUSED);
```
## Properties
TODO include properties generated by style_api_gen.py
For the full list of style properties click [here](/overview/style-props).
### Typical background properties
In the documentation of the widgets you will see sentences like "The widget use the typical background properties". The "typical background properties" are the ones related to:

32
docs/porting/display.md
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@@ -15,15 +15,15 @@ Once rendering is ready the content of the draw buffer is send to display using
A draw draw buffer can be initialized via a `lv_disp_draw_buf_t` variable like this:
```c
/*A static or global variable to store the buffers*/
static lv_disp_draw_buf_t disp_buf;
/*A static or global variable to store the buffers*/
static lv_disp_draw_buf_t disp_buf;
/*Static or global buffer(s). The second buffer is optional*/
static lv_color_t buf_1[MY_DISP_HOR_RES * 10];
static lv_color_t buf_2[MY_DISP_HOR_RES * 10];
/*Static or global buffer(s). The second buffer is optional*/
static lv_color_t buf_1[MY_DISP_HOR_RES * 10];
static lv_color_t buf_2[MY_DISP_HOR_RES * 10];
/*Initialize `disp_buf` with the buffer(s) */
lv_disp_draw_buf_init(&disp_buf, buf_1, buf_2, MY_DISP_HOR_RES*10);
/*Initialize `disp_buf` with the buffer(s) */
lv_disp_draw_buf_init(&disp_buf, buf_1, buf_2, MY_DISP_HOR_RES*10);
```
Note that `lv_disp_draw_buf_t` needs to be static, global or dynamically allocated and not a local variable destroyed if goes out of the scope.
@@ -90,15 +90,15 @@ To use a GPU the following callbacks can be used:
### Examples
All together it looks like this:
```c
static lv_disp_drv_t disp_drv; /*A variable to hold the drivers. Must be static or global.*/
lv_disp_drv_init(&disp_drv); /*Basic initialization*/
disp_drv.draw_buf = &disp_buf; /*Set an initialized buffer*/
disp_drv.flush_cb = my_flush_cb; /*Set a flush callback to draw to the display*/
disp_drv.hor_res = 320; /*Set the horizontal resolution in pixels*/
disp_drv.ver_res = 240; /*Set the vertical resolution in pixels*/
lv_disp_t * disp;
disp = lv_disp_drv_register(&disp_drv); /*Register the driver and save the created display objects*/
static lv_disp_drv_t disp_drv; /*A variable to hold the drivers. Must be static or global.*/
lv_disp_drv_init(&disp_drv); /*Basic initialization*/
disp_drv.draw_buf = &disp_buf; /*Set an initialized buffer*/
disp_drv.flush_cb = my_flush_cb; /*Set a flush callback to draw to the display*/
disp_drv.hor_res = 320; /*Set the horizontal resolution in pixels*/
disp_drv.ver_res = 240; /*Set the vertical resolution in pixels*/
lv_disp_t * disp;
disp = lv_disp_drv_register(&disp_drv); /*Register the driver and save the created display objects*/
```
Here are some simple examples of the callbacks:

3
docs/porting/indev.md
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@@ -48,9 +48,6 @@ void my_input_read(lv_indev_drv_t * drv, lv_indev_data_t*data)
}
```
``` important:: Touchpad drivers must return the last X/Y coordinates even when the state is *LV_INDEV_STATE_REL*.
```
To set a mouse cursor use `lv_indev_set_cursor(my_indev, &img_cursor)`. (`my_indev` is the return value of `lv_indev_drv_register`)
### Keypad or keyboard