github-code/lvgl
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

feat(indev): add multi touch gestures (#7078)

Browse Source
This commit is contained in:
Erik Tagirov
2024-11-18 09:52:25 +01:00
committed by GitHub
parent c81e69ec74
commit f677c25abc
15 changed files with 1340 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

67
docs/details/main-components/indev.rst
View File

@@ -123,7 +123,6 @@ If you did some action on a gesture you can call
:cpp:expr:`lv_indev_wait_release(lv_indev_active())` in the event handler to
prevent LVGL sending further input-device-related events.
.. _indev_crown:
Crown Behavior
@@ -157,6 +156,72 @@ For example, if both the indev and widget sensitivity is set to 128 (0.5), the i
diff will be multiplied by 0.25. The value of the Widget will be incremented by that
value or the Widget will be scrolled that amount of pixels.
Multi-touch gestures
====================
LVGL has the ability to recognize multi-touch gestures, when a gesture
is detected a ``LV_EVENT_GESTURE`` is passed to the object on which the
gesture occurred. Currently, only the pinch gesture is supported
more gesture types will be implemented soon.
To enable the multi-touch gesture recognition set the
``LV_USE_GESTURE_RECOGNITION`` option in the ``lv_conf.h`` file.
Touch event collection
~~~~~~~~~~~~~~~~~~~~~~
The driver or application collects touch events until the indev read callback
is called. It is the responsibility of the driver to call
the gesture recognition function of the appropriate type. For example
to recognise pinch gestures call ``lv_indev_gesture_detect_pinch``.
After calling the gesture detection function, it's necessary to call
the ``lv_indev_set_gesture_data`` function to set the ``gesture_data``
and ``gesture_type`` fields of the structure ``lv_indev_data_t``
.. code-block::
/* The recognizer keeps the state of the gesture */
static lv_indev_gesture_recognizer_t recognizer;
/* An array that stores the collected touch events */
static lv_indev_touch_data_t touches[10];
/* A counter that needs to be incremented each time a touch event is recieved */
static uint8_t touch_cnt;
static void touch_read_callback(lv_indev_t * drv, lv_indev_data_t * data)
{
lv_indev_touch_data_t * touch;
uint8_t i;
touch = &touches[0];
lv_indev_gesture_detect_pinch(recognizer, &touches[0],
touch_cnt);
touch_cnt = 0;
/* Set the gesture information, before returning to LVGL */
lv_indev_set_gesture_data(data, recognizer);
}
A touch event is represented by the ``lv_indev_touch_data_t`` structure, the fields
being 1:1 compatible with events emitted by the `libinput <https://wayland.freedesktop.org/libinput/doc/latest/>`_ library
Handling touch events
~~~~~~~~~~~~~~~~~~~~~
Touch events are handled like any other event. First, setup a listener for the ``LV_EVENT_GESTURE`` event type by defining and setting the callback function.
The state or scale of the pinch gesture can be retrieved by
calling the ``lv_event_get_pinch_scale`` and ``lv_indev_get_gesture_state`` from within the
callback.
An example of such an application is available in
the source tree ``examples/others/gestures/lv_example_gestures.c``
Keypad or Keyboard
------------------