App:Library:LVGL:docs:Overview:Input devices

https://docs.lvgl.io/8.2/overview/style.html

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Input devices

An input device usually means:

• Pointer-like input device like touchpad or mouse
• Keypads like a normal keyboard or simple numeric keypad
• Encoders with left/right turn and push options
• External hardware buttons which are assigned to specific points on the screen

Important

Before reading further, please read the [Porting](/porting/indev) section of Input devices

Pointers

Cursor

Pointer input devices (like a mouse) can have a cursor.

...
lv_indev_t * mouse_indev = lv_indev_drv_register(&indev_drv);

LV_IMG_DECLARE(mouse_cursor_icon);                          /*Declare the image source.*/
lv_obj_t * cursor_obj = lv_img_create(lv_scr_act());       /*Create an image object for the cursor */
lv_img_set_src(cursor_obj, &mouse_cursor_icon);             /*Set the image source*/
lv_indev_set_cursor(mouse_indev, cursor_obj);               /*Connect the image  object to the driver*/

Note that the cursor object should have lv_obj_clear_flag(cursor_obj, LV_OBJ_FLAG_CLICKABLE). For images, clicking is disabled by default.

Gestures

Pointer input devices can detect basic gestures. By default, most of the widgets send the gestures to its parent, so finally the gestures can be detected on the screen object in a form of an LV_EVENT_GESTURE event. For example:

void my_event(lv_event_t * e)
{
  lv_obj_t * screen = lv_event_get_current_target(e);
  lv_dir_t dir = lv_indev_get_gesture_dir(lv_indev_act());
  switch(dir) {
    case LV_DIR_LEFT:
      ...
      break;
    case LV_DIR_RIGHT:
      ...
      break;
    case LV_DIR_TOP:
      ...
      break;
    case LV_DIR_BOTTOM:
      ...
      break;
  }
}

...

lv_obj_add_event_cb(screen1, my_event, LV_EVENT_GESTURE, NULL);

To prevent passing the gesture event to the parent from an object use lv_obj_clear_flag(obj, LV_OBJ_FLAG_GESTURE_BUBBLE).

Note that, gestures are not triggered if an object is being scrolled.

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