=========================
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();
        }
    }
