ndg/lib/lv_drivers/wayland/README.md

Wayland display and input driver

Wayland display and input driver, with support for keyboard, pointer (i.e. mouse) and touchscreen. Keyboard support is based on libxkbcommon.

Following shell are supported:

• wl_shell (deprecated)
• xdg_shell

xdg_shell requires an extra build step; see section Generate protocols below.

Basic client-side window decorations (simple title bar, minimize and close buttons) are supported, while integration with desktop environments is not.

Install headers and libraries

Ubuntu

sudo apt-get install libwayland-dev libxkbcommon-dev libwayland-bin wayland-protocols

Fedora

sudo dnf install wayland-devel libxkbcommon-devel wayland-utils wayland-protocols-devel

Generate protocols

Support for non-basic shells (i.e. other than wl_shell) requires additional source files to be generated before the first build of the project. To do so, navigate to the wayland folder (the one which includes this file) and issue the following commands:

cmake .
make

Build configuration under Eclipse

In "Project properties > C/C++ Build > Settings" set the followings:

• "Cross GCC Compiler > Command line pattern"

  • Add ${wayland-cflags} and ${xkbcommon-cflags} to the end (add a space between the last command and this)

• "Cross GCC Linker > Command line pattern"

  • Add ${wayland-libs} and ${xkbcommon-libs} to the end (add a space between the last command and this)

• In "C/C++ Build > Build variables"

  • Configuration: [All Configuration]

  • Add

    • Variable name: wayland-cflags
      • Type: String
      • Value: pkg-config --cflags wayland-client
    • Variable name: wayland-libs
      • Type: String
      • Value: pkg-config --libs wayland-client
    • Variable name: xkbcommon-cflags
      • Type: String
      • Value: pkg-config --cflags xkbcommon
    • Variable name: xkbcommon-libs
      • Type: String
      • Value: pkg-config --libs xkbcommon

Init Wayland in LVGL

1. In main.c #incude "lv_drivers/wayland/wayland.h"
2. Enable the Wayland driver in lv_drv_conf.h with USE_WAYLAND 1 and configure its features below, enabling at least support for one shell.
3. LV_COLOR_DEPTH should be set either to 32 or 16 in lv_conf.h; support for 8 and 1 depends on target platform.
4. After lv_init() call lv_wayland_init().
5. Add a display (or more than one) using lv_wayland_create_window(), possibly with a close callback to track the status of each display:

  #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
• a ENCODER connected to Wayland pointer axis events Handles for input devices of each display can be get using respectively lv_wayland_get_indev_keyboard(), lv_wayland_get_indev_touchscreen(), lv_wayland_get_indev_pointer() and lv_wayland_get_indev_pointeraxis(), using disp as argument.

5. After lv_deinit() (if used), or in any case during de-initialization, call lv_wayland_deinit().

Fullscreen mode

In order to set one window as fullscreen or restore it as a normal one, call the lv_wayland_window_set_fullscreen() function respectively with true or false as fullscreen argument.

Disable window client-side decoration at runtime

Even when client-side decorations are enabled at compile time, they can be disabled at runtime setting the LV_WAYLAND_DISABLE_WINDOWDECORATION environment variable to 1.

Event-driven timer handler

Set LV_WAYLAND_TIMER_HANDLER in lv_drv_conf.h and call lv_wayland_timer_handler() in your timer loop (in place of lv_timer_handler()).

You can now sleep/wait until the next timer/event is ready, e.g.:

/* [After initialization and display creation] */
#include <limits.h>
#include <errno.h>
#include <poll.h>

struct pollfd pfd;
uint32_t time_till_next;
int sleep;

pfd.fd = lv_wayland_get_fd();
pfd.events = POLLIN;

while (1) {
    /* Handle any Wayland/LVGL timers/events */
    time_till_next = lv_wayland_timer_handler();

    /* Run until the last window closes */
    if (!lv_wayland_window_is_open(NULL)) {
        break;
    }

    /* Wait for something interesting to happen */
    if (time_till_next == LV_NO_TIMER_READY) {
        sleep = -1;
    } else if (time_till_next > INT_MAX) {
        sleep = INT_MAX;
    } else {
       sleep = time_till_next;
    }

    while ((poll(&pfd, 1, sleep) < 0) && (errno == EINTR));
}