程式語言 - Wayland - Wayland Client (xdg-shell) - OpenGL ES 2.0 - Get Version

參考資訊：
https://jan.newmarch.name/Wayland/index.html
https://wayland.freedesktop.org/docs/html/apa.html
https://bugaevc.gitbooks.io/writing-wayland-clients/content/

main.c

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <wayland-egl.h>
#include <wayland-client.h>
#include <linux/input-event-codes.h>

#include <EGL/egl.h>
#include <GLES2/gl2.h>
 
#include "xdg-shell-client-protocol.h"
 
#define LCD_W  640
#define LCD_H  480
#define STRIDE (LCD_W * 2)
#define SIZE   (STRIDE * LCD_H)
    
static bool configured = false;
static bool running = true;
 
struct wl_region *regn = NULL;
struct wl_display *dis = NULL;
struct wl_surface *surf = NULL;
struct wl_registry *reg = NULL;
struct wl_compositor *comp = NULL;
struct wl_egl_window *egl_win = NULL;
struct xdg_surface *xdg_surf = NULL;
struct xdg_toplevel *xdg_toplevel = NULL;
struct xdg_wm_base *xdg_wm_base = NULL;

EGLConfig egl_conf = 0;
EGLContext egl_ctx = 0;
EGLDisplay egl_dis = 0;
EGLSurface egl_surf = 0;
  
EGLint egl_attribs[] = {
    EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
    EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
    EGL_RED_SIZE,   8,
    EGL_GREEN_SIZE, 8,
    EGL_BLUE_SIZE,  8,
    EGL_NONE
};
  
EGLint ctx_attribs[] = {
    EGL_CONTEXT_CLIENT_VERSION, 
    2, 
    EGL_NONE
};
 
void cb_redraw(void *dat, struct wl_callback *cb, uint32_t time);
 
static void xdg_wm_base_handle_ping(void *data, struct xdg_wm_base *xdg_wm_base, uint32_t serial)
{
    xdg_wm_base_pong(xdg_wm_base, serial);
}
 
static const struct xdg_wm_base_listener xdg_wm_base_listener = {
    .ping = xdg_wm_base_handle_ping,
};
  
void cb_handle(void *dat, struct wl_registry *reg, uint32_t id, const char *intf, uint32_t ver)
{
    if (strcmp(intf, wl_compositor_interface.name) == 0) {
        comp = wl_registry_bind(reg, id, &wl_compositor_interface, 1);
    }
    else if (strcmp(intf, xdg_wm_base_interface.name) == 0) {
        xdg_wm_base = wl_registry_bind(reg, id, &xdg_wm_base_interface, 1);
        xdg_wm_base_add_listener(xdg_wm_base, &xdg_wm_base_listener, NULL);
    }
}
      
void cb_remove(void *dat, struct wl_registry *reg, uint32_t id)
{
}
      
struct wl_registry_listener cb = {
    .global = cb_handle,
    .global_remove = cb_remove
};
 
static void xdg_surface_handle_configure(void *data, struct xdg_surface *xdg_surface, uint32_t serial)
{
    xdg_surface_ack_configure(xdg_surface, serial);
 
    if (configured) {
        wl_surface_commit(surf);
    }
 
    configured = true;
}
 
static const struct xdg_surface_listener xdg_surface_listener = {
    .configure = xdg_surface_handle_configure,
};
 
static void xdg_toplevel_handle_close(void *data, struct xdg_toplevel *xdg_toplevel)
{
    running = false;
}
 
static void noop(void*, struct xdg_toplevel*, int32_t,  int32_t,  struct wl_array*)
{
}
 
static const struct xdg_toplevel_listener xdg_toplevel_listener = {
    .configure = noop,
    .close = xdg_toplevel_handle_close,
};
 
int main(int argc, char **argv)
{
    dis = wl_display_connect(NULL);
    reg = wl_display_get_registry(dis);
  
    wl_registry_add_listener(reg, &cb, NULL);
    wl_display_roundtrip(dis);
    printf("comp = 0x%08x\n", comp);
 
    surf = wl_compositor_create_surface(comp);
    printf("surf = 0x%08x\n", surf);
 
    xdg_surf = xdg_wm_base_get_xdg_surface(xdg_wm_base, surf);
    printf("xdg_surf = 0x%08x\n", xdg_surf);
 
    xdg_toplevel = xdg_surface_get_toplevel(xdg_surf);
    xdg_surface_add_listener(xdg_surf, &xdg_surface_listener, NULL);
    xdg_toplevel_add_listener(xdg_toplevel, &xdg_toplevel_listener, NULL);
 
    wl_surface_commit(surf);
    while (wl_display_dispatch(dis) != -1 && !configured) {
    }

    regn = wl_compositor_create_region(comp);
    wl_region_add(regn, 0, 0, LCD_W, LCD_H);
    wl_surface_set_opaque_region(surf, regn);
    egl_win = wl_egl_window_create(surf, LCD_W, LCD_H);
  
    EGLConfig cfg = 0;
    EGLint major = 0, minor = 0, cnt = 0;
  
    egl_dis = eglGetDisplay((EGLNativeDisplayType)dis);
    eglInitialize(egl_dis, &major, &minor);
    eglGetConfigs(egl_dis, NULL, 0, &cnt);
    eglChooseConfig(egl_dis, egl_attribs, &cfg, 1, &cnt);
    egl_surf = eglCreateWindowSurface(egl_dis, cfg, egl_win, NULL);
    egl_ctx = eglCreateContext(egl_dis, cfg, EGL_NO_CONTEXT, ctx_attribs);
    eglMakeCurrent(egl_dis, egl_surf, egl_surf, egl_ctx);
    printf("egl diplay = %p\n", egl_dis);
    printf("egl major=%d, minor=%d\n", major, minor);
  
    glClearColor(1.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);
    eglSwapBuffers(egl_dis, egl_surf);
    usleep(30000000); 
 
    xdg_toplevel_destroy(xdg_toplevel);
    xdg_surface_destroy(xdg_surf);
    wl_surface_destroy(surf);
    wl_compositor_destroy(comp);
    wl_registry_destroy(reg);
    wl_display_disconnect(dis);
    return 0;
}

編譯、執行

$ wayland-scanner private-code /usr/share/wayland-protocols/stable/xdg-shell/xdg-shell.xml xdg-shell-protocol.c
$ wayland-scanner client-header /usr/share/wayland-protocols/stable/xdg-shell/xdg-shell.xml xdg-shell-client-protocol.h
$ mutter --nested --wayland &
$ gcc main.c xdg-shell-protocol.c -o main -lwayland-client -lwayland-egl -lEGL -lGL
$ ./main
    comp = 0x2a127780
    surf = 0x2a126830
    xdg_surf = 0x2a126890
    egl diplay = 0x56492a12f480
    egl major=1, minor=5