程式語言 - Wayland - Wayland Client (xdg-shell) - Create Buffer

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-client.h>
#include <linux/input-event-codes.h>

#include "xdg-shell-client-protocol.h"

#define WIDTH  640
#define HEIGHT 480
#define STRIDE (WIDTH * 2)
#define SIZE   (STRIDE * HEIGHT)
   
static bool configured = false;
static bool running = true;

struct wl_shm *shm = NULL;
struct wl_buffer *buf = NULL; 
struct wl_display *dis = NULL;
struct wl_surface *surf = NULL;
struct wl_registry *reg = NULL;
struct wl_shm_pool *pool = NULL;
struct wl_compositor *comp = NULL;
struct xdg_surface *xdg_surf = NULL;
struct xdg_toplevel *xdg_toplevel = NULL;
struct xdg_wm_base *xdg_wm_base = NULL;

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);
    }
    else if (strcmp(intf, wl_shm_interface.name) == 0) {
        shm = wl_registry_bind(reg, id, &wl_shm_interface, 1);
    }
}
     
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);

    unlink("/tmp/shm");
    int fd = open("/tmp/shm", O_RDWR | O_EXCL | O_CREAT);
    ftruncate(fd, SIZE);

    uint16_t *addr = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    pool = wl_shm_create_pool(shm, fd, SIZE);
    buf = wl_shm_pool_create_buffer(pool, 0, WIDTH, HEIGHT, STRIDE, WL_SHM_FORMAT_RGB565);
    wl_shm_pool_destroy(pool);
   
    printf("pool = %p\n", pool);
    printf("buf = %p\n", buf);
    printf("mmap = %p\n", addr);
    
    wl_surface_attach(surf, buf, 0, 0);
    wl_surface_commit(surf);
    wl_display_dispatch(dis);
    wl_display_roundtrip(dis);

    xdg_toplevel_destroy(xdg_toplevel);
	xdg_surface_destroy(xdg_surf);
	wl_surface_destroy(surf);
    wl_shm_destroy(shm);
    wl_compositor_destroy(comp);
    wl_registry_destroy(reg);
    wl_display_disconnect(dis);
    munmap(addr, SIZE);
    close(fd);

    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
$ ./main
    comp = 0xa93fe120
    surf = 0xa93fd1d0
    xdg_surf = 0xa93fd230
    pool = 0x563da93fd700
    buf = 0x563da93fd760
    mmap = 0x7fca5920f000