Wayland窗口绘制
Wayland窗口绘制有两种：1) 共享内存方式、2)EGL。
本文使用方式1绘制窗口。
Wayland窗口：wl_surface
Wayland窗口绘制完全由程序控制，包括标题栏绘制，边框绘制，窗口移动，改变大小等。 其中与窗口绘制有关的函数有：
wl_surface_attach() 将缓存绑定到窗口上，窗口大小会根据缓存重新计算。
wl_surface_damage() 标记窗口失效的区域
wl_surface_commit() 缓存提交请求，合成器会锁定提交的缓存，直到下一次wl_surface_attach或合成器主动释放。
wl_surface_frame() 申请帧绘制回调，每当绘制完一帧就发送wl_callback::done消息。
Walyand缓存：wl_buffer
Wayland窗口显示的内容由wl_buffer负责。Wayland与X Server不同，Wayland只支持客户端直接绘制，合成器不提供对wl_buffer的绘制操作。与wl_buffer有关的函数有：
wl_shm_create_pool() 创建一个缓存池，缓存池可以mmap到程序的内存空间中。
wl_shm_pool_create() 创建一个wl_buffer。
示例代码：
lpBuffer->data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); //lpBuffer->data == MAP_FAILED HSHMPOOL pool = wl_shm_create_pool(wlGetRegistry()->s_shm, fd, size); lpBuffer->buffer = wl_shm_pool_create_buffer(pool, 0, width, height, stride, WL_SHM_FORMAT_XRGB8888);窗口绘制：
void buffer_release(void *data, struct wl_buffer *buffer) { LPPAINTBUFFER lpBuffer = data; lpBuffer->busy = 0; } static const struct wl_buffer_listener buffer_listener = { .release = buffer_release }; void _wlCreatePaintStructure(int width, int height, LPPAINTBUFFER lpBuffer) { int stride = width * 4; int size = stride * height; char filename[] = "/tmp/weston-shared-XXXXXX"; int fd = mkstemp(filename); fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC); unlink(filename); ftruncate(fd, size); lpBuffer->busy = 0; lpBuffer->data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); //lpBuffer->data == MAP_FAILED HSHMPOOL pool = wl_shm_create_pool(wlGetRegistry()->s_shm, fd, size); lpBuffer->buffer = wl_shm_pool_create_buffer(pool, 0, width, height, stride, WL_SHM_FORMAT_XRGB8888); wl_buffer_add_listener(lpBuffer->buffer, &buffer_listener, lpBuffer); wl_shm_pool_destroy(pool); close(fd); } void wlBeginPaint(HSURFACE surface, LPPAINTSTRUCTURE lpPaint) { LPSURFACEPRIVATE _priv = _wlGetSurfacePrivate(surface); if (!_priv->buffer[0].busy && _priv->buffer[0].buffer) { lpPaint->buffer = &_priv->buffer[0]; } else if (!_priv->buffer[1].busy && _priv->buffer[1].buffer) { lpPaint->buffer = &_priv->buffer[1]; } else { SIZE sz = wlGetSurfaceSize(surface); _wlCreatePaintStructure(sz.width, sz.height, &_priv->buffer[0]); lpPaint->buffer = &_priv->buffer[0]; } } void wlEndPaint(HSURFACE surface, LPPAINTSTRUCTURE lpPaint) { lpPaint->buffer->busy = 1; wl_surface_attach(surface, lpPaint->buffer->buffer, 0, 0); SIZE sz = wlGetSurfaceSize(surface); wl_surface_damage(surface, 0, 0, sz.width, sz.height); wl_surface_commit(surface); } void frame_listener_done(void *data, HCALLBACK callback, uint32_t time) { HSURFACE surface = (HSURFACE)data; /* 每次都需要重新设置回调函数 */ _wlSetFrameListener(surface); /* 绘制一帧 */ _wlDrawFrame(surface, time); } static struct wl_callback_listener frame_listener = { frame_listener_done }; void _wlSetFrameListener(HSURFACE surface) { static struct wl_callback_listener frame_listener; frame_listener.done = frame_listener_done; HCALLBACK callback = wl_surface_frame(surface); wl_callback_add_listener(callback, &frame_listener, surface); } void _wlDrawFrame(HSURFACE surface, uint32_t time) { PAINTSTRUCTURE ps; memset(&ps, 0, sizeof(ps)); wlBeginPaint(surface, &ps); wlCallPaintProc(surface, &ps, time); wlEndPaint(surface, &ps); } void wlSetPaintProc(HSURFACE surface, REPAINTPROC surfaceproc) { _wlGetSurfacePrivate(surface)->surfaceproc = surfaceproc; _wlSetFrameListener(surface); _wlDrawFrame(surface, 0); }