compositor: Only send release event in response to wl_surface.attach

The current semantics would implicitly attach the most recently attached
buffer at commit time and send a release event when the buffer enventually
was released.  The implicit attach is a little too subtle though and this
patch changes the semantics to always only send release events in response
to an attach event.  As a consequence, once a compositor releases a buffer,
it no longer has a reference to it and wl_surfcea.damage is undefined.
Thus, the client side visible change is that damage request must always
be preceeded by a wl_surface.attach request, to ensure there's a valid buffer,
even if that means attaching the same buffer again.

diff --git a/clients/simple-shm.c b/clients/simple-shm.c
index c2eda61..f187b10 100644 (file)
--- a/clients/simple-shm.c
+++ b/clients/simple-shm.c
@@ -269,11 +269,7 @@ redraw(void *data, struct wl_callback *callback, uint32_t time)
 
        paint_pixels(buffer->shm_data, 20, window->width, window->height, time);
 
-       if (window->prev_buffer != buffer) {
-               wl_surface_attach(window->surface, buffer->buffer, 0, 0);
-               window->prev_buffer = buffer;
-       }
-
+       wl_surface_attach(window->surface, buffer->buffer, 0, 0);
        wl_surface_damage(window->surface,
                          20, 20, window->width - 40, window->height - 40);
 

diff --git a/src/compositor.c b/src/compositor.c
index 248d3b4..a2860fd 100644 (file)
--- a/src/compositor.c
+++ b/src/compositor.c
@@ -1426,6 +1426,9 @@ surface_commit(struct wl_client *client, struct wl_resource *resource)
                surface->configure(surface, surface->pending.sx,
                                   surface->pending.sy, buffer_width, buffer_height);
 
+       if (surface->pending.buffer)
+               wl_list_remove(&surface->pending.buffer_destroy_listener.link);
+       surface->pending.buffer = NULL;
        surface->pending.sx = 0;
        surface->pending.sy = 0;
        surface->pending.newly_attached = 0;