compositor: Add surface commit signal

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

libweston/compositor.c

@@ -455,6 +455,7 @@ weston_surface_create(struct weston_compositor *compositor)
 		return NULL;
 
 	wl_signal_init(&surface->destroy_signal);
+	wl_signal_init(&surface->commit_signal);
 
 	surface->compositor = compositor;
 	surface->ref_count = 1;
@@ -2888,6 +2889,8 @@ weston_surface_commit_state(struct weston_surface *surface,
 	wl_list_insert_list(&surface->feedback_list,
 			    &state->feedback_list);
 	wl_list_init(&state->feedback_list);
+
+	wl_signal_emit(&surface->commit_signal, surface);
 }
 
 static void

libweston/compositor.h

@@ -1015,6 +1015,7 @@ struct weston_surface {
 	struct wl_resource *resource;
 	struct wl_signal destroy_signal; /* callback argument: this surface */
 	struct weston_compositor *compositor;
+	struct wl_signal commit_signal;
 
 	/** Damage in local coordinates from the client, for tex upload. */
 	pixman_region32_t damage;