Add a destroy_signal on weston_output

src/compositor.c

@@ -2906,6 +2906,8 @@ weston_output_destroy(struct weston_output *output)
 {
 	struct weston_compositor *c = output->compositor;
 
+	wl_signal_emit(&output->destroy_signal, output);
+
 	pixman_region32_fini(&output->region);
 	pixman_region32_fini(&output->previous_damage);
 	output->compositor->output_id_pool &= ~(1 << output->id);
@@ -3064,6 +3066,7 @@ weston_output_init(struct weston_output *output, struct weston_compositor *c,
 	weston_output_damage(output);
 
 	wl_signal_init(&output->frame_signal);
+	wl_signal_init(&output->destroy_signal);
 	wl_list_init(&output->animation_list);
 	wl_list_init(&output->resource_list);
 

src/compositor.h

@@ -175,6 +175,7 @@ struct weston_output {
 	struct weston_output_zoom zoom;
 	int dirty;
 	struct wl_signal frame_signal;
+	struct wl_signal destroy_signal;
 	uint32_t frame_time;
 	int disable_planes;