render: add wlr_renderer.events.lost

include/wlr/render/wlr_renderer.h

@@ -26,6 +26,12 @@ struct wlr_fbox;
 struct wlr_renderer {
 	struct {
 		struct wl_signal destroy;
+		/**
+		 * Emitted when the GPU is lost, e.g. on GPU reset.
+		 *
+		 * Compositors should destroy the renderer and re-create it.
+		 */
+		struct wl_signal lost;
 	} events;
 
 	// private state

render/wlr_renderer.c

@@ -44,6 +44,7 @@ void wlr_renderer_init(struct wlr_renderer *renderer,
 	renderer->impl = impl;
 
 	wl_signal_init(&renderer->events.destroy);
+	wl_signal_init(&renderer->events.lost);
 }
 
 void wlr_renderer_destroy(struct wlr_renderer *r) {