compositor: add wlr_compositor_set_renderer()

Allows compositors to switch the wlr_renderer at runtime.

Useful for handling GPU resets.

include/wlr/types/wlr_compositor.h

@@ -524,4 +524,16 @@ const pixman_region32_t *wlr_region_from_resource(struct wl_resource *resource);
 struct wlr_compositor *wlr_compositor_create(struct wl_display *display,
 	uint32_t version, struct wlr_renderer *renderer);
 
+/**
+ * Set the renderer used for creating struct wlr_texture objects from client
+ * buffers on surface commit.
+ *
+ * The renderer may be NULL, in which case no textures are created.
+ *
+ * Calling this function does not update existing textures, it only affects
+ * future surface commits.
+ */
+void wlr_compositor_set_renderer(struct wlr_compositor *compositor,
+	struct wlr_renderer *renderer);
+
 #endif

types/wlr_compositor.c

@@ -1342,9 +1342,7 @@ static void compositor_handle_renderer_destroy(
 		struct wl_listener *listener, void *data) {
 	struct wlr_compositor *compositor =
 		wl_container_of(listener, compositor, renderer_destroy);
-	compositor->renderer = NULL;
+	wlr_compositor_set_renderer(compositor, NULL);
-	wl_list_remove(&compositor->renderer_destroy.link);
-	wl_list_init(&compositor->renderer_destroy.link);
 }
 
 struct wlr_compositor *wlr_compositor_create(struct wl_display *display,
@@ -1362,22 +1360,30 @@ struct wlr_compositor *wlr_compositor_create(struct wl_display *display,
 		free(compositor);
 		return NULL;
 	}
-	compositor->renderer = renderer;
 
 	wl_signal_init(&compositor->events.new_surface);
 	wl_signal_init(&compositor->events.destroy);
+	wl_list_init(&compositor->renderer_destroy.link);
 
 	compositor->display_destroy.notify = compositor_handle_display_destroy;
 	wl_display_add_destroy_listener(display, &compositor->display_destroy);
 
+	wlr_compositor_set_renderer(compositor, renderer);
+
+	return compositor;
+}
+
+void wlr_compositor_set_renderer(struct wlr_compositor *compositor,
+		struct wlr_renderer *renderer) {
+	wl_list_remove(&compositor->renderer_destroy.link);
+	compositor->renderer = renderer;
+
 	if (renderer != NULL) {
 		compositor->renderer_destroy.notify = compositor_handle_renderer_destroy;
 		wl_signal_add(&renderer->events.destroy, &compositor->renderer_destroy);
 	} else {
 		wl_list_init(&compositor->renderer_destroy.link);
 	}
-
-	return compositor;
 }
 
 static bool surface_state_add_synced(struct wlr_surface_state *state, void *value) {