compositor: introduce unified map logic

include/wlr/types/wlr_compositor.h

@@ -76,6 +76,7 @@ struct wlr_surface_role {
 	void (*commit)(struct wlr_surface *surface);
 	void (*precommit)(struct wlr_surface *surface,
 		const struct wlr_surface_state *state);
+	void (*unmap)(struct wlr_surface *surface);
 	void (*destroy)(struct wlr_surface *surface);
 };
 
@@ -135,6 +136,8 @@ struct wlr_surface {
 
 	struct wl_list cached; // wlr_surface_state.cached_link
 
+	bool mapped;
+
 	const struct wlr_surface_role *role; // the lifetime-bound role or NULL
 	void *role_data; // role-specific data
 
@@ -142,6 +145,20 @@ struct wlr_surface {
 		struct wl_signal client_commit;
 		struct wl_signal precommit; // const struct wlr_surface_state *
 		struct wl_signal commit;
+
+		/**
+		 * The `map` event signals that the surface has a non-null buffer
+		 * committed and is ready to be displayed.
+		 */
+		struct wl_signal map;
+		/**
+		 * The `unmap` event signals that the surface shouldn't be displayed
+		 * anymore. This can happen when a null buffer is committed,
+		 * the associated role object is destroyed, or when the role-specific
+		 * conditions for the surface to be mapped no longer apply.
+		 */
+		struct wl_signal unmap;
+
 		struct wl_signal new_subsurface;
 		struct wl_signal destroy;
 	} events;
@@ -200,6 +217,20 @@ bool wlr_surface_set_role(struct wlr_surface *surface,
  */
 void wlr_surface_destroy_role_object(struct wlr_surface *surface);
 
+/**
+ * Map the surface. If the surface is already mapped, this is no-op.
+ *
+ * This function must only be used by surface role implementations.
+ */
+void wlr_surface_map(struct wlr_surface *surface);
+
+/**
+ * Unmap the surface. If the surface is already unmapped, this is no-op.
+ *
+ * This function must only be used by surface role implementations.
+ */
+void wlr_surface_unmap(struct wlr_surface *surface);
+
 /**
  * Whether or not this surface currently has an attached buffer. A surface has
  * an attached buffer when it commits with a non-null buffer in its pending

types/wlr_compositor.c

@@ -442,6 +442,10 @@ static void surface_commit_state(struct wlr_surface *surface,
 
 	bool invalid_buffer = next->committed & WLR_SURFACE_STATE_BUFFER;
 
+	if (invalid_buffer && next->buffer == NULL) {
+		wlr_surface_unmap(surface);
+	}
+
 	surface_update_damage(&surface->buffer_damage, &surface->current, next);
 
 	pixman_region32_clear(&surface->external_damage);
@@ -696,6 +700,8 @@ static struct wlr_surface *surface_create(struct wl_client *client,
 	wl_signal_init(&surface->events.client_commit);
 	wl_signal_init(&surface->events.precommit);
 	wl_signal_init(&surface->events.commit);
+	wl_signal_init(&surface->events.map);
+	wl_signal_init(&surface->events.unmap);
 	wl_signal_init(&surface->events.destroy);
 	wl_signal_init(&surface->events.new_subsurface);
 	wl_list_init(&surface->current_outputs);
@@ -727,6 +733,26 @@ bool wlr_surface_has_buffer(struct wlr_surface *surface) {
 	return surface->has_buffer;
 }
 
+void wlr_surface_map(struct wlr_surface *surface) {
+	if (surface->mapped) {
+		return;
+	}
+	assert(wlr_surface_has_buffer(surface));
+	surface->mapped = true;
+	wl_signal_emit_mutable(&surface->events.map, NULL);
+}
+
+void wlr_surface_unmap(struct wlr_surface *surface) {
+	if (!surface->mapped) {
+		return;
+	}
+	surface->mapped = false;
+	wl_signal_emit_mutable(&surface->events.unmap, NULL);
+	if (surface->role != NULL && surface->role->unmap != NULL) {
+		surface->role->unmap(surface);
+	}
+}
+
 bool wlr_surface_set_role(struct wlr_surface *surface,
 		const struct wlr_surface_role *role, void *role_data,
 		struct wl_resource *error_resource, uint32_t error_code) {
@@ -758,6 +784,7 @@ void wlr_surface_destroy_role_object(struct wlr_surface *surface) {
 	if (surface->role_data == NULL) {
 		return;
 	}
+	wlr_surface_unmap(surface);
 	if (surface->role->destroy != NULL) {
 		surface->role->destroy(surface);
 	}