compositor: keep track of the weston_layer a weston_view is in

This introduces a new struct, weston_layer_entry, which is now used
in place of wl_list to keep the link for the layer list in weston_view
and the head of the list in weston_layer.
weston_layer_entry also has a weston_layer*, which points to the layer
the view is in or, in the case the entry it's the head of the list, to
the layer itself.

src/compositor.c

@@ -345,9 +345,10 @@ weston_view_create(struct weston_surface *surface)
 
 	wl_signal_init(&view->destroy_signal);
 	wl_list_init(&view->link);
-	wl_list_init(&view->layer_link);
+	wl_list_init(&view->layer_link.link);
 
 	view->plane = NULL;
+	view->layer_link.layer = NULL;
 
 	pixman_region32_init(&view->clip);
 
@@ -1366,8 +1367,7 @@ weston_view_unmap(struct weston_view *view)
 	weston_view_damage_below(view);
 	view->output = NULL;
 	view->plane = NULL;
-	wl_list_remove(&view->layer_link);
-	wl_list_init(&view->layer_link);
+	weston_layer_entry_remove(&view->layer_link);
 	wl_list_remove(&view->link);
 	wl_list_init(&view->link);
 	view->output_mask = 0;
@@ -1422,7 +1422,7 @@ weston_view_destroy(struct weston_view *view)
 	}
 
 	wl_list_remove(&view->link);
-	wl_list_remove(&view->layer_link);
+	weston_layer_entry_remove(&view->layer_link);
 
 	pixman_region32_fini(&view->clip);
 	pixman_region32_fini(&view->transform.boundingbox);
@@ -1783,18 +1783,18 @@ weston_compositor_build_view_list(struct weston_compositor *compositor)
 	struct weston_layer *layer;
 
 	wl_list_for_each(layer, &compositor->layer_list, link)
-		wl_list_for_each(view, &layer->view_list, layer_link)
+		wl_list_for_each(view, &layer->view_list.link, layer_link.link)
 			surface_stash_subsurface_views(view->surface);
 
 	wl_list_init(&compositor->view_list);
 	wl_list_for_each(layer, &compositor->layer_list, link) {
-		wl_list_for_each(view, &layer->view_list, layer_link) {
+		wl_list_for_each(view, &layer->view_list.link, layer_link.link) {
 			view_list_add(compositor, view);
 		}
 	}
 
 	wl_list_for_each(layer, &compositor->layer_list, link)
-		wl_list_for_each(view, &layer->view_list, layer_link)
+		wl_list_for_each(view, &layer->view_list.link, layer_link.link)
 			surface_free_unused_subsurface_views(view->surface);
 }
 
@@ -1912,10 +1912,27 @@ idle_repaint(void *data)
 	output->start_repaint_loop(output);
 }
 
+WL_EXPORT void
+weston_layer_entry_insert(struct weston_layer_entry *list,
+			  struct weston_layer_entry *entry)
+{
+	wl_list_insert(&list->link, &entry->link);
+	entry->layer = list->layer;
+}
+
+WL_EXPORT void
+weston_layer_entry_remove(struct weston_layer_entry *entry)
+{
+	wl_list_remove(&entry->link);
+	wl_list_init(&entry->link);
+	entry->layer = NULL;
+}
+
 WL_EXPORT void
 weston_layer_init(struct weston_layer *layer, struct wl_list *below)
 {
-	wl_list_init(&layer->view_list);
+	wl_list_init(&layer->view_list.link);
+	layer->view_list.layer = layer;
 	if (below != NULL)
 		wl_list_insert(below, &layer->link);
 }

src/compositor.h

@@ -526,8 +526,13 @@ enum {
                                          * to off */
 };
 
+struct weston_layer_entry {
+	struct wl_list link;
+	struct weston_layer *layer;
+};
+
 struct weston_layer {
-	struct wl_list view_list;
+	struct weston_layer_entry view_list;
 	struct wl_list link;
 };
 
@@ -731,7 +736,7 @@ struct weston_view {
 	struct wl_signal destroy_signal;
 
 	struct wl_list link;
-	struct wl_list layer_link;
+	struct weston_layer_entry layer_link;
 	struct weston_plane *plane;
 
 	pixman_region32_t clip;
@@ -996,6 +1001,11 @@ notify_touch(struct weston_seat *seat, uint32_t time, int touch_id,
 void
 notify_touch_frame(struct weston_seat *seat);
 
+void
+weston_layer_entry_insert(struct weston_layer_entry *list,
+			  struct weston_layer_entry *entry);
+void
+weston_layer_entry_remove(struct weston_layer_entry *entry);
 void
 weston_layer_init(struct weston_layer *layer, struct wl_list *below);
 

src/data-device.c

@@ -180,7 +180,7 @@ drag_surface_configure(struct weston_drag *drag,
 		       struct weston_surface *es,
 		       int32_t sx, int32_t sy)
 {
-	struct wl_list *list;
+	struct weston_layer_entry *list;
 	float fx, fy;
 
 	assert((pointer != NULL && touch == NULL) ||
@@ -193,8 +193,8 @@ drag_surface_configure(struct weston_drag *drag,
 		else
 			list = &es->compositor->cursor_layer.view_list;
 
-		wl_list_remove(&drag->icon->layer_link);
-		wl_list_insert(list, &drag->icon->layer_link);
+		weston_layer_entry_remove(&drag->icon->layer_link);
+		weston_layer_entry_insert(list, &drag->icon->layer_link);
 		weston_view_update_transform(drag->icon);
 		pixman_region32_clear(&es->pending.input);
 	}

src/input.c

@@ -1555,8 +1555,8 @@ pointer_cursor_surface_configure(struct weston_surface *es,
 	empty_region(&es->input);
 
 	if (!weston_surface_is_mapped(es)) {
-		wl_list_insert(&es->compositor->cursor_layer.view_list,
-			       &pointer->sprite->layer_link);
+		weston_layer_entry_insert(&es->compositor->cursor_layer.view_list,
+					  &pointer->sprite->layer_link);
 		weston_view_update_transform(pointer->sprite);
 	}
 }