layer_shell: Handle popups through popup descriptor

We tried to synchronize layer shell popups with the parent layer shell
on commits, but this is subtly wrong because we would only update
the position for one layer shell that was committed, but not any other
layer that might be affected. By moving handling to the scene descriptor
we can iterate all popups and ensure they are synchronized.

include/sway/layers.h

@@ -3,6 +3,7 @@
 #include <stdbool.h>
 #include <wlr/types/wlr_compositor.h>
 #include <wlr/types/wlr_layer_shell_v1.h>
+#include "sway/tree/view.h"
 
 struct sway_layer_surface {
 	struct wl_listener map;
@@ -14,10 +15,12 @@ struct sway_layer_surface {
 
 	bool mapped;
 
+	struct wlr_scene_tree *popups;
+	struct sway_popup_desc desc;
+
 	struct sway_output *output;
 	struct wlr_scene_layer_surface_v1 *scene;
 	struct wlr_scene_tree *tree;
-	struct wlr_scene_tree *popups;
 	struct wlr_layer_surface_v1 *layer_surface;
 };
 

sway/desktop/layer_shell.c

@@ -122,6 +122,16 @@ static struct sway_layer_surface *sway_layer_surface_create(
 		return NULL;
 	}
 
+	surface->desc.relative = &scene->tree->node;
+
+	if (!scene_descriptor_assign(&popups->node,
+			SWAY_SCENE_DESC_POPUP, &surface->desc)) {
+		sway_log(SWAY_ERROR, "Failed to allocate a popup scene descriptor");
+		wlr_scene_node_destroy(&popups->node);
+		free(surface);
+		return NULL;
+	}
+
 	surface->tree = scene->tree;
 	surface->scene = scene;
 	surface->layer_surface = scene->layer_surface;
@@ -224,10 +234,6 @@ static void handle_surface_commit(struct wl_listener *listener, void *data) {
 		arrange_layers(surface->output);
 		transaction_commit_dirty();
 	}
-
-	int lx, ly;
-	wlr_scene_node_coords(&surface->scene->tree->node, &lx, &ly);
-	wlr_scene_node_set_position(&surface->popups->node, lx, ly);
 }
 
 static void handle_map(struct wl_listener *listener, void *data) {

sway/desktop/transaction.c

@@ -612,15 +612,11 @@ void arrange_popups(struct wlr_scene_tree *popups) {
 		struct sway_popup_desc *popup = scene_descriptor_try_get(node,
 			SWAY_SCENE_DESC_POPUP);
 
-		// the popup layer may have popups from layer_shell surfaces, in this
-		// case those don't have a scene descriptor, so lets skip those here.
-		if (popup) {
 		int lx, ly;
 		wlr_scene_node_coords(popup->relative, &lx, &ly);
 		wlr_scene_node_set_position(node, lx, ly);
 	}
 }
-}
 
 static void arrange_root(struct sway_root *root) {
 	struct sway_container *fs = root->fullscreen_global;

sway/input/cursor.c

@@ -92,7 +92,7 @@ struct sway_node *node_at_coords(
 			if (!con) {
 				struct sway_popup_desc *popup =
 					scene_descriptor_try_get(current, SWAY_SCENE_DESC_POPUP);
-				if (popup) {
+				if (popup && popup->view) {
 					con = popup->view->container;
 				}
 			}