view: decouple always-on-top windows from the omnipresent state

Before this commit, always-on-{top,bottom} windows were always visible
on all workspaces (omnipresent) because the they were not in
per-workspace trees like normal windows.

This commit fixes this by removing per-workspace trees and instead
showing/hiding views individually based on view->workspace.

include/config/types.h

@@ -62,10 +62,7 @@ enum lab_view_criteria {
 	/* No filter -> all focusable views */
 	LAB_VIEW_CRITERIA_NONE = 0,
 
-	/*
+	/* Includes omnipresent (visible on all desktops) views */
-	 * Includes always-on-top views, e.g.
-	 * what is visible on the current workspace
-	 */
 	LAB_VIEW_CRITERIA_CURRENT_WORKSPACE       = 1 << 0,
 
 	/* Positive criteria */

include/workspaces.h

@@ -8,14 +8,12 @@
 
 struct seat;
 struct server;
-struct wlr_scene_tree;
 
 struct workspace {
 	struct wl_list link; /* struct server.workspaces */
 	struct server *server;
 
 	char *name;
-	struct wlr_scene_tree *tree;
 
 	struct lab_cosmic_workspace *cosmic_workspace;
 	struct {

src/debug.c

@@ -106,15 +106,6 @@ get_special(struct server *server, struct wlr_scene_node *node)
 	if (node == &server->view_tree_always_on_top->node) {
 		return "server->always_on_top";
 	}
-	if (node->parent == server->view_tree) {
-		struct workspace *workspace;
-		wl_list_for_each(workspace, &server->workspaces.all, link) {
-			if (&workspace->tree->node == node) {
-				return workspace->name;
-			}
-		}
-		return "unknown workspace";
-	}
 	if (node->parent == &server->scene->tree) {
 		struct output *output;
 		wl_list_for_each(output, &server->outputs, link) {

src/desktop.c

@@ -96,9 +96,9 @@ desktop_focus_view(struct view *view, bool raise)
 
 	/*
 	 * Switch workspace if necessary to make the view visible
-	 * (unnecessary for "always on {top,bottom}" views).
+	 * (unnecessary for omnipresent views).
 	 */
-	if (!view_is_always_on_top(view) && !view_is_always_on_bottom(view)) {
+	if (!view->visible_on_all_workspaces) {
 		workspaces_switch_to(view->workspace, /*update_focus*/ false);
 	}
 

src/view.c

@@ -267,13 +267,7 @@ matches_criteria(struct view *view, enum lab_view_criteria criteria)
 		return false;
 	}
 	if (criteria & LAB_VIEW_CRITERIA_CURRENT_WORKSPACE) {
-		/*
+		if (view->workspace != view->server->workspaces.current) {
-		 * Always-on-top views are always on the current desktop and are
-		 * special in that they live in a different tree.
-		 */
-		struct server *server = view->server;
-		if (view->scene_tree->node.parent != server->workspaces.current->tree
-				&& !view_is_always_on_top(view)) {
 			return false;
 		}
 	}
@@ -303,11 +297,7 @@ matches_criteria(struct view *view, enum lab_view_criteria criteria)
 		}
 	}
 	if (criteria & LAB_VIEW_CRITERIA_NO_OMNIPRESENT) {
-		/*
+		if (view->visible_on_all_workspaces) {
-		 * TODO: Once always-on-top views use a per-workspace
-		 *       sub-tree we can remove the check from this condition.
-		 */
-		if (view->visible_on_all_workspaces || view_is_always_on_top(view)) {
 			return false;
 		}
 	}
@@ -1562,9 +1552,8 @@ view_toggle_always_on_top(struct view *view)
 {
 	assert(view);
 	if (view_is_always_on_top(view)) {
-		view->workspace = view->server->workspaces.current;
 		wlr_scene_node_reparent(&view->scene_tree->node,
-			view->workspace->tree);
+			view->server->view_tree);
 	} else {
 		wlr_scene_node_reparent(&view->scene_tree->node,
 			view->server->view_tree_always_on_top);
@@ -1584,9 +1573,8 @@ view_toggle_always_on_bottom(struct view *view)
 {
 	assert(view);
 	if (view_is_always_on_bottom(view)) {
-		view->workspace = view->server->workspaces.current;
 		wlr_scene_node_reparent(&view->scene_tree->node,
-			view->workspace->tree);
+			view->server->view_tree);
 	} else {
 		wlr_scene_node_reparent(&view->scene_tree->node,
 			view->server->view_tree_always_on_bottom);
@@ -1608,8 +1596,7 @@ view_move_to_workspace(struct view *view, struct workspace *workspace)
 	assert(workspace);
 	if (view->workspace != workspace) {
 		view->workspace = workspace;
-		wlr_scene_node_reparent(&view->scene_tree->node,
+		view_update_visibility(view);
-			workspace->tree);
 	}
 }
 
@@ -2411,7 +2398,9 @@ mappable_disconnect(struct mappable *mappable)
 void
 view_update_visibility(struct view *view)
 {
-	bool visible = view->mapped && !view->minimized;
+	struct server *server = view->server;
+	bool visible = view->mapped && !view->minimized
+			&& view->workspace == server->workspaces.current;
 	if (visible == view->scene_tree->node.enabled) {
 		return;
 	}

src/workspaces.c

@@ -234,9 +234,7 @@ add_workspace(struct server *server, const char *name)
 	struct workspace *workspace = znew(*workspace);
 	workspace->server = server;
 	workspace->name = xstrdup(name);
-	workspace->tree = wlr_scene_tree_create(server->view_tree);
 	wl_list_append(&server->workspaces.all, &workspace->link);
-	wlr_scene_node_set_enabled(&workspace->tree->node, false);
 
 	/* cosmic */
 	workspace->cosmic_workspace = lab_cosmic_workspace_create(server->workspaces.cosmic_group);
@@ -435,7 +433,6 @@ workspaces_init(struct server *server)
 	}
 
 	server->workspaces.current = initial;
-	wlr_scene_node_set_enabled(&initial->tree->node, true);
 	lab_cosmic_workspace_set_active(initial->cosmic_workspace, true);
 	lab_ext_workspace_set_active(initial->ext_workspace, true);
 }
@@ -454,28 +451,11 @@ workspaces_switch_to(struct workspace *target, bool update_focus)
 		return;
 	}
 
-	/* Disable the old workspace */
-	wlr_scene_node_set_enabled(
-		&server->workspaces.current->tree->node, false);
-
 	lab_cosmic_workspace_set_active(
 		server->workspaces.current->cosmic_workspace, false);
 	lab_ext_workspace_set_active(
 		server->workspaces.current->ext_workspace, false);
 
-	/* Move Omnipresent views to new workspace */
-	struct view *view;
-	enum lab_view_criteria criteria =
-		LAB_VIEW_CRITERIA_CURRENT_WORKSPACE;
-	for_each_view_reverse(view, &server->views, criteria) {
-		if (view->visible_on_all_workspaces) {
-			view_move_to_workspace(view, target);
-		}
-	}
-
-	/* Enable the new workspace */
-	wlr_scene_node_set_enabled(&target->tree->node, true);
-
 	/* Save the last visited workspace */
 	server->workspaces.last = server->workspaces.current;
 
@@ -483,24 +463,26 @@ workspaces_switch_to(struct workspace *target, bool update_focus)
 	server->workspaces.current = target;
 
 	struct view *grabbed_view = server->grabbed_view;
-	if (grabbed_view && !view_is_always_on_top(grabbed_view)) {
+	if (grabbed_view) {
 		view_move_to_workspace(grabbed_view, target);
 	}
 
+	struct view *view;
+	wl_list_for_each(view, &server->views, link) {
+		/* Omnipresent views are always in the current workspace */
+		if (view->visible_on_all_workspaces) {
+			view->workspace = target;
+		}
+		view_update_visibility(view);
+	}
+
 	/*
 	 * Make sure we are focusing what the user sees. Only refocus if
-	 * the focus is not already on an omnipresent or always-on-top view.
+	 * the focus is not already on an omnipresent.
-	 *
-	 * TODO: Decouple always-on-top views from the omnipresent state.
-	 *       One option for that would be to create a new scene tree
-	 *       as child of every workspace tree and then reparent a-o-t
-	 *       windows to that one. Combined with adjusting the condition
-	 *       below that should take care of the issue.
 	 */
 	if (update_focus) {
 		struct view *active_view = server->active_view;
-		if (!active_view || (!active_view->visible_on_all_workspaces
+		if (!active_view || !active_view->visible_on_all_workspaces) {
-				&& !view_is_always_on_top(active_view))) {
 			desktop_focus_topmost_view(server);
 		}
 	}
@@ -514,9 +496,6 @@ workspaces_switch_to(struct workspace *target, bool update_focus)
 	 */
 	cursor_update_focus(server);
 
-	/* Ensure that only currently visible fullscreen windows hide the top layer */
-	desktop_update_top_layer_visibility(server);
-
 	lab_cosmic_workspace_set_active(target->cosmic_workspace, true);
 	lab_ext_workspace_set_active(target->ext_workspace, true);
 }
@@ -569,7 +548,6 @@ workspaces_find(struct workspace *anchor, const char *name, bool wrap)
 static void
 destroy_workspace(struct workspace *workspace)
 {
-	wlr_scene_node_destroy(&workspace->tree->node);
 	zfree(workspace->name);
 	wl_list_remove(&workspace->link);
 	wl_list_remove(&workspace->on_cosmic.activate.link);

src/xdg.c

@@ -1019,7 +1019,7 @@ handle_new_xdg_toplevel(struct wl_listener *listener, void *data)
 	}
 
 	view->workspace = server->workspaces.current;
-	view->scene_tree = wlr_scene_tree_create(view->workspace->tree);
+	view->scene_tree = wlr_scene_tree_create(server->view_tree);
 	wlr_scene_node_set_enabled(&view->scene_tree->node, false);
 
 	struct wlr_scene_tree *tree = wlr_scene_xdg_surface_create(

src/xwayland.c

@@ -1010,7 +1010,7 @@ xwayland_view_create(struct server *server,
 	xsurface->data = view;
 
 	view->workspace = server->workspaces.current;
-	view->scene_tree = wlr_scene_tree_create(view->workspace->tree);
+	view->scene_tree = wlr_scene_tree_create(server->view_tree);
 	node_descriptor_create(&view->scene_tree->node,
 		LAB_NODE_VIEW, view, /*data*/ NULL);