overlay: refactor

- Use a single `lab_scene_rect` for both overlay background and outlines,
  like I described in the TODO comment in ffd4005.
- Simplify the resource management by destroying the overlay tree when
  it's hidden. I think its overhead is pretty minimal.
- Share a single `lab_scene_rect` for both region/edge overlays.

include/overlay.h

@@ -6,19 +6,8 @@
 
 struct seat;
 
-/* TODO: replace this with single lab_scene_rect */
-struct overlay_rect {
-	struct wlr_scene_tree *tree;
-
-	bool bg_enabled;
-	struct wlr_scene_rect *bg_rect;
-
-	bool border_enabled;
-	struct lab_scene_rect *border_rect;
-};
-
 struct overlay {
-	struct overlay_rect region_rect, edge_rect;
+	struct lab_scene_rect *rect;
 
 	/* Represents currently shown or delayed overlay */
 	struct {
@@ -34,15 +23,13 @@ struct overlay {
 	struct wl_event_source *timer;
 };
 
-void overlay_reconfigure(struct seat *seat);
-
-/* Calls overlay_hide() internally if there's no overlay to show */
+/*
+ * Shows or updates an overlay when the grabbed window can be snapped to
+ * a region or an output edge. Calls overlay_finish() otherwise.
+ */
 void overlay_update(struct seat *seat);
 
-/* This function must be called when server->grabbed_view is destroyed */
-void overlay_hide(struct seat *seat);
-
-/* This function is called to clean up the timer on exit */
+/* Destroys the overlay if it exists */
 void overlay_finish(struct seat *seat);
 
 #endif

src/debug.c

@@ -22,7 +22,7 @@
 #define IGNORE_SSD true
 #define IGNORE_MENU true
 #define IGNORE_OSD_PREVIEW_OUTLINE true
-#define IGNORE_SNAPPING_PREVIEW_OUTLINE true
+#define IGNORE_SNAPPING_OVERLAY true
 
 static struct view *last_view;
 
@@ -141,15 +141,10 @@ get_special(struct server *server, struct wlr_scene_node *node)
 	if (node == &server->seat.drag.icons->node) {
 		return "seat->drag.icons";
 	}
-	if (server->seat.overlay.region_rect.tree
-			&& node == &server->seat.overlay.region_rect.tree->node) {
+	if (server->seat.overlay.rect
+			&& node == &server->seat.overlay.rect->tree->node) {
 		/* Created on-demand */
-		return "seat->overlay.region_rect";
-	}
-	if (server->seat.overlay.edge_rect.tree
-			&& node == &server->seat.overlay.edge_rect.tree->node) {
-		/* Created on-demand */
-		return "seat->overlay.edge_rect";
+		return "seat->overlay.rect";
 	}
 	if (server->seat.input_method_relay->popup_tree
 			&& node == &server->seat.input_method_relay->popup_tree->node) {
@@ -224,21 +219,13 @@ dump_tree(struct server *server, struct wlr_scene_node *node,
 
 	struct lab_scene_rect *osd_preview_outline =
 		server->osd_state.preview_outline;
-	struct lab_scene_rect *region_snapping_overlay_outline =
-		server->seat.overlay.region_rect.border_rect;
-	struct lab_scene_rect *edge_snapping_overlay_outline =
-		server->seat.overlay.edge_rect.border_rect;
 	if ((IGNORE_MENU && node == &server->menu_tree->node)
 			|| (IGNORE_SSD && last_view
 				&& ssd_debug_is_root_node(last_view->ssd, node))
 			|| (IGNORE_OSD_PREVIEW_OUTLINE && osd_preview_outline
 				&& node == &osd_preview_outline->tree->node)
-			|| (IGNORE_SNAPPING_PREVIEW_OUTLINE
-				&& region_snapping_overlay_outline
-				&& node == &region_snapping_overlay_outline->tree->node)
-			|| (IGNORE_SNAPPING_PREVIEW_OUTLINE
-				&& edge_snapping_overlay_outline
-				&& node == &edge_snapping_overlay_outline->tree->node)) {
+			|| (IGNORE_SNAPPING_OVERLAY && server->seat.overlay.rect
+				&& node == &server->seat.overlay.rect->tree->node)) {
 		printf("%*c%s\n", pos + 4 + INDENT_SIZE, ' ', "<skipping children>");
 		return;
 	}

src/interactive.c

@@ -303,7 +303,7 @@ interactive_cancel(struct view *view)
 		return;
 	}
 
-	overlay_hide(&view->server->seat);
+	overlay_finish(&view->server->seat);
 
 	resize_indicator_hide(view);
 

src/output.c

@@ -171,7 +171,7 @@ handle_output_destroy(struct wl_listener *listener, void *data)
 	regions_evacuate_output(output);
 	regions_destroy(seat, &output->regions);
 	if (seat->overlay.active.output == output) {
-		overlay_hide(seat);
+		overlay_finish(seat);
 	}
 	wl_list_remove(&output->link);
 	wl_list_remove(&output->frame.link);

src/overlay.c

@@ -11,97 +11,40 @@
 #include "view.h"
 
 static void
-create_overlay_rect(struct seat *seat, struct overlay_rect *rect,
-		struct theme_snapping_overlay *theme)
-{
-	struct server *server = seat->server;
-
-	rect->bg_enabled = theme->bg_enabled;
-	rect->border_enabled = theme->border_enabled;
-	rect->tree = wlr_scene_tree_create(&server->scene->tree);
-
-	if (rect->bg_enabled) {
-		/* Create a filled rectangle */
-		rect->bg_rect = wlr_scene_rect_create(
-			rect->tree, 0, 0, theme->bg_color);
-	}
-
-	if (rect->border_enabled) {
-		/* Create outlines */
-		struct lab_scene_rect_options opts = {
-			.border_colors = (float *[3]) {
-				theme->border_color[0],
-				theme->border_color[1],
-				theme->border_color[2],
-			},
-			.nr_borders = 3,
-			.border_width = theme->border_width,
-		};
-		rect->border_rect = lab_scene_rect_create(rect->tree, &opts);
-	}
-
-	wlr_scene_node_set_enabled(&rect->tree->node, false);
-}
-
-void overlay_reconfigure(struct seat *seat)
-{
-	if (seat->overlay.region_rect.tree) {
-		wlr_scene_node_destroy(&seat->overlay.region_rect.tree->node);
-	}
-	if (seat->overlay.edge_rect.tree) {
-		wlr_scene_node_destroy(&seat->overlay.edge_rect.tree->node);
-	}
-
-	struct theme *theme = seat->server->theme;
-	create_overlay_rect(seat, &seat->overlay.region_rect,
-		&theme->snapping_overlay_region);
-	create_overlay_rect(seat, &seat->overlay.edge_rect,
-		&theme->snapping_overlay_edge);
-}
-
-static void
-show_overlay(struct seat *seat, struct overlay_rect *rect, struct wlr_box *box)
+show_overlay(struct seat *seat, struct theme_snapping_overlay *overlay_theme,
+		struct wlr_box *box)
 {
 	struct server *server = seat->server;
 	struct view *view = server->grabbed_view;
 	assert(view);
+	assert(!seat->overlay.rect);
 
-	if (!rect->tree) {
-		overlay_reconfigure(seat);
-		assert(rect->tree);
+	struct lab_scene_rect_options opts = {
+		.width = box->width,
+		.height = box->height,
+	};
+	if (overlay_theme->bg_enabled) {
+		/* Create a filled rectangle */
+		opts.bg_color = overlay_theme->bg_color;
+	}
+	float *border_colors[3] = {
+		overlay_theme->border_color[0],
+		overlay_theme->border_color[1],
+		overlay_theme->border_color[2],
+	};
+	if (overlay_theme->border_enabled) {
+		/* Create outlines */
+		opts.border_colors = border_colors;
+		opts.nr_borders = 3;
+		opts.border_width = overlay_theme->border_width;
 	}
 
-	if (rect->bg_enabled) {
-		wlr_scene_rect_set_size(rect->bg_rect, box->width, box->height);
-	}
-	if (rect->border_enabled) {
-		lab_scene_rect_set_size(rect->border_rect, box->width, box->height);
-	}
+	seat->overlay.rect =
+		lab_scene_rect_create(view->scene_tree->node.parent, &opts);
 
-	struct wlr_scene_node *node = &rect->tree->node;
-	wlr_scene_node_reparent(node, view->scene_tree->node.parent);
+	struct wlr_scene_node *node = &seat->overlay.rect->tree->node;
 	wlr_scene_node_place_below(node, &view->scene_tree->node);
 	wlr_scene_node_set_position(node, box->x, box->y);
-	wlr_scene_node_set_enabled(node, true);
-}
-
-static void
-inactivate_overlay(struct overlay *overlay)
-{
-	if (overlay->region_rect.tree) {
-		wlr_scene_node_set_enabled(
-			&overlay->region_rect.tree->node, false);
-	}
-	if (overlay->edge_rect.tree) {
-		wlr_scene_node_set_enabled(
-			&overlay->edge_rect.tree->node, false);
-	}
-	overlay->active.region = NULL;
-	overlay->active.edge = LAB_EDGE_NONE;
-	overlay->active.output = NULL;
-	if (overlay->timer) {
-		wl_event_source_timer_update(overlay->timer, 0);
-	}
 }
 
 static void
@@ -110,11 +53,11 @@ show_region_overlay(struct seat *seat, struct region *region)
 	if (region == seat->overlay.active.region) {
 		return;
 	}
-	inactivate_overlay(&seat->overlay);
+	overlay_finish(seat);
 	seat->overlay.active.region = region;
 
 	struct wlr_box geo = view_get_region_snap_box(NULL, region);
-	show_overlay(seat, &seat->overlay.region_rect, &geo);
+	show_overlay(seat, &rc.theme->snapping_overlay_region, &geo);
 }
 
 static struct wlr_box
@@ -135,7 +78,7 @@ handle_edge_overlay_timeout(void *data)
 		&& seat->overlay.active.output);
 	struct wlr_box box = get_edge_snap_box(seat->overlay.active.edge,
 		seat->overlay.active.output);
-	show_overlay(seat, &seat->overlay.edge_rect, &box);
+	show_overlay(seat, &rc.theme->snapping_overlay_edge, &box);
 	return 0;
 }
 
@@ -165,7 +108,7 @@ show_edge_overlay(struct seat *seat, enum lab_edge edge1, enum lab_edge edge2,
 			&& seat->overlay.active.output == output) {
 		return;
 	}
-	inactivate_overlay(&seat->overlay);
+	overlay_finish(seat);
 	seat->overlay.active.edge = edge;
 	seat->overlay.active.output = output;
 
@@ -186,8 +129,7 @@ show_edge_overlay(struct seat *seat, enum lab_edge edge1, enum lab_edge edge2,
 		wl_event_source_timer_update(seat->overlay.timer, delay);
 	} else {
 		/* Show overlay now */
-		struct wlr_box box = get_edge_snap_box(edge, output);
-		show_overlay(seat, &seat->overlay.edge_rect, &box);
+		handle_edge_overlay_timeout(seat);
 	}
 }
 
@@ -213,36 +155,17 @@ overlay_update(struct seat *seat)
 		return;
 	}
 
-	overlay_hide(seat);
-}
-
-void
-overlay_hide(struct seat *seat)
-{
-	struct overlay *overlay = &seat->overlay;
-	struct server *server = seat->server;
-
-	inactivate_overlay(overlay);
-
-	/*
-	 * Reparent the rectangle nodes to server's scene-tree so they don't
-	 * get destroyed on view destruction
-	 */
-	if (overlay->region_rect.tree) {
-		wlr_scene_node_reparent(&overlay->region_rect.tree->node,
-			&server->scene->tree);
-	}
-	if (overlay->edge_rect.tree) {
-		wlr_scene_node_reparent(&overlay->edge_rect.tree->node,
-			&server->scene->tree);
-	}
+	overlay_finish(seat);
 }
 
 void
 overlay_finish(struct seat *seat)
 {
+	if (seat->overlay.rect) {
+		wlr_scene_node_destroy(&seat->overlay.rect->tree->node);
+	}
 	if (seat->overlay.timer) {
 		wl_event_source_remove(seat->overlay.timer);
-		seat->overlay.timer = NULL;
 	}
+	seat->overlay = (struct overlay){0};
 }

src/regions.c

@@ -166,7 +166,7 @@ regions_destroy(struct seat *seat, struct wl_list *regions)
 	wl_list_for_each_safe(region, region_tmp, regions, link) {
 		wl_list_remove(&region->link);
 		if (seat && seat->overlay.active.region == region) {
-			overlay_hide(seat);
+			overlay_finish(seat);
 		}
 		zfree(region->name);
 		zfree(region);

src/seat.c

@@ -731,7 +731,7 @@ seat_reconfigure(struct server *server)
 	struct seat *seat = &server->seat;
 	struct input *input;
 	cursor_reload(seat);
-	overlay_reconfigure(seat);
+	overlay_finish(seat);
 	keyboard_reset_current_keybind();
 	wl_list_for_each(input, &seat->inputs, link) {
 		switch (input->wlr_input_device->type) {

src/workspaces.c

@@ -602,7 +602,7 @@ workspaces_reconfigure(struct server *server)
 	}
 
 	/* # of configured workspaces decreased */
-	overlay_hide(&server->seat);
+	overlay_finish(&server->seat);
 	struct workspace *first_workspace =
 		wl_container_of(server->workspaces.all.next, first_workspace, link);