wlr_scene: Rework damage handling

Simplify damage handling by using our cached visibility state.
Damaging can happen in one step because since we can use the old visibility
state which represent what portions of the screen the scene node was. This
way we can damage everything in one step after the fact.

types/scene/wlr_scene.c

@@ -67,8 +67,6 @@ static void scene_node_init(struct wlr_scene_node *node,
 	wlr_addon_set_init(&node->addons);
 }
 
-static void scene_node_damage_whole(struct wlr_scene_node *node);
-
 struct highlight_region {
 	pixman_region32_t region;
 	struct timespec when;
@@ -241,14 +239,44 @@ static bool scene_nodes_in_box(struct wlr_scene_node *node, struct wlr_box *box,
 	return _scene_nodes_in_box(node, box, iterator, user_data, x, y);
 }
 
-// This function must be called whenever the coordinates/dimensions of a scene
+struct scene_update_data {
-// buffer or scene output change. It is not necessary to call when a scene
+	pixman_region32_t *visible;
-// buffer's node is enabled/disabled or obscured by other nodes.
+	pixman_region32_t *update_region;
-static void scene_buffer_update_outputs(struct wlr_scene_buffer *scene_buffer,
+	struct wl_list *outputs;
-		int lx, int ly, struct wlr_scene *scene,
+};
-		struct wlr_scene_output *ignore) {
+
-	struct wlr_box buffer_box = { .x = lx, .y = ly };
+static void scene_damage_outputs(struct wlr_scene *scene, pixman_region32_t *damage) {
-	scene_node_get_size(&scene_buffer->node, &buffer_box.width, &buffer_box.height);
+	if (!pixman_region32_not_empty(damage)) {
+		return;
+	}
+
+	struct wlr_scene_output *scene_output;
+	wl_list_for_each(scene_output, &scene->outputs, link) {
+		pixman_region32_t output_damage;
+		pixman_region32_init(&output_damage);
+		pixman_region32_copy(&output_damage, damage);
+		pixman_region32_translate(&output_damage,
+			-scene_output->x, -scene_output->y);
+		wlr_region_scale(&output_damage, &output_damage,
+			scene_output->output->scale);
+		if (wlr_damage_ring_add(&scene_output->damage_ring, &output_damage)) {
+			wlr_output_schedule_frame(scene_output->output);
+		}
+		pixman_region32_fini(&output_damage);
+	}
+}
+
+static void update_node_update_outputs(struct wlr_scene_node *node,
+		struct wl_list *outputs, struct wlr_scene_output *ignore) {
+	if (node->type != WLR_SCENE_NODE_BUFFER) {
+		return;
+	}
+
+	struct wlr_scene_buffer *scene_buffer = wlr_scene_buffer_from_node(node);
+
+	struct wlr_box buffer_box;
+	wlr_scene_node_coords(node, &buffer_box.x, &buffer_box.y);
+	scene_node_get_size(node, &buffer_box.width, &buffer_box.height);
 
 	int largest_overlap = 0;
 	scene_buffer->primary_output = NULL;
@@ -262,7 +290,7 @@ static void scene_buffer_update_outputs(struct wlr_scene_buffer *scene_buffer,
 	// to have a reasonable value. Otherwise, they may get a value that's in
 	// the middle of a calculation.
 	struct wlr_scene_output *scene_output;
-	wl_list_for_each(scene_output, &scene->outputs, link) {
+	wl_list_for_each(scene_output, outputs, link) {
 		if (scene_output == ignore) {
 			continue;
 		}
@@ -291,7 +319,7 @@ static void scene_buffer_update_outputs(struct wlr_scene_buffer *scene_buffer,
 	uint64_t old_active = scene_buffer->active_outputs;
 	scene_buffer->active_outputs = active_outputs;
 
-	wl_list_for_each(scene_output, &scene->outputs, link) {
+	wl_list_for_each(scene_output, outputs, link) {
 		uint64_t mask = 1ull << scene_output->index;
 		bool intersects = active_outputs & mask;
 		bool intersects_before = old_active & mask;
@@ -304,29 +332,118 @@ static void scene_buffer_update_outputs(struct wlr_scene_buffer *scene_buffer,
 	}
 }
 
-static void _scene_node_update_outputs(struct wlr_scene_node *node,
+static bool scene_node_update_iterator(struct wlr_scene_node *node,
-		int lx, int ly, struct wlr_scene *scene,
+		int lx, int ly, void *_data) {
-		struct wlr_scene_output *ignore) {
+	struct scene_update_data *data = _data;
-	if (node->type == WLR_SCENE_NODE_BUFFER) {
+
-		struct wlr_scene_buffer *scene_buffer =
+	struct wlr_box box = { .x = lx, .y = ly };
-			wlr_scene_buffer_from_node(node);
+	scene_node_get_size(node, &box.width, &box.height);
-		scene_buffer_update_outputs(scene_buffer, lx, ly, scene, ignore);
+
-	} else if (node->type == WLR_SCENE_NODE_TREE) {
+	pixman_region32_fini(&node->visible);
+	pixman_region32_init_rect(&node->visible, lx, ly, box.width, box.height);
+
+	update_node_update_outputs(node, data->outputs, NULL);
+
+	return false;
+}
+
+static void scene_node_visibility(struct wlr_scene_node *node,
+		pixman_region32_t *visible) {
+	if (!node->enabled) {
+		return;
+	}
+
+	if (node->type == WLR_SCENE_NODE_TREE) {
 		struct wlr_scene_tree *scene_tree = scene_tree_from_node(node);
 		struct wlr_scene_node *child;
 		wl_list_for_each(child, &scene_tree->children, link) {
-			_scene_node_update_outputs(child, lx + child->x,
+			scene_node_visibility(child, visible);
-				ly + child->y, scene, ignore);
 		}
+		return;
+	}
+
+	pixman_region32_union(visible, visible, &node->visible);
 }
+
+static void scene_node_bounds(struct wlr_scene_node *node,
+		int x, int y, pixman_region32_t *visible) {
+	if (!node->enabled) {
+		return;
+	}
+
+	if (node->type == WLR_SCENE_NODE_TREE) {
+		struct wlr_scene_tree *scene_tree = scene_tree_from_node(node);
+		struct wlr_scene_node *child;
+		wl_list_for_each(child, &scene_tree->children, link) {
+			scene_node_bounds(child, x + child->x, y + child->y, visible);
+		}
+		return;
 	}
 
-static void scene_node_update_outputs(struct wlr_scene_node *node,
+	int width, height;
-		struct wlr_scene_output *ignore) {
+	scene_node_get_size(node, &width, &height);
+	pixman_region32_union_rect(visible, visible, x, y, width, height);
+}
+
+static void scene_update_region(struct wlr_scene *scene,
+		pixman_region32_t *update_region) {
+	pixman_region32_t visible;
+	pixman_region32_init(&visible);
+	pixman_region32_copy(&visible, update_region);
+
+	struct scene_update_data data = {
+		.visible = &visible,
+		.update_region = update_region,
+		.outputs = &scene->outputs,
+	};
+
+	struct pixman_box32 *region_box = pixman_region32_extents(update_region);
+	struct wlr_box box = {
+		.x = region_box->x1,
+		.y = region_box->y1,
+		.width = region_box->x2 - region_box->x1,
+		.height = region_box->y2 - region_box->y1,
+	};
+
+	// update node visibility and output enter/leave events
+	scene_nodes_in_box(&scene->tree.node, &box, scene_node_update_iterator, &data);
+
+	pixman_region32_fini(&visible);
+}
+
+static void scene_node_update(struct wlr_scene_node *node,
+		pixman_region32_t *damage) {
 	struct wlr_scene *scene = scene_node_get_root(node);
-	int lx, ly;
+
-	wlr_scene_node_coords(node, &lx, &ly);
+	int x, y;
-	_scene_node_update_outputs(node, lx, ly, scene, ignore);
+	if (!wlr_scene_node_coords(node, &x, &y)) {
+		if (damage) {
+			scene_update_region(scene, damage);
+			scene_damage_outputs(scene, damage);
+			pixman_region32_fini(damage);
+		}
+
+		return;
+	}
+
+	pixman_region32_t visible;
+	if (!damage) {
+		pixman_region32_init(&visible);
+		scene_node_visibility(node, &visible);
+		damage = &visible;
+	}
+
+	pixman_region32_t update_region;
+	pixman_region32_init(&update_region);
+	pixman_region32_copy(&update_region, damage);
+	scene_node_bounds(node, x, y, &update_region);
+
+	scene_update_region(scene, &update_region);
+	pixman_region32_fini(&update_region);
+
+	scene_node_visibility(node, damage);
+	scene_damage_outputs(scene, damage);
+	pixman_region32_fini(damage);
 }
 
 struct wlr_scene_rect *wlr_scene_rect_create(struct wlr_scene_tree *parent,
@@ -343,7 +460,7 @@ struct wlr_scene_rect *wlr_scene_rect_create(struct wlr_scene_tree *parent,
 	scene_rect->height = height;
 	memcpy(scene_rect->color, color, sizeof(scene_rect->color));
 
-	scene_node_damage_whole(&scene_rect->node);
+	scene_node_update(&scene_rect->node, NULL);
 
 	return scene_rect;
 }
@@ -353,10 +470,9 @@ void wlr_scene_rect_set_size(struct wlr_scene_rect *rect, int width, int height)
 		return;
 	}
 
-	scene_node_damage_whole(&rect->node);
 	rect->width = width;
 	rect->height = height;
-	scene_node_damage_whole(&rect->node);
+	scene_node_update(&rect->node, NULL);
 }
 
 void wlr_scene_rect_set_color(struct wlr_scene_rect *rect, const float color[static 4]) {
@@ -365,7 +481,7 @@ void wlr_scene_rect_set_color(struct wlr_scene_rect *rect, const float color[sta
 	}
 
 	memcpy(rect->color, color, sizeof(rect->color));
-	scene_node_damage_whole(&rect->node);
+	scene_node_update(&rect->node, NULL);
 }
 
 struct wlr_scene_buffer *wlr_scene_buffer_create(struct wlr_scene_tree *parent,
@@ -386,9 +502,7 @@ struct wlr_scene_buffer *wlr_scene_buffer_create(struct wlr_scene_tree *parent,
 	wl_signal_init(&scene_buffer->events.output_present);
 	wl_signal_init(&scene_buffer->events.frame_done);
 
-	scene_node_damage_whole(&scene_buffer->node);
+	scene_node_update(&scene_buffer->node, NULL);
-
-	scene_node_update_outputs(&scene_buffer->node, NULL);
 
 	return scene_buffer;
 }
@@ -401,10 +515,6 @@ void wlr_scene_buffer_set_buffer_with_damage(struct wlr_scene_buffer *scene_buff
 	assert(buffer || !damage);
 
 	if (buffer != scene_buffer->buffer) {
-		if (!damage) {
-			scene_node_damage_whole(&scene_buffer->node);
-		}
-
 		wlr_texture_destroy(scene_buffer->texture);
 		scene_buffer->texture = NULL;
 		wlr_buffer_unlock(scene_buffer->buffer);
@@ -415,10 +525,8 @@ void wlr_scene_buffer_set_buffer_with_damage(struct wlr_scene_buffer *scene_buff
 			scene_buffer->buffer = NULL;
 		}
 
-		scene_node_update_outputs(&scene_buffer->node, NULL);
-
 		if (!damage) {
-			scene_node_damage_whole(&scene_buffer->node);
+			scene_node_update(&scene_buffer->node, NULL);
 		}
 	}
 
@@ -500,7 +608,7 @@ void wlr_scene_buffer_set_source_box(struct wlr_scene_buffer *scene_buffer,
 		memset(cur, 0, sizeof(*cur));
 	}
 
-	scene_node_damage_whole(&scene_buffer->node);
+	scene_node_update(&scene_buffer->node, NULL);
 }
 
 void wlr_scene_buffer_set_dest_size(struct wlr_scene_buffer *scene_buffer,
@@ -509,12 +617,9 @@ void wlr_scene_buffer_set_dest_size(struct wlr_scene_buffer *scene_buffer,
 		return;
 	}
 
-	scene_node_damage_whole(&scene_buffer->node);
 	scene_buffer->dst_width = width;
 	scene_buffer->dst_height = height;
-	scene_node_damage_whole(&scene_buffer->node);
+	scene_node_update(&scene_buffer->node, NULL);
-
-	scene_node_update_outputs(&scene_buffer->node, NULL);
 }
 
 void wlr_scene_buffer_set_transform(struct wlr_scene_buffer *scene_buffer,
@@ -523,11 +628,8 @@ void wlr_scene_buffer_set_transform(struct wlr_scene_buffer *scene_buffer,
 		return;
 	}
 
-	scene_node_damage_whole(&scene_buffer->node);
 	scene_buffer->transform = transform;
-	scene_node_damage_whole(&scene_buffer->node);
+	scene_node_update(&scene_buffer->node, NULL);
-
-	scene_node_update_outputs(&scene_buffer->node, NULL);
 }
 
 void wlr_scene_buffer_send_frame_done(struct wlr_scene_buffer *scene_buffer,
@@ -594,67 +696,21 @@ static void scale_box(struct wlr_box *box, float scale) {
 	box->y = round(box->y * scale);
 }
 
-static void _scene_node_damage_whole(struct wlr_scene_node *node,
-		struct wlr_scene *scene, int lx, int ly) {
-	if (!node->enabled) {
-		return;
-	}
-
-	if (node->type == WLR_SCENE_NODE_TREE) {
-		struct wlr_scene_tree *scene_tree = scene_tree_from_node(node);
-		struct wlr_scene_node *child;
-		wl_list_for_each(child, &scene_tree->children, link) {
-			_scene_node_damage_whole(child, scene,
-				lx + child->x, ly + child->y);
-		}
-	}
-
-	int width, height;
-	scene_node_get_size(node, &width, &height);
-
-	pixman_region32_fini(&node->visible);
-	pixman_region32_init_rect(&node->visible, lx, ly, width, height);
-
-	struct wlr_scene_output *scene_output;
-	wl_list_for_each(scene_output, &scene->outputs, link) {
-		struct wlr_box box = {
-			.x = lx - scene_output->x,
-			.y = ly - scene_output->y,
-			.width = width,
-			.height = height,
-		};
-
-		scale_box(&box, scene_output->output->scale);
-
-		if (wlr_damage_ring_add_box(&scene_output->damage_ring, &box)) {
-			wlr_output_schedule_frame(scene_output->output);
-		}
-	}
-}
-
-static void scene_node_damage_whole(struct wlr_scene_node *node) {
-	struct wlr_scene *scene = scene_node_get_root(node);
-	if (wl_list_empty(&scene->outputs)) {
-		return;
-	}
-
-	int lx, ly;
-	if (!wlr_scene_node_coords(node, &lx, &ly)) {
-		return;
-	}
-
-	_scene_node_damage_whole(node, scene, lx, ly);
-}
-
 void wlr_scene_node_set_enabled(struct wlr_scene_node *node, bool enabled) {
 	if (node->enabled == enabled) {
 		return;
 	}
 
-	// One of these damage_whole() calls will short-circuit and be a no-op
+	int x, y;
-	scene_node_damage_whole(node);
+	pixman_region32_t visible;
+	pixman_region32_init(&visible);
+	if (wlr_scene_node_coords(node, &x, &y)) {
+		scene_node_visibility(node, &visible);
+	}
+
 	node->enabled = enabled;
-	scene_node_damage_whole(node);
+
+	scene_node_update(node, &visible);
 }
 
 void wlr_scene_node_set_position(struct wlr_scene_node *node, int x, int y) {
@@ -662,12 +718,9 @@ void wlr_scene_node_set_position(struct wlr_scene_node *node, int x, int y) {
 		return;
 	}
 
-	scene_node_damage_whole(node);
 	node->x = x;
 	node->y = y;
-	scene_node_damage_whole(node);
+	scene_node_update(node, NULL);
-
-	scene_node_update_outputs(node, NULL);
 }
 
 void wlr_scene_node_place_above(struct wlr_scene_node *node,
@@ -681,9 +734,7 @@ void wlr_scene_node_place_above(struct wlr_scene_node *node,
 
 	wl_list_remove(&node->link);
 	wl_list_insert(&sibling->link, &node->link);
-
+	scene_node_update(node, NULL);
-	scene_node_damage_whole(node);
-	scene_node_damage_whole(sibling);
 }
 
 void wlr_scene_node_place_below(struct wlr_scene_node *node,
@@ -697,9 +748,7 @@ void wlr_scene_node_place_below(struct wlr_scene_node *node,
 
 	wl_list_remove(&node->link);
 	wl_list_insert(sibling->link.prev, &node->link);
-
+	scene_node_update(node, NULL);
-	scene_node_damage_whole(node);
-	scene_node_damage_whole(sibling);
 }
 
 void wlr_scene_node_raise_to_top(struct wlr_scene_node *node) {
@@ -734,15 +783,17 @@ void wlr_scene_node_reparent(struct wlr_scene_node *node,
 		assert(&ancestor->node != node);
 	}
 
-	scene_node_damage_whole(node);
+	int x, y;
+	pixman_region32_t visible;
+	pixman_region32_init(&visible);
+	if (wlr_scene_node_coords(node, &x, &y)) {
+		scene_node_visibility(node, &visible);
+	}
 
 	wl_list_remove(&node->link);
 	node->parent = new_parent;
 	wl_list_insert(new_parent->children.prev, &node->link);
-
+	scene_node_update(node, &visible);
-	scene_node_damage_whole(node);
-
-	scene_node_update_outputs(node, NULL);
 }
 
 bool wlr_scene_node_coords(struct wlr_scene_node *node,
@@ -1026,13 +1077,28 @@ static const struct wlr_addon_interface output_addon_impl = {
 	.destroy = scene_output_handle_destroy,
 };
 
+static void scene_node_output_update(struct wlr_scene_node *node,
+		struct wl_list *outputs, struct wlr_scene_output *ignore) {
+	if (node->type == WLR_SCENE_NODE_TREE) {
+		struct wlr_scene_tree *scene_tree = scene_tree_from_node(node);
+		struct wlr_scene_node *child;
+		wl_list_for_each(child, &scene_tree->children, link) {
+			scene_node_output_update(child, outputs, ignore);
+		}
+		return;
+	}
+
+	update_node_update_outputs(node, outputs, ignore);
+}
+
 static void scene_output_update_geometry(struct wlr_scene_output *scene_output) {
 	int width, height;
 	wlr_output_transformed_resolution(scene_output->output, &width, &height);
 	wlr_damage_ring_set_bounds(&scene_output->damage_ring, width, height);
 	wlr_output_schedule_frame(scene_output->output);
 
-	scene_node_update_outputs(&scene_output->scene->tree.node, NULL);
+	scene_node_output_update(&scene_output->scene->tree.node,
+			&scene_output->scene->outputs, NULL);
 }
 
 static void scene_output_handle_commit(struct wl_listener *listener, void *data) {
@@ -1131,7 +1197,8 @@ void wlr_scene_output_destroy(struct wlr_scene_output *scene_output) {
 
 	wlr_signal_emit_safe(&scene_output->events.destroy, NULL);
 
-	scene_node_update_outputs(&scene_output->scene->tree.node, scene_output);
+	scene_node_output_update(&scene_output->scene->tree.node,
+		&scene_output->scene->outputs, scene_output);
 
 	struct highlight_region *damage, *tmp_damage;
 	wl_list_for_each_safe(damage, tmp_damage, &scene_output->damage_highlight_regions, link) {