scene: add wlr_scene_subsurface_tree_create

include/wlr/types/wlr_scene.h

@@ -224,4 +224,11 @@ bool wlr_scene_output_commit(struct wlr_scene_output *scene_output);
 bool wlr_scene_attach_output_layout(struct wlr_scene *scene,
 	struct wlr_output_layout *output_layout);
 
+/**
+ * Add a node displaying a surface and all of its sub-surfaces to the
+ * scene-graph.
+ */
+struct wlr_scene_node *wlr_scene_subsurface_tree_create(
+	struct wlr_scene_node *parent, struct wlr_surface *surface);
+
 #endif

types/meson.build

@@ -3,6 +3,7 @@ wlr_files += files(
 	'data_device/wlr_data_offer.c',
 	'data_device/wlr_data_source.c',
 	'data_device/wlr_drag.c',
+	'scene/subsurface_tree.c',
 	'scene/wlr_scene.c',
 	'scene/output_layout.c',
 	'seat/wlr_seat_keyboard.c',

types/scene/subsurface_tree.c

@@ -0,0 +1,218 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <wlr/types/wlr_scene.h>
+#include <wlr/util/addon.h>
+
+/**
+ * A tree for a surface and all of its child sub-surfaces.
+ *
+ * `tree` contains `scene_surface` and one node per sub-surface.
+ */
+struct wlr_scene_subsurface_tree {
+	struct wlr_scene_tree *tree;
+	struct wlr_surface *surface;
+	struct wlr_scene_surface *scene_surface;
+
+	struct wlr_scene_subsurface_tree *parent; // NULL for the top-level surface
+	struct wlr_addon surface_addon; // only set if there's a parent
+
+	struct wl_listener tree_destroy;
+	struct wl_listener surface_destroy;
+	struct wl_listener surface_commit;
+	struct wl_listener surface_new_subsurface;
+};
+
+static void subsurface_tree_destroy(struct wlr_scene_subsurface_tree *subsurface_tree) {
+	// tree and scene_surface will be cleaned up by scene_node_finish
+	if (subsurface_tree->parent) {
+		wlr_addon_finish(&subsurface_tree->surface_addon);
+	}
+	wl_list_remove(&subsurface_tree->tree_destroy.link);
+	wl_list_remove(&subsurface_tree->surface_destroy.link);
+	wl_list_remove(&subsurface_tree->surface_commit.link);
+	wl_list_remove(&subsurface_tree->surface_new_subsurface.link);
+	free(subsurface_tree);
+}
+
+static void subsurface_tree_handle_tree_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		wl_container_of(listener, subsurface_tree, tree_destroy);
+	subsurface_tree_destroy(subsurface_tree);
+}
+
+static void subsurface_tree_handle_surface_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		wl_container_of(listener, subsurface_tree, surface_destroy);
+	wlr_scene_node_destroy(&subsurface_tree->tree->node);
+}
+
+static const struct wlr_addon_interface subsurface_tree_addon_impl;
+
+static struct wlr_scene_subsurface_tree *subsurface_tree_from_subsurface(
+		struct wlr_scene_subsurface_tree *parent,
+		struct wlr_subsurface *subsurface) {
+	struct wlr_addon *addon = wlr_addon_find(&subsurface->surface->addons,
+		parent, &subsurface_tree_addon_impl);
+	assert(addon != NULL);
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		wl_container_of(addon, subsurface_tree, surface_addon);
+	return subsurface_tree;
+}
+
+static void subsurface_tree_reconfigure(
+		struct wlr_scene_subsurface_tree *subsurface_tree) {
+	struct wlr_surface *surface = subsurface_tree->surface;
+
+	struct wlr_scene_node *prev = NULL;
+	struct wlr_subsurface *subsurface;
+	wl_list_for_each(subsurface, &surface->current.subsurfaces_below,
+			current.link) {
+		struct wlr_scene_subsurface_tree *child =
+			subsurface_tree_from_subsurface(subsurface_tree, subsurface);
+		if (prev != NULL) {
+			wlr_scene_node_place_above(&child->tree->node, prev);
+		}
+		prev = &child->tree->node;
+
+		wlr_scene_node_set_position(&child->tree->node,
+			subsurface->current.x, subsurface->current.y);
+	}
+
+	if (prev != NULL) {
+		wlr_scene_node_place_above(&subsurface_tree->scene_surface->node, prev);
+	}
+	prev = &subsurface_tree->scene_surface->node;
+
+	wl_list_for_each(subsurface, &surface->current.subsurfaces_above,
+			current.link) {
+		struct wlr_scene_subsurface_tree *child =
+			subsurface_tree_from_subsurface(subsurface_tree, subsurface);
+		wlr_scene_node_place_above(&child->tree->node, prev);
+		prev = &child->tree->node;
+
+		wlr_scene_node_set_position(&child->tree->node,
+			subsurface->current.x, subsurface->current.y);
+	}
+}
+
+static void subsurface_tree_handle_surface_commit(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		wl_container_of(listener, subsurface_tree, surface_commit);
+
+	// TODO: only do this on subsurface order or position change
+	subsurface_tree_reconfigure(subsurface_tree);
+}
+
+static void subsurface_tree_addon_destroy(struct wlr_addon *addon) {
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		wl_container_of(addon, subsurface_tree, surface_addon);
+	wlr_scene_node_destroy(&subsurface_tree->tree->node);
+}
+
+static const struct wlr_addon_interface subsurface_tree_addon_impl = {
+	.name = "wlr_scene_subsurface_tree",
+	.destroy = subsurface_tree_addon_destroy,
+};
+
+static struct wlr_scene_subsurface_tree *scene_surface_tree_create(
+	struct wlr_scene_node *parent, struct wlr_surface *surface);
+
+static bool subsurface_tree_create_subsurface(
+		struct wlr_scene_subsurface_tree *parent,
+		struct wlr_subsurface *subsurface) {
+	struct wlr_scene_subsurface_tree *child = scene_surface_tree_create(
+		&parent->tree->node, subsurface->surface);
+	if (child == NULL) {
+		return false;
+	}
+
+	child->parent = parent;
+	wlr_addon_init(&child->surface_addon, &subsurface->surface->addons,
+		parent, &subsurface_tree_addon_impl);
+
+	return true;
+}
+
+static void subsurface_tree_handle_surface_new_subsurface(
+		struct wl_listener *listener, void *data) {
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		wl_container_of(listener, subsurface_tree, surface_new_subsurface);
+	struct wlr_subsurface *subsurface = data;
+	if (!subsurface_tree_create_subsurface(subsurface_tree, subsurface)) {
+		wl_resource_post_no_memory(subsurface->resource);
+	}
+}
+
+static struct wlr_scene_subsurface_tree *scene_surface_tree_create(
+		struct wlr_scene_node *parent, struct wlr_surface *surface) {
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		calloc(1, sizeof(*subsurface_tree));
+	if (subsurface_tree == NULL) {
+		return NULL;
+	}
+
+	subsurface_tree->tree = wlr_scene_tree_create(parent);
+	if (subsurface_tree->tree == NULL) {
+		goto error_surface_tree;
+	}
+
+	subsurface_tree->scene_surface =
+		wlr_scene_surface_create(&subsurface_tree->tree->node, surface);
+	if (subsurface_tree->scene_surface == NULL) {
+		goto error_scene_surface;
+	}
+
+	subsurface_tree->surface = surface;
+
+	struct wlr_subsurface *subsurface;
+	wl_list_for_each(subsurface, &surface->current.subsurfaces_below,
+			current.link) {
+		if (!subsurface_tree_create_subsurface(subsurface_tree, subsurface)) {
+			goto error_scene_surface;
+		}
+	}
+	wl_list_for_each(subsurface, &surface->current.subsurfaces_above,
+			current.link) {
+		if (!subsurface_tree_create_subsurface(subsurface_tree, subsurface)) {
+			goto error_scene_surface;
+		}
+	}
+
+	subsurface_tree_reconfigure(subsurface_tree);
+
+	subsurface_tree->tree_destroy.notify = subsurface_tree_handle_tree_destroy;
+	wl_signal_add(&subsurface_tree->tree->node.events.destroy,
+		&subsurface_tree->tree_destroy);
+
+	subsurface_tree->surface_destroy.notify = subsurface_tree_handle_surface_destroy;
+	wl_signal_add(&surface->events.destroy, &subsurface_tree->surface_destroy);
+
+	subsurface_tree->surface_commit.notify = subsurface_tree_handle_surface_commit;
+	wl_signal_add(&surface->events.commit, &subsurface_tree->surface_commit);
+
+	subsurface_tree->surface_new_subsurface.notify =
+		subsurface_tree_handle_surface_new_subsurface;
+	wl_signal_add(&surface->events.new_subsurface,
+		&subsurface_tree->surface_new_subsurface);
+
+	return subsurface_tree;
+
+error_scene_surface:
+	wlr_scene_node_destroy(&subsurface_tree->tree->node);
+error_surface_tree:
+	free(subsurface_tree);
+	return NULL;
+}
+
+struct wlr_scene_node *wlr_scene_subsurface_tree_create(
+		struct wlr_scene_node *parent, struct wlr_surface *surface) {
+	struct wlr_scene_subsurface_tree *subsurface_tree =
+		scene_surface_tree_create(parent, surface);
+	if (subsurface_tree == NULL) {
+		return NULL;
+	}
+	return &subsurface_tree->tree->node;
+}