scene: add wlr_scene_xdg_surface_create

This allows compositors to easily add an xdg_surface to the
scene-graph while retaining the ability to unconstraint popups
and decide their final position.

Compositors can handle new popups with the wlr_xdg_shell.new_surface
event, get the parent scene-graph node via wlr_xdg_popup.parent.data,
create a new scene-graph node via wlr_scene_xdg_surface_tree_create,
and unconstraint the popup if they want to.

include/wlr/types/wlr_scene.h

@@ -25,6 +25,7 @@
 
 struct wlr_output;
 struct wlr_output_layout;
+struct wlr_xdg_surface;
 
 enum wlr_scene_node_type {
 	WLR_SCENE_NODE_ROOT,
@@ -298,4 +299,14 @@ bool wlr_scene_attach_output_layout(struct wlr_scene *scene,
 struct wlr_scene_node *wlr_scene_subsurface_tree_create(
 	struct wlr_scene_node *parent, struct wlr_surface *surface);
 
+/**
+ * Add a node displaying an xdg_surface and all of its sub-surfaces to the
+ * scene-graph.
+ *
+ * The origin of the returned scene-graph node will match the top-left corner
+ * of the xdg_surface window geometry.
+ */
+struct wlr_scene_node *wlr_scene_xdg_surface_create(
+	struct wlr_scene_node *parent, struct wlr_xdg_surface *xdg_surface);
+
 #endif

types/meson.build

@@ -10,6 +10,7 @@ wlr_files += files(
 	'scene/subsurface_tree.c',
 	'scene/wlr_scene.c',
 	'scene/output_layout.c',
+	'scene/xdg_shell.c',
 	'seat/wlr_seat_keyboard.c',
 	'seat/wlr_seat_pointer.c',
 	'seat/wlr_seat_touch.c',

types/scene/xdg_shell.c

@@ -0,0 +1,124 @@
+#include <stdlib.h>
+#include <wlr/types/wlr_scene.h>
+#include <wlr/types/wlr_xdg_shell.h>
+
+struct wlr_scene_xdg_surface {
+	struct wlr_scene_tree *tree;
+	struct wlr_xdg_surface *xdg_surface;
+	struct wlr_scene_node *surface_node;
+
+	struct wl_listener tree_destroy;
+	struct wl_listener xdg_surface_destroy;
+	struct wl_listener xdg_surface_map;
+	struct wl_listener xdg_surface_unmap;
+	struct wl_listener xdg_surface_commit;
+};
+
+static void scene_xdg_surface_handle_tree_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_xdg_surface *scene_xdg_surface =
+		wl_container_of(listener, scene_xdg_surface, tree_destroy);
+	// tree and surface_node will be cleaned up by scene_node_finish
+	wl_list_remove(&scene_xdg_surface->tree_destroy.link);
+	wl_list_remove(&scene_xdg_surface->xdg_surface_destroy.link);
+	wl_list_remove(&scene_xdg_surface->xdg_surface_map.link);
+	wl_list_remove(&scene_xdg_surface->xdg_surface_unmap.link);
+	wl_list_remove(&scene_xdg_surface->xdg_surface_commit.link);
+	free(scene_xdg_surface);
+}
+
+static void scene_xdg_surface_handle_xdg_surface_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_xdg_surface *scene_xdg_surface =
+		wl_container_of(listener, scene_xdg_surface, xdg_surface_destroy);
+	wlr_scene_node_destroy(&scene_xdg_surface->tree->node);
+}
+
+static void scene_xdg_surface_handle_xdg_surface_map(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_xdg_surface *scene_xdg_surface =
+		wl_container_of(listener, scene_xdg_surface, xdg_surface_map);
+	wlr_scene_node_set_enabled(&scene_xdg_surface->tree->node, true);
+}
+
+static void scene_xdg_surface_handle_xdg_surface_unmap(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_xdg_surface *scene_xdg_surface =
+		wl_container_of(listener, scene_xdg_surface, xdg_surface_unmap);
+	wlr_scene_node_set_enabled(&scene_xdg_surface->tree->node, false);
+}
+
+static void scene_xdg_surface_update_position(
+		struct wlr_scene_xdg_surface *scene_xdg_surface) {
+	struct wlr_xdg_surface *xdg_surface = scene_xdg_surface->xdg_surface;
+
+	struct wlr_box geo = {0};
+	wlr_xdg_surface_get_geometry(xdg_surface, &geo);
+	wlr_scene_node_set_position(scene_xdg_surface->surface_node,
+		-geo.x, -geo.y);
+
+	if (xdg_surface->role == WLR_XDG_SURFACE_ROLE_POPUP) {
+		struct wlr_xdg_popup *popup = xdg_surface->popup;
+		wlr_scene_node_set_position(&scene_xdg_surface->tree->node,
+			popup->geometry.x, popup->geometry.y);
+	}
+}
+
+static void scene_xdg_surface_handle_xdg_surface_commit(struct wl_listener *listener,
+		void *data) {
+	struct wlr_scene_xdg_surface *scene_xdg_surface =
+		wl_container_of(listener, scene_xdg_surface, xdg_surface_commit);
+	scene_xdg_surface_update_position(scene_xdg_surface);
+}
+
+struct wlr_scene_node *wlr_scene_xdg_surface_create(
+		struct wlr_scene_node *parent, struct wlr_xdg_surface *xdg_surface) {
+	struct wlr_scene_xdg_surface *scene_xdg_surface =
+		calloc(1, sizeof(*scene_xdg_surface));
+	if (scene_xdg_surface == NULL) {
+		return NULL;
+	}
+
+	scene_xdg_surface->xdg_surface = xdg_surface;
+
+	scene_xdg_surface->tree = wlr_scene_tree_create(parent);
+	if (scene_xdg_surface->tree == NULL) {
+		free(scene_xdg_surface);
+		return NULL;
+	}
+
+	scene_xdg_surface->surface_node = wlr_scene_subsurface_tree_create(
+		&scene_xdg_surface->tree->node, xdg_surface->surface);
+	if (scene_xdg_surface->surface_node == NULL) {
+		wlr_scene_node_destroy(&scene_xdg_surface->tree->node);
+		free(scene_xdg_surface);
+		return NULL;
+	}
+
+	scene_xdg_surface->tree_destroy.notify =
+		scene_xdg_surface_handle_tree_destroy;
+	wl_signal_add(&scene_xdg_surface->tree->node.events.destroy,
+		&scene_xdg_surface->tree_destroy);
+
+	scene_xdg_surface->xdg_surface_destroy.notify =
+		scene_xdg_surface_handle_xdg_surface_destroy;
+	wl_signal_add(&xdg_surface->events.destroy, &scene_xdg_surface->xdg_surface_destroy);
+
+	scene_xdg_surface->xdg_surface_map.notify =
+		scene_xdg_surface_handle_xdg_surface_map;
+	wl_signal_add(&xdg_surface->events.map, &scene_xdg_surface->xdg_surface_map);
+
+	scene_xdg_surface->xdg_surface_unmap.notify =
+		scene_xdg_surface_handle_xdg_surface_unmap;
+	wl_signal_add(&xdg_surface->events.unmap, &scene_xdg_surface->xdg_surface_unmap);
+
+	scene_xdg_surface->xdg_surface_commit.notify =
+		scene_xdg_surface_handle_xdg_surface_commit;
+	wl_signal_add(&xdg_surface->surface->events.commit,
+		&scene_xdg_surface->xdg_surface_commit);
+
+	wlr_scene_node_set_enabled(&scene_xdg_surface->tree->node, xdg_surface->mapped);
+	scene_xdg_surface_update_position(scene_xdg_surface);
+
+	return &scene_xdg_surface->tree->node;
+}