Merge 8a11a66d87 into f9626f7951

cage.c

@@ -1,7 +1,7 @@
 /*
  * Cage: A Wayland kiosk.
  *
- * Copyright (C) 2018-2020 Jente Hidskes
+ * Copyright (C) 2018-2021 Jente Hidskes
  *
  * See the LICENSE file accompanying this file.
  */
@@ -27,6 +27,7 @@
 #include <wlr/types/wlr_gamma_control_v1.h>
 #include <wlr/types/wlr_idle_inhibit_v1.h>
 #include <wlr/types/wlr_idle_notify_v1.h>
+#include <wlr/types/wlr_layer_shell_v1.h>
 #include <wlr/types/wlr_output_layout.h>
 #include <wlr/types/wlr_output_management_v1.h>
 #include <wlr/types/wlr_presentation_time.h>
@@ -52,6 +53,7 @@
 #endif
 
 #include "idle_inhibit_v1.h"
+#include "layer_shell_v1.h"
 #include "output.h"
 #include "seat.h"
 #include "server.h"
@@ -461,6 +463,15 @@ main(int argc, char *argv[])
 		goto end;
 	}
 
+	server.layer_shell_v1 = wlr_layer_shell_v1_create(server.wl_display, 4);
+	if (!server.layer_shell_v1) {
+		wlr_log(WLR_ERROR, "Unable to create the layer shell");
+		ret = 1;
+		goto end;
+	}
+	server.new_layer_shell_v1_surface.notify = handle_layer_shell_v1_surface_new;
+	wl_signal_add(&server.layer_shell_v1->events.new_surface, &server.new_layer_shell_v1_surface);
+
 	if (!wlr_export_dmabuf_manager_v1_create(server.wl_display)) {
 		wlr_log(WLR_ERROR, "Unable to create the export DMABUF manager");
 		ret = 1;
@@ -606,6 +617,7 @@ main(int argc, char *argv[])
 
 	wl_list_remove(&server.new_virtual_pointer.link);
 	wl_list_remove(&server.new_virtual_keyboard.link);
+	wl_list_remove(&server.new_layer_shell_v1_surface.link);
 	wl_list_remove(&server.output_manager_apply.link);
 	wl_list_remove(&server.output_manager_test.link);
 	wl_list_remove(&server.xdg_toplevel_decoration.link);

layer_shell_v1.c

@@ -0,0 +1,337 @@
+/*
+ * Cage: A Wayland kiosk.
+ *
+ * Copyright (C) 2021 Jente Hidskes
+ *
+ * See the LICENSE file accompanying this file.
+ */
+
+#define _POSIX_C_SOURCE 200809L
+
+#include "layer_shell_v1.h"
+#include "output.h"
+#include "seat.h"
+#include "server.h"
+
+#include <math.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <wayland-server-core.h>
+#include <wlr/types/wlr_fractional_scale_v1.h>
+#include <wlr/types/wlr_layer_shell_v1.h>
+#include <wlr/types/wlr_output_layout.h>
+#include <wlr/types/wlr_scene.h>
+#include <wlr/types/wlr_xdg_shell.h>
+#include <wlr/util/log.h>
+
+static struct wlr_scene_tree *
+get_layer_scene(struct cg_output *output, enum zwlr_layer_shell_v1_layer type)
+{
+	switch (type) {
+	case ZWLR_LAYER_SHELL_V1_LAYER_BACKGROUND:
+		return output->layers.shell_background;
+	case ZWLR_LAYER_SHELL_V1_LAYER_BOTTOM:
+		return output->layers.shell_bottom;
+	case ZWLR_LAYER_SHELL_V1_LAYER_TOP:
+		return output->layers.shell_top;
+	case ZWLR_LAYER_SHELL_V1_LAYER_OVERLAY:
+		return output->layers.shell_overlay;
+	}
+
+	wlr_log(WLR_ERROR, "Invalid layer shell layer: %d", type);
+	return NULL;
+}
+
+static void popup_handle_destroy(struct wl_listener *listener, void *data);
+static void popup_handle_new_popup(struct wl_listener *listener, void *data);
+static void popup_handle_commit(struct wl_listener *listener, void *data);
+
+static void
+popup_unconstrain(struct cg_layer_popup *popup)
+{
+	struct wlr_xdg_popup *wlr_popup = popup->wlr_popup;
+	struct cg_output *output = popup->toplevel->output;
+
+	if (!output) {
+		return;
+	}
+
+	int lx, ly;
+	wlr_scene_node_coords(&popup->toplevel->scene->tree->node, &lx, &ly);
+
+	struct wlr_box output_box;
+	wlr_output_layout_get_box(output->server->output_layout, output->wlr_output, &output_box);
+
+	struct wlr_box output_toplevel_sx_box = {
+		.x = output_box.x - lx,
+		.y = output_box.y - ly,
+		.width = output->wlr_output->width,
+		.height = output->wlr_output->height,
+	};
+
+	wlr_xdg_popup_unconstrain_from_box(wlr_popup, &output_toplevel_sx_box);
+}
+
+static void
+popup_handle_commit(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_popup *popup = wl_container_of(listener, popup, commit);
+	if (popup->wlr_popup->base->initial_commit) {
+		popup_unconstrain(popup);
+	}
+}
+
+static struct cg_layer_popup *
+create_popup(struct wlr_xdg_popup *wlr_popup, struct cg_layer_surface *toplevel, struct wlr_scene_tree *parent)
+{
+	struct cg_layer_popup *popup = calloc(1, sizeof(*popup));
+	if (popup == NULL) {
+		return NULL;
+	}
+
+	popup->toplevel = toplevel;
+	popup->wlr_popup = wlr_popup;
+	popup->scene = wlr_scene_xdg_surface_create(parent, wlr_popup->base);
+
+	if (!popup->scene) {
+		free(popup);
+		return NULL;
+	}
+
+	popup->destroy.notify = popup_handle_destroy;
+	wl_signal_add(&wlr_popup->base->events.destroy, &popup->destroy);
+	popup->new_popup.notify = popup_handle_new_popup;
+	wl_signal_add(&wlr_popup->base->events.new_popup, &popup->new_popup);
+	popup->commit.notify = popup_handle_commit;
+	wl_signal_add(&wlr_popup->base->surface->events.commit, &popup->commit);
+
+	return popup;
+}
+
+static void
+popup_handle_destroy(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_popup *popup = wl_container_of(listener, popup, destroy);
+
+	wl_list_remove(&popup->destroy.link);
+	wl_list_remove(&popup->new_popup.link);
+	wl_list_remove(&popup->commit.link);
+	free(popup);
+}
+
+static void
+popup_handle_new_popup(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_popup *popup = wl_container_of(listener, popup, new_popup);
+	struct wlr_xdg_popup *wlr_popup = data;
+	create_popup(wlr_popup, popup->toplevel, popup->scene);
+}
+
+static void
+handle_new_popup(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_surface *layer_surface = wl_container_of(listener, layer_surface, new_popup);
+	struct wlr_xdg_popup *wlr_popup = data;
+	create_popup(wlr_popup, layer_surface, layer_surface->popups);
+}
+
+static void
+handle_surface_commit(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_surface *surface = wl_container_of(listener, surface, surface_commit);
+	struct wlr_layer_surface_v1 *layer_surface = surface->layer_surface;
+	uint32_t committed = layer_surface->current.committed;
+
+	if (!surface->output) {
+		return;
+	}
+
+	if (layer_surface->initial_commit) {
+		wlr_fractional_scale_v1_notify_scale(layer_surface->surface, layer_surface->output->scale);
+		wlr_surface_set_preferred_buffer_scale(layer_surface->surface, ceil(layer_surface->output->scale));
+	}
+
+	if (layer_surface->initialized && committed & WLR_LAYER_SURFACE_V1_STATE_LAYER) {
+		enum zwlr_layer_shell_v1_layer layer_type = layer_surface->current.layer;
+		struct wlr_scene_tree *output_layer = get_layer_scene(surface->output, layer_type);
+		if (output_layer) {
+			wlr_scene_node_reparent(&surface->scene->tree->node, output_layer);
+			wlr_scene_node_reparent(&surface->popups->node, &surface->output->server->scene->tree);
+		}
+	}
+
+	bool mapped_changed = layer_surface->surface->mapped != surface->mapped;
+	if (!layer_surface->initial_commit && !committed && !mapped_changed) {
+		return;
+	}
+
+	surface->mapped = layer_surface->surface->mapped;
+	arrange_layers(surface->output);
+}
+
+static void
+handle_map(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_surface *surface = wl_container_of(listener, surface, map);
+	struct wlr_layer_surface_v1 *layer_surface = surface->scene->layer_surface;
+
+	if (!surface->output) {
+		return;
+	}
+
+	struct cg_seat *seat = surface->output->server->seat;
+
+	wlr_scene_node_set_enabled(&surface->scene->tree->node, true);
+
+	if (layer_surface->current.keyboard_interactive &&
+	    (layer_surface->current.layer == ZWLR_LAYER_SHELL_V1_LAYER_OVERLAY ||
+	     layer_surface->current.layer == ZWLR_LAYER_SHELL_V1_LAYER_TOP)) {
+		if (!seat->focused_layer || seat->focused_layer->current.layer >= layer_surface->current.layer) {
+			seat_set_focus_layer(seat, layer_surface);
+		}
+	}
+
+	arrange_layers(surface->output);
+}
+
+static void
+handle_unmap(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_surface *surface = wl_container_of(listener, surface, unmap);
+
+	wlr_scene_node_set_enabled(&surface->scene->tree->node, false);
+
+	if (!surface->output) {
+		return;
+	}
+
+	struct cg_seat *seat = surface->output->server->seat;
+
+	if (seat->focused_layer == surface->layer_surface) {
+		seat_set_focus_layer(seat, NULL);
+	}
+
+	arrange_layers(surface->output);
+}
+
+static void
+handle_node_destroy(struct wl_listener *listener, void *data)
+{
+	struct cg_layer_surface *layer = wl_container_of(listener, layer, node_destroy);
+
+	if (layer->output) {
+		arrange_layers(layer->output);
+	}
+
+	wlr_scene_node_destroy(&layer->popups->node);
+
+	wl_list_remove(&layer->map.link);
+	wl_list_remove(&layer->unmap.link);
+	wl_list_remove(&layer->surface_commit.link);
+	wl_list_remove(&layer->node_destroy.link);
+	wl_list_remove(&layer->new_popup.link);
+
+	layer->layer_surface->data = NULL;
+
+	wl_list_remove(&layer->link);
+	free(layer);
+}
+
+static struct cg_layer_surface *
+create_layer_surface(struct wlr_scene_layer_surface_v1 *scene, struct cg_output *output)
+{
+	struct cg_layer_surface *surface = calloc(1, sizeof(*surface));
+	if (!surface) {
+		wlr_log(WLR_ERROR, "Could not allocate a layer surface");
+		return NULL;
+	}
+
+	struct wlr_scene_tree *popups = wlr_scene_tree_create(&output->server->scene->tree);
+	if (!popups) {
+		wlr_log(WLR_ERROR, "Could not allocate a layer popup node");
+		free(surface);
+		return NULL;
+	}
+
+	surface->tree = scene->tree;
+	surface->scene = scene;
+	surface->layer_surface = scene->layer_surface;
+	surface->popups = popups;
+	surface->layer_surface->data = surface;
+	surface->output = output;
+
+	return surface;
+}
+
+void
+handle_layer_shell_v1_surface_new(struct wl_listener *listener, void *data)
+{
+	struct cg_server *server = wl_container_of(listener, server, new_layer_shell_v1_surface);
+	struct wlr_layer_surface_v1 *layer_surface = data;
+
+	wlr_log(WLR_DEBUG, "New layer shell surface: namespace %s layer %d anchor %d size %dx%d margin %d,%d,%d,%d",
+		layer_surface->namespace, layer_surface->pending.layer, layer_surface->pending.anchor,
+		layer_surface->pending.desired_width, layer_surface->pending.desired_height,
+		layer_surface->pending.margin.top, layer_surface->pending.margin.right,
+		layer_surface->pending.margin.bottom, layer_surface->pending.margin.left);
+
+	if (!layer_surface->output) {
+		struct cg_seat *seat = server->seat;
+		if (seat && seat->focused_output) {
+			layer_surface->output = seat->focused_output;
+		} else if (!wl_list_empty(&server->outputs)) {
+			struct cg_output *output = wl_container_of(server->outputs.next, output, link);
+			layer_surface->output = output->wlr_output;
+		} else {
+			wlr_log(WLR_ERROR, "No output to assign layer surface '%s' to", layer_surface->namespace);
+			wlr_layer_surface_v1_destroy(layer_surface);
+			return;
+		}
+	}
+
+	struct cg_output *output = layer_surface->output->data;
+	if (!output) {
+		wlr_log(WLR_ERROR, "Layer surface has no output data");
+		wlr_layer_surface_v1_destroy(layer_surface);
+		return;
+	}
+
+	enum zwlr_layer_shell_v1_layer layer_type = layer_surface->pending.layer;
+	struct wlr_scene_tree *output_layer = get_layer_scene(output, layer_type);
+	if (!output_layer) {
+		wlr_log(WLR_ERROR, "Invalid layer %d for layer surface '%s'", layer_type, layer_surface->namespace);
+		wlr_layer_surface_v1_destroy(layer_surface);
+		return;
+	}
+
+	struct wlr_scene_layer_surface_v1 *scene_surface =
+		wlr_scene_layer_surface_v1_create(output_layer, layer_surface);
+	if (!scene_surface) {
+		wlr_log(WLR_ERROR, "Could not allocate a layer_surface_v1");
+		return;
+	}
+
+	struct cg_layer_surface *surface = create_layer_surface(scene_surface, output);
+	if (!surface) {
+		wlr_layer_surface_v1_destroy(layer_surface);
+		wlr_log(WLR_ERROR, "Could not allocate a layer surface");
+		return;
+	}
+
+	wl_list_insert(&output->layer_surfaces, &surface->link);
+
+	wlr_fractional_scale_v1_notify_scale(surface->layer_surface->surface, layer_surface->output->scale);
+	wlr_surface_set_preferred_buffer_scale(surface->layer_surface->surface, ceil(layer_surface->output->scale));
+
+	surface->surface_commit.notify = handle_surface_commit;
+	wl_signal_add(&layer_surface->surface->events.commit, &surface->surface_commit);
+	surface->map.notify = handle_map;
+	wl_signal_add(&layer_surface->surface->events.map, &surface->map);
+	surface->unmap.notify = handle_unmap;
+	wl_signal_add(&layer_surface->surface->events.unmap, &surface->unmap);
+	surface->new_popup.notify = handle_new_popup;
+	wl_signal_add(&layer_surface->events.new_popup, &surface->new_popup);
+
+	surface->node_destroy.notify = handle_node_destroy;
+	wl_signal_add(&scene_surface->tree->node.events.destroy, &surface->node_destroy);
+}

layer_shell_v1.h

@@ -0,0 +1,42 @@
+#ifndef CG_LAYER_SHELL_V1_H
+#define CG_LAYER_SHELL_V1_H
+
+#include <stdbool.h>
+#include <wayland-server-core.h>
+#include <wlr/types/wlr_layer_shell_v1.h>
+#include <wlr/types/wlr_scene.h>
+
+struct cg_output;
+
+struct cg_layer_surface {
+	struct wl_listener map;
+	struct wl_listener unmap;
+	struct wl_listener surface_commit;
+	struct wl_listener node_destroy;
+	struct wl_listener new_popup;
+
+	bool mapped;
+
+	struct wlr_scene_tree *popups;
+
+	struct cg_output *output;
+	struct wl_list link; // cg_output::layer_surfaces
+
+	struct wlr_scene_layer_surface_v1 *scene;
+	struct wlr_scene_tree *tree;
+	struct wlr_layer_surface_v1 *layer_surface;
+};
+
+struct cg_layer_popup {
+	struct wlr_xdg_popup *wlr_popup;
+	struct wlr_scene_tree *scene;
+	struct cg_layer_surface *toplevel;
+
+	struct wl_listener destroy;
+	struct wl_listener new_popup;
+	struct wl_listener commit;
+};
+
+void handle_layer_shell_v1_surface_new(struct wl_listener *listener, void *data);
+
+#endif

meson.build

@@ -41,28 +41,7 @@ wayland_server = dependency('wayland-server')
 xkbcommon      = dependency('xkbcommon')
 math           = cc.find_library('m')
 
-wl_protocol_dir = wayland_protos.get_variable('pkgdatadir')
-wayland_scanner = find_program('wayland-scanner')
-wayland_scanner_server = generator(
-  wayland_scanner,
-  output: '@BASENAME@-protocol.h',
-  arguments: ['server-header', '@INPUT@', '@OUTPUT@'],
-)
-
-server_protocols = [
-  [wl_protocol_dir, 'stable/xdg-shell/xdg-shell.xml'],
-]
-
-server_protos_headers = []
-
-foreach p : server_protocols
-  xml = join_paths(p)
-  server_protos_headers += wayland_scanner_server.process(xml)
-endforeach
-
-server_protos = declare_dependency(
-  sources: server_protos_headers,
-)
+subdir('protocols')
 
 have_xwayland = wlroots.get_variable(pkgconfig: 'have_xwayland', internal: 'have_xwayland') == 'true'
 
@@ -113,6 +92,7 @@ endif
 cage_sources = [
   'cage.c',
   'idle_inhibit_v1.c',
+  'layer_shell_v1.c',
   'output.c',
   'seat.c',
   'view.c',
@@ -124,6 +104,7 @@ cage_headers = [
                  output: 'config.h',
                  configuration: conf_data),
   'idle_inhibit_v1.h',
+  'layer_shell_v1.h',
   'output.h',
   'seat.h',
   'server.h',

output.c

@@ -21,6 +21,11 @@
 #if WLR_HAS_X11_BACKEND
 #include <wlr/backend/x11.h>
 #endif
+#include "layer_shell_v1.h"
+#include "output.h"
+#include "seat.h"
+#include "server.h"
+#include "view.h"
 #include <wlr/render/swapchain.h>
 #include <wlr/render/wlr_renderer.h>
 #include <wlr/types/wlr_compositor.h>
@@ -33,11 +38,6 @@
 #include <wlr/types/wlr_xdg_shell.h>
 #include <wlr/util/log.h>
 #include <wlr/util/region.h>
-
-#include "output.h"
-#include "seat.h"
-#include "server.h"
-#include "view.h"
 #if CAGE_HAS_XWAYLAND
 #include "xwayland.h"
 #endif
@@ -205,12 +205,23 @@ output_destroy(struct cg_output *output)
 
 	output->wlr_output->data = NULL;
 
+	struct cg_layer_surface *layer, *layer_tmp;
+	wl_list_for_each_safe (layer, layer_tmp, &output->layer_surfaces, link) {
+		layer->output = NULL;
+		wlr_layer_surface_v1_destroy(layer->layer_surface);
+	}
+
 	wl_list_remove(&output->destroy.link);
 	wl_list_remove(&output->commit.link);
 	wl_list_remove(&output->request_state.link);
 	wl_list_remove(&output->frame.link);
 	wl_list_remove(&output->link);
 
+	wlr_scene_node_destroy(&output->layers.shell_background->node);
+	wlr_scene_node_destroy(&output->layers.shell_bottom->node);
+	wlr_scene_node_destroy(&output->layers.shell_top->node);
+	wlr_scene_node_destroy(&output->layers.shell_overlay->node);
+
 	output_layout_remove(output);
 
 	free(output);
@@ -231,6 +242,18 @@ handle_output_destroy(struct wl_listener *listener, void *data)
 	output_destroy(output);
 }
 
+static struct wlr_scene_tree *
+create_layer_for_output(struct cg_output *output)
+{
+	struct cg_server *server = output->server;
+	struct wlr_scene_tree *layer = wlr_scene_tree_create(&server->scene->tree);
+	if (layer == NULL) {
+		return NULL;
+	}
+	layer->node.data = output->wlr_output;
+	return layer;
+}
+
 void
 handle_new_output(struct wl_listener *listener, void *data)
 {
@@ -252,6 +275,7 @@ handle_new_output(struct wl_listener *listener, void *data)
 	wlr_output->data = output;
 	output->server = server;
 
+	wl_list_init(&output->layer_surfaces);
 	wl_list_insert(&server->outputs, &output->link);
 
 	output->commit.notify = handle_output_commit;
@@ -296,6 +320,11 @@ handle_new_output(struct wl_listener *listener, void *data)
 		output_disable(next);
 	}
 
+	output->layers.shell_background = create_layer_for_output(output);
+	output->layers.shell_bottom = create_layer_for_output(output);
+	output->layers.shell_top = create_layer_for_output(output);
+	output->layers.shell_overlay = create_layer_for_output(output);
+
 	if (!wlr_xcursor_manager_load(server->seat->xcursor_manager, wlr_output->scale)) {
 		wlr_log(WLR_ERROR, "Cannot load XCursor theme for output '%s' with scale %f", wlr_output->name,
 			wlr_output->scale);
@@ -391,6 +420,87 @@ out:
 	return ok;
 }
 
+static void
+arrange_surface(struct cg_output *output, const struct wlr_box *full_area, struct wlr_box *usable_area,
+		enum zwlr_layer_shell_v1_layer layer, bool exclusive)
+{
+	struct cg_layer_surface *surface;
+	wl_list_for_each (surface, &output->layer_surfaces, link) {
+		struct wlr_layer_surface_v1 *layer_surface = surface->layer_surface;
+
+		if (layer_surface->current.layer != layer) {
+			continue;
+		}
+
+		if (!layer_surface->initialized) {
+			continue;
+		}
+
+		if ((layer_surface->current.exclusive_zone > 0) != exclusive) {
+			continue;
+		}
+
+		wlr_scene_layer_surface_v1_configure(surface->scene, full_area, usable_area);
+	}
+}
+
+void
+arrange_layers(struct cg_output *output)
+{
+	struct wlr_box usable_area = {0};
+	wlr_output_effective_resolution(output->wlr_output, &usable_area.width, &usable_area.height);
+	const struct wlr_box full_area = usable_area;
+
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_OVERLAY, true);
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_TOP, true);
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_BOTTOM, true);
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_BACKGROUND, true);
+
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_OVERLAY, false);
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_TOP, false);
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_BOTTOM, false);
+	arrange_surface(output, &full_area, &usable_area, ZWLR_LAYER_SHELL_V1_LAYER_BACKGROUND, false);
+
+	if (!wlr_box_equal(&usable_area, &output->usable_area)) {
+		wlr_log(WLR_DEBUG, "Usable area changed, rearranging output");
+		output->usable_area = usable_area;
+		view_position_all(output->server);
+	}
+
+	enum zwlr_layer_shell_v1_layer layers_above_shell[] = {
+		ZWLR_LAYER_SHELL_V1_LAYER_OVERLAY,
+		ZWLR_LAYER_SHELL_V1_LAYER_TOP,
+	};
+	size_t nlayers = sizeof(layers_above_shell) / sizeof(layers_above_shell[0]);
+	struct cg_layer_surface *topmost = NULL;
+	for (size_t i = 0; i < nlayers; ++i) {
+		struct cg_layer_surface *surface;
+		wl_list_for_each_reverse (surface, &output->layer_surfaces, link) {
+			struct wlr_layer_surface_v1 *layer_surface = surface->layer_surface;
+			if (layer_surface->current.layer != layers_above_shell[i]) {
+				continue;
+			}
+			if (layer_surface->current.keyboard_interactive ==
+				    ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_EXCLUSIVE &&
+			    layer_surface->surface->mapped) {
+				topmost = surface;
+				break;
+			}
+		}
+		if (topmost != NULL) {
+			break;
+		}
+	}
+
+	struct cg_seat *seat = output->server->seat;
+	if (topmost != NULL) {
+		seat_set_focus_layer(seat, topmost->layer_surface);
+	} else if (seat->focused_layer && seat->focused_layer->current.keyboard_interactive !=
+						  ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_EXCLUSIVE) {
+		seat_set_focus_layer(seat, NULL);
+	}
+}
+
 void
 handle_output_manager_apply(struct wl_listener *listener, void *data)
 {

output.h

@@ -17,6 +17,17 @@ struct cg_output {
 	struct wl_listener destroy;
 	struct wl_listener frame;
 
+	struct {
+		struct wlr_scene_tree *shell_background;
+		struct wlr_scene_tree *shell_bottom;
+		struct wlr_scene_tree *shell_top;
+		struct wlr_scene_tree *shell_overlay;
+	} layers;
+
+	struct wlr_box usable_area;
+
+	struct wl_list layer_surfaces; // cg_layer_surface::link
+
 	struct wl_list link; // cg_server::outputs
 };
 
@@ -25,5 +36,6 @@ void handle_output_manager_test(struct wl_listener *listener, void *data);
 void handle_output_layout_change(struct wl_listener *listener, void *data);
 void handle_new_output(struct wl_listener *listener, void *data);
 void output_set_window_title(struct cg_output *output, const char *title);
+void arrange_layers(struct cg_output *output);
 
 #endif

protocols/meson.build

@@ -0,0 +1,39 @@
+wl_protocol_dir = wayland_protos.get_variable('pkgdatadir')
+wayland_scanner = find_program('wayland-scanner', native: true)
+
+wayland_scanner_server_header = generator(
+  wayland_scanner,
+  output: '@BASENAME@-protocol.h',
+  arguments: ['server-header', '@INPUT@', '@OUTPUT@'],
+)
+
+wayland_scanner_private_code = generator(
+  wayland_scanner,
+  output: '@BASENAME@-protocol.c',
+  arguments: ['private-code', '@INPUT@', '@OUTPUT@'],
+)
+
+server_protocols = [
+  [wl_protocol_dir, 'stable/xdg-shell/xdg-shell.xml'],
+  ['wlr-layer-shell-unstable-v1.xml'],
+]
+
+wl_protos_headers = []
+wl_protos_src = []
+
+foreach p : server_protocols
+  xml = join_paths(p)
+  wl_protos_headers += wayland_scanner_server_header.process(xml)
+  wl_protos_src += wayland_scanner_private_code.process(xml)
+endforeach
+
+lib_server_protos = static_library(
+  'server_protos',
+  wl_protos_headers + wl_protos_src,
+  dependencies: wayland_server.partial_dependency(compile_args: true),
+)
+
+server_protos = declare_dependency(
+  link_with: lib_server_protos,
+  sources: wl_protos_headers,
+)

protocols/wlr-layer-shell-unstable-v1.xml

@@ -0,0 +1,390 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="wlr_layer_shell_unstable_v1">
+  <copyright>
+    Copyright © 2017 Drew DeVault
+
+    Permission to use, copy, modify, distribute, and sell this
+    software and its documentation for any purpose is hereby granted
+    without fee, provided that the above copyright notice appear in
+    all copies and that both that copyright notice and this permission
+    notice appear in supporting documentation, and that the name of
+    the copyright holders not be used in advertising or publicity
+    pertaining to distribution of the software without specific,
+    written prior permission.  The copyright holders make no
+    representations about the suitability of this software for any
+    purpose.  It is provided "as is" without express or implied
+    warranty.
+
+    THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+    SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+    FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+    SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+    AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+    ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+    THIS SOFTWARE.
+  </copyright>
+
+  <interface name="zwlr_layer_shell_v1" version="4">
+    <description summary="create surfaces that are layers of the desktop">
+      Clients can use this interface to assign the surface_layer role to
+      wl_surfaces. Such surfaces are assigned to a "layer" of the output and
+      rendered with a defined z-depth respective to each other. They may also be
+      anchored to the edges and corners of a screen and specify input handling
+      semantics. This interface should be suitable for the implementation of
+      many desktop shell components, and a broad number of other applications
+      that interact with the desktop.
+    </description>
+
+    <request name="get_layer_surface">
+      <description summary="create a layer_surface from a surface">
+        Create a layer surface for an existing surface. This assigns the role of
+        layer_surface, or raises a protocol error if another role is already
+        assigned.
+
+        Creating a layer surface from a wl_surface which has a buffer attached
+        or committed is a client error, and any attempts by a client to attach
+        or manipulate a buffer prior to the first layer_surface.configure call
+        must also be treated as errors.
+
+        After creating a layer_surface object and setting it up, the client
+        must perform an initial commit without any buffer attached.
+        The compositor will reply with a layer_surface.configure event.
+        The client must acknowledge it and is then allowed to attach a buffer
+        to map the surface.
+
+        You may pass NULL for output to allow the compositor to decide which
+        output to use. Generally this will be the one that the user most
+        recently interacted with.
+
+        Clients can specify a namespace that defines the purpose of the layer
+        surface.
+      </description>
+      <arg name="id" type="new_id" interface="zwlr_layer_surface_v1"/>
+      <arg name="surface" type="object" interface="wl_surface"/>
+      <arg name="output" type="object" interface="wl_output" allow-null="true"/>
+      <arg name="layer" type="uint" enum="layer" summary="layer to add this surface to"/>
+      <arg name="namespace" type="string" summary="namespace for the layer surface"/>
+    </request>
+
+    <enum name="error">
+      <entry name="role" value="0" summary="wl_surface has another role"/>
+      <entry name="invalid_layer" value="1" summary="layer value is invalid"/>
+      <entry name="already_constructed" value="2" summary="wl_surface has a buffer attached or committed"/>
+    </enum>
+
+    <enum name="layer">
+      <description summary="available layers for surfaces">
+        These values indicate which layers a surface can be rendered in. They
+        are ordered by z depth, bottom-most first. Traditional shell surfaces
+        will typically be rendered between the bottom and top layers.
+        Fullscreen shell surfaces are typically rendered at the top layer.
+        Multiple surfaces can share a single layer, and ordering within a
+        single layer is undefined.
+      </description>
+
+      <entry name="background" value="0"/>
+      <entry name="bottom" value="1"/>
+      <entry name="top" value="2"/>
+      <entry name="overlay" value="3"/>
+    </enum>
+
+    <!-- Version 3 additions -->
+
+    <request name="destroy" type="destructor" since="3">
+      <description summary="destroy the layer_shell object">
+        This request indicates that the client will not use the layer_shell
+        object any more. Objects that have been created through this instance
+        are not affected.
+      </description>
+    </request>
+  </interface>
+
+  <interface name="zwlr_layer_surface_v1" version="4">
+    <description summary="layer metadata interface">
+      An interface that may be implemented by a wl_surface, for surfaces that
+      are designed to be rendered as a layer of a stacked desktop-like
+      environment.
+
+      Layer surface state (layer, size, anchor, exclusive zone,
+      margin, interactivity) is double-buffered, and will be applied at the
+      time wl_surface.commit of the corresponding wl_surface is called.
+
+      Attaching a null buffer to a layer surface unmaps it.
+
+      Unmapping a layer_surface means that the surface cannot be shown by the
+      compositor until it is explicitly mapped again. The layer_surface
+      returns to the state it had right after layer_shell.get_layer_surface.
+      The client can re-map the surface by performing a commit without any
+      buffer attached, waiting for a configure event and handling it as usual.
+    </description>
+
+    <request name="set_size">
+      <description summary="sets the size of the surface">
+        Sets the size of the surface in surface-local coordinates. The
+        compositor will display the surface centered with respect to its
+        anchors.
+
+        If you pass 0 for either value, the compositor will assign it and
+        inform you of the assignment in the configure event. You must set your
+        anchor to opposite edges in the dimensions you omit; not doing so is a
+        protocol error. Both values are 0 by default.
+
+        Size is double-buffered, see wl_surface.commit.
+      </description>
+      <arg name="width" type="uint"/>
+      <arg name="height" type="uint"/>
+    </request>
+
+    <request name="set_anchor">
+      <description summary="configures the anchor point of the surface">
+        Requests that the compositor anchor the surface to the specified edges
+        and corners. If two orthogonal edges are specified (e.g. 'top' and
+        'left'), then the anchor point will be the intersection of the edges
+        (e.g. the top left corner of the output); otherwise the anchor point
+        will be centered on that edge, or in the center if none is specified.
+
+        Anchor is double-buffered, see wl_surface.commit.
+      </description>
+      <arg name="anchor" type="uint" enum="anchor"/>
+    </request>
+
+    <request name="set_exclusive_zone">
+      <description summary="configures the exclusive geometry of this surface">
+        Requests that the compositor avoids occluding an area with other
+        surfaces. The compositor's use of this information is
+        implementation-dependent - do not assume that this region will not
+        actually be occluded.
+
+        A positive value is only meaningful if the surface is anchored to one
+        edge or an edge and both perpendicular edges. If the surface is not
+        anchored, anchored to only two perpendicular edges (a corner), anchored
+        to only two parallel edges or anchored to all edges, a positive value
+        will be treated the same as zero.
+
+        A positive zone is the distance from the edge in surface-local
+        coordinates to consider exclusive.
+
+        Surfaces that do not wish to have an exclusive zone may instead specify
+        how they should interact with surfaces that do. If set to zero, the
+        surface indicates that it would like to be moved to avoid occluding
+        surfaces with a positive exclusive zone. If set to -1, the surface
+        indicates that it would not like to be moved to accommodate for other
+        surfaces, and the compositor should extend it all the way to the edges
+        it is anchored to.
+
+        For example, a panel might set its exclusive zone to 10, so that
+        maximized shell surfaces are not shown on top of it. A notification
+        might set its exclusive zone to 0, so that it is moved to avoid
+        occluding the panel, but shell surfaces are shown underneath it. A
+        wallpaper or lock screen might set their exclusive zone to -1, so that
+        they stretch below or over the panel.
+
+        The default value is 0.
+
+        Exclusive zone is double-buffered, see wl_surface.commit.
+      </description>
+      <arg name="zone" type="int"/>
+    </request>
+
+    <request name="set_margin">
+      <description summary="sets a margin from the anchor point">
+        Requests that the surface be placed some distance away from the anchor
+        point on the output, in surface-local coordinates. Setting this value
+        for edges you are not anchored to has no effect.
+
+        The exclusive zone includes the margin.
+
+        Margin is double-buffered, see wl_surface.commit.
+      </description>
+      <arg name="top" type="int"/>
+      <arg name="right" type="int"/>
+      <arg name="bottom" type="int"/>
+      <arg name="left" type="int"/>
+    </request>
+
+    <enum name="keyboard_interactivity">
+      <description summary="types of keyboard interaction possible for a layer shell surface">
+        Types of keyboard interaction possible for layer shell surfaces. The
+        rationale for this is twofold: (1) some applications are not interested
+        in keyboard events and not allowing them to be focused can improve the
+        desktop experience; (2) some applications will want to take exclusive
+        keyboard focus.
+      </description>
+
+      <entry name="none" value="0">
+        <description summary="no keyboard focus is possible">
+          This value indicates that this surface is not interested in keyboard
+          events and the compositor should never assign it the keyboard focus.
+
+          This is the default value, set for newly created layer shell surfaces.
+
+          This is useful for e.g. desktop widgets that display information or
+          only have interaction with non-keyboard input devices.
+        </description>
+      </entry>
+      <entry name="exclusive" value="1">
+        <description summary="request exclusive keyboard focus">
+          Request exclusive keyboard focus if this surface is above the shell surface layer.
+
+          For the top and overlay layers, the seat will always give
+          exclusive keyboard focus to the top-most layer which has keyboard
+          interactivity set to exclusive. If this layer contains multiple
+          surfaces with keyboard interactivity set to exclusive, the compositor
+          determines the one receiving keyboard events in an implementation-
+          defined manner. In this case, no guarantee is made when this surface
+          will receive keyboard focus (if ever).
+
+          For the bottom and background layers, the compositor is allowed to use
+          normal focus semantics.
+
+          This setting is mainly intended for applications that need to ensure
+          they receive all keyboard events, such as a lock screen or a password
+          prompt.
+        </description>
+      </entry>
+      <entry name="on_demand" value="2" since="4">
+        <description summary="request regular keyboard focus semantics">
+          This requests the compositor to allow this surface to be focused and
+          unfocused by the user in an implementation-defined manner. The user
+          should be able to unfocus this surface even regardless of the layer
+          it is on.
+
+          Typically, the compositor will want to use its normal mechanism to
+          manage keyboard focus between layer shell surfaces with this setting
+          and regular toplevels on the desktop layer (e.g. click to focus).
+          Nevertheless, it is possible for a compositor to require a special
+          interaction to focus or unfocus layer shell surfaces (e.g. requiring
+          a click even if focus follows the mouse normally, or providing a
+          keybinding to switch focus between layers).
+
+          This setting is mainly intended for desktop shell components (e.g.
+          panels) that allow keyboard interaction. Using this option can allow
+          implementing a desktop shell that can be fully usable without the
+          mouse.
+        </description>
+      </entry>
+    </enum>
+
+    <request name="set_keyboard_interactivity">
+      <description summary="requests keyboard events">
+        Set how keyboard events are delivered to this surface. By default,
+        layer shell surfaces do not receive keyboard events; this request can
+        be used to change this.
+
+        This setting is inherited by child surfaces set by the get_popup
+        request.
+
+        Layer surfaces receive pointer, touch, and tablet events normally. If
+        you do not want to receive them, set the input region on your surface
+        to an empty region.
+
+        Keyboard interactivity is double-buffered, see wl_surface.commit.
+      </description>
+      <arg name="keyboard_interactivity" type="uint" enum="keyboard_interactivity"/>
+    </request>
+
+    <request name="get_popup">
+      <description summary="assign this layer_surface as an xdg_popup parent">
+        This assigns an xdg_popup's parent to this layer_surface.  This popup
+        should have been created via xdg_surface::get_popup with the parent set
+        to NULL, and this request must be invoked before committing the popup's
+        initial state.
+
+        See the documentation of xdg_popup for more details about what an
+        xdg_popup is and how it is used.
+      </description>
+      <arg name="popup" type="object" interface="xdg_popup"/>
+    </request>
+
+    <request name="ack_configure">
+      <description summary="ack a configure event">
+        When a configure event is received, if a client commits the
+        surface in response to the configure event, then the client
+        must make an ack_configure request sometime before the commit
+        request, passing along the serial of the configure event.
+
+        If the client receives multiple configure events before it
+        can respond to one, it only has to ack the last configure event.
+
+        A client is not required to commit immediately after sending
+        an ack_configure request - it may even ack_configure several times
+        before its next surface commit.
+
+        A client may send multiple ack_configure requests before committing, but
+        only the last request sent before a commit indicates which configure
+        event the client really is responding to.
+      </description>
+      <arg name="serial" type="uint" summary="the serial from the configure event"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the layer_surface">
+        This request destroys the layer surface.
+      </description>
+    </request>
+
+    <event name="configure">
+      <description summary="suggest a surface change">
+        The configure event asks the client to resize its surface.
+
+        Clients should arrange their surface for the new states, and then send
+        an ack_configure request with the serial sent in this configure event at
+        some point before committing the new surface.
+
+        The client is free to dismiss all but the last configure event it
+        received.
+
+        The width and height arguments specify the size of the window in
+        surface-local coordinates.
+
+        The size is a hint, in the sense that the client is free to ignore it if
+        it doesn't resize, pick a smaller size (to satisfy aspect ratio or
+        resize in steps of NxM pixels). If the client picks a smaller size and
+        is anchored to two opposite anchors (e.g. 'top' and 'bottom'), the
+        surface will be centered on this axis.
+
+        If the width or height arguments are zero, it means the client should
+        decide its own window dimension.
+      </description>
+      <arg name="serial" type="uint"/>
+      <arg name="width" type="uint"/>
+      <arg name="height" type="uint"/>
+    </event>
+
+    <event name="closed">
+      <description summary="surface should be closed">
+        The closed event is sent by the compositor when the surface will no
+        longer be shown. The output may have been destroyed or the user may
+        have asked for it to be removed. Further changes to the surface will be
+        ignored. The client should destroy the resource after receiving this
+        event, and create a new surface if they so choose.
+      </description>
+    </event>
+
+    <enum name="error">
+      <entry name="invalid_surface_state" value="0" summary="provided surface state is invalid"/>
+      <entry name="invalid_size" value="1" summary="size is invalid"/>
+      <entry name="invalid_anchor" value="2" summary="anchor bitfield is invalid"/>
+      <entry name="invalid_keyboard_interactivity" value="3" summary="keyboard interactivity is invalid"/>
+    </enum>
+
+    <enum name="anchor" bitfield="true">
+      <entry name="top" value="1" summary="the top edge of the anchor rectangle"/>
+      <entry name="bottom" value="2" summary="the bottom edge of the anchor rectangle"/>
+      <entry name="left" value="4" summary="the left edge of the anchor rectangle"/>
+      <entry name="right" value="8" summary="the right edge of the anchor rectangle"/>
+    </enum>
+
+    <!-- Version 2 additions -->
+
+    <request name="set_layer" since="2">
+      <description summary="change the layer of the surface">
+        Change the layer that the surface is rendered on.
+
+        Layer is double-buffered, see wl_surface.commit.
+      </description>
+      <arg name="layer" type="uint" enum="zwlr_layer_shell_v1.layer" summary="layer to move this surface to"/>
+    </request>
+  </interface>
+</protocol>

seat.c

@@ -74,17 +74,23 @@ desktop_view_at(struct cg_server *server, double lx, double ly, struct wlr_surfa
 
 	/* Walk up the tree until we find a node with a data pointer. When done,
 	 * we've found the node representing the view. */
-	while (!node->data) {
+	while (node) {
+		if (node->data) {
+			struct cg_view *candidate = node->data;
+			struct cg_view *view;
+			wl_list_for_each (view, &server->views, link) {
+				if (view == candidate) {
+					return view;
+				}
+			}
+		}
 		if (!node->parent) {
-			node = NULL;
 			break;
 		}
-
 		node = &node->parent->node;
 	}
 
-	assert(node != NULL);
-	return node->data;
+	return NULL;
 }
 
 static void
@@ -104,7 +110,7 @@ press_cursor_button(struct cg_seat *seat, struct wlr_input_device *device, uint3
 
 		/* Focus that client if the button was pressed and
 		   it has no open dialogs. */
-		if (view && !view_is_transient_for(current, view)) {
+		if (view && (!current || !view_is_transient_for(current, view))) {
 			seat_set_focus(seat, view);
 		}
 	}
@@ -625,8 +631,8 @@ process_cursor_motion(struct cg_seat *seat, uint32_t time_msec, double dx, doubl
 	struct wlr_seat *wlr_seat = seat->seat;
 	struct wlr_surface *surface = NULL;
 
-	struct cg_view *view = desktop_view_at(seat->server, seat->cursor->x, seat->cursor->y, &surface, &sx, &sy);
-	if (!view) {
+	desktop_view_at(seat->server, seat->cursor->x, seat->cursor->y, &surface, &sx, &sy);
+	if (!surface) {
 		wlr_seat_pointer_clear_focus(wlr_seat);
 	} else {
 		wlr_seat_pointer_notify_enter(wlr_seat, surface, sx, sy);
@@ -787,8 +793,7 @@ handle_destroy(struct wl_listener *listener, void *data)
 
 	struct cg_keyboard_group *group, *group_tmp;
 	wl_list_for_each_safe (group, group_tmp, &seat->keyboard_groups, link) {
-		wlr_keyboard_group_destroy(group->wlr_group);
-		free(group);
+		keyboard_group_destroy(group);
 	}
 	struct cg_pointer *pointer, *pointer_tmp;
 	wl_list_for_each_safe (pointer, pointer_tmp, &seat->pointers, link) {
@@ -910,6 +915,7 @@ seat_destroy(struct cg_seat *seat)
 
 	// Destroying the wlr seat will trigger the destroy handler on our seat,
 	// which will in turn free it.
+
 	wlr_seat_destroy(seat->seat);
 }
 
@@ -920,6 +926,11 @@ seat_get_focus(struct cg_seat *seat)
 	if (!prev_surface) {
 		return NULL;
 	}
+
+	if (seat->focused_layer && seat->focused_layer->surface == prev_surface) {
+		return NULL;
+	}
+
 	return view_from_wlr_surface(prev_surface);
 }
 
@@ -973,6 +984,34 @@ seat_set_focus(struct cg_seat *seat, struct cg_view *view)
 	process_cursor_motion(seat, -1, 0, 0, 0, 0);
 }
 
+void
+seat_set_focus_layer(struct cg_seat *seat, struct wlr_layer_surface_v1 *layer)
+{
+	if (seat->focused_layer == layer) {
+		return;
+	}
+
+	seat->focused_layer = layer;
+
+	if (!layer) {
+		struct cg_view *view = seat_get_focus(seat);
+		if (view) {
+			seat_set_focus(seat, view);
+		}
+		return;
+	}
+
+	if (layer->current.keyboard_interactive != ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_NONE) {
+		struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->seat);
+		if (keyboard) {
+			wlr_seat_keyboard_notify_enter(seat->seat, layer->surface, keyboard->keycodes,
+						       keyboard->num_keycodes, &keyboard->modifiers);
+		} else {
+			wlr_seat_keyboard_notify_enter(seat->seat, layer->surface, NULL, 0, NULL);
+		}
+	}
+}
+
 void
 seat_center_cursor(struct cg_seat *seat)
 {

seat.h

@@ -5,6 +5,7 @@
 #include <wlr/types/wlr_cursor.h>
 #include <wlr/types/wlr_data_device.h>
 #include <wlr/types/wlr_input_device.h>
+#include <wlr/types/wlr_layer_shell_v1.h>
 #include <wlr/types/wlr_seat.h>
 #include <wlr/types/wlr_xcursor_manager.h>
 
@@ -48,6 +49,9 @@ struct cg_seat {
 	struct wl_listener request_set_cursor;
 	struct wl_listener request_set_selection;
 	struct wl_listener request_set_primary_selection;
+
+	struct wlr_layer_surface_v1 *focused_layer;
+	struct wlr_output *focused_output;
 };
 
 struct cg_keyboard_group {
@@ -91,6 +95,7 @@ struct cg_seat *seat_create(struct cg_server *server, struct wlr_backend *backen
 void seat_destroy(struct cg_seat *seat);
 struct cg_view *seat_get_focus(struct cg_seat *seat);
 void seat_set_focus(struct cg_seat *seat, struct cg_view *view);
+void seat_set_focus_layer(struct cg_seat *seat, struct wlr_layer_surface_v1 *layer);
 void seat_center_cursor(struct cg_seat *seat);
 
 #endif

server.h

@@ -52,6 +52,9 @@ struct cg_server {
 
 	struct wl_listener new_virtual_keyboard;
 	struct wl_listener new_virtual_pointer;
+
+	struct wlr_layer_shell_v1 *layer_shell_v1;
+	struct wl_listener new_layer_shell_v1_surface;
 #if CAGE_HAS_XWAYLAND
 	struct wl_listener new_xwayland_surface;
 #endif

view.c

@@ -115,8 +115,6 @@ view_unmap(struct cg_view *view)
 {
 	wl_list_remove(&view->link);
 
-	wlr_scene_node_destroy(&view->scene_tree->node);
-
 	view->wlr_surface->data = NULL;
 	view->wlr_surface = NULL;
 }
@@ -124,12 +122,16 @@ view_unmap(struct cg_view *view)
 void
 view_map(struct cg_view *view, struct wlr_surface *surface)
 {
-	view->scene_tree = wlr_scene_subsurface_tree_create(&view->server->scene->tree, surface);
 	if (!view->scene_tree) {
-		wl_resource_post_no_memory(surface->resource);
-		return;
+		view->scene_tree = wlr_scene_subsurface_tree_create(&view->server->scene->tree, surface);
+		if (!view->scene_tree) {
+			wl_resource_post_no_memory(surface->resource);
+			return;
+		}
+	}
+	if (view->scene_tree) {
+		view->scene_tree->node.data = view;
 	}
-	view->scene_tree->node.data = view;
 
 	view->wlr_surface = surface;
 	surface->data = view;
@@ -137,11 +139,12 @@ view_map(struct cg_view *view, struct wlr_surface *surface)
 #if CAGE_HAS_XWAYLAND
 	/* We shouldn't position override-redirect windows. They set
 	   their own (x,y) coordinates in handle_wayland_surface_map. */
-	if (view->type != CAGE_XWAYLAND_VIEW || xwayland_view_should_manage(view))
-#endif
-	{
+	if (view->type != CAGE_XWAYLAND_VIEW || xwayland_view_should_manage(view)) {
 		view_position(view);
 	}
+#else
+	view_position(view);
+#endif
 
 	wl_list_insert(&view->server->views, &view->link);
 	seat_set_focus(view->server->seat, view);