Add wlr_surface_is_subsurface and wlr_subsurface_from_surface

include/wlr/types/wlr_compositor.h

@@ -4,6 +4,8 @@
 #include <wayland-server.h>
 #include <wlr/render/wlr_renderer.h>
 
+struct wlr_surface;
+
 struct wlr_compositor {
 	struct wl_global *wl_global;
 	struct wl_list wl_resources;
@@ -22,4 +24,8 @@ void wlr_compositor_destroy(struct wlr_compositor *wlr_compositor);
 struct wlr_compositor *wlr_compositor_create(struct wl_display *display,
 		struct wlr_renderer *renderer);
 
+bool wlr_surface_is_subsurface(struct wlr_surface *surface);
+
+struct wlr_subsurface *wlr_subsurface_from_surface(struct wlr_surface *surface);
+
 #endif

types/wlr_compositor.c

@@ -7,6 +7,18 @@
 #include <wlr/util/log.h>
 #include "util/signal.h"
 
+static const char *subsurface_role = "wl_subsurface";
+
+bool wlr_surface_is_subsurface(struct wlr_surface *surface) {
+	return strcmp(surface->role, subsurface_role) == 0;
+}
+
+struct wlr_subsurface *wlr_subsurface_from_surface(
+		struct wlr_surface *surface) {
+	assert(wlr_surface_is_subsurface(surface));
+	return (struct wlr_subsurface *)surface->role_data;
+}
+
 static const struct wl_compositor_interface wl_compositor_impl;
 
 static struct wlr_compositor *compositor_from_resource(struct wl_resource *resource) {
@@ -134,7 +146,7 @@ static void subcompositor_get_subsurface(struct wl_client *client,
 		return;
 	}
 
-	if (wlr_surface_set_role(surface, "wl_subsurface", resource,
+	if (wlr_surface_set_role(surface, subsurface_role, resource,
 				WL_SUBCOMPOSITOR_ERROR_BAD_SURFACE) < 0) {
 		return;
 	}
@@ -144,6 +156,8 @@ static void subcompositor_get_subsurface(struct wl_client *client,
 		wl_resource_post_no_memory(resource);
 		return;
 	}
+
+	surface->role_data = surface->subsurface;
 }