types/wlr_buffer: create custom wlr_buffer from wl_resource

types/wlr_buffer.c

@@ -181,6 +181,18 @@ void wlr_buffer_register_resource_interface(
 	*iface_ptr = iface;
 }
 
+static const struct wlr_buffer_resource_interface *get_buffer_resource_iface(
+		struct wl_resource *resource) {
+	struct wlr_buffer_resource_interface **iface_ptr;
+	wl_array_for_each(iface_ptr, &buffer_resource_interfaces) {
+		if ((*iface_ptr)->is_instance(resource)) {
+			return *iface_ptr;
+		}
+	}
+
+	return NULL;
+}
+
 struct wlr_buffer *wlr_buffer_from_resource(struct wl_resource *resource) {
 	assert(resource && wlr_resource_is_buffer(resource));
 
@@ -202,10 +214,22 @@ struct wlr_buffer *wlr_buffer_from_resource(struct wl_resource *resource) {
 			wlr_drm_buffer_from_resource(resource);
 		buffer = wlr_buffer_lock(&drm_buffer->base);
 	} else {
+		const struct wlr_buffer_resource_interface *iface =
+				get_buffer_resource_iface(resource);
+		if (!iface) {
 			wlr_log(WLR_ERROR, "Unknown buffer type");
 			return NULL;
 		}
 
+		struct wlr_buffer *custom_buffer = iface->from_resource(resource);
+		if (!custom_buffer) {
+			wlr_log(WLR_ERROR, "Failed to create %s buffer", iface->name);
+			return NULL;
+		}
+
+		buffer = wlr_buffer_lock(custom_buffer);
+	}
+
 	return buffer;
 }