compositor: add wlr_surface_role.no_object

This commit allows to make a role as not represented by an object,
which fixes calling role commit handlers for roles like cursor
surfaces.

Fixes: 099b9de752

include/wlr/types/wlr_compositor.h

@@ -73,8 +73,16 @@ struct wlr_surface_state {
 
 struct wlr_surface_role {
 	const char *name;
+	/**
+	 * If true, the role isn't represented by any object.
+	 * For example, this applies to cursor surfaces.
+	 */
+	bool no_object;
 	/**
 	 * Called when a new surface state is committed. May be NULL.
+	 *
+	 * If the role is represented by an object, this is only called if
+	 * such object exists.
 	 */
 	void (*commit)(struct wlr_surface *surface);
 	/**
@@ -224,6 +232,10 @@ typedef void (*wlr_surface_iterator_func_t)(struct wlr_surface *surface,
 /**
  * Set the lifetime role for this surface. Returns true on success or false if
  * the role cannot be set.
+ *
+ * If the role is represented by an object, role_data must be non-NULL.
+ * Alternatively, if the role isn't represented by any object, role_data must
+ * be NULL.
  */
 bool wlr_surface_set_role(struct wlr_surface *surface,
 	const struct wlr_surface_role *role, void *role_data,

types/data_device/wlr_drag.c

@@ -365,6 +365,7 @@ static void drag_icon_surface_role_commit(struct wlr_surface *surface) {
 
 const struct wlr_surface_role drag_icon_surface_role = {
 	.name = "wl_data_device-icon",
+	.no_object = true,
 	.commit = drag_icon_surface_role_commit,
 };
 

types/seat/wlr_seat_pointer.c

@@ -79,6 +79,7 @@ static void pointer_cursor_surface_handle_commit(struct wlr_surface *surface) {
 
 static const struct wlr_surface_role pointer_cursor_surface_role = {
 	.name = "wl_pointer-cursor",
+	.no_object = true,
 	.commit = pointer_cursor_surface_handle_commit,
 };
 

types/tablet_v2/wlr_tablet_v2_tool.c

@@ -25,6 +25,7 @@ static void tablet_tool_cursor_surface_handle_commit(struct wlr_surface *surface
 
 static const struct wlr_surface_role tablet_tool_cursor_surface_role = {
 	.name = "wp_tablet_tool-cursor",
+	.no_object = true,
 	.commit = tablet_tool_cursor_surface_handle_commit,
 };
 

types/wlr_compositor.c

@@ -491,7 +491,8 @@ static void surface_commit_state(struct wlr_surface *surface,
 		surface->pending.seq++;
 	}
 
-	if (surface->role_data != NULL && surface->role->commit != NULL) {
+	if (surface->role != NULL && surface->role->commit != NULL &&
+			(surface->role_data != NULL || surface->role->no_object)) {
 		surface->role->commit(surface);
 	}
 
@@ -768,6 +769,7 @@ bool wlr_surface_set_role(struct wlr_surface *surface,
 		const struct wlr_surface_role *role, void *role_data,
 		struct wl_resource *error_resource, uint32_t error_code) {
 	assert(role != NULL);
+	assert((role_data == NULL) == role->no_object);
 
 	if (surface->role != NULL && surface->role != role) {
 		if (error_resource != NULL) {