rootston: only allow one drag icon per seat

include/rootston/seat.h

@@ -29,7 +29,7 @@ struct roots_seat {
 	struct wl_list views; // roots_seat_view::link
 	bool has_focus;
 
-	struct wl_list drag_icons; // roots_drag_icon::link
+	struct roots_drag_icon *drag_icon; // can be NULL
 
 	struct wl_list keyboards;
 	struct wl_list pointers;
@@ -61,7 +61,6 @@ struct roots_seat_view {
 struct roots_drag_icon {
 	struct roots_seat *seat;
 	struct wlr_drag_icon *wlr_drag_icon;
-	struct wl_list link;
 
 	double x, y;
 

rootston/cursor.c

@@ -151,9 +151,8 @@ static void roots_passthrough_cursor(struct roots_cursor *cursor,
 		wlr_seat_pointer_clear_focus(seat->seat);
 	}
 
-	struct roots_drag_icon *drag_icon;
-	wl_list_for_each(drag_icon, &seat->drag_icons, link) {
-		roots_drag_icon_update_position(drag_icon);
+	if (seat->drag_icon != NULL) {
+		roots_drag_icon_update_position(seat->drag_icon);
 	}
 }
 

rootston/output.c

@@ -120,17 +120,16 @@ static void drag_icons_for_each_surface(struct roots_input *input,
 		void *user_data) {
 	struct roots_seat *seat;
 	wl_list_for_each(seat, &input->seats, link) {
-		struct roots_drag_icon *drag_icon;
-		wl_list_for_each(drag_icon, &seat->drag_icons, link) {
-			if (!drag_icon->wlr_drag_icon->mapped) {
+		struct roots_drag_icon *drag_icon = seat->drag_icon;
+		if (drag_icon == NULL || !drag_icon->wlr_drag_icon->mapped) {
 			continue;
 		}
+
 		surface_for_each_surface(drag_icon->wlr_drag_icon->surface,
 			drag_icon->x, drag_icon->y, 0, layout_data,
 			iterator, user_data);
 	}
 }
-}
 
 static void layer_for_each_surface(struct wl_list *layer,
 		const struct wlr_box *output_layout_box,

rootston/seat.c

@@ -594,7 +594,9 @@ static void roots_drag_icon_handle_destroy(struct wl_listener *listener,
 		wl_container_of(listener, icon, destroy);
 	roots_drag_icon_damage_whole(icon);
 
-	wl_list_remove(&icon->link);
+	assert(icon->seat->drag_icon == icon);
+	icon->seat->drag_icon = NULL;
+
 	wl_list_remove(&icon->surface_commit.link);
 	wl_list_remove(&icon->unmap.link);
 	wl_list_remove(&icon->destroy.link);
@@ -622,7 +624,8 @@ static void roots_seat_handle_new_drag_icon(struct wl_listener *listener,
 	icon->destroy.notify = roots_drag_icon_handle_destroy;
 	wl_signal_add(&wlr_drag_icon->events.destroy, &icon->destroy);
 
-	wl_list_insert(&seat->drag_icons, &icon->link);
+	assert(seat->drag_icon == NULL);
+	seat->drag_icon = icon;
 
 	roots_drag_icon_update_position(icon);
 }
@@ -706,7 +709,6 @@ struct roots_seat *roots_seat_create(struct roots_input *input, char *name) {
 	wl_list_init(&seat->tablet_pads);
 	wl_list_init(&seat->switches);
 	wl_list_init(&seat->views);
-	wl_list_init(&seat->drag_icons);
 
 	seat->input = input;