libobs,UI: Issue appropriate signals on group / ungroup

Due to the way the frontend works, the logic for inserting the row for
the group in the UI was dropped since the new item_add message will
insert one automatically since it forces a refresh of the scene items.
The reliance on that implicit row insertion when grouping items is a
bit of a code smell, although the alternative would be to add logic to
disable handling the signal for that instant, which is probably a
worse choice.

UI/source-tree.cpp

@@ -967,28 +967,17 @@ void SourceTreeModel::GroupSelectedItems(QModelIndexList &indices)
 	for (obs_sceneitem_t *item : item_order)
 		obs_sceneitem_select(item, false);
 
-	int newIdx = indices[0].row();
-
-	beginInsertRows(QModelIndex(), newIdx, newIdx);
-	items.insert(newIdx, item);
-	endInsertRows();
-
-	for (int i = 0; i < indices.size(); i++) {
-		int fromIdx = indices[i].row() + 1;
-		int toIdx = newIdx + i + 1;
-		if (fromIdx != toIdx) {
-			beginMoveRows(QModelIndex(), fromIdx, fromIdx,
-				      QModelIndex(), toIdx);
-			MoveItem(items, fromIdx, toIdx);
-			endMoveRows();
-		}
-	}
-
 	hasGroups = true;
 	st->UpdateWidgets(true);
 
 	obs_sceneitem_select(item, true);
 
+	/* ----------------------------------------------------------------- */
+	/* obs_scene_insert_group triggers a full refresh of scene items via */
+	/* the item_add signal. No need to insert a row, just edit the one   */
+	/* that's created automatically.                                     */
+
+	int newIdx = indices[0].row();
 	QMetaObject::invokeMethod(st, "NewGroupEdit", Qt::QueuedConnection,
 				  Q_ARG(int, newIdx));
 }

libobs/obs-scene.c

@@ -3332,6 +3332,15 @@ obs_sceneitem_t *obs_scene_insert_group(obs_scene_t *scene, const char *name,
 	full_unlock(sub_scene);
 	full_unlock(scene);
 
+	struct calldata params;
+	uint8_t stack[128];
+
+	calldata_init_fixed(&params, stack, sizeof(stack));
+	calldata_set_ptr(&params, "scene", scene);
+	calldata_set_ptr(&params, "item", item);
+	signal_handler_signal(scene->source->context.signals, "item_add",
+			      &params);
+
 	/* ------------------------- */
 
 	return item;
@@ -3397,6 +3406,8 @@ void obs_sceneitem_group_ungroup(obs_sceneitem_t *item)
 	obs_sceneitem_t *first;
 	obs_sceneitem_t *last;
 
+	signal_item_remove(item);
+
 	full_lock(scene);
 
 	/* ------------------------- */