create_focus_event_step_3.dart

bool _handleScrollNotification(ScrollNotification notification) {
    if (_didDragStart(notification)) {
      _dragOffset = 0;
      _pullToReachStarted = true;
    }

    if (_didDragEnd(notification)) {
      _dragOffset = 0;
      _pullToReachStarted = false;

      _notifySelectIfNeeded();
    }

    if (_pullToReachStarted) {
      _shouldNotifyOnDragEnd = true;
    } else {
      return false;
    }

    var progress = _calculateScrollProgress(notification);
    var index = indexCalculator.getIndexForScrollPercent(progress);

    if (_itemIndex != index) {
      _itemIndex = index;
      PullToReachScope.of(context).setFocusIndex(_itemIndex);
    }

    return false;
  }