setCanDrag method

@override void setCanDrag(bool canDrag)

Whether the user can drag the widget, for example to initiate a scroll.

Implementation

@override
void setCanDrag(bool canDrag) {
  if (canDrag == _lastCanDrag && (!canDrag || axis == _lastAxisDirection)) return;
  if (!canDrag) {
    _gestureRecognizers = const <Type, GestureRecognizerFactory>{};
  } else {
    switch (axis) {
      case Axis.vertical:
        // Vertical drag gesture recognizer to trigger vertical scroll.
        _gestureRecognizers = <Type, GestureRecognizerFactory>{
          ScrollVerticalDragGestureRecognizer: GestureRecognizerFactoryWithHandlers<ScrollVerticalDragGestureRecognizer>(
            () => ScrollVerticalDragGestureRecognizer(),
            (ScrollVerticalDragGestureRecognizer instance) {
              instance
                ..isAcceptedDrag = _isAcceptedVerticalDrag
                ..onDown = _handleDragDown
                ..onStart = _handleDragStart
                ..onUpdate = _handleDragUpdate
                ..onEnd = _handleDragEnd
                ..onCancel = _handleDragCancel
                ..minFlingDistance = _physics.minFlingDistance
                ..minFlingVelocity = _physics.minFlingVelocity
                ..maxFlingVelocity = _physics.maxFlingVelocity
                ..dragStartBehavior = dragStartBehavior;
            },
          ),
        };
        break;
      case Axis.horizontal:
        // Horizontal drag gesture recognizer to horizontal vertical scroll.
        _gestureRecognizers = <Type, GestureRecognizerFactory>{
          ScrollHorizontalDragGestureRecognizer: GestureRecognizerFactoryWithHandlers<ScrollHorizontalDragGestureRecognizer>(
            () => ScrollHorizontalDragGestureRecognizer(),
            (ScrollHorizontalDragGestureRecognizer instance) {
              instance
                ..isAcceptedDrag = _isAcceptedHorizontalDrag
                ..onDown = _handleDragDown
                ..onStart = _handleDragStart
                ..onUpdate = _handleDragUpdate
                ..onEnd = _handleDragEnd
                ..onCancel = _handleDragCancel
                ..minFlingDistance = _physics.minFlingDistance
                ..minFlingVelocity = _physics.minFlingVelocity
                ..maxFlingVelocity = _physics.maxFlingVelocity
                ..dragStartBehavior = dragStartBehavior;
            },
          ),
        };
        break;
    }
  }
  _lastCanDrag = canDrag;
  _lastAxisDirection = axis;
  _syncAll(_gestureRecognizers);
}