onDragStart property

Stream<DraggableEvent> onDragStart

Fired when the user starts dragging.

Note: The onDragStart is fired not on touchStart or mouseDown but as soon as there is a drag movement. When a drag is started an onDrag event will also be fired.

Implementation

Stream<DraggableEvent> get onDragStart {
  if (_onDragStart == null) {
    _onDragStart = StreamController<DraggableEvent>.broadcast(
        sync: true, onCancel: () => _onDragStart = null);
  }
  return _onDragStart!.stream;
}