drag method
- @override
override
Start a drag activity corresponding to the given DragStartDetails.
The onDragCanceled argument will be invoked if the drag is ended
prematurely (e.g. from another activity taking over). See
ScrollDragController.onDragCanceled for details.
Implementation
@override
Drag drag(DragStartDetails details, VoidCallback dragCancelCallback) {
final ScrollDragController drag = ScrollDragController(
delegate: this,
details: details,
onDragCanceled: dragCancelCallback,
carriedVelocity: physics.carriedMomentum(_heldPreviousVelocity),
motionStartDistanceThreshold: physics.dragStartDistanceMotionThreshold,
);
beginActivity(DragScrollActivity(this, drag));
assert(_currentDrag == null);
_currentDrag = drag;
return drag;
}