Use case

DragGestureRecognizer relies on abstract methods that VerticalDragGestureRecognizer, HorizontalDragGestureRecognizer and PanGestureRecognizer implement.

Such methods include _considerFling, _hasSufficientGlobalDistanceToAccept, among others.

Since these methods are private, developers can't extend DragGestureRecognizer to create their own recognizers. For example, a developer might want to modify the distance required to accept the gesture. Currently, developers need to copy the whole DragGestureRecognizer to modify that.

Proposal

Make the abstract methods public. Also, provide public getters to the private members that the subclasses access, like _finalPosition and _globalDistanceMoved.