rejectGesture method
- int pointer
 
override
    Called when this member loses the arena for the given pointer id.
Implementation
@override
void rejectGesture(int pointer) {
  super.rejectGesture(pointer);
  if (pointer == primaryPointer) {
    // Another gesture won the arena.
    assert(state != GestureRecognizerState.possible);
    if (_sentTapDown) {
      _checkCancel(null, 'forced');
    }
    _reset();
  }
}