down method

PointerDownEvent down (Offset newLocation, { Duration timeStamp: Duration.zero })

Create a PointerDownEvent at the given location.

By default, the time stamp on the event is Duration.zero. You can give a specific time stamp by passing the timeStamp argument.

Implementation 

PointerDownEvent down(Offset newLocation, { Duration timeStamp = Duration.zero }) {
  assert(!isDown);
  _isDown = true;
  _location = newLocation;
  return PointerDownEvent(
    timeStamp: timeStamp,
    pointer: pointer,
    position: location
  );
}