method handleEvent

Source

@override
void handleEvent(PointerEvent event) {
  assert(_state != _DragState.ready);
  if (event is PointerMoveEvent) {
    VelocityTracker tracker = _velocityTrackers[event.pointer];
    assert(tracker != null);
    tracker.addPosition(event.timeStamp, event.position);
    Offset delta = event.delta;
    if (_state == _DragState.accepted) {
      if (onUpdate != null) {
        invokeCallback/*<Null>*/('onUpdate', () => onUpdate(new DragUpdateDetails( // ignore: STRONG_MODE_INVALID_CAST_FUNCTION_EXPR, https://github.com/dart-lang/sdk/issues/27504
          delta: _getDeltaForDetails(delta),
          primaryDelta: _getPrimaryDeltaForDetails(delta),
          globalPosition: event.position
        )));
      }
    } else {
      _pendingDragOffset += delta;
      if (_hasSufficientPendingDragDeltaToAccept)
        resolve(GestureDisposition.accepted);
    }
  }
  stopTrackingIfPointerNoLongerDown(event);
}