onTouchEnd method
      
void
onTouchEnd(
    
    
- dynamic event
Implementation
void onTouchEnd(event) {
  switch (_pointers.length) {
    case 0:
      _state = OrbitState.none;
      break;
    case 1:
      _state = OrbitState.touchRotate;
      _moveCurr.setFrom(getMouseOnCircle(event.pageX, event.pageY));
      _movePrev.setFrom(_moveCurr);
      break;
    case 2:
      _state = OrbitState.touchZoomPan;
      _moveCurr.setFrom(getMouseOnCircle(event.pageX - _movePrev.x, event.pageY - _movePrev.y));
      _movePrev.setFrom(_moveCurr);
      break;
  }
  scope.dispatchEvent(_endEvent);
}