@Override
  public void onGestureBegin(MultiPointerGestureDetector detector) {
    if (mListener != null) {
      mListener.onGestureBegin(this);
    }
  }
Handles the given motion event.

@param event event to handle
@return whether or not the event was handled
samples/gestures/src/main/java/com/facebook/samples/gestures/TransformGestureDetector.java