docs: private int getPressedPointerIndex(MotionEvent event, int i) {
      final int count = event.getPointerCount();
      final int action = event.getActionMasked();
      final int index = event.getActionIndex();
      if (action == MotionEvent.ACTION_UP ||
          action == MotionEvent.ACTION_POINTER_UP) {
        if (i >= index) {
          i++;
        }
      }
      return (i < count) ? i : -1;
    }