docs: private boolean checkTouchSlop(View child, float dx, float dy) {
          if (child == null) {
              return false;
          }
          final boolean checkHorizontal = mCallback.getViewHorizontalDragRange(child) > 0;
          final boolean checkVertical = mCallback.getViewVerticalDragRange(child) > 0;
  
          if (checkHorizontal && checkVertical) {
              return dx * dx + dy * dy > mTouchSlop * mTouchSlop;
          } else if (checkHorizontal) {
              return Math.abs(dx) > mTouchSlop;
          } else if (checkVertical) {
              return Math.abs(dy) > mTouchSlop;
          }
          return false;
      }