code: private void initCropArea() {
  
          if (isCropping()) {
              // crop area is set up correctly
              // adjust target image height or width if required
              if (m_width < 0) {
                  m_width = m_cropWidth;
              }
              if (m_height < 0) {
                  m_height = m_cropHeight;
              }
              if ((getType() != 6) && (getType() != 7) && (getType() != 8)) {
                  // cropping type can only be 6 or 7 (point cropping)
                  // all other values with cropping coordinates are invalid
                  setType(0);
              }
          }
      }
docs: Initializes the crop area setting.<p>
  
  Only if all 4 required parameters have been set, the crop area is set accordingly.
  Moreover, it is not required to specify the target image width and height when using crop,
  because these parameters can be calculated from the crop area.<p>
  
  Scale type 6 and 7 are used for a 'crop around point' operation, see {@link #getType()} for a description.<p>