sclass IIImageSurface extends ImageSurface {
  IBWIntegralImage ii;

  *() {}
  
  *(IBWIntegralImage *ii) {}
  *(IBWIntegralImage *ii, BufferedImage img) { super(img); }
  
  void drawImageItself(int w, int h, Graphics2D g) {
    if (ii == null)
      ret with super.drawImageItself(w, h, g);
      
    int iw = getZoomedWidth(), ih = getZoomedHeight();
    
    Rect r = toRect(getVisibleRect());
    //_print(visibleRect := r);
    
    // TODO: scale only the visible part
    //var scaled = scaledGrayImageFromBWIntegralImage(ii, iw, ih);
    var scaled = scaledGrayImageFromBWIntegralImage_clip(ii, doubleRatio(iw, ii.getWidth()), r);
    g.drawImage(scaled, r.x, r.y, null);
  }
  
  public void setImage(BufferedImage img) {
    ii = null;
    super.setImage(img);
  }
  
  void setImage(BWIntegralImage ii, BufferedImage img default null) {
    this.ii = ii;
    super.setImage(img);
  }
  
  bool hasImage() { ret ii != null || image != null; }
  int w() { ret ii != null ? ii.getWidth() : super.w(); }
  int h() { ret ii != null ? ii.getHeight() : super.h(); }
}

Began life as a copy of #1004553