abstract sclass DynImageSurface extends DynModule {
  transient ImageSurface imageSurface;
  transient BufferedImage image;
  transient S imageID;

  visualize {
    ret jscroll_center(imageSurface = imageSurface(image));
  }
  
  // hold image during reload (not during reboot yet)
  
  O _getReloadData() { ret image; }
  void _setReloadData(BufferedImage image) { this.image = image; }
  
  // API
  
  void setImage(MakesBufferedImage image) { imageID = null; setImage(image == null ? null : image.getBufferedImage()); }
  
  void setImage(BufferedImage image) { this.image = image; imageID = null; if (imageSurface != null) imageSurface.setImage(image); }
  
  void setImage(S imageID) {
    if (sameSnippetID(this.imageID, imageID)) ret;
    setImage(loadImage2(imageID));
    this.imageID = imageID;
  }
  
  BufferedImage getImage() { ret image; }
  bool hasImage() { ret image != null; }
}