abstract sclass DynImageSurface extends DynModule {
  transient ImageSurface imageSurface;
  transient BufferedImage image;
  transient S imageID;
  transient bool useUpdateHack;
  transient O onNewImage;

  visualize {
    imageSurface = imageSurface(image);
    imageSurface.onNewImage = r newImageFromSurface;
    ret jscroll_center(imageSurface);
  }
  
  // call after visualize
  void enableDoubleBuffering {
    if (imageSurface != null) imageSurface.setDoubleBuffered(true);
  }
  
  // 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 newImageFromSurface {
    setImage(imageSurface.getImage());
  }
  
  void setImage(BufferedImage image) {
    this.image = image; imageID = null;
    if (imageSurface != null) {
      temp tempSetField(imageSurface, onNewImage := null); // avoid recursion
      imageSurface.setImage(image);
    }
    vmBus_send('newImage, this);
    pcallF(onNewImage, image);
  }
  
  void setImage(S imageID) {
    if (sameSnippetID(this.imageID, imageID)) ret;
    setImage(loadImage2(imageID));
    this.imageID = imageID;
  }
  
  BufferedImage getImage() {
    if (useUpdateHack) {
      // HACKY: to get changes in ImageSurface (e.g. images drag&dropped in there directly)
      ImageSurface is = imageSurface;
      if (is != null && is.getImage() != image) setImage(is.getImage());
    }
    
    ret image;
  }
  bool hasImage() { ret image != null; }
  
  void setZoom(double zoom) { if (imageSurface != null) imageSurface.setZoom(zoom); }
  
  Rect getSelection() { ret imageSurface == null ? null : toRect(imageSurface.getSelection()); }
  
  void setSelection(Rect r) { if (imageSurface != null) imageSurface.setSelection(toRectangle(r)); }
  
  int imageWidth() { ret imageSurface.getImage().getWidth(); }
  int imageHeight() { ret imageSurface.getImage().getHeight(); }
}