!7

sclass ImagePreview extends DynSCP {
  new DynModuleRef mate;
  
  transient Image shownImage;

  JComponent visualize2() {
    Image image = shownImage;
    if (image == null) ret jcenteredlabel("Need image");
    ret jimage(image);
  }
  
  Image imageFromMate() {
    ret castCall(mate!, 'getImage);
  }
  
  void update {
    lock lock;
    
    // notice mate gone away
    if (mate! != null && !dm_moduleStillThere(mate!)) {
      mate.set(null);
      setField(shownImage := null);
      revisualize2();
    }
    
    // find new mate
    if (mate! == null)
      if (setField(mate := DynModuleRef(dm_findMateOfType(this, 'ImageInfo))))
        revisualize2();
        
    if (setField(shownImage := imageFromMate()))
      revisualize2();
  }
}

Began life as a copy of #1015922