sclass JFFMPEGVideoPlayer is Swingable {
  ImageSurface imageSurface = imageSurface();
  JPanel buttons = rightAlignedLine();
  
  ImageStreamFromVideoFile stream;
  
  {
    buttons.add("Open", rThread openDialog);
    bindToComponent(imageSurface, null, rThread closeStream);
  }
  
  visual
    centerAndSouthWithMargin(
      jscroll_center_borderless(imageSurface),
      buttons
    );
    
  void openDialog swing {
    new JFileChooser fc;
    fc.setDialogTitle("Open video");
    play(execFileChooser(fc));
  }
  
  void play(File videoFile) {
    if (videoFile == null) ret;
    closeStream();
    stream = new ImageStreamFromVideoFile;
    stream.open(videoFile);
    stream.onHaveImage((image, pos) -> {
      // TODO: sleep
      imageSurface.setImage(image);
    });
    stream.startDecodeThread();
  }
  
  void closeStream {
    imageSurface.noImage();
    dispose stream;
  }
}