sclass JPaintTool > MetaWithChangeListeners is Swingable, AutoCloseable {

  settableWithVar File autoPersistFile;

  settableWithVar double autoPersistInterval = 10.0;

  settableWithVar Color brushColor = Color.black;

  settableWithVar bool drawingAllowed = true;

  settable Color bgColor = Color.lightGray; // background color around image surface

  event imageChanged(BufferedImage image);

  transient settableWithChange volatile bool dirty;

  transient gettable BufferedImage image;

  transient gettable ImageSurface imageSurface;

  transient bool autoPersistInstalled;

  transient ReliableSingleThread rstPersist = new(r _persist);

  transient JPanel buttons;

  // tools

  transient new ImageSurfaceScribbleTool scribbler;

  transient new ImageSurfaceDragger dragger;

  transient new ImageSurfaceSelector selector;

  transient JComboBox<WidthAndHeight> cbImageSize;

  //transient settableWithVar S status;

  transient new ButtonGroup colorButtonGroup;

  transient new ButtonGroup toolSelectButtonGroup;

  transient simplyCached void init() {

    imageSurface = makeImageSurface();

    imageSurface.onUserModifiedImage(image -> {

      print("userModifiedImage");

      setImage(image);

      fireImageChanged();

    });

    cbImageSize = jTypedComboBox(imageSizes());

    main onChange(cbImageSize, l1 setImageSize);

    printVars("JPaintTool.init", +image, +autoPersistFile);

    if (image == null) {

      setImage(makeNewImage());

      if (autoPersistFile != null) {

        pcall {

          var img = loadImage2(autoPersistFile);

          if (img != null) {

            setImage(img);

            print("Image loaded");

          }

        }

        if (!autoPersistInstalled) {

          set autoPersistInstalled;

          awtEvery(imageSurface, autoPersistInterval, rstPersist);

          bindToComponent(imageSurface, null, rstPersist);

        }

      }

    }

    varDrawingAllowed().onChangeAndNow(b -> scribbler.enabled(print(scribblerEnabled := b)));

  }

  BufferedImage makeNewImage() {

    ret main newImage(defaultImageSize());

  }

  WidthAndHeight defaultImageSize() { ret getSelected(cbImageSize); }

  cachedVisualize {

    init();

    var filePathLabel = new JFilePathLabel(autoPersistFile).nameOnly();

    varAutoPersistFile().onChange(file -> filePathLabel.setFile(file));

    var filePathLabelVis = filePathLabel.visualize();

    componentPopupMenuItem(filePathLabel.button.visualize(),

      "Save image now", r { set dirty; rstPersist!; });

    ret withTopMargin(northCenterAndSouthWithMargin(

      // north buttons

      buttons = jcenteredline(flattenToList(

        jbutton("New image", rThread newImage),

        withLabel("Size:", cbImageSize),

        map colorSelectButton(colors()),

        swing(-> new JImageSwitch(#1103077, #1103078, varDrawingAllowed())

          .setToolTips(

            "Drawing allowed (click to change)",

            "Drawing not allowed (click to change)")),

      )),

      // image surface

      centerAndEastWithMargin(

        jscroll_borderless(setBackground(bgColor, jFullCenter(imageSurface))),

        //jscroll_center_borderless(imageSurface),

        vstackWithSpacing(

          makeToolSelectors()

        )

      ),

      // south controls

      centerAndEast(

        withLeftMargin(bottomLeftControls()),

        autoPersistFile == null ? jpanel()

          : withSideMargin(withLabel("Image:", filePathLabelVis))

      )

    ));

  }

  void setImage(BufferedImage image) {

    this.image = image;

    imageSurface.setImage(image);

    imageChanged(image);

  }

  transient swappable ImageSurface makeImageSurface() {  

    var is = pixelatedImageSurface();

    //is.setAutoZoomToDisplay(true);

    is.specialPurposed = true;

    is.allowPaste(true);

    is.zoomable(false);

    is.removeAllTools();

    //scribbler.onScribbleDone(scribble -> printStruct(scribble));

    scribbler.onPainted(l0 fireImageChanged);

    varBrushColor().onChangeAndNow(color -> scribbler.setColor(color));

    is.setTool(scribbler);

    ret is;

  }

  void fireImageChanged {

    set dirty;

    imageChanged(getImage());

  }

  void _persist {

    if (autoPersistFile != null && dirty) {

      dirty = false;

      savePNGVerbose(autoPersistFile, image);

    }

  }

  // doesn't allow drawing immediately

  void loadImageProtected(File file) {

    loadImage(file);

    drawingAllowed(false);

  }

  // Note: also auto-persists to that file

  void loadImage(File file) {  

    close(); // persist

    var img = loadImage2(file);

    autoPersistFile(file);

    setImage(img);

  }

  void newImage() ctex {

    close(); // persist

    //if (dirty && !swingConfirm(imageSurface, "Discard image")) ret;

    var file = createAutoPersistFile();

    print("Created auto persist file: " + f2s(file));

    autoPersistFile(file);

    setImage(makeNewImage());

    drawingAllowed(true);

    dirty = false;

  }

  // swap to make a new file every time user clicks "New image"

  swappable File createAutoPersistFile() { ret autoPersistFile(); }

  JToggleButton colorSelectButton(Color color) {

    var btn = jImageToggleButton(main newImage(16, color),

      "Select color to draw with", -> setBrushColor(color),

      eq(brushColor(), color));

    ret addToButtonGroup(colorButtonGroup, btn);

  }

  L<Color> colors() {

    ret colorPaletteByBits(1); // 8 primary colors

  }

  L<WidthAndHeight> imageSizes() {

    ret mapLL sixteenToNine_p(

      240, 360, 480, 720

    );

  }

  void setImageSize(WidthAndHeight size) {

    if (!sameSize(getImage(), size))

      newImage();

  }

  close {

    rstPersist.triggerAndWait();

  }

  transient swappable JComponent bottomLeftControls() { ret jpanel(); }

  void selectTool(ImageSurfaceMouseHandler tool) {

    imageSurface.setTool(tool);

  }

  JToggleButton toolSelectButton(ImageSurfaceMouseHandler tool,

    S imageID, S toolTip) {

    ret addToButtonGroup(toolSelectButtonGroup, jImageToggleButton(imageID, toolTip,

      -> selectTool(tool),

      imageSurface.hasTool(tool));

  }

  L<JComponent> makeToolSelectors() {

    ret ll(

      instaToolTip(-> "Draw on image with left mouse button"

        + stringIf(!drawingAllowed, " (click lock icon to start)"),

        toolSelectButton(scribbler, #1103080, null)),

      toolSelectButton(dragger, #1103079, "Scroll image with left mouse button"),

      toolSelectButton(selector, #1103081, "Select rectangular area with left mouse button")

    );

  }

}