sclass ImageSurfaceSelector extends MouseAdapter is AutoCloseable {
  ImageSurface is;
  Point startingPoint;
  bool enabled = true;
  static bool verbose = false;

  *(ImageSurface *is) {
    if (containsInstance(is.tools, ImageSurfaceSelector)) ret;
    is.tools.add(this);
    is.addMouseListener(this);
    is.addMouseMotionListener(this);
  }

  public void mousePressed(MouseEvent evt) {
    if (verbose) print("mousePressed");
    if (evt.getButton() != MouseEvent.BUTTON1) return;
    if (enabled)
      startingPoint = getPoint(evt);
  }

  public void mouseDragged(MouseEvent e) {
    if (verbose) print("mouseDragged");
    if (startingPoint != null) {
      Point endPoint = getPoint(e);
      Rectangle r = new Rectangle(startingPoint, new Dimension(endPoint.x-startingPoint.x+1, endPoint.y-startingPoint.y+1));
      normalize(r);
      r.width = min(r.width, is.getImage().getWidth()-r.x);
      r.height = min(r.height, is.getImage().getHeight()-r.y);
      is.setSelection(r);
    }
    if (verbose) print("mouseDragged done");
  }

  public static void normalize(Rectangle r) {
    if (r.width < 0) {
      r.x += r.width;
      r.width = -r.width;
    }
    if (r.height < 0) {
      r.y += r.height;
      r.height = -r.height;
    }
  }

  public void mouseReleased(MouseEvent e) {
    if (verbose) print("mouseReleased");
    mouseDragged(e);
    if (getPoint(e).equals(startingPoint))
      is.setSelection((Rectangle) null);
    startingPoint = null;
  }
  
  Point getPoint(MouseEvent e) {
    return new Point((int) (e.getX()/is.getZoomX()), (int) (e.getY()/is.getZoomY()));
  }
  
  close {
    if (is == null) ret;
    is.tools.remove(this);
    is.removeMouseListener(this);
    is.removeMouseMotionListener(this);
    is = null;
  }
}