sclass ImageSurfaceScribbleTool extends ImageSurfaceMouseHandler {
  settable Stroke stroke = new BasicStroke(5);
  settable Color color = Color.black;
  Pt lastPt;

  *(ImageSurface is) {
    if (containsInstance(is.tools, ImageSurfaceSelector)) ret;
    register(is);
  }

  public void mousePressed(MouseEvent evt) {
    if (verbose) print("mousePressed");
    if (evt.getButton() != MouseEvent.BUTTON1) return;
    lastPt = getPt(evt);
    drawPoint(lastPt);
  }

  public void mouseDragged aka mouseReleased(MouseEvent e) {
    if (lastPt == null) ret;
    Pt p = getPt(e);
    if (!eq(p, lastP))
      drawLine(lastPt, p);
    lastPt = p;
    is.repaint(); // That's gonna be slow...
  }
  
  void drawPoint(Pt p) {
    drawLine(p, p);
  }
  
  void drawLine(Pt a, Pt b) {
    Graphics2D g = getImage().createGraphics();
    g.setStroke(stroke);
    g.setColor(color);
    g.drawLine(a, b);
    g.dispose();
  }
}