OverlayLayoutで複数のJButtonを重ねて複合ボタンを作成

private static JComponent makeCompoundButton(final Dimension d) {
  JPanel p = new JPanel() {
    @Override public Dimension getPreferredSize() {
      return d;
    }
  };
  p.setLayout(new OverlayLayout(p));
  p.add(new CompoundButton(d, ButtonLocation.NORTH));
  p.add(new CompoundButton(d, ButtonLocation.SOUTH));
  p.add(new CompoundButton(d, ButtonLocation.EAST));
  p.add(new CompoundButton(d, ButtonLocation.WEST));
  p.add(new CompoundButton(d, ButtonLocation.CENTER));
  return p;
}

class CompoundButton extends JButton {
  protected final Color fc = new Color(100, 150, 255, 200);
  protected final Color ac = new Color(230, 230, 230);
  protected final Color rc = Color.ORANGE;
  protected Shape shape;
  protected Shape base = null;
  private final ButtonLocation bl;
  private final Dimension dim;
  public CompoundButton(Dimension d, ButtonLocation bl) {
    super();
    this.dim = d;
    this.bl = bl;
    setIcon(new Icon() {
      @Override public void paintIcon(Component c, Graphics g, int x, int y) {
        Graphics2D g2 = (Graphics2D) g.create();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);
        if (getModel().isArmed()) {
          g2.setColor(ac);
          g2.fill(shape);
        } else if (isRolloverEnabled() && getModel().isRollover()) {
          paintFocusAndRollover(g2, rc);
        } else if (hasFocus()) {
          paintFocusAndRollover(g2, fc);
        } else {
          g2.setColor(getBackground());
          g2.fill(shape);
        }
        g2.dispose();
      }

      @Override public int getIconWidth()  {
        return dim.width;
      }

      @Override public int getIconHeight() {
        return dim.height;
      }
    });
    setFocusPainted(false);
    setContentAreaFilled(false);
    setBackground(new Color(250, 250, 250));
    initShape();
  }

  @Override public Dimension getPreferredSize() {
    return dim;
  }

  protected void initShape() {
    if (!getBounds().equals(base)) {
      base = getBounds();
      float ww = getWidth() * .5f;
      float xx = ww * .5f;
      Shape inner = new Ellipse2D.Float(xx, xx, ww, ww);
      if (ButtonLocation.CENTER == bl) {
        shape = inner;
      } else {
        Shape outer = new Arc2D.Float(
          1, 1, getWidth() - 2, getHeight() - 2,
          bl.getStartDegree(), 90f, Arc2D.PIE);
        Area area = new Area(outer);
        area.subtract(new Area(inner));
        shape = area;
      }
    }
  }

  private void paintFocusAndRollover(Graphics2D g2, Color color) {
    g2.setPaint(new GradientPaint(
        0, 0, color, getWidth() - 1, getHeight() - 1, color.brighter(), true));
    g2.fill(shape);
    g2.setColor(getBackground());
  }

  @Override protected void paintComponent(Graphics g) {
    initShape();
    super.paintComponent(g);
  }

  @Override protected void paintBorder(Graphics g) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                        RenderingHints.VALUE_ANTIALIAS_ON);
    g2.setColor(getForeground());
    g2.draw(shape);
    g2.dispose();
  }

  @Override public boolean contains(int x, int y) {
    // initShape();
    return shape.contains(x, y);
  }
}