Swing/ToggleButtonBar のバックアップ(No.1)

enum Location {
  FIRST, CENTER, LAST;
}

class ToggleButtonBarCellIcon implements Icon {
  private static final Color TL = new Color(1f,1f,1f,.2f);
  private static final Color BR = new Color(0f,0f,0f,.2f);
  private static final Color ST = new Color(1f,1f,1f,.4f);
  private static final Color SB = new Color(1f,1f,1f,.1f);

  private Color ssc;
  private Color bgc;
  private Location l;
  public ToggleButtonBarCellIcon() {
    this(Location.CENTER);
  }
  public ToggleButtonBarCellIcon(Location l) {
    this.l = l;
  }
  @Override public void paintIcon(Component c, Graphics g, int x, int y) {
    int r = 8;
    int w = c.getWidth();
    int h = c.getHeight();

    Graphics2D g2 = (Graphics2D)g.create();
    g2.setRenderingHint(
        RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

    Path2D.Float p = new Path2D.Float();
    if(Location.CENTER.equals(l)) {
      p.moveTo(x, y);
      p.lineTo(x + w, y);
      p.lineTo(x + w, y + h);
      p.lineTo(x, y + h);
    } else if(Location.FIRST.equals(l)) {
      p.moveTo(x, y + r);
      p.quadTo(x, y, x + r, y);
      p.lineTo(x + w, y);
      p.lineTo(x + w, y + h);
      p.lineTo(x + r, y + h);
      p.quadTo(x, y + h, x, y + h - r);
    } else if(Location.LAST.equals(l)) {
      p.moveTo(x, y);
      p.lineTo(x + w - r, y);
      p.quadTo(x + w, y, x + w, y + r);
      p.lineTo(x + w, y + h - r);
      p.quadTo(x + w, y + h, x + w -r, y + h);
      p.lineTo(x, y + h);
    }
    p.closePath();
    Area area = new Area(p);

    g2.setPaint(c.getBackground());
    g2.fill(area);

    ssc = TL;
    bgc = BR;
    if(c instanceof AbstractButton) {
      ButtonModel m = ((AbstractButton)c).getModel();
      if(m.isSelected() || m.isRollover()) {
        ssc = ST;
        bgc = SB;
      }
    }
    g2.setPaint(new GradientPaint(x, y, ssc, x, y+h, bgc, true));
    g2.fill(area);

    g2.setPaint(BR);
    g2.draw(area);

    g2.dispose();
  }
  @Override public int getIconWidth()  {
    return 80;
  }
  @Override public int getIconHeight() {
    return 20;
  }
}