Swing/CheckBoxRolloverIcon のバックアップ(No.1)

// UIManager
class CheckBoxIcon implements Icon {
  private final Icon checkIcon = UIManager.getIcon("CheckBox.icon");

  @Override public void paintIcon(Component c, Graphics g, int x, int y) {
    if (c instanceof AbstractButton) {
      Graphics2D g2 = (Graphics2D) g.create();
      g2.translate(x, y);
      AbstractButton b = (AbstractButton) c;
      ButtonModel model = b.getModel();
      if (!model.isSelected() && model.isRollover()) {
        checkIcon.paintIcon(c, g2, 0, 0);
        g2.setComposite(AlphaComposite.getInstance(
            AlphaComposite.SRC_OVER, .2f));
        b.setSelected(true);
        checkIcon.paintIcon(b, g2, 0, 0);
        b.setSelected(false);
      } else {
        checkIcon.paintIcon(c, g2, 0, 0);
      }
      g2.dispose();
    }
  }

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

  @Override public int getIconHeight() {
    return checkIcon.getIconHeight();
  }
}

// UIDefaults
JCheckBox check3 = new JCheckBox("UIDefaults CheckBox[MouseOver].iconPainter") {
  @Override public void updateUI() {
    super.updateUI();
    UIDefaults d = UIManager.getLookAndFeelDefaults();
    Painter<JCheckBox> painter0 = getIconPainter(d, "Focused+Selected");
    Painter<JCheckBox> painter1 = getIconPainter(d, "MouseOver");
    Painter<JCheckBox> painter2 = (g, object, width, height) -> {
      painter1.paint(g, object, width, height);
      Graphics2D g2 = (Graphics2D) g.create();
      g2.setPaint(Color.WHITE);
      g2.setComposite(AlphaComposite.getInstance(
          AlphaComposite.SRC_OVER, .2f));
      object.setSelected(true);
      painter0.paint(g2, object, width, height);
      object.setSelected(false);
      g2.dispose();
    };
    d.put("CheckBox[MouseOver].iconPainter", painter2);
    d.put("CheckBox[Focused+MouseOver].iconPainter", painter2);
    putClientProperty("Nimbus.Overrides", d);
    putClientProperty("Nimbus.Overrides.InheritDefaults", true);
  }
};