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

private static void configureUI() {
  UIDefaults d = UIManager.getLookAndFeelDefaults();
  d.put("TabbedPane:TabbedPaneContent.contentMargins", new Insets(0, 5, 5, 5));
  //d.put("TabbedPane:TabbedPaneTab.contentMargins",     new Insets(2, 8, 3, 8));
  //d.put("TabbedPane:TabbedPaneTabArea.contentMargins", new Insets(3, 10, 4, 10));
  d.put("TabbedPane:TabbedPaneTabArea.contentMargins", new Insets(3, 10, OVERPAINT, 10));

  Painter<JComponent> tabAreaPainter = new TabAreaPainter();
  d.put("TabbedPane:TabbedPaneTabArea[Disabled].backgroundPainter",          tabAreaPainter);
  d.put("TabbedPane:TabbedPaneTabArea[Enabled].backgroundPainter",           tabAreaPainter);
  d.put("TabbedPane:TabbedPaneTabArea[Enabled+MouseOver].backgroundPainter", tabAreaPainter);
  d.put("TabbedPane:TabbedPaneTabArea[Enabled+Pressed].backgroundPainter",   tabAreaPainter);

  d.put("TabbedPane:TabbedPaneContent.backgroundPainter", new TabContentPainter());

  Painter<JComponent> tabPainter = new TabPainter(false);
  d.put("TabbedPane:TabbedPaneTab[Enabled+MouseOver].backgroundPainter", tabPainter);
  d.put("TabbedPane:TabbedPaneTab[Enabled+Pressed].backgroundPainter",   tabPainter);
  d.put("TabbedPane:TabbedPaneTab[Enabled].backgroundPainter",           tabPainter);

  Painter<JComponent> selectedTabPainter = new TabPainter(true);
  d.put("TabbedPane:TabbedPaneTab[Focused+MouseOver+Selected].backgroundPainter", selectedTabPainter);
  d.put("TabbedPane:TabbedPaneTab[Focused+Pressed+Selected].backgroundPainter",   selectedTabPainter);
  d.put("TabbedPane:TabbedPaneTab[Focused+Selected].backgroundPainter",           selectedTabPainter);
  d.put("TabbedPane:TabbedPaneTab[MouseOver+Selected].backgroundPainter",         selectedTabPainter);
  d.put("TabbedPane:TabbedPaneTab[Selected].backgroundPainter",                   selectedTabPainter);
  d.put("TabbedPane:TabbedPaneTab[Pressed+Selected].backgroundPainter",           selectedTabPainter);
}
public static void createAndShowGUI() {
  try {
    for (UIManager.LookAndFeelInfo laf : UIManager.getInstalledLookAndFeels()) {
      if ("Nimbus".equals(laf.getName())) {
        UIManager.setLookAndFeel(laf.getClassName());
        configureUI();
      }
    }
  } catch (ClassNotFoundException | InstantiationException
             | IllegalAccessException | UnsupportedLookAndFeelException ex) {
    ex.printStackTrace();
  }
  JFrame frame = new JFrame("@title@");
  frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
  frame.getContentPane().add(new MainPanel());
  frame.pack();
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
}
private static class TabPainter implements Painter<JComponent> {
  private final Color color;
  private final boolean selected;
  protected TabPainter(boolean selected) {
    this.selected = selected;
    this.color = selected ? Color.WHITE : Color.ORANGE;
  }
  @Override public void paint(Graphics2D g, JComponent c, int width, int height) {
    int a = selected ? OVERPAINT : 0;
    int r = 6;
    int x = 3;
    int y = 3;
    Graphics2D g2 = (Graphics2D) g.create(0, 0, width, height + a);
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    int w = width - r - 1;
    int h = height + r;
    for (int i = 0; i < x; i++) {
      g2.setColor(new Color(0, 0, 0, 20));
      g2.fill(new RoundRectangle2D.Double(x - i, y - i, w + i + i, h, r, r));
    }
    g2.setColor(color);
    g2.fill(new RoundRectangle2D.Double(x, y, w, h + OVERPAINT, r, r));
    if (selected) {
      g2.setColor(Color.GREEN);
      g2.fill(new Rectangle2D.Double(0, height + STROKE_SIZE, width, OVERPAINT));
    }
    g2.dispose();
  }
}
private static class TabAreaPainter implements Painter<JComponent> {
  @Override public void paint(Graphics2D g, JComponent c, int w, int h) {
    Graphics2D g2 = (Graphics2D) g.create(0, 0, w, h);
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

    RoundRectangle2D r = new RoundRectangle2D.Double(
      0, h - OVERPAINT,
      w - STROKE_SIZE,
      h - STROKE_SIZE,
      ARC, ARC);

    g2.setPaint(Color.WHITE);
    g2.fill(r);
    g2.setColor(Color.RED);
    g2.setStroke(new BasicStroke(STROKE_SIZE));
    g2.draw(r);
    g2.dispose();
  }
}
private static class TabContentPainter implements Painter<JComponent> {
  @Override public void paint(Graphics2D g, JComponent c, int w, int h) {
    Graphics2D g2 = (Graphics2D) g.create(0, 0, w, h);
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    g2.translate(0, -OVERPAINT);

    RoundRectangle2D r = new RoundRectangle2D.Double(
      0, 0,
      w - STROKE_SIZE,
      h - STROKE_SIZE + OVERPAINT,
      ARC, ARC);

    g2.setPaint(Color.WHITE);
    g2.fill(r);
    g2.setColor(Color.ORANGE);
    g2.setStroke(new BasicStroke(STROKE_SIZE));
    g2.draw(r);
    g2.dispose();
  }
}