Swing/ClippedTitleTab のバックアップ(No.21)

final Insets tabInsets = UIManager.getInsets("TabbedPane.tabInsets");
tab1.setUI(new BasicTabbedPaneUI() {
  @Override protected int calculateTabWidth(
      int tabPlacement, int tabIndex, FontMetrics metrics) {
    Insets insets = tabPane.getInsets();
    Insets tabAreaInsets = getTabAreaInsets(tabPlacement);
    int width = tabPane.getWidth() - insets.left - insets.right
                                   - tabAreaInsets.left - tabAreaInsets.right;
    switch (tabPlacement) {
      case LEFT: case RIGHT:
        return (int) (width / 4);
      case BOTTOM: case TOP: default:
        return (int) (width / tabPane.getTabCount());
      }
  }
  @Override protected void paintText(
      Graphics g, int tabPlacement, Font font, FontMetrics metrics,
      int tabIndex, String title, Rectangle textRect, boolean isSelected) {
    Rectangle tabRect = rects[tabIndex];
    Rectangle rect = new Rectangle(textRect.x + tabInsets.left, textRect.y,
      tabRect.width - tabInsets.left - tabInsets.right, textRect.height);
    String clippedText = SwingUtilities.layoutCompoundLabel(metrics, title, null,
                                    SwingUtilities.CENTER, SwingUtilities.CENTER,
                                    SwingUtilities.CENTER, SwingUtilities.TRAILING,
                                    rect, new Rectangle(), rect, 0);
    if (title.equals(clippedText)) {
      super.paintText(g, tabPlacement, font, metrics, tabIndex,
                      title, textRect, isSelected);
    } else {
      rect = new Rectangle(textRect.x + tabInsets.left, textRect.y,
        tabRect.width - tabInsets.left - tabInsets.right, textRect.height);
      super.paintText(g, tabPlacement, font, metrics, tabIndex,
                      clippedText, rect, isSelected);
    }
  }
});