Swing/CarouselCardLayout のバックアップ(No.4)

CardLayout cardLayout = new CardLayout(50, 5);

JPanel cards = new JPanel(cardLayout) {
  @Override protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    for (Component c: getComponents()) {
      if (c.isVisible()) {
        paintSideComponents(g, getComponentZOrder(c));
        return;
      }
    }
  }

  private void paintSideComponents(Graphics g, int current) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setComposite(AlphaComposite.SrcOver.derive(.5f));
    Insets insets = getInsets();
    int hgap = cardLayout.getHgap();
    int vgap = cardLayout.getVgap();
    int cw = getWidth() - (hgap * 2 + insets.left + insets.right);
    // int ch = getHeight() - (vgap * 2 + insets.top + insets.bottom);
    int gap = 10;
    int nc = getComponentCount();

    g2.translate(hgap + insets.left - cw - gap, vgap + insets.top);
    Component prev = getComponent(current > 0 ? current - 1 : nc - 1);
    prev.print(g2);

    g2.translate((cw + gap) * 2, 0);
    Component next = getComponent((current + 1) % nc);
    next.print(g2);

    g2.dispose();
  }
};