Swing/RotatedIcon のバックアップ(No.16)

class RotateIcon implements Icon {
  private final Dimension d = new Dimension();
  private final Image image;
  private AffineTransform trans;
  protected RotateIcon(Icon icon, int rotate) {
    if (rotate % 90 != 0) {
      throw new IllegalArgumentException(
        rotate + ": Rotate must be (rotate % 90 == 0)");
    }
    d.setSize(icon.getIconWidth(), icon.getIconHeight());
    image = new BufferedImage(d.width, d.height, BufferedImage.TYPE_INT_ARGB);
    Graphics g = image.getGraphics();
    icon.paintIcon(null, g, 0, 0);
    g.dispose();

    int numquadrants = (rotate / 90) % 4;
    if (numquadrants == 1 || numquadrants == -3) {
      trans = AffineTransform.getTranslateInstance(d.height, 0);
      int v = d.width;
      d.width = d.height;
      d.height = v;
    } else if (numquadrants == -1 || numquadrants == 3) {
      trans = AffineTransform.getTranslateInstance(0, d.width);
      int v = d.width;
      d.width = d.height;
      d.height = v;
    } else if (Math.abs(numquadrants) == 2) {
      trans = AffineTransform.getTranslateInstance(d.width, d.height);
    } else {
      trans = AffineTransform.getTranslateInstance(0, 0);
    }
    trans.rotate(Math.toRadians(90d * numquadrants));
    // trans.quadrantRotate(numquadrants);
  }

  @Override public void paintIcon(Component c, Graphics g, int x, int y) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.translate(x, y);
    g2.drawImage(image, trans, c);
    g2.dispose();
  }

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

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