Iconを生成する

class DragHereIcon implements Icon {
  private static int ICON_SIZE = 100;
  private static float BORDER_WIDTH = 8f;
  private static float SLIT_WIDTH = 8f;
  private static int ARC_SIZE = 16;
  private static int SLIT_NUM = 3;
  private static Shape BORDER = new RoundRectangle2D.Float(
    BORDER_WIDTH, BORDER_WIDTH,
    ICON_SIZE - 2 * BORDER_WIDTH - 1, ICON_SIZE-2*BORDER_WIDTH - 1,
    ARC_SIZE, ARC_SIZE);
  private static Font font = new Font(Font.MONOSPACED, Font.BOLD, ICON_SIZE);
  private static FontRenderContext frc = new FontRenderContext(null, true, true);
  // DOWNWARDS WHITE ARROW
  private static Shape ARROW = new TextLayout("\u21E9", font, frc).getOutline(null);
  // DOWNWARDS BLACK ARROW
  // private static Shape ARROW = new TextLayout("\u2B07", font, frc).getOutline(null);
  private static Color LINE_COLOR = Color.GRAY;
  @Override public void paintIcon(Component c, Graphics g, int x, int y) {
    Graphics2D g2 = (Graphics2D) g.create();
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                        RenderingHints.VALUE_ANTIALIAS_ON);
    g2.translate(x, y);

    g2.setStroke(new BasicStroke(BORDER_WIDTH));
    g2.setPaint(LINE_COLOR);
    g2.draw(BORDER);

    g2.setStroke(new BasicStroke(SLIT_WIDTH));
    g2.setColor(UIManager.getColor("Panel.background"));

    int n = SLIT_NUM + 1;
    int v = ICON_SIZE / n;
    int m = n * v;
    for (int i = 1; i < n; i++) {
      int a = i * v;
      g2.drawLine(a, 0, a, m);
      g2.drawLine(0, a, m, a);
    }

    // g2.drawLine(1 * v, 0 * v, 1 * v, 4 * v);
    // g2.drawLine(2 * v, 0 * v, 2 * v, 4 * v);
    // g2.drawLine(3 * v, 0 * v, 3 * v, 4 * v);
    // g2.drawLine(0 * v, 1 * v, 4 * v, 1 * v);
    // g2.drawLine(0 * v, 2 * v, 4 * v, 2 * v);
    // g2.drawLine(0 * v, 3 * v, 4 * v, 3 * v);

    g2.setPaint(LINE_COLOR);
    Rectangle2D b = ARROW.getBounds2D();
    Point2D p = new Point2D.Double(
        b.getX() + b.getWidth() / 2d, b.getY() + b.getHeight() / 2d);
    AffineTransform toCenterAT = AffineTransform.getTranslateInstance(
        ICON_SIZE / 2d - p.getX(), ICON_SIZE / 2d - p.getY());
    g2.fill(toCenterAT.createTransformedShape(ARROW));
    g2.dispose();
  }

  @Override public int getIconWidth()  {
    return ICON_SIZE;
  }

  @Override public int getIconHeight() {
    return ICON_SIZE;
  }
}