TITLE:JComboBoxの角を丸める

Posted by aterai at 2012-04-23

JComboBoxの角を丸める

JComboBoxの左上、右上の角を丸めるBorderを設定します。

  • &jnlp;
  • &jar;
  • &zip;
RoundedComboBox.png

サンプルコード

class RoundedCornerBorder2 extends AbstractBorder {
  @Override public void paintBorder(
    Component c, Graphics g, int x, int y, int width, int height) {
    Graphics2D g2 = (Graphics2D)g.create();
    int r = 12;

    int w = width  - 1;
    int h = height - 1;
    Path2D.Float p = new Path2D.Float();
    p.moveTo(x, y + h);
    p.lineTo(x, y + r);
    p.quadTo(x, y, x + r, y);
    p.lineTo(x + w - r, y);
    p.quadTo(x + w, y, x + w, y + r);
    p.lineTo(x + w, y + h);
    p.closePath();
    Area round = new Area(p);

    Container parent = c.getParent();
    if(parent!=null) {
      g2.setColor(parent.getBackground());
      Area corner = new Area(new Rectangle2D.Float(x, y, width, height));
      corner.subtract(round);
      g2.fill(corner);
    }
    g2.setPaint(c.getForeground());
    g2.draw(round);
    g2.dispose();
  }
  @Override public Insets getBorderInsets(Component c) {
    return new Insets(4, 8, 4, 8);
  }
  @Override public Insets getBorderInsets(Component c, Insets insets) {
    insets.left = insets.right = 8;
    insets.top = insets.bottom = 4;
    return insets;
  }
}
View in GitHub: Java, Kotlin

解説

  • 上、中
    • RoundRectangle2D に、下の角を上書きするような矩形を追加して作成
Area round = new Area(new RoundRectangle2D.Float(x, y, width-1, height-1, r, r));
Rectangle b = round.getBounds();
b.setBounds(b.x, b.y + r, b.width, b.height - r);
round.add(new Area(b));
    • Path2D#lineTo, Path2D#quadTo で作成

参考リンク

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