using rubber band selection in JList

• download example.jar
• download src.zip
• repository

Code

class RubberBandSelectionList<E extends ListItem> extends JList<E> {
  private static final AlphaComposite ALPHA =
    AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .1f);
  private RubberBandListCellRenderer<E> renderer;
  private Color polygonColor;
  public RubberBandSelectionList(ListModel<E> model) {
    super(model);
  }

  @Override public void updateUI() {
    setSelectionForeground(null);
    setSelectionBackground(null);
    setCellRenderer(null);
    if (renderer == null) {
      renderer = new RubberBandListCellRenderer<E>();
    } else {
      removeMouseMotionListener(renderer);
      removeMouseListener(renderer);
    }
    super.updateUI();
    EventQueue.invokeLater(() -> {
      setCellRenderer(renderer);
      addMouseMotionListener(renderer);
      addMouseListener(renderer);
      setLayoutOrientation(JList.HORIZONTAL_WRAP);
      setVisibleRowCount(0);
      setFixedCellWidth(62);
      setFixedCellHeight(62);
      setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
    });
    Color c = getSelectionBackground();
    int r = c.getRed();
    int g = c.getGreen();
    int b = c.getBlue();
    polygonColor = r > g ? r > b ? new Color(r, 0, 0) : new Color(0, 0, b)
                         : g > b ? new Color(0, g, 0) : new Color(0, 0, b);
  }

  @Override protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    if (renderer != null && renderer.polygon != null) {
      Graphics2D g2 = (Graphics2D) g.create();
      g2.setPaint(getSelectionBackground());
      g2.draw(renderer.polygon);
      g2.setComposite(ALPHA);
      g2.setPaint(polygonColor);
      g2.fill(renderer.polygon);
      g2.dispose();
    }
  }
}

References

• XP Style Icons - Windows Application Icon, Software XP Icons
• using rubber band selection in JList(Japanese)
• rubber band selection, drag and drop reordering