JTableのセル選択を半透明化して上書き

class TranslucentCellSelectionLayerUI extends LayerUI<JScrollPane> {
  private static final Stroke BORDER_STROKE = new BasicStroke(2f);

  @Override public void paint(Graphics g, JComponent c) {
    super.paint(g, c);
    JTable table = getTable(c);
    int cc = table.getSelectedColumnCount();
    int rc = table.getSelectedRowCount();
    if (cc != 0 && rc != 0 && !table.isEditing()) {
      Graphics2D g2 = (Graphics2D) g.create();
      g2.setRenderingHint(
          RenderingHints.KEY_ANTIALIASING,
          RenderingHints.VALUE_ANTIALIAS_ON);
      Area area = new Area();
      for (int row : table.getSelectedRows()) {
        for (int col : table.getSelectedColumns()) {
          addArea(c, table, area, row, col);
        }
      }
      Dimension ics = table.getIntercellSpacing();
      Color v = table.getSelectionBackground();
      Color sbc = new Color(v.getRed(), v.getGreen(), v.getBlue(), 0x32);
      for (Area a : GeomUtils.singularization(area)) {
        Rectangle r = a.getBounds();
        r.width -= ics.width - 1;
        r.height -= ics.height - 1;
        g2.setPaint(sbc);
        g2.fill(r);
        g2.setPaint(v);
        g2.setStroke(BORDER_STROKE);
        g2.draw(r);
      }
      g2.dispose();
    }
  }

  private static void addArea(Component c, JTable table, Area area, int row, int col) {
    if (table.isCellSelected(row, col)) {
      Rectangle r = table.getCellRect(row, col, true);
      area.add(new Area(SwingUtilities.convertRectangle(table, r, c)));
    }
  }

  private static JTable getTable(Component c) {
    JTable table = null;
    if (c instanceof JLayer) {
      Component c1 = ((JLayer<?>) c).getView();
      if (c1 instanceof JScrollPane) {
        table = (JTable) ((JScrollPane) c1).getViewport().getView();
      }
    }
    return table;
  }
}