Swing/RollOverTree のバックアップ(No.10)

class MyTreeCellRenderer extends DefaultTreeCellRenderer implements MouseMotionListener {
  private static final Color rollOverRowColor = new Color(220, 240, 255);
  private final JTree tree;
  private final TreeCellRenderer renderer;
  public MyTreeCellRenderer(JTree tree, TreeCellRenderer renderer) {
    this.tree = tree;
    this.renderer = renderer;
    tree.addMouseMotionListener(this);
  }
  @Override public Component getTreeCellRendererComponent(
          JTree tree, Object value, boolean isSelected,
          boolean expanded, boolean leaf, int row, boolean hasFocus) {
    JComponent c = (JComponent) renderer.getTreeCellRendererComponent(
        tree, value, isSelected, expanded, leaf, row, hasFocus);
    if (row == rollOverRowIndex) {
      c.setOpaque(true);
      c.setBackground(rollOverRowColor);
      if (isSelected) {
        c.setForeground(getTextNonSelectionColor());
      }
    } else {
      c.setOpaque(false);
    }
    return c;
  }
  private int rollOverRowIndex = -1;
  @Override public void mouseMoved(MouseEvent e) {
    int row = tree.getRowForLocation(e.getX(), e.getY());
    if (row != rollOverRowIndex) {
      //System.out.println(row);
      rollOverRowIndex = row;
      tree.repaint();
    }
  }
  @Override public void mouseDragged(MouseEvent e) {}
}