Swing/ClearSelection のバックアップ(No.5)

class ClearSelectionListener extends MouseAdapter {
  private static void clearSelectionAndFocus(JList list) {
    list.clearSelection();
    list.getSelectionModel().setAnchorSelectionIndex(-1);
    list.getSelectionModel().setLeadSelectionIndex(-1);
  }
  private static boolean contains(JList list, Point pt) {
    for(int i=0;i<list.getModel().getSize();i++) {
      Rectangle r = list.getCellBounds(i, i);
      if(r.contains(pt)) return true;
    }
    return false;
  }
  private boolean startOutside = false;
  @Override public void mousePressed(MouseEvent e) {
    JList list = (JList)e.getSource();
    startOutside = !contains(list, e.getPoint());
    if(startOutside) {
      clearSelectionAndFocus(list);
    }
  }
  @Override public void mouseReleased(MouseEvent e) {
    startOutside = false;
  }
  @Override public void mouseDragged(MouseEvent e) {
    JList list = (JList)e.getSource();
    if(contains(list, e.getPoint())) {
      startOutside = false;
    }else if(startOutside) {
      clearSelectionAndFocus(list);
    }
  }
}