Swing/CustomDecoratedFrame のバックアップ(No.10)

class ResizeWindowListener extends MouseAdapter {
  private Rectangle startSide = null;
  private final JFrame frame;
  public ResizeWindowListener(JFrame frame) {
    this.frame = frame;
  }
  @Override public void mousePressed(MouseEvent e) {
    startSide = frame.getBounds();
  }
  @Override public void mouseDragged(MouseEvent e) {
    if(startSide==null) return;
    Component c = e.getComponent();
    if(c==topleft) {
      startSide.y += e.getY();
      startSide.height -= e.getY();
      startSide.x += e.getX();
      startSide.width -= e.getX();
    }else if(c==top) {
      startSide.y += e.getY();
      startSide.height -= e.getY();
    }else if(c==topright) {
      startSide.y += e.getY();
      startSide.height -= e.getY();
      startSide.width += e.getX();
    }else if(c==left) {
      startSide.x += e.getX();
      startSide.width -= e.getX();
    }else if(c==right) {
      startSide.width += e.getX();
    }else if(c==bottomleft) {
      startSide.height += e.getY();
      startSide.x += e.getX();
      startSide.width -= e.getX();
    }else if(c==bottom) {
      startSide.height += e.getY();
    }else if(c==bottomright) {
      startSide.height += e.getY();
      startSide.width += e.getX();
    }
    frame.setBounds(startSide);
  }
}