1 /*
   2  * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package javax.swing.plaf.basic;
  27 
  28 import javax.swing.*;
  29 import javax.swing.plaf.UIResource;
  30 
  31 import java.awt.Container;
  32 import java.awt.Dimension;
  33 
  34 /**
  35  * The default layout manager for Popup menus and menubars.  This
  36  * class is an extension of BoxLayout which adds the UIResource tag
  37  * so that pluggable L&Fs can distinguish it from user-installed
  38  * layout managers on menus.
  39  *
  40  * @author Georges Saab
  41  */
  42 
  43 public class DefaultMenuLayout extends BoxLayout implements UIResource {
  44     public DefaultMenuLayout(Container target, int axis) {
  45         super(target, axis);
  46     }
  47 
  48     public Dimension preferredLayoutSize(Container target) {
  49         if (target instanceof JPopupMenu) {
  50             JPopupMenu popupMenu = (JPopupMenu) target;
  51             sun.swing.MenuItemLayoutHelper.clearUsedClientProperties(popupMenu);
  52             if (popupMenu.getComponentCount() == 0) {
  53                 return new Dimension(0, 0);
  54             }
  55         }
  56 
  57         // Make BoxLayout recalculate cached preferred sizes
  58         super.invalidateLayout(target);
  59 
  60         return super.preferredLayoutSize(target);
  61     }
  62 }