001    /* PopupFactory.java --
002       Copyright (C) 2003 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.swing;
040    
041    import java.awt.Component;
042    import java.awt.Dimension;
043    import java.awt.Point;
044    
045    
046    /**
047     * A factory for <code>Popup</code> objects. These are used to
048     * managed little windows that float over everything else,
049     * typically containing a popup menu.
050     *
051     * @since 1.4
052     *
053     * @author Sascha Brawer (brawer@dandelis.ch)
054     */
055    public class PopupFactory
056    {
057      /**
058       * The shared factory object.
059       *
060       * @see #getSharedInstance
061       * @see #setSharedInstance
062       */
063      private static PopupFactory sharedFactory;
064    
065    
066      /**
067       * Constructs a new <code>PopupFactory</code>. Usually, a single
068       * <code>PopupFactory</code> is shared among multiple consumers
069       * of <code>Popup</code>. Use {@link #getSharedInstance} to retrieve
070       * the current factory.
071       */
072      public PopupFactory()
073      {
074        // Nothing to do here.
075      }
076    
077    
078      /**
079       * Sets the shared factory.
080       *
081       * @param factory the PopupFactory that future invocations of
082       *        {@link #getSharedInstance} will return.
083       *
084       * @throws IllegalArgumentException if <code>factory</code>
085       *         is <code>null</code>.
086       */
087      public static void setSharedInstance(PopupFactory factory)
088      {
089        if (factory == null)
090          throw new IllegalArgumentException();
091    
092        /* Swing is not designed to be thread-safe, so there is no
093         * need to synchronize the access to the global variable.
094         */
095        sharedFactory = factory;
096      }
097    
098    
099      /**
100       * Retrieves the shared factory, creating a new factory if
101       * necessary.
102       *
103       * @return a <code>PopupFactory</code> that can be used
104       *         to create <code>Popup</code> objects.
105       */
106      public static PopupFactory getSharedInstance()
107      {
108        /* Swing is not designed to be thread-safe, so there is no
109         * need to synchronize the access to the global variable.
110         */
111        if (sharedFactory == null)
112          sharedFactory = new PopupFactory();
113    
114        return sharedFactory;
115      }
116    
117    
118      /**
119       * Creates a new <code>Popup</code> given its owner,
120       * contents and the screen position where the popup
121       * will appear.
122       *
123       * @param owner the Component to which <code>x</code> and
124       *        <code>y</code> are relative, or <code>null</code> for
125       *        placing the popup relative to the origin of the screen.
126       *
127       * @param contents the contents that will be displayed inside
128       *        the <code>Popup</code>.
129       *
130       * @param x the horizontal position where the Popup will appear.
131       *
132       * @param y the vertical position where the Popup will appear.
133       *
134       * @throws IllegalArgumentException if <code>contents</code>
135       *         is <code>null</code>.
136       */
137      public Popup getPopup(Component owner, Component contents,
138                            int x, int y)
139      {
140        Popup popup = null;
141        // By default we enable lightweight popups since they are more efficient
142        // than heavyweight popups.
143        boolean lightweightEnabled = true;
144        // Special case JPopupMenu here, since it supports a lightweightEnabled
145        // flag that we must respect.
146        if (contents instanceof JPopupMenu)
147          {
148            JPopupMenu menu = (JPopupMenu) contents;
149            lightweightEnabled = menu.isLightWeightPopupEnabled();
150          }
151    
152        // If we have a root pane and the contents fits within the root pane and
153        // lightweight popups are enabled, than we can use a lightweight popup.
154        JRootPane root = SwingUtilities.getRootPane(owner);
155        if (root != null)
156          {
157            Point rootLoc = root.getLocationOnScreen();
158            Dimension contentsSize = contents.getSize();
159            Dimension rootSize = root.getSize();
160            if (x >= rootLoc.x && y > rootLoc.y
161                && (x - rootLoc.x) + contentsSize.width < rootSize.width
162                && (y - rootLoc.y) + contentsSize.height < rootSize.height)
163              popup = new Popup.LightweightPopup(owner, contents, x, y);
164            else
165              popup = new Popup.JWindowPopup(owner, contents, x, y);
166          }
167        else
168          popup = new Popup.JWindowPopup(owner, contents, x, y);
169        return popup;
170      }
171    }