001/* ========================================================================
002 * JCommon : a free general purpose class library for the Java(tm) platform
003 * ========================================================================
004 *
005 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
006 * 
007 * Project Info:  http://www.jfree.org/jcommon/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it 
010 * under the terms of the GNU Lesser General Public License as published by 
011 * the Free Software Foundation; either version 2.1 of the License, or 
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but 
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022 * USA.  
023 *
024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025 * in the United States and other countries.]
026 * 
027 * ------------------
028 * JTextObserver.java
029 * ------------------
030 * (C) Copyright 2004, by Thomas Morgner and Contributors.
031 *
032 * Original Author:  Thomas Morgner;
033 * Contributor(s):   David Gilbert (for Object Refinery Limited);
034 *
035 * $Id: JTextObserver.java,v 1.5 2005/10/18 13:18:34 mungady Exp $
036 *
037 * Changes
038 * -------
039 * 07-Jun-2004 : Added JCommon header (DG);
040 *
041 */
042
043package org.jfree.ui;
044
045import java.awt.event.FocusEvent;
046import java.awt.event.FocusListener;
047
048import javax.swing.text.JTextComponent;
049
050/**
051 * An observer that selects all the text when a field gains the focus.
052 *
053 * @author Thomas Morgner
054 */
055public final class JTextObserver implements FocusListener {
056
057    /** The singleton instance. */
058    private static JTextObserver singleton;
059
060    /**
061     * Creates a new instance.
062     */
063    private JTextObserver() {
064        // nothing required
065    }
066
067    /**
068     * Returns the single instance.
069     * 
070     * @return The single instance.
071     */
072    public static JTextObserver getInstance() {
073        if (singleton == null) {
074           singleton = new JTextObserver();
075        }
076        return singleton;
077    }
078
079    /**
080     * Selects all the text when a field gains the focus.
081     * 
082     * @param e  the focus event.
083     */
084    public void focusGained(final FocusEvent e) {
085        if (e.getSource() instanceof JTextComponent) {
086            final JTextComponent tex = (JTextComponent) e.getSource();
087            tex.selectAll();
088        }
089    }
090
091    /**
092     * Deselects the text when a field loses the focus.
093     * 
094     * @param e  the event.
095     */
096    public void focusLost(final FocusEvent e) {
097        if (e.getSource() instanceof JTextComponent) {
098            final JTextComponent tex = (JTextComponent) e.getSource();
099            tex.select(0, 0);
100        }
101    }
102
103    /**
104     * Adds this instance as a listener for the specified text component.
105     * 
106     * @param t  the text component.
107     */
108    public static void addTextComponent(final JTextComponent t) {
109        if (singleton == null) {
110            singleton = new JTextObserver();
111        }
112        t.addFocusListener(singleton);
113    }
114
115    /**
116     * Removes this instance as a listener for the specified text component.
117     * 
118     * @param t  the text component.
119     */
120   public static void removeTextComponent(final JTextComponent t) {
121        if (singleton == null) {
122            singleton = new JTextObserver();
123        }
124        t.removeFocusListener(singleton);
125    }
126    
127}