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 1.6 2007/11/02 17:50:36 taqua 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;
047import javax.swing.text.JTextComponent;
048
049/**
050 * An observer that selects all the text when a field gains the focus.
051 *
052 * @author Thomas Morgner
053 */
054public final class JTextObserver implements FocusListener {
055
056    /** The singleton instance. */
057    private static JTextObserver singleton;
058
059    /**
060     * Creates a new instance.
061     */
062    private JTextObserver() {
063        // nothing required
064    }
065
066    /**
067     * Returns the single instance.
068     * 
069     * @return The single instance.
070     */
071    public static JTextObserver getInstance() {
072        if (singleton == null) {
073           singleton = new JTextObserver();
074        }
075        return singleton;
076    }
077
078    /**
079     * Selects all the text when a field gains the focus.
080     * 
081     * @param e  the focus event.
082     */
083    public void focusGained(final FocusEvent e) {
084        if (e.getSource() instanceof JTextComponent) {
085            final JTextComponent tex = (JTextComponent) e.getSource();
086            tex.selectAll();
087        }
088    }
089
090    /**
091     * Deselects the text when a field loses the focus.
092     * 
093     * @param e  the event.
094     */
095    public void focusLost(final FocusEvent e) {
096        if (e.getSource() instanceof JTextComponent) {
097            final JTextComponent tex = (JTextComponent) e.getSource();
098            tex.select(0, 0);
099        }
100    }
101
102    /**
103     * Adds this instance as a listener for the specified text component.
104     * 
105     * @param t  the text component.
106     */
107    public static void addTextComponent(final JTextComponent t) {
108        if (singleton == null) {
109            singleton = new JTextObserver();
110        }
111        t.addFocusListener(singleton);
112    }
113
114    /**
115     * Removes this instance as a listener for the specified text component.
116     * 
117     * @param t  the text component.
118     */
119   public static void removeTextComponent(final JTextComponent t) {
120        if (singleton == null) {
121            singleton = new JTextObserver();
122        }
123        t.removeFocusListener(singleton);
124    }
125    
126}