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    
043    package org.jfree.ui;
044    
045    import java.awt.event.FocusEvent;
046    import java.awt.event.FocusListener;
047    
048    import 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     */
055    public 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    }