001 /* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
006 *
007 * Project Info: http://www.jfree.org/jfreechart/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 * AbstractOverlay.java
029 * --------------------
030 * (C) Copyright 2009, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * Changes:
036 * --------
037 * 09-Apr-2009 : Version 1 (DG);
038 *
039 */
040
041 package org.jfree.chart.panel;
042
043 import javax.swing.event.EventListenerList;
044 import org.jfree.chart.ChartPanel;
045 import org.jfree.chart.event.ChartChangeEvent;
046 import org.jfree.chart.event.OverlayChangeEvent;
047 import org.jfree.chart.event.OverlayChangeListener;
048
049 /**
050 * A base class for implementing overlays for a {@link ChartPanel}.
051 *
052 * @since 1.0.13
053 */
054 public class AbstractOverlay {
055
056 /** Storage for registered change listeners. */
057 private transient EventListenerList changeListeners;
058
059 /**
060 * Default constructor.
061 */
062 public AbstractOverlay() {
063 this.changeListeners = new EventListenerList();
064 }
065
066 /**
067 * Registers an object for notification of changes to the overlay.
068 *
069 * @param listener the listener (<code>null</code> not permitted).
070 *
071 * @see #removeChangeListener(OverlayChangeListener)
072 */
073 public void addChangeListener(OverlayChangeListener listener) {
074 if (listener == null) {
075 throw new IllegalArgumentException("Null 'listener' argument.");
076 }
077 this.changeListeners.add(OverlayChangeListener.class, listener);
078 }
079
080 /**
081 * Deregisters an object for notification of changes to the overlay.
082 *
083 * @param listener the listener (<code>null</code> not permitted)
084 *
085 * @see #addChangeListener(OverlayChangeListener)
086 */
087 public void removeChangeListener(OverlayChangeListener listener) {
088 if (listener == null) {
089 throw new IllegalArgumentException("Null 'listener' argument.");
090 }
091 this.changeListeners.remove(OverlayChangeListener.class, listener);
092 }
093
094 /**
095 * Sends a default {@link ChartChangeEvent} to all registered listeners.
096 * <P>
097 * This method is for convenience only.
098 */
099 public void fireOverlayChanged() {
100 OverlayChangeEvent event = new OverlayChangeEvent(this);
101 notifyListeners(event);
102 }
103
104 /**
105 * Sends a {@link ChartChangeEvent} to all registered listeners.
106 *
107 * @param event information about the event that triggered the
108 * notification.
109 */
110 protected void notifyListeners(OverlayChangeEvent event) {
111 Object[] listeners = this.changeListeners.getListenerList();
112 for (int i = listeners.length - 2; i >= 0; i -= 2) {
113 if (listeners[i] == OverlayChangeListener.class) {
114 ((OverlayChangeListener) listeners[i + 1]).overlayChanged(
115 event);
116 }
117 }
118 }
119
120 }
121