/* ===========================================================
* JFreeChart : a free chart library for the Java(tm) platform
* ===========================================================
*
* (C) Copyright 2000-2012, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jfreechart/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
* Other names may be trademarks of their respective owners.]
*
* --------------------
* AbstractOverlay.java
* --------------------
* (C) Copyright 2009, by Object Refinery Limited.
*
* Original Author: David Gilbert (for Object Refinery Limited);
* Contributor(s): -;
*
* Changes:
* --------
* 09-Apr-2009 : Version 1 (DG);
*
*/
package org.jfree.chart.panel;
import javax.swing.event.EventListenerList;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.event.ChartChangeEvent;
import org.jfree.chart.event.OverlayChangeEvent;
import org.jfree.chart.event.OverlayChangeListener;
/**
* A base class for implementing overlays for a {@link ChartPanel}.
*
* @since 1.0.13
*/
public class AbstractOverlay {
/** Storage for registered change listeners. */
private transient EventListenerList changeListeners;
/**
* Default constructor.
*/
public AbstractOverlay() {
this.changeListeners = new EventListenerList();
}
/**
* Registers an object for notification of changes to the overlay.
*
* @param listener the listener (<code>null</code> not permitted).
*
* @see #removeChangeListener(OverlayChangeListener)
*/
public void addChangeListener(OverlayChangeListener listener) {
if (listener == null) {
throw new IllegalArgumentException("Null 'listener' argument.");
}
this.changeListeners.add(OverlayChangeListener.class, listener);
}
/**
* Deregisters an object for notification of changes to the overlay.
*
* @param listener the listener (<code>null</code> not permitted)
*
* @see #addChangeListener(OverlayChangeListener)
*/
public void removeChangeListener(OverlayChangeListener listener) {
if (listener == null) {
throw new IllegalArgumentException("Null 'listener' argument.");
}
this.changeListeners.remove(OverlayChangeListener.class, listener);
}
/**
* Sends a default {@link ChartChangeEvent} to all registered listeners.
* <P>
* This method is for convenience only.
*/
public void fireOverlayChanged() {
OverlayChangeEvent event = new OverlayChangeEvent(this);
notifyListeners(event);
}
/**
* Sends a {@link ChartChangeEvent} to all registered listeners.
*
* @param event information about the event that triggered the
* notification.
*/
protected void notifyListeners(OverlayChangeEvent event) {
Object[] listeners = this.changeListeners.getListenerList();
for (int i = listeners.length - 2; i >= 0; i -= 2) {
if (listeners[i] == OverlayChangeListener.class) {
((OverlayChangeListener) listeners[i + 1]).overlayChanged(
event);
}
}
}
}