    001/* ===========================================================
    002 * JFreeChart : a free chart library for the Java(tm) platform
    003 * ===========================================================
    004 *
    005 * (C) Copyright 2000-2011, 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 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
    025 * Other names may be trademarks of their respective owners.]
    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
    041package org.jfree.chart.panel;
    042
    043import javax.swing.event.EventListenerList;
    044import org.jfree.chart.ChartPanel;
    045import org.jfree.chart.event.ChartChangeEvent;
    046import org.jfree.chart.event.OverlayChangeEvent;
    047import 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 */
    054public 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