    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
    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