    001    /* ===========================================================
    002     * JFreeChart : a free chart library for the Java(tm) platform
    003     * ===========================================================
    004     *
    005     * (C) Copyright 2000-2007, 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     * AbstractDialLayer.java
    029     * ----------------------
    030     * (C) Copyright 2006-2007, by Object Refinery Limited.
    031     *
    032     * Original Author:  David Gilbert (for Object Refinery Limited);
    033     * Contributor(s):   -;
    034     *
    035     * Changes
    036     * -------
    037     * 06-Nov-2006 : Version 1 (DG);
    038     * 17-Nov-2006 : Added visible flag (DG);
    039     * 16-Oct-2007 : Implemented equals() and clone() (DG);
    040     *
    041     */
    042
    043    package org.jfree.chart.plot.dial;
    044
    045    import java.io.IOException;
    046    import java.io.ObjectInputStream;
    047    import java.util.Arrays;
    048    import java.util.EventListener;
    049    import java.util.List;
    050
    051    import javax.swing.event.EventListenerList;
    052
    053    import org.jfree.chart.HashUtilities;
    054
    055    /**
    056     * A base class that can be used to implement a {@link DialLayer}.  It includes
    057     * an event notification mechanism.
    058     *
    059     * @since 1.0.7
    060     */
    061    public abstract class AbstractDialLayer implements DialLayer {
    062
    063        /** A flag that controls whether or not the layer is visible. */
    064        private boolean visible;
    065
    066        /** Storage for registered listeners. */
    067        private transient EventListenerList listenerList;
    068
    069        /**
    070         * Creates a new instance.
    071         */
    072        protected AbstractDialLayer() {
    073            this.visible = true;
    074            this.listenerList = new EventListenerList();
    075        }
    076
    077        /**
    078         * Returns <code>true</code> if this layer is visible (should be displayed),
    079         * and <code>false</code> otherwise.
    080         *
    081         * @return A boolean.
    082         *
    083         * @see #setVisible(boolean)
    084         */
    085        public boolean isVisible() {
    086            return this.visible;
    087        }
    088
    089        /**
    090         * Sets the flag that determines whether or not this layer is drawn by
    091         * the plot, and sends a {@link DialLayerChangeEvent} to all registered
    092         * listeners.
    093         *
    094         * @param visible  the flag.
    095         *
    096         * @see #isVisible()
    097         */
    098        public void setVisible(boolean visible) {
    099            this.visible = visible;
    100            notifyListeners(new DialLayerChangeEvent(this));
    101        }
    102
    103        /**
    104         * Tests this instance for equality with an arbitrary object.
    105         *
    106         * @param obj  the object (<code>null</code> permitted).
    107         *
    108         * @return A boolean.
    109         */
    110        public boolean equals(Object obj) {
    111            if (obj == this) {
    112                return true;
    113            }
    114            if (!(obj instanceof AbstractDialLayer)) {
    115                return false;
    116            }
    117            AbstractDialLayer that = (AbstractDialLayer) obj;
    118            return this.visible == that.visible;
    119        }
    120
    121        /**
    122         * Returns a hash code for this instance.
    123         *
    124         * @return A hash code.
    125         */
    126        public int hashCode() {
    127            int result = 23;
    128            result = HashUtilities.hashCode(result, this.visible);
    129            return result;
    130        }
    131
    132        /**
    133         * Returns a clone of this instance.
    134         *
    135         * @return A clone.
    136         *
    137         * @throws CloneNotSupportedException if there is a problem cloning this
    138         *     instance.
    139         */
    140        public Object clone() throws CloneNotSupportedException {
    141            AbstractDialLayer clone = (AbstractDialLayer) super.clone();
    142            // we don't clone the listeners
    143            clone.listenerList = new EventListenerList();
    144            return clone;
    145        }
    146
    147        /**
    148         * Registers an object for notification of changes to the dial layer.
    149         *
    150         * @param listener  the object that is being registered.
    151         *
    152         * @see #removeChangeListener(DialLayerChangeListener)
    153         */
    154        public void addChangeListener(DialLayerChangeListener listener) {
    155            this.listenerList.add(DialLayerChangeListener.class, listener);
    156        }
    157
    158        /**
    159         * Deregisters an object for notification of changes to the dial layer.
    160         *
    161         * @param listener  the object to deregister.
    162         *
    163         * @see #addChangeListener(DialLayerChangeListener)
    164         */
    165        public void removeChangeListener(DialLayerChangeListener listener) {
    166            this.listenerList.remove(DialLayerChangeListener.class, listener);
    167        }
    168
    169        /**
    170         * Returns <code>true</code> if the specified object is registered with
    171         * the dataset as a listener.  Most applications won't need to call this
    172         * method, it exists mainly for use by unit testing code.
    173         *
    174         * @param listener  the listener.
    175         *
    176         * @return A boolean.
    177         */
    178        public boolean hasListener(EventListener listener) {
    179            List list = Arrays.asList(this.listenerList.getListenerList());
    180            return list.contains(listener);
    181        }
    182
    183        /**
    184         * Notifies all registered listeners that the dial layer has changed.
    185         * The {@link DialLayerChangeEvent} provides information about the change.
    186         *
    187         * @param event  information about the change to the axis.
    188         */
    189        protected void notifyListeners(DialLayerChangeEvent event) {
    190            Object[] listeners = this.listenerList.getListenerList();
    191            for (int i = listeners.length - 2; i >= 0; i -= 2) {
    192                if (listeners[i] == DialLayerChangeListener.class) {
    193                    ((DialLayerChangeListener) listeners[i + 1]).dialLayerChanged(
    194                            event);
    195                }
    196            }
    197        }
    198
    199        /**
    200         * Provides serialization support.
    201         *
    202         * @param stream  the input stream.
    203         */
    204        private void readObject(ObjectInputStream stream)
    205            throws IOException, ClassNotFoundException {
    206            stream.defaultReadObject();
    207            this.listenerList = new EventListenerList();
    208        }
    209
    210    }