001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2020, 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 * AbstractDialLayer.java
029 * ----------------------
030 * (C) Copyright 2006-2020, by Object Refinery Limited.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.chart.plot.dial;
038
039import java.io.IOException;
040import java.io.ObjectInputStream;
041import java.util.Arrays;
042import java.util.EventListener;
043import java.util.List;
044
045import javax.swing.event.EventListenerList;
046
047import org.jfree.chart.HashUtils;
048
049/**
050 * A base class that can be used to implement a {@link DialLayer}.  It includes
051 * an event notification mechanism.
052 *
053 * @since 1.0.7
054 */
055public abstract class AbstractDialLayer implements DialLayer {
056
057    /** A flag that controls whether or not the layer is visible. */
058    private boolean visible;
059
060    /** Storage for registered listeners. */
061    private transient EventListenerList listenerList;
062
063    /**
064     * Creates a new instance.
065     */
066    protected AbstractDialLayer() {
067        this.visible = true;
068        this.listenerList = new EventListenerList();
069    }
070
071    /**
072     * Returns {@code true} if this layer is visible (should be displayed),
073     * and {@code false} otherwise.
074     *
075     * @return A boolean.
076     *
077     * @see #setVisible(boolean)
078     */
079    @Override
080    public boolean isVisible() {
081        return this.visible;
082    }
083
084    /**
085     * Sets the flag that determines whether or not this layer is drawn by
086     * the plot, and sends a {@link DialLayerChangeEvent} to all registered
087     * listeners.
088     *
089     * @param visible  the flag.
090     *
091     * @see #isVisible()
092     */
093    public void setVisible(boolean visible) {
094        this.visible = visible;
095        notifyListeners(new DialLayerChangeEvent(this));
096    }
097
098    /**
099     * Tests this instance for equality with an arbitrary object.
100     *
101     * @param obj  the object ({@code null} permitted).
102     *
103     * @return A boolean.
104     */
105    @Override
106    public boolean equals(Object obj) {
107        if (obj == this) {
108            return true;
109        }
110        if (!(obj instanceof AbstractDialLayer)) {
111            return false;
112        }
113        AbstractDialLayer that = (AbstractDialLayer) obj;
114        return this.visible == that.visible;
115    }
116
117    /**
118     * Returns a hash code for this instance.
119     *
120     * @return A hash code.
121     */
122    @Override
123    public int hashCode() {
124        int result = 23;
125        result = HashUtils.hashCode(result, this.visible);
126        return result;
127    }
128
129    /**
130     * Returns a clone of this instance.
131     *
132     * @return A clone.
133     *
134     * @throws CloneNotSupportedException if there is a problem cloning this
135     *     instance.
136     */
137    @Override
138    public Object clone() throws CloneNotSupportedException {
139        AbstractDialLayer clone = (AbstractDialLayer) super.clone();
140        // we don't clone the listeners
141        clone.listenerList = new EventListenerList();
142        return clone;
143    }
144
145    /**
146     * Registers an object for notification of changes to the dial layer.
147     *
148     * @param listener  the object that is being registered.
149     *
150     * @see #removeChangeListener(DialLayerChangeListener)
151     */
152    @Override
153    public void addChangeListener(DialLayerChangeListener listener) {
154        this.listenerList.add(DialLayerChangeListener.class, listener);
155    }
156
157    /**
158     * Deregisters an object for notification of changes to the dial layer.
159     *
160     * @param listener  the object to deregister.
161     *
162     * @see #addChangeListener(DialLayerChangeListener)
163     */
164    @Override
165    public void removeChangeListener(DialLayerChangeListener listener) {
166        this.listenerList.remove(DialLayerChangeListener.class, listener);
167    }
168
169    /**
170     * Returns {@code true} 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    @Override
179    public boolean hasListener(EventListener listener) {
180        List list = Arrays.asList(this.listenerList.getListenerList());
181        return list.contains(listener);
182    }
183
184    /**
185     * Notifies all registered listeners that the dial layer has changed.
186     * The {@link DialLayerChangeEvent} provides information about the change.
187     *
188     * @param event  information about the change to the axis.
189     */
190    protected void notifyListeners(DialLayerChangeEvent event) {
191        Object[] listeners = this.listenerList.getListenerList();
192        for (int i = listeners.length - 2; i >= 0; i -= 2) {
193            if (listeners[i] == DialLayerChangeListener.class) {
194                ((DialLayerChangeListener) listeners[i + 1]).dialLayerChanged(
195                        event);
196            }
197        }
198    }
199
200    /**
201     * Provides serialization support.
202     *
203     * @param stream  the input stream.
204     *
205     * @throws IOException  if there is an I/O error.
206     * @throws ClassNotFoundException  if there is a classpath problem.
207     */
208    private void readObject(ObjectInputStream stream)
209        throws IOException, ClassNotFoundException {
210        stream.defaultReadObject();
211        this.listenerList = new EventListenerList();
212    }
213
214}