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 * DialLayer.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 * 03-Nov-2006 : Version 1 (DG);
038 * 
039 */
040
041package org.jfree.chart.plot.dial;
042
043import java.awt.Graphics2D;
044import java.awt.geom.Rectangle2D;
045import java.io.Serializable;
046import java.util.EventListener;
047
048/**
049 * A dial layer draws itself within a reference frame.  The view frame is a
050 * subset of the reference frame, and defines the area that is actually 
051 * visible. 
052 * <br><br>
053 * Classes that implement this interface should be {@link Serializable}, 
054 * otherwise chart serialization may fail.
055 */
056public interface DialLayer {
057   
058    /** 
059     * Returns a flag that indicates whether or not the layer is visible. 
060     * 
061     * @return A boolean.
062     */
063    public boolean isVisible();
064    
065    /**
066     * Registers a listener with this layer, so that it receives notification
067     * of changes to this layer.
068     * 
069     * @param listener  the listener.
070     */
071    public void addChangeListener(DialLayerChangeListener listener);
072    
073    /**
074     * Deregisters a listener, so that it no longer receives notification of
075     * changes to this layer.
076     * 
077     * @param listener  the listener.
078     */
079    public void removeChangeListener(DialLayerChangeListener listener);
080    
081    /**
082     * Returns <code>true</code> if the specified listener is currently 
083     * registered with the this layer.
084     * 
085     * @param listener  the listener.
086     * 
087     * @return A boolean.
088     */    
089    public boolean hasListener(EventListener listener);
090    
091    /**
092     * Returns <code>true</code> if the drawing should be clipped to the
093     * dial window (which is defined by the {@link DialFrame}), and 
094     * <code>false</code> otherwise.
095     *
096     * @return A boolean.
097     */
098    public boolean isClippedToWindow();
099    
100    /**
101     * Draws the content of this layer.
102     *
103     * @param g2  the graphics target (<code>null</code> not permitted).
104     * @param plot  the plot (typically this should not be <code>null</code>, 
105     *     but for a layer that doesn't need to reference the plot, it may
106     *     be permitted).
107     * @param frame  the reference frame for the dial's geometry 
108     *     (<code>null</code> not permitted).  This is typically larger than
109     *     the visible area of the dial (see the next parameter).
110     * @param view  the visible area for the dial (<code>null</code> not 
111     *     permitted).
112     */
113    public void draw(Graphics2D g2, DialPlot plot, Rectangle2D frame, 
114            Rectangle2D view);
115    
116}