001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-present, by David Gilbert 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 * DialLayer.java
029 * --------------
030 * (C) Copyright 2006-present, by David Gilbert.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.chart.plot.dial;
038
039import java.awt.Graphics2D;
040import java.awt.geom.Rectangle2D;
041import java.io.Serializable;
042import java.util.EventListener;
043
044/**
045 * A dial layer draws itself within a reference frame.  The view frame is a
046 * subset of the reference frame, and defines the area that is actually
047 * visible.
048 * <br><br>
049 * Classes that implement this interface should be {@link Serializable},
050 * otherwise chart serialization may fail.
051 */
052public interface DialLayer {
053
054    /**
055     * Returns a flag that indicates whether or not the layer is visible.
056     *
057     * @return A boolean.
058     */
059    boolean isVisible();
060
061    /**
062     * Registers a listener with this layer, so that it receives notification
063     * of changes to this layer.
064     *
065     * @param listener  the listener.
066     */
067    void addChangeListener(DialLayerChangeListener listener);
068
069    /**
070     * Deregisters a listener, so that it no longer receives notification of
071     * changes to this layer.
072     *
073     * @param listener  the listener.
074     */
075    void removeChangeListener(DialLayerChangeListener listener);
076
077    /**
078     * Returns {@code true} if the specified listener is currently
079     * registered with the this layer.
080     *
081     * @param listener  the listener.
082     *
083     * @return A boolean.
084     */
085    boolean hasListener(EventListener listener);
086
087    /**
088     * Returns {@code true} if the drawing should be clipped to the
089     * dial window (which is defined by the {@link DialFrame}), and
090     * {@code false} otherwise.
091     *
092     * @return A boolean.
093     */
094    boolean isClippedToWindow();
095
096    /**
097     * Draws the content of this layer.
098     *
099     * @param g2  the graphics target ({@code null} not permitted).
100     * @param plot  the plot (typically this should not be {@code null},
101     *     but for a layer that doesn't need to reference the plot, it may
102     *     be permitted).
103     * @param frame  the reference frame for the dial's geometry
104     *     ({@code null} not permitted).  This is typically larger than
105     *     the visible area of the dial (see the next parameter).
106     * @param view  the visible area for the dial ({@code null} not
107     *     permitted).
108     */
109    void draw(Graphics2D g2, DialPlot plot, Rectangle2D frame,
110              Rectangle2D view);
111
112}