    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 * Overlay.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 */
    040package org.jfree.chart.panel;
    041
    042import java.awt.Graphics2D;
    043import org.jfree.chart.ChartPanel;
    044import org.jfree.chart.event.OverlayChangeListener;
    045
    046/**
    047 * Defines the interface for an overlay that can be added to a
    048 * {@link ChartPanel}.
    049 *
    050 * @since 1.0.13
    051 */
    052public interface Overlay {
    053
    054    /**
    055     * Paints the crosshairs in the layer.
    056     *
    057     * @param g2  the graphics target.
    058     * @param chartPanel  the chart panel.
    059     */
    060    public void paintOverlay(Graphics2D g2, ChartPanel chartPanel);
    061
    062    /**
    063     * Registers a change listener with the overlay.
    064     *
    065     * @param listener  the listener.
    066     */
    067    public void addChangeListener(OverlayChangeListener listener);
    068
    069    /**
    070     * Deregisters a listener from the overlay.
    071     *
    072     * @param listener  the listener.
    073     */
    074    public void removeChangeListener(OverlayChangeListener listener);
    075
    076}