content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
   * in the United States and other countries.]
   *
   * ------------
   * Overlay.java
   * ------------
   * (C) Copyright 2009, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes:
   * --------
   * 09-Apr-2009 : Version 1 (DG);
   *
   */
  package org.jfree.chart.panel;
  
  import java.awt.Graphics2D;
  import org.jfree.chart.ChartPanel;
  import org.jfree.chart.event.OverlayChangeListener;
  
  /**
   * Defines the interface for an overlay that can be added to a
   * {@link ChartPanel}.
   *
   * @since 1.0.13
   */
  public interface Overlay {
  
      /**
       * Paints the crosshairs in the layer.
       *
       * @param g2  the graphics target.
       * @param chartPanel  the chart panel.
       */
      public void paintOverlay(Graphics2D g2, ChartPanel chartPanel);
  
      /**
       * Registers a change listener with the overlay.
       * 
       * @param listener  the listener.
       */
      public void addChangeListener(OverlayChangeListener listener);
  
      /**
       * Deregisters a listener from the overlay.
       * 
       * @param listener  the listener.
       */
      public void removeChangeListener(OverlayChangeListener listener);
  
  }
  