/* ===========================================================

 * JFreeChart : a free chart library for the Java(tm) platform

 * ===========================================================

 *

 * (C) Copyright 2000-2004, 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., 59 Temple Place, Suite 330,

 * Boston, MA 02111-1307, USA.

 *

 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 

 * in the United States and other countries.]

 *

 * -------------------------

 * XYDifferenceRenderer.java

 * -------------------------

 * (C) Copyright 2003, 2004, by Object Refinery Limited.

 *

 * Original Author:  David Gilbert (for Object Refinery Limited);

 * Contributor(s):   Christian W. Zuckschwerdt;

 *

 * $Id: XYDifferenceRenderer.java,v 1.1 2004/08/31 14:49:29 mungady Exp $

 *

 * Changes:

 * --------

 * 30-Apr-2003 : Version 1 (DG);

 * 30-Jul-2003 : Modified entity constructor (CZ);

 * 20-Aug-2003 : Implemented Cloneable and PublicCloneable (DG);

 * 16-Sep-2003 : Changed ChartRenderingInfo --> PlotRenderingInfo (DG);

 * 09-Feb-2004 : Updated to support horizontal plot orientation (DG);

 * 10-Feb-2004 : Added default constructor, setter methods and updated Javadocs (DG);

 * 25-Feb-2004 : Replaced CrosshairInfo with CrosshairState (DG);

 * 30-Mar-2004 : Fixed bug in getNegativePaint() method (DG);

 * 15-Jul-2004 : Switched getX() with getXValue() and getY() with getYValue() (DG);

 * 25-Aug-2004 : Fixed a bug preventing the use of crosshairs (DG);

 * 

 */



package org.jfree.chart.renderer.xy;



import java.awt.Color;

import java.awt.Graphics2D;

import java.awt.Paint;

import java.awt.Shape;

import java.awt.Stroke;

import java.awt.geom.GeneralPath;

import java.awt.geom.Line2D;

import java.awt.geom.Rectangle2D;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.Serializable;



import org.jfree.chart.axis.ValueAxis;

import org.jfree.chart.entity.EntityCollection;

import org.jfree.chart.entity.XYItemEntity;

import org.jfree.chart.event.RendererChangeEvent;

import org.jfree.chart.labels.XYToolTipGenerator;

import org.jfree.chart.plot.CrosshairState;

import org.jfree.chart.plot.PlotOrientation;

import org.jfree.chart.plot.PlotRenderingInfo;

import org.jfree.chart.plot.XYPlot;

import org.jfree.data.xy.XYDataset;

import org.jfree.io.SerialUtilities;

import org.jfree.ui.RectangleEdge;

import org.jfree.util.PublicCloneable;



/**

 * A renderer for an {@link XYPlot} that highlights the differences between two

 * series.  The renderer expects a dataset that:

 * <ul>

 * <li>has exactly two series;</li>

 * <li>each series has the same x-values;</li>

 * <li>no <code>null</code> values;

 * </ul>

 */

public class XYDifferenceRenderer extends AbstractXYItemRenderer 

                                  implements XYItemRenderer, 

                                             Cloneable,

                                             PublicCloneable,

                                             Serializable {



    /** The paint used to highlight positive differences (y(0) > y(1)). */

    private transient Paint positivePaint;



    /** The paint used to highlight negative differences (y(0) < y(1)). */

    private transient Paint negativePaint;



    /** Display shapes at each point? */

    private boolean plotShapes = true;



    /**

     * Creates a new renderer with default attributes.

     */

    public XYDifferenceRenderer() {

        this(Color.green, Color.red, false);

    }

    

    /**

     * Creates a new renderer.

     *

     * @param positivePaint  the highlight color for positive differences (<code>null</code> not

     *                       permitted).

     * @param negativePaint  the highlight color for negative differences (<code>null</code> not

     *                       permitted).

     * @param shapes  draw shapes?

     */

    public XYDifferenceRenderer(Paint positivePaint, Paint negativePaint, boolean shapes) {

        if (positivePaint == null) {

            throw new IllegalArgumentException("Null 'positivePaint' argument.");

        }

        if (negativePaint == null) {

            throw new IllegalArgumentException("Null 'negativePaint' argument.");

        }

        this.positivePaint = positivePaint;

        this.negativePaint = negativePaint;

        this.plotShapes = shapes;

    }



    /**

     * Returns the paint used to highlight positive differences.

     *

     * @return the paint (never <code>null</code>).

     */

    public Paint getPositivePaint() {

        return this.positivePaint;

    }



    /**

     * Sets the paint used to highlight positive differences.

     * 

     * @param paint  the paint (<code>null</code> not permitted).

     */

    public void setPositivePaint(Paint paint) {

        if (paint == null) {

            throw new IllegalArgumentException("Null 'paint' argument.");

        }

        this.positivePaint = paint;

        notifyListeners(new RendererChangeEvent(this));

    }



    /**

     * Returns the paint used to highlight negative differences.

     *

     * @return the paint (never <code>null</code>).

     */

    public Paint getNegativePaint() {

        return this.negativePaint;

    }

    

    /**

     * Sets the paint used to highlight negative differences.

     * 

     * @param paint  the paint (<code>null</code> not permitted).

     */

    public void setNegativePaint(Paint paint) {

        if (paint == null) {

            throw new IllegalArgumentException("Null 'paint' argument.");

        }

        this.negativePaint = paint;

        notifyListeners(new RendererChangeEvent(this));

    }



    /**

     * Returns a flag that controls whether or not shapes are drawn for each data value.

     * 

     * @return a boolean.

     */

    public boolean getPlotShapes() {

        return this.plotShapes;

    }



    /**

     * Sets a flag that controls whether or not shapes are drawn for each data value.

     * 

     * @param flag  the flag.

     */

    public void setPlotShapes(boolean flag) {

        this.plotShapes = flag;

        notifyListeners(new RendererChangeEvent(this));

    }

    

    /**

     * Initialises the renderer and returns a state object that should be passed to subsequent

     * calls to the drawItem() method.  This method will be called before the first

     * item is rendered, giving the renderer an opportunity to initialise any

     * state information it wants to maintain.  The renderer can do nothing if it chooses.

     *

     * @param g2  the graphics device.

     * @param dataArea  the area inside the axes.

     * @param plot  the plot.

     * @param data  the data.

     * @param info  an optional info collection object to return data back to the caller.

     *

     * @return a state object.

     */

    public XYItemRendererState initialise(Graphics2D g2,

                                          Rectangle2D dataArea,

                                          XYPlot plot,

                                          XYDataset data,

                                          PlotRenderingInfo info) {



        return super.initialise(g2, dataArea, plot, data, info);



    }



    /**

     * Returns <code>2</code>, the number of passes required by the renderer.  The {@link XYPlot} 

     * will run through the dataset this number of times.

     * 

     * @return the number of passes required by the renderer.

     */

    public int getPassCount() {

        return 2;

    }

    

    /**

     * Draws the visual representation of a single data item.

     *

     * @param g2  the graphics device.

     * @param state  the renderer state.

     * @param dataArea  the area within which the data is being drawn.

     * @param info  collects information about the drawing.

     * @param plot  the plot (can be used to obtain standard color information etc).

     * @param domainAxis  the domain (horizontal) axis.

     * @param rangeAxis  the range (vertical) axis.

     * @param dataset  the dataset.

     * @param series  the series index (zero-based).

     * @param item  the item index (zero-based).

     * @param crosshairState  crosshair information for the plot (<code>null</code> permitted).

     * @param pass  the pass index.

     */

    public void drawItem(Graphics2D g2,

                         XYItemRendererState state,

                         Rectangle2D dataArea,

                         PlotRenderingInfo info,

                         XYPlot plot,

                         ValueAxis domainAxis,

                         ValueAxis rangeAxis,

                         XYDataset dataset,

                         int series,

                         int item,

                         CrosshairState crosshairState,

                         int pass) {



        if (pass == 0) {

            drawItemPass0(

                g2, dataArea, info, plot, domainAxis, rangeAxis, dataset,

                series, item, crosshairState

            );

        }

        else if (pass == 1) {

            drawItemPass1(

                g2, dataArea, info, plot, domainAxis, rangeAxis, dataset,

                series, item, crosshairState

            );

        }



    }



    /**

     * Draws the visual representation of a single data item, first pass.

     *

     * @param g2  the graphics device.

     * @param dataArea  the area within which the data is being drawn.

     * @param info  collects information about the drawing.

     * @param plot  the plot (can be used to obtain standard color information etc).

     * @param domainAxis  the domain (horizontal) axis.

     * @param rangeAxis  the range (vertical) axis.

     * @param dataset  the dataset.

     * @param series  the series index (zero-based).

     * @param item  the item index (zero-based).

     * @param crosshairState  crosshair information for the plot (<code>null</code> permitted).

     */

    protected void drawItemPass0(Graphics2D g2,

                                 Rectangle2D dataArea,

                                 PlotRenderingInfo info,

                                 XYPlot plot,

                                 ValueAxis domainAxis,

                                 ValueAxis rangeAxis,

                                 XYDataset dataset,

                                 int series,

                                 int item,

                                 CrosshairState crosshairState) {



        if (series == 0) {



            // get the data points...

            Number y0n = dataset.getY(0, item);

            Number x1n = dataset.getX(1, item);

            Number y1n = dataset.getY(1, item);



            PlotOrientation orientation = plot.getOrientation();

            RectangleEdge domainAxisLocation = plot.getDomainAxisEdge();

            RectangleEdge rangeAxisLocation = plot.getRangeAxisEdge();

            

            double y0 = y0n.doubleValue();

            double transY0 = rangeAxis.valueToJava2D(y0, dataArea, rangeAxisLocation);



            double x1 = x1n.doubleValue();

            double y1 = y1n.doubleValue();

            double transX1 = domainAxis.valueToJava2D(x1, dataArea, domainAxisLocation);

            double transY1 = rangeAxis.valueToJava2D(y1, dataArea, rangeAxisLocation);



            if (item > 0) {

                // get the previous data points...

                // get the data points...

                Number prevx0n = dataset.getX(0, item - 1);

                Number prevy0n = dataset.getY(0, item - 1);

                Number prevy1n = dataset.getY(1, item - 1);



                double prevx0 = prevx0n.doubleValue();

                double prevy0 = prevy0n.doubleValue();

                double prevtransX0 = domainAxis.valueToJava2D(prevx0, dataArea, domainAxisLocation);

                double prevtransY0 = rangeAxis.valueToJava2D(prevy0, dataArea, rangeAxisLocation);



                double prevy1 = prevy1n.doubleValue();

                double prevtransY1 = rangeAxis.valueToJava2D(prevy1, dataArea, rangeAxisLocation);



                Shape positive = getPositiveArea(

                    (float) prevtransX0, (float) prevtransY0, (float) prevtransY1,

                    (float) transX1, (float) transY0, (float) transY1,

                    orientation

                );

                if (positive != null) {

                    g2.setPaint(getPositivePaint());

                    g2.fill(positive);

                }



                Shape negative = getNegativeArea(

                    (float) prevtransX0, (float) prevtransY0, (float) prevtransY1,

                    (float) transX1, (float) transY0, (float) transY1,

                    orientation

                );



                if (negative != null) {

                    g2.setPaint(getNegativePaint());

                    g2.fill(negative);

                }

            }

        }



    }



    /**

     * Draws the visual representation of a single data item, second pass.  In the second pass, the

     * renderer draws the lines and shapes for the individual points in the two series.

     *

     * @param g2  the graphics device.

     * @param dataArea  the area within which the data is being drawn.

     * @param info  collects information about the drawing.

     * @param plot  the plot (can be used to obtain standard color information etc).

     * @param domainAxis  the domain (horizontal) axis.

     * @param rangeAxis  the range (vertical) axis.

     * @param dataset  the dataset.

     * @param series  the series index (zero-based).

     * @param item  the item index (zero-based).

     * @param crosshairState  crosshair information for the plot (<code>null</code> permitted).

     */

    protected void drawItemPass1(Graphics2D g2,

                                 Rectangle2D dataArea,

                                 PlotRenderingInfo info,

                                 XYPlot plot,

                                 ValueAxis domainAxis,

                                 ValueAxis rangeAxis,

                                 XYDataset dataset,

                                 int series,

                                 int item,

                                 CrosshairState crosshairState) {



        Shape entityArea = null;

        EntityCollection entities = null;

        if (info != null) {

            entities = info.getOwner().getEntityCollection();

        }



        Paint seriesPaint = getItemPaint(series, item);

        Stroke seriesStroke = getItemStroke(series, item);

        g2.setPaint(seriesPaint);

        g2.setStroke(seriesStroke);



        if (series == 0) {

            Number x0n = dataset.getX(0, item);

            Number y0n = dataset.getY(0, item);

            Number x1n = dataset.getX(1, item);

            Number y1n = dataset.getY(1, item);



            PlotOrientation orientation = plot.getOrientation(); 

            RectangleEdge domainAxisLocation = plot.getDomainAxisEdge();

            RectangleEdge rangeAxisLocation = plot.getRangeAxisEdge();



            double x0 = x0n.doubleValue();

            double y0 = y0n.doubleValue();

            double transX0 = domainAxis.valueToJava2D(x0, dataArea, domainAxisLocation);

            double transY0 = rangeAxis.valueToJava2D(y0, dataArea, rangeAxisLocation);



            double x1 = x1n.doubleValue();

            double y1 = y1n.doubleValue();

            double transX1 = domainAxis.valueToJava2D(x1, dataArea, domainAxisLocation);

            double transY1 = rangeAxis.valueToJava2D(y1, dataArea, rangeAxisLocation);



            if (item > 0) {

                // get the previous data points...

                Number prevx0n = dataset.getX(0, item - 1);

                Number prevy0n = dataset.getY(0, item - 1);

                Number prevx1n = dataset.getX(1, item - 1);

                Number prevy1n = dataset.getY(1, item - 1);



                double prevx0 = prevx0n.doubleValue();

                double prevy0 = prevy0n.doubleValue();

                double prevtransX0 = domainAxis.valueToJava2D(prevx0, dataArea, domainAxisLocation);

                double prevtransY0 = rangeAxis.valueToJava2D(prevy0, dataArea, rangeAxisLocation);



                double prevx1 = prevx1n.doubleValue();

                double prevy1 = prevy1n.doubleValue();

                double prevtransX1 = domainAxis.valueToJava2D(prevx1, dataArea, domainAxisLocation);

                double prevtransY1 = rangeAxis.valueToJava2D(prevy1, dataArea, rangeAxisLocation);



                Line2D line0 = null;

                Line2D line1 = null;

                if (orientation == PlotOrientation.HORIZONTAL) {

                    line0 = new Line2D.Double(transY0, transX0, prevtransY0, prevtransX0);

                    line1 = new Line2D.Double(transY1, transX1, prevtransY1, prevtransX1);

                }

                else if (orientation == PlotOrientation.VERTICAL) {

                    line0 = new Line2D.Double(transX0, transY0, prevtransX0, prevtransY0);

                    line1 = new Line2D.Double(transX1, transY1, prevtransX1, prevtransY1);

                }

                if (line0 != null && line0.intersects(dataArea)) {

                    g2.setPaint(getItemPaint(series, item));

                    g2.draw(line0);

                }

                if (line1 != null && line1.intersects(dataArea)) {

                    g2.setPaint(getItemPaint(1, item));

                    g2.draw(line1);

                }

            }



            if (getPlotShapes()) {

                Shape shape0 = getItemShape(series, item);

                if (orientation == PlotOrientation.HORIZONTAL) {

                    shape0 = createTransformedShape(shape0, transY0, transX0);

                }

                else {  // vertical

                    shape0 = createTransformedShape(shape0, transX0, transY0);

                }

                if (shape0.intersects(dataArea)) {

                    g2.setPaint(getItemPaint(series, item));

                    g2.fill(shape0);

                }

                entityArea = shape0;



                // add an entity for the item...

                if (entities != null) {

                    if (entityArea == null) {

                        entityArea = new Rectangle2D.Double(transX0 - 2, transY0 - 2, 4, 4);

                    }

                    String tip = null;

                    XYToolTipGenerator generator = getToolTipGenerator(series, item);

                    if (generator != null) {

                        tip = generator.generateToolTip(dataset, series, item);

                    }

                    String url = null;

                    if (getURLGenerator() != null) {

                        url = getURLGenerator().generateURL(dataset, series, item);

                    }

                    XYItemEntity entity = new XYItemEntity(entityArea, dataset, series, item, 

                                                           tip, url);

                    entities.addEntity(entity);

                }



                Shape shape1 = getItemShape(series + 1, item);

                shape1 = createTransformedShape(shape1, transX1, transY1);

                if (shape1.intersects(dataArea)) {

                    g2.setPaint(getItemPaint(series + 1, item));

                    g2.fill(shape1);

                }

                entityArea = shape1;



                // add an entity for the item...

                if (entities != null) {

                    if (entityArea == null) {

                        entityArea = new Rectangle2D.Double(transX1 - 2, transY1 - 2, 4, 4);

                    }

                    String tip = null;

                    XYToolTipGenerator generator = getToolTipGenerator(series, item);

                    if (generator != null) {

                        tip = generator.generateToolTip(dataset, series + 1, item);

                    }

                    String url = null;

                    if (getURLGenerator() != null) {

                        url = getURLGenerator().generateURL(dataset, series + 1, item);

                    }

                    XYItemEntity entity = new XYItemEntity(entityArea, dataset, series + 1, item, 

                                                           tip, url);

                    entities.addEntity(entity);

                }

            }

            updateCrosshairValues(crosshairState, x1, y1, transX1, transY1, orientation);

        }



    }



    /**

     * Returns the positive area for a crossover point.

     * 

     * @param x0  x coordinate.

     * @param y0A  y coordinate A.

     * @param y0B  y coordinate B.

     * @param x1  x coordinate.

     * @param y1A  y coordinate A.

     * @param y1B  y coordinate B.

     * @param orientation  the plot orientation.

     * 

     * @return The positive area.

     */

    protected Shape getPositiveArea(float x0, float y0A, float y0B, 

                                    float x1, float y1A, float y1B,

                                    PlotOrientation orientation) {



        Shape result = null;



        boolean startsNegative = (y0A >= y0B);  

        boolean endsNegative = (y1A >= y1B);

        if (orientation == PlotOrientation.HORIZONTAL) {

            startsNegative = (y0B >= y0A);

            endsNegative = (y1B >= y1A);

        }

        

        if (startsNegative) {  // starts negative

            if (endsNegative) {

                // all negative - return null

            }

            else {

                // changed from negative to positive

                float[] p = getIntersection(x0, y0A, x1, y1A, x0, y0B, x1, y1B);

                GeneralPath area = new GeneralPath();

                if (orientation == PlotOrientation.HORIZONTAL) {

                    area.moveTo(y1A, x1);

                    area.lineTo(p[1], p[0]);

                    area.lineTo(y1B, x1);

                    area.closePath();

                }

                else if (orientation == PlotOrientation.VERTICAL) {

                    area.moveTo(x1, y1A);

                    area.lineTo(p[0], p[1]);

                    area.lineTo(x1, y1B);

                    area.closePath();

                }

                result = area;

            }

        }

        else {  // starts positive

            if (endsNegative) {

                // changed from positive to negative

                float[] p = getIntersection(x0, y0A, x1, y1A, x0, y0B, x1, y1B);

                GeneralPath area = new GeneralPath();

                if (orientation == PlotOrientation.HORIZONTAL) {

                    area.moveTo(y0A, x0);

                    area.lineTo(p[1], p[0]);

                    area.lineTo(y0B, x0);

                    area.closePath();

                }

                else if (orientation == PlotOrientation.VERTICAL) {

                    area.moveTo(x0, y0A);

                    area.lineTo(p[0], p[1]);

                    area.lineTo(x0, y0B);

                    area.closePath();

                }

                result = area;



            }

            else {

                GeneralPath area = new GeneralPath();

                if (orientation == PlotOrientation.HORIZONTAL) {

                    area.moveTo(y0A, x0);

                    area.lineTo(y1A, x1);

                    area.lineTo(y1B, x1);

                    area.lineTo(y0B, x0);

                    area.closePath();

                }

                else if (orientation == PlotOrientation.VERTICAL) {

                    area.moveTo(x0, y0A);

                    area.lineTo(x1, y1A);

                    area.lineTo(x1, y1B);

                    area.lineTo(x0, y0B);

                    area.closePath();

                }

                result = area;

            }



        }



        return result;



    }



    /**

     * Returns the negative area for a cross-over section.

     * 

     * @param x0  x coordinate.

     * @param y0A  y coordinate A.

     * @param y0B  y coordinate B.

     * @param x1  x coordinate.

     * @param y1A  y coordinate A.

     * @param y1B  y coordinate B.

     * @param orientation  the plot orientation.

     * 

     * @return The negative area.

     */

    protected Shape getNegativeArea(float x0, float y0A, float y0B, 

                                    float x1, float y1A, float y1B,

                                    PlotOrientation orientation) {



        Shape result = null;



        boolean startsNegative = (y0A >= y0B);

        boolean endsNegative = (y1A >= y1B);

        if (orientation == PlotOrientation.HORIZONTAL) {

            startsNegative = (y0B >= y0A);

            endsNegative = (y1B >= y1A);

        }

        if (startsNegative) {  // starts negative

            if (endsNegative) {  // all negative

                GeneralPath area = new GeneralPath();

                if (orientation == PlotOrientation.HORIZONTAL) {

                    area.moveTo(y0A, x0);

                    area.lineTo(y1A, x1);

                    area.lineTo(y1B, x1);

                    area.lineTo(y0B, x0);

                    area.closePath();

                }

                else if (orientation == PlotOrientation.VERTICAL) {

                    area.moveTo(x0, y0A);

                    area.lineTo(x1, y1A);

                    area.lineTo(x1, y1B);

                    area.lineTo(x0, y0B);

                    area.closePath();

                }

                result = area;

            }

            else {  // changed from negative to positive

                float[] p = getIntersection(x0, y0A, x1, y1A, x0, y0B, x1, y1B);

                GeneralPath area = new GeneralPath();

                if (orientation == PlotOrientation.HORIZONTAL) {

                    area.moveTo(y0A, x0);

                    area.lineTo(p[1], p[0]);

                    area.lineTo(y0B, x0);

                    area.closePath();

                }

                else if (orientation == PlotOrientation.VERTICAL) {

                    area.moveTo(x0, y0A);

                    area.lineTo(p[0], p[1]);

                    area.lineTo(x0, y0B);

                    area.closePath();

                }

                result = area;

            }

        }

        else {

            if (endsNegative) {

                // changed from positive to negative

                float[] p = getIntersection(x0, y0A, x1, y1A, x0, y0B, x1, y1B);

                GeneralPath area = new GeneralPath();

                if (orientation == PlotOrientation.HORIZONTAL) {

                    area.moveTo(y1A, x1);

                    area.lineTo(p[1], p[0]);

                    area.lineTo(y1B, x1);

                    area.closePath();

                }

                else if (orientation == PlotOrientation.VERTICAL) {

                    area.moveTo(x1, y1A);

                    area.lineTo(p[0], p[1]);

                    area.lineTo(x1, y1B);

                    area.closePath();

                }

                result = area;

            }

            else {

                // all negative - return null

            }



        }



        return result;



    }



    /**

     * Returns the intersection point of two lines.

     * 

     * @param x1  x1

     * @param y1  y1

     * @param x2  x2

     * @param y2  y2

     * @param x3  x3

     * @param y3  y3

     * @param x4  x4

     * @param y4  y4

     * 

     * @return The intersection point.

     */

    private float[] getIntersection(float x1, float y1, float x2, float y2,

                                    float x3, float y3, float x4, float y4) {



        float n = (x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3);

        float d = (y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1);

        float u = n / d;



        float[] result = new float[2];

        result[0] = x1 + u * (x2 - x1);

        result[1] = y1 + u * (y2 - y1);

        return result;



    }

    

    /**

     * Returns a clone of the renderer.

     * 

     * @return A clone.

     * 

     * @throws CloneNotSupportedException  if the renderer cannot be cloned.

     */

    public Object clone() throws CloneNotSupportedException {

        return super.clone();

    }



    /**

     * Provides serialization support.

     *

     * @param stream  the output stream.

     *

     * @throws IOException  if there is an I/O error.

     */

    private void writeObject(ObjectOutputStream stream) throws IOException {

        stream.defaultWriteObject();

        SerialUtilities.writePaint(this.positivePaint, stream);

        SerialUtilities.writePaint(this.negativePaint, stream);

    }



    /**

     * Provides serialization support.

     *

     * @param stream  the input stream.

     *

     * @throws IOException  if there is an I/O error.

     * @throws ClassNotFoundException  if there is a classpath problem.

     */

    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {

        stream.defaultReadObject();

        this.positivePaint = SerialUtilities.readPaint(stream);

        this.negativePaint = SerialUtilities.readPaint(stream);

    }



}

