/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2007, 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.]
 *
 * ----------------
 * BarRenderer.java
 * ----------------
 * (C) Copyright 2002-2007, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   Christian W. Zuckschwerdt;
 *
 * Changes
 * -------
 * 14-Mar-2002 : Version 1 (DG);
 * 23-May-2002 : Added tooltip generator to renderer (DG);
 * 29-May-2002 : Moved tooltip generator to abstract super-class (DG);
 * 25-Jun-2002 : Changed constructor to protected and removed redundant 
 *               code (DG);
 * 26-Jun-2002 : Added axis to initialise method, and record upper and lower 
 *               clip values (DG);
 * 24-Sep-2002 : Added getLegendItem() method (DG);
 * 09-Oct-2002 : Modified constructor to include URL generator (DG);
 * 05-Nov-2002 : Base dataset is now TableDataset not CategoryDataset (DG);
 * 10-Jan-2003 : Moved get/setItemMargin() method up from subclasses (DG);
 * 17-Jan-2003 : Moved plot classes into a separate package (DG);
 * 25-Mar-2003 : Implemented Serializable (DG);
 * 01-May-2003 : Modified clipping to allow for dual axes and datasets (DG);
 * 12-May-2003 : Merged horizontal and vertical bar renderers (DG);
 * 12-Jun-2003 : Updates for item labels (DG);
 * 30-Jul-2003 : Modified entity constructor (CZ);
 * 02-Sep-2003 : Changed initialise method to fix bug 790407 (DG);
 * 16-Sep-2003 : Changed ChartRenderingInfo --> PlotRenderingInfo (DG);
 * 07-Oct-2003 : Added renderer state (DG);
 * 27-Oct-2003 : Merged drawHorizontalItem() and drawVerticalItem() 
 *               methods (DG);
 * 28-Oct-2003 : Added support for gradient paint on bars (DG);
 * 14-Nov-2003 : Added 'maxBarWidth' attribute (DG);
 * 10-Feb-2004 : Small changes inside drawItem() method to ease cut-and-paste 
 *               overriding (DG);
 * 19-Mar-2004 : Fixed bug introduced with separation of tool tip and item 
 *               label generators.  Fixed equals() method (DG);
 * 11-May-2004 : Fix for null pointer exception (bug id 951127) (DG);
 * 05-Nov-2004 : Modified drawItem() signature (DG);
 * 26-Jan-2005 : Provided override for getLegendItem() method (DG);
 * 20-Apr-2005 : Generate legend labels, tooltips and URLs (DG);
 * 18-May-2005 : Added configurable base value (DG);
 * 09-Jun-2005 : Use addItemEntity() method from superclass (DG);
 * 01-Dec-2005 : Update legend item to use/not use outline (DG);
 * ------------: JFreeChart 1.0.x ---------------------------------------------
 * 06-Dec-2005 : Fixed bug 1374222 (JDK 1.4 specific code) (DG);
 * 11-Jan-2006 : Fixed bug 1401856 (bad rendering for non-zero base) (DG);
 * 04-Aug-2006 : Fixed bug 1467706 (missing item labels for zero value 
 *               bars) (DG);
 * 04-Dec-2006 : Fixed bug in rendering to non-primary axis (DG);
 * 13-Dec-2006 : Add support for GradientPaint display in legend items (DG);
 * 20-Apr-2007 : Updated getLegendItem() for renderer change (DG);
 * 11-May-2007 : Check for visibility in getLegendItem() (DG);
 * 17-May-2007 : Set datasetIndex and seriesIndex in getLegendItem() (DG);
 * 18-May-2007 : Set dataset and seriesKey for LegendItem (DG);
 * 
 */

package org.jfree.chart.renderer.category;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.Paint;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.io.Serializable;

import org.jfree.chart.LegendItem;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.entity.EntityCollection;
import org.jfree.chart.event.RendererChangeEvent;
import org.jfree.chart.labels.CategoryItemLabelGenerator;
import org.jfree.chart.labels.ItemLabelAnchor;
import org.jfree.chart.labels.ItemLabelPosition;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.plot.PlotRenderingInfo;
import org.jfree.data.Range;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.general.DatasetUtilities;
import org.jfree.text.TextUtilities;
import org.jfree.ui.GradientPaintTransformer;
import org.jfree.ui.RectangleEdge;
import org.jfree.ui.StandardGradientPaintTransformer;
import org.jfree.util.ObjectUtilities;
import org.jfree.util.PublicCloneable;

/**
 * A {@link CategoryItemRenderer} that draws individual data items as bars.
 */
public class BarRenderer extends AbstractCategoryItemRenderer 
                         implements Cloneable, PublicCloneable, Serializable {

    /** For serialization. */
    private static final long serialVersionUID = 6000649414965887481L;
    
    /** The default item margin percentage. */
    public static final double DEFAULT_ITEM_MARGIN = 0.20;

    /** 
     * Constant that controls the minimum width before a bar has an outline 
     * drawn. 
     */
    public static final double BAR_OUTLINE_WIDTH_THRESHOLD = 3.0;

    /** The margin between items (bars) within a category. */
    private double itemMargin;

    /** A flag that controls whether or not bar outlines are drawn. */
    private boolean drawBarOutline;
    
    /** The maximum bar width as a percentage of the available space. */
    private double maximumBarWidth;
    
    /** The minimum bar length (in Java2D units). */
    private double minimumBarLength;
    
    /** 
     * An optional class used to transform gradient paint objects to fit each 
     * bar. 
     */
    private GradientPaintTransformer gradientPaintTransformer;
    
    /** 
     * The fallback position if a positive item label doesn't fit inside the 
     * bar. 
     */
    private ItemLabelPosition positiveItemLabelPositionFallback;
    
    /** 
     * The fallback position if a negative item label doesn't fit inside the 
     * bar. 
     */
    private ItemLabelPosition negativeItemLabelPositionFallback;
    
    /** The upper clip (axis) value for the axis. */
    private double upperClip;  
    // TODO:  this needs to move into the renderer state

    /** The lower clip (axis) value for the axis. */
    private double lowerClip;  
    // TODO:  this needs to move into the renderer state

    /** The base value for the bars (defaults to 0.0). */
    private double base;
    
    /** 
     * A flag that controls whether the base value is included in the range
     * returned by the findRangeBounds() method.
     */
    private boolean includeBaseInRange;
    
    /**
     * Creates a new bar renderer with default settings.
     */
    public BarRenderer() {
        super();
        this.base = 0.0;
        this.includeBaseInRange = true;
        this.itemMargin = DEFAULT_ITEM_MARGIN;
        this.drawBarOutline = false;
        this.maximumBarWidth = 1.0;  
            // 100 percent, so it will not apply unless changed
        this.positiveItemLabelPositionFallback = null;
        this.negativeItemLabelPositionFallback = null;
        this.gradientPaintTransformer = new StandardGradientPaintTransformer();
        this.minimumBarLength = 0.0;
    }

    /**
     * Returns the base value for the bars.  The default value is 
     * <code>0.0</code>.
     * 
     * @return The base value for the bars.
     * 
     * @see #setBase(double)
     */
    public double getBase() {
        return this.base;    
    }
    
    /**
     * Sets the base value for the bars and sends a {@link RendererChangeEvent}
     * to all registered listeners.
     * 
     * @param base  the new base value.
     * 
     * @see #getBase()
     */
    public void setBase(double base) {
        this.base = base;
        notifyListeners(new RendererChangeEvent(this));
    }
    
    /**
     * Returns the item margin as a percentage of the available space for all 
     * bars.
     *
     * @return The margin percentage (where 0.10 is ten percent).
     * 
     * @see #setItemMargin(double)
     */
    public double getItemMargin() {
        return this.itemMargin;
    }

    /**
     * Sets the item margin and sends a {@link RendererChangeEvent} to all 
     * registered listeners.  The value is expressed as a percentage of the 
     * available width for plotting all the bars, with the resulting amount to 
     * be distributed between all the bars evenly.
     *
     * @param percent  the margin (where 0.10 is ten percent).
     * 
     * @see #getItemMargin()
     */
    public void setItemMargin(double percent) {
        this.itemMargin = percent;
        notifyListeners(new RendererChangeEvent(this));
    }

    /**
     * Returns a flag that controls whether or not bar outlines are drawn.
     * 
     * @return A boolean.
     * 
     * @see #setDrawBarOutline(boolean)
     */
    public boolean isDrawBarOutline() {
        return this.drawBarOutline;    
    }
    
    /**
     * Sets the flag that controls whether or not bar outlines are drawn and 
     * sends a {@link RendererChangeEvent} to all registered listeners.
     * 
     * @param draw  the flag.
     * 
     * @see #isDrawBarOutline()
     */
    public void setDrawBarOutline(boolean draw) {
        this.drawBarOutline = draw;
        notifyListeners(new RendererChangeEvent(this));
    }
    
    /**
     * Returns the maximum bar width, as a percentage of the available drawing 
     * space.
     * 
     * @return The maximum bar width.
     * 
     * @see #setMaximumBarWidth(double)
     */
    public double getMaximumBarWidth() {
        return this.maximumBarWidth;
    }
    
    /**
     * Sets the maximum bar width, which is specified as a percentage of the 
     * available space for all bars, and sends a {@link RendererChangeEvent} to
     * all registered listeners.
     * 
     * @param percent  the percent (where 0.05 is five percent).
     * 
     * @see #getMaximumBarWidth()
     */
    public void setMaximumBarWidth(double percent) {
        this.maximumBarWidth = percent;
        notifyListeners(new RendererChangeEvent(this));
    }

    /**
     * Returns the minimum bar length (in Java2D units).
     * 
     * @return The minimum bar length.
     * 
     * @see #setMinimumBarLength(double)
     */
    public double getMinimumBarLength() {
        return this.minimumBarLength;
    }
    
    /**
     * Sets the minimum bar length and sends a {@link RendererChangeEvent} to 
     * all registered listeners.  The minimum bar length is specified in Java2D
     * units, and can be used to prevent bars that represent very small data 
     * values from disappearing when drawn on the screen.
     * 
     * @param min  the minimum bar length (in Java2D units).
     * 
     * @see #getMinimumBarLength()
     */
    public void setMinimumBarLength(double min) {
        this.minimumBarLength = min;
        notifyListeners(new RendererChangeEvent(this));
    }
    
    /**
     * Returns the gradient paint transformer (an object used to transform 
     * gradient paint objects to fit each bar).
     * 
     * @return A transformer (<code>null</code> possible).
     * 
     * @see #setGradientPaintTransformer(GradientPaintTransformer)
     */    
    public GradientPaintTransformer getGradientPaintTransformer() {
        return this.gradientPaintTransformer;    
    }
    
    /**
     * Sets the gradient paint transformer and sends a 
     * {@link RendererChangeEvent} to all registered listeners.
     * 
     * @param transformer  the transformer (<code>null</code> permitted).
     * 
     * @see #getGradientPaintTransformer()
     */
    public void setGradientPaintTransformer(
            GradientPaintTransformer transformer) {
        this.gradientPaintTransformer = transformer;
        notifyListeners(new RendererChangeEvent(this));
    }
    
    /**
     * Returns the fallback position for positive item labels that don't fit 
     * within a bar.
     * 
     * @return The fallback position (<code>null</code> possible).
     * 
     * @see #setPositiveItemLabelPositionFallback(ItemLabelPosition)
     */
    public ItemLabelPosition getPositiveItemLabelPositionFallback() {
        return this.positiveItemLabelPositionFallback;
    }
    
    /**
     * Sets the fallback position for positive item labels that don't fit 
     * within a bar, and sends a {@link RendererChangeEvent} to all registered
     * listeners.
     * 
     * @param position  the position (<code>null</code> permitted).
     * 
     * @see #getPositiveItemLabelPositionFallback()
     */
    public void setPositiveItemLabelPositionFallback(
            ItemLabelPosition position) {
        this.positiveItemLabelPositionFallback = position;
        notifyListeners(new RendererChangeEvent(this));
    }
    
    /**
     * Returns the fallback position for negative item labels that don't fit 
     * within a bar.
     * 
     * @return The fallback position (<code>null</code> possible).
     * 
     * @see #setPositiveItemLabelPositionFallback(ItemLabelPosition)
     */
    public ItemLabelPosition getNegativeItemLabelPositionFallback() {
        return this.negativeItemLabelPositionFallback;
    }
    
    /**
     * Sets the fallback position for negative item labels that don't fit 
     * within a bar, and sends a {@link RendererChangeEvent} to all registered
     * listeners.
     * 
     * @param position  the position (<code>null</code> permitted).
     * 
     * @see #getNegativeItemLabelPositionFallback()
     */
    public void setNegativeItemLabelPositionFallback(
            ItemLabelPosition position) {
        this.negativeItemLabelPositionFallback = position;
        notifyListeners(new RendererChangeEvent(this));
    }
    
    /**
     * Returns the flag that controls whether or not the base value for the 
     * bars is included in the range calculated by 
     * {@link #findRangeBounds(CategoryDataset)}.
     * 
     * @return <code>true</code> if the base is included in the range, and
     *         <code>false</code> otherwise.
     * 
     * @since 1.0.1
     * 
     * @see #setIncludeBaseInRange(boolean)
     */
    public boolean getIncludeBaseInRange() {
        return this.includeBaseInRange;
    }
    
    /**
     * Sets the flag that controls whether or not the base value for the bars 
     * is included in the range calculated by 
     * {@link #findRangeBounds(CategoryDataset)}.  If the flag is changed,
     * a {@link RendererChangeEvent} is sent to all registered listeners.
     * 
     * @param include  the new value for the flag.
     * 
     * @since 1.0.1
     * 
     * @see #getIncludeBaseInRange()
     */
    public void setIncludeBaseInRange(boolean include) {
        if (this.includeBaseInRange != include) {
            this.includeBaseInRange = include;
            notifyListeners(new RendererChangeEvent(this));
        }
    }
    
    /**
     * Returns the lower clip value.  This value is recalculated in the 
     * initialise() method.
     *
     * @return The value.
     */
    public double getLowerClip() {
        // TODO:  this attribute should be transferred to the renderer state.
        return this.lowerClip;
    }

    /**
     * Returns the upper clip value.  This value is recalculated in the 
     * initialise() method.
     *
     * @return The value.
     */
    public double getUpperClip() {
        // TODO:  this attribute should be transferred to the renderer state.
        return this.upperClip;
    }

    /**
     * Initialises the renderer and returns a state object that will be passed 
     * to subsequent calls to the drawItem method.  This method gets called 
     * once at the start of the process of drawing a chart.
     *
     * @param g2  the graphics device.
     * @param dataArea  the area in which the data is to be plotted.
     * @param plot  the plot.
     * @param rendererIndex  the renderer index.
     * @param info  collects chart rendering information for return to caller.
     * 
     * @return The renderer state.
     */
    public CategoryItemRendererState initialise(Graphics2D g2,
                                                Rectangle2D dataArea,
                                                CategoryPlot plot,
                                                int rendererIndex,
                                                PlotRenderingInfo info) {

        CategoryItemRendererState state = super.initialise(g2, dataArea, plot, 
                rendererIndex, info);

        // get the clipping values...
        ValueAxis rangeAxis = plot.getRangeAxisForDataset(rendererIndex);
        this.lowerClip = rangeAxis.getRange().getLowerBound();
        this.upperClip = rangeAxis.getRange().getUpperBound();

        // calculate the bar width
        calculateBarWidth(plot, dataArea, rendererIndex, state);

        return state;
        
    }
    
    /**
     * Calculates the bar width and stores it in the renderer state.
     * 
     * @param plot  the plot.
     * @param dataArea  the data area.
     * @param rendererIndex  the renderer index.
     * @param state  the renderer state.
     */
    protected void calculateBarWidth(CategoryPlot plot, 
                                     Rectangle2D dataArea, 
                                     int rendererIndex,
                                     CategoryItemRendererState state) {
                                         
        CategoryAxis domainAxis = getDomainAxis(plot, rendererIndex);
        CategoryDataset dataset = plot.getDataset(rendererIndex);
        if (dataset != null) {
            int columns = dataset.getColumnCount();
            int rows = dataset.getRowCount();
            double space = 0.0;
            PlotOrientation orientation = plot.getOrientation();
            if (orientation == PlotOrientation.HORIZONTAL) {
                space = dataArea.getHeight();
            }
            else if (orientation == PlotOrientation.VERTICAL) {
                space = dataArea.getWidth();
            }
            double maxWidth = space * getMaximumBarWidth();
            double categoryMargin = 0.0;
            double currentItemMargin = 0.0;
            if (columns > 1) {
                categoryMargin = domainAxis.getCategoryMargin();
            }
            if (rows > 1) {
                currentItemMargin = getItemMargin();
            }
            double used = space * (1 - domainAxis.getLowerMargin() 
                                     - domainAxis.getUpperMargin()
                                     - categoryMargin - currentItemMargin);
            if ((rows * columns) > 0) {
                state.setBarWidth(Math.min(used / (rows * columns), maxWidth));
            }
            else {
                state.setBarWidth(Math.min(used, maxWidth));
            }
        }
    }

    /**
     * Calculates the coordinate of the first "side" of a bar.  This will be 
     * the minimum x-coordinate for a vertical bar, and the minimum 
     * y-coordinate for a horizontal bar.
     *
     * @param plot  the plot.
     * @param orientation  the plot orientation.
     * @param dataArea  the data area.
     * @param domainAxis  the domain axis.
     * @param state  the renderer state (has the bar width precalculated).
     * @param row  the row index.
     * @param column  the column index.
     * 
     * @return The coordinate.
     */
    protected double calculateBarW0(CategoryPlot plot, 
                                    PlotOrientation orientation, 
                                    Rectangle2D dataArea,
                                    CategoryAxis domainAxis,
                                    CategoryItemRendererState state,
                                    int row,
                                    int column) {
        // calculate bar width...
        double space = 0.0;
        if (orientation == PlotOrientation.HORIZONTAL) {
            space = dataArea.getHeight();
        }
        else {
            space = dataArea.getWidth();
        }
        double barW0 = domainAxis.getCategoryStart(column, getColumnCount(), 
                dataArea, plot.getDomainAxisEdge());
        int seriesCount = getRowCount();
        int categoryCount = getColumnCount();
        if (seriesCount > 1) {
            double seriesGap = space * getItemMargin() 
                               / (categoryCount * (seriesCount - 1));
            double seriesW = calculateSeriesWidth(space, domainAxis, 
                    categoryCount, seriesCount);
            barW0 = barW0 + row * (seriesW + seriesGap) 
                          + (seriesW / 2.0) - (state.getBarWidth() / 2.0);
        }
        else {
            barW0 = domainAxis.getCategoryMiddle(column, getColumnCount(), 
                    dataArea, plot.getDomainAxisEdge()) - state.getBarWidth() 
                    / 2.0;
        }
        return barW0;
    }
    
    /**
     * Calculates the coordinates for the length of a single bar.
     * 
     * @param value  the value represented by the bar.
     * 
     * @return The coordinates for each end of the bar (or <code>null</code> if 
     *         the bar is not visible for the current axis range).
     */
    protected double[] calculateBarL0L1(double value) {
        double lclip = getLowerClip();
        double uclip = getUpperClip();
        double barLow = Math.min(this.base, value);
        double barHigh = Math.max(this.base, value);
        if (barHigh < lclip) {  // bar is not visible
            return null;
        }
        if (barLow > uclip) {   // bar is not visible
            return null;
        }
        barLow = Math.max(barLow, lclip);
        barHigh = Math.min(barHigh, uclip);
        return new double[] {barLow, barHigh};
    }

    /**
     * Returns the range of values the renderer requires to display all the 
     * items from the specified dataset.  This takes into account the range
     * of values in the dataset, plus the flag that determines whether or not
     * the base value for the bars should be included in the range.
     * 
     * @param dataset  the dataset (<code>null</code> permitted).
     * 
     * @return The range (or <code>null</code> if the dataset is 
     *         <code>null</code> or empty).
     */
    public Range findRangeBounds(CategoryDataset dataset) {
        Range result = DatasetUtilities.findRangeBounds(dataset);
        if (result != null) {
            if (this.includeBaseInRange) {
                result = Range.expandToInclude(result, this.base);
            }
        }
        return result;
    }

    /**
     * Returns a legend item for a series.
     *
     * @param datasetIndex  the dataset index (zero-based).
     * @param series  the series index (zero-based).
     *
     * @return The legend item (possibly <code>null</code>).
     */
    public LegendItem getLegendItem(int datasetIndex, int series) {

        CategoryPlot cp = getPlot();
        if (cp == null) {
            return null;
        }

        // check that a legend item needs to be displayed...
        if (!isSeriesVisible(series) || !isSeriesVisibleInLegend(series)) {
            return null;
        }

        CategoryDataset dataset = cp.getDataset(datasetIndex);
        String label = getLegendItemLabelGenerator().generateLabel(dataset, 
                series);
        String description = label;
        String toolTipText = null; 
        if (getLegendItemToolTipGenerator() != null) {
            toolTipText = getLegendItemToolTipGenerator().generateLabel(
                    dataset, series);   
        }
        String urlText = null;
        if (getLegendItemURLGenerator() != null) {
            urlText = getLegendItemURLGenerator().generateLabel(dataset, 
                    series);   
        }
        Shape shape = new Rectangle2D.Double(-4.0, -4.0, 8.0, 8.0);
        Paint paint = lookupSeriesPaint(series);
        Paint outlinePaint = lookupSeriesOutlinePaint(series);
        Stroke outlineStroke = lookupSeriesOutlineStroke(series);

        LegendItem result = new LegendItem(label, description, toolTipText, 
                urlText, true, shape, true, paint, isDrawBarOutline(), 
                outlinePaint, outlineStroke, false, new Line2D.Float(), 
                new BasicStroke(1.0f), Color.black);
        result.setDataset(dataset);
        result.setDatasetIndex(datasetIndex);
        result.setSeriesKey(dataset.getRowKey(series));
        result.setSeriesIndex(series);
        if (this.gradientPaintTransformer != null) {
            result.setFillPaintTransformer(this.gradientPaintTransformer);
        }
        return result;
    }

    /**
     * Draws the bar for a single (series, category) data item.
     *
     * @param g2  the graphics device.
     * @param state  the renderer state.
     * @param dataArea  the data area.
     * @param plot  the plot.
     * @param domainAxis  the domain axis.
     * @param rangeAxis  the range axis.
     * @param dataset  the dataset.
     * @param row  the row index (zero-based).
     * @param column  the column index (zero-based).
     * @param pass  the pass index.
     */
    public void drawItem(Graphics2D g2,
                         CategoryItemRendererState state,
                         Rectangle2D dataArea,
                         CategoryPlot plot,
                         CategoryAxis domainAxis,
                         ValueAxis rangeAxis,
                         CategoryDataset dataset,
                         int row,
                         int column,
                         int pass) {

        // nothing is drawn for null values...
        Number dataValue = dataset.getValue(row, column);
        if (dataValue == null) {
            return;
        }
        
        double value = dataValue.doubleValue();
        
        PlotOrientation orientation = plot.getOrientation();
        double barW0 = calculateBarW0(plot, orientation, dataArea, domainAxis, 
                state, row, column);
        double[] barL0L1 = calculateBarL0L1(value);
        if (barL0L1 == null) {
            return;  // the bar is not visible
        }
        
        RectangleEdge edge = plot.getRangeAxisEdge();
        double transL0 = rangeAxis.valueToJava2D(barL0L1[0], dataArea, edge);
        double transL1 = rangeAxis.valueToJava2D(barL0L1[1], dataArea, edge);
        double barL0 = Math.min(transL0, transL1);
        double barLength = Math.max(Math.abs(transL1 - transL0), 
                getMinimumBarLength());

        // draw the bar...
        Rectangle2D bar = null;
        if (orientation == PlotOrientation.HORIZONTAL) {
            bar = new Rectangle2D.Double(barL0, barW0, barLength, 
                    state.getBarWidth());
        }
        else {
            bar = new Rectangle2D.Double(barW0, barL0, state.getBarWidth(), 
                    barLength);
        }
        Paint itemPaint = getItemPaint(row, column);
        GradientPaintTransformer t = getGradientPaintTransformer();
        if (t != null && itemPaint instanceof GradientPaint) {
            itemPaint = t.transform((GradientPaint) itemPaint, bar);
        }
        g2.setPaint(itemPaint);
        g2.fill(bar);

        // draw the outline...
        if (isDrawBarOutline() 
                && state.getBarWidth() > BAR_OUTLINE_WIDTH_THRESHOLD) {
            Stroke stroke = getItemOutlineStroke(row, column);
            Paint paint = getItemOutlinePaint(row, column);
            if (stroke != null && paint != null) {
                g2.setStroke(stroke);
                g2.setPaint(paint);
                g2.draw(bar);
            }
        }

        CategoryItemLabelGenerator generator 
            = getItemLabelGenerator(row, column);
        if (generator != null && isItemLabelVisible(row, column)) {
            drawItemLabel(g2, dataset, row, column, plot, generator, bar, 
                    (value < 0.0));
        }        

        // add an item entity, if this information is being collected
        EntityCollection entities = state.getEntityCollection();
        if (entities != null) {
            addItemEntity(entities, dataset, row, column, bar);
        }

    }

    /**
     * Calculates the available space for each series.
     * 
     * @param space  the space along the entire axis (in Java2D units).
     * @param axis  the category axis.
     * @param categories  the number of categories.
     * @param series  the number of series.
     * 
     * @return The width of one series.
     */
    protected double calculateSeriesWidth(double space, CategoryAxis axis, 
                                          int categories, int series) {
        double factor = 1.0 - getItemMargin() - axis.getLowerMargin() 
                            - axis.getUpperMargin();
        if (categories > 1) {
            factor = factor - axis.getCategoryMargin();
        }
        return (space * factor) / (categories * series);
    }
    
    /**
     * Draws an item label.  This method is overridden so that the bar can be 
     * used to calculate the label anchor point.
     * 
     * @param g2  the graphics device.
     * @param data  the dataset.
     * @param row  the row.
     * @param column  the column.
     * @param plot  the plot.
     * @param generator  the label generator.
     * @param bar  the bar.
     * @param negative  a flag indicating a negative value.
     */
    protected void drawItemLabel(Graphics2D g2,
                                 CategoryDataset data,
                                 int row,
                                 int column,
                                 CategoryPlot plot,
                                 CategoryItemLabelGenerator generator,
                                 Rectangle2D bar,
                                 boolean negative) {
                                     
        String label = generator.generateLabel(data, row, column);
        if (label == null) {
            return;  // nothing to do   
        }
        
        Font labelFont = getItemLabelFont(row, column);
        g2.setFont(labelFont);
        Paint paint = getItemLabelPaint(row, column);
        g2.setPaint(paint);

        // find out where to place the label...
        ItemLabelPosition position = null;
        if (!negative) {
            position = getPositiveItemLabelPosition(row, column);
        }
        else {
            position = getNegativeItemLabelPosition(row, column);
        }

        // work out the label anchor point...
        Point2D anchorPoint = calculateLabelAnchorPoint(
                position.getItemLabelAnchor(), bar, plot.getOrientation());
        
        if (isInternalAnchor(position.getItemLabelAnchor())) {
            Shape bounds = TextUtilities.calculateRotatedStringBounds(label, 
                    g2, (float) anchorPoint.getX(), (float) anchorPoint.getY(),
                    position.getTextAnchor(), position.getAngle(),
                    position.getRotationAnchor());
            
            if (bounds != null) {
                if (!bar.contains(bounds.getBounds2D())) {
                    if (!negative) {
                        position = getPositiveItemLabelPositionFallback();
                    }
                    else {
                        position = getNegativeItemLabelPositionFallback();
                    }
                    if (position != null) {
                        anchorPoint = calculateLabelAnchorPoint(
                                position.getItemLabelAnchor(), bar, 
                                plot.getOrientation());
                    }
                }
            }
        
        }
        
        if (position != null) {
            TextUtilities.drawRotatedString(label, g2, 
                    (float) anchorPoint.getX(), (float) anchorPoint.getY(),
                    position.getTextAnchor(), position.getAngle(), 
                    position.getRotationAnchor());
        }        
    }
    
    /**
     * Calculates the item label anchor point.
     *
     * @param anchor  the anchor.
     * @param bar  the bar.
     * @param orientation  the plot orientation.
     *
     * @return The anchor point.
     */
    private Point2D calculateLabelAnchorPoint(ItemLabelAnchor anchor,
                                              Rectangle2D bar, 
                                              PlotOrientation orientation) {

        Point2D result = null;
        double offset = getItemLabelAnchorOffset();
        double x0 = bar.getX() - offset;
        double x1 = bar.getX();
        double x2 = bar.getX() + offset;
        double x3 = bar.getCenterX();
        double x4 = bar.getMaxX() - offset;
        double x5 = bar.getMaxX();
        double x6 = bar.getMaxX() + offset;

        double y0 = bar.getMaxY() + offset;
        double y1 = bar.getMaxY();
        double y2 = bar.getMaxY() - offset;
        double y3 = bar.getCenterY();
        double y4 = bar.getMinY() + offset;
        double y5 = bar.getMinY();
        double y6 = bar.getMinY() - offset;

        if (anchor == ItemLabelAnchor.CENTER) {
            result = new Point2D.Double(x3, y3);
        }
        else if (anchor == ItemLabelAnchor.INSIDE1) {
            result = new Point2D.Double(x4, y4);
        }
        else if (anchor == ItemLabelAnchor.INSIDE2) {
            result = new Point2D.Double(x4, y4);
        }
        else if (anchor == ItemLabelAnchor.INSIDE3) {
            result = new Point2D.Double(x4, y3);
        }
        else if (anchor == ItemLabelAnchor.INSIDE4) {
            result = new Point2D.Double(x4, y2);
        }
        else if (anchor == ItemLabelAnchor.INSIDE5) {
            result = new Point2D.Double(x4, y2);
        }
        else if (anchor == ItemLabelAnchor.INSIDE6) {
            result = new Point2D.Double(x3, y2);
        }
        else if (anchor == ItemLabelAnchor.INSIDE7) {
            result = new Point2D.Double(x2, y2);
        }
        else if (anchor == ItemLabelAnchor.INSIDE8) {
            result = new Point2D.Double(x2, y2);
        }
        else if (anchor == ItemLabelAnchor.INSIDE9) {
            result = new Point2D.Double(x2, y3);
        }
        else if (anchor == ItemLabelAnchor.INSIDE10) {
            result = new Point2D.Double(x2, y4);
        }
        else if (anchor == ItemLabelAnchor.INSIDE11) {
            result = new Point2D.Double(x2, y4);
        }
        else if (anchor == ItemLabelAnchor.INSIDE12) {
            result = new Point2D.Double(x3, y4);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE1) {
            result = new Point2D.Double(x5, y6);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE2) {
            result = new Point2D.Double(x6, y5);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE3) {
            result = new Point2D.Double(x6, y3);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE4) {
            result = new Point2D.Double(x6, y1);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE5) {
            result = new Point2D.Double(x5, y0);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE6) {
            result = new Point2D.Double(x3, y0);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE7) {
            result = new Point2D.Double(x1, y0);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE8) {
            result = new Point2D.Double(x0, y1);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE9) {
            result = new Point2D.Double(x0, y3);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE10) {
            result = new Point2D.Double(x0, y5);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE11) {
            result = new Point2D.Double(x1, y6);
        }
        else if (anchor == ItemLabelAnchor.OUTSIDE12) {
            result = new Point2D.Double(x3, y6);
        }

        return result;

    }
    
    /**
     * Returns <code>true</code> if the specified anchor point is inside a bar.
     * 
     * @param anchor  the anchor point.
     * 
     * @return A boolean.
     */
    private boolean isInternalAnchor(ItemLabelAnchor anchor) {
        return anchor == ItemLabelAnchor.CENTER 
               || anchor == ItemLabelAnchor.INSIDE1
               || anchor == ItemLabelAnchor.INSIDE2
               || anchor == ItemLabelAnchor.INSIDE3
               || anchor == ItemLabelAnchor.INSIDE4
               || anchor == ItemLabelAnchor.INSIDE5
               || anchor == ItemLabelAnchor.INSIDE6
               || anchor == ItemLabelAnchor.INSIDE7
               || anchor == ItemLabelAnchor.INSIDE8
               || anchor == ItemLabelAnchor.INSIDE9
               || anchor == ItemLabelAnchor.INSIDE10
               || anchor == ItemLabelAnchor.INSIDE11
               || anchor == ItemLabelAnchor.INSIDE12;  
    }
    
    /**
     * Tests this instance for equality with an arbitrary object.
     * 
     * @param obj  the object (<code>null</code> permitted).
     * 
     * @return A boolean.
     */
    public boolean equals(Object obj) {
        
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof BarRenderer)) {
            return false;
        }
        if (!super.equals(obj)) {
            return false;
        }
        BarRenderer that = (BarRenderer) obj;
        if (this.base != that.base) {
            return false;   
        }
        if (this.itemMargin != that.itemMargin) {
            return false;
        }              
        if (this.drawBarOutline != that.drawBarOutline) {
            return false;
        }
        if (this.maximumBarWidth != that.maximumBarWidth) {
            return false;
        }
        if (this.minimumBarLength != that.minimumBarLength) {
            return false;
        }
        if (!ObjectUtilities.equal(this.gradientPaintTransformer, 
                that.gradientPaintTransformer)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.positiveItemLabelPositionFallback, 
            that.positiveItemLabelPositionFallback)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.negativeItemLabelPositionFallback, 
            that.negativeItemLabelPositionFallback)) {
            return false;
        }
        return true;
        
    }

}