PlotOrientation orientation = plot.getOrientation();
            if (orientation == PlotOrientation.HORIZONTAL) {
                space = dataArea.getHeight();
            }
            else if (orientation == PlotOrientation.VERTICAL) {
                space = dataArea.getWidth();
            }
            double maxWidth = space * getMaxItemWidth();
            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;
    }
    
    /**
     * 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);
        RectangleEdge edge = plot.getRangeAxisEdge();
        double barL = rangeAxis.valueToJava2D(value, dataArea, edge);

        // draw the bar...
        Line2D line = null;
        double x = 0.0;
        double y = 0.0;
        if (orientation == PlotOrientation.HORIZONTAL) {
            x = barL;
            y = barW0 + state.getBarWidth() / 2.0;
            line = new Line2D.Double(barL, barW0, barL, 
                    barW0 + state.getBarWidth());
        }
        else {
            x = barW0 + state.getBarWidth() / 2.0;
            y = barL;
            line = new Line2D.Double(barW0, barL, barW0 + state.getBarWidth(), 
                    barL);
        }
        Stroke itemStroke = getItemStroke(row, column);
        Paint itemPaint = getItemPaint(row, column);
        g2.setStroke(itemStroke);
        g2.setPaint(itemPaint);
        g2.draw(line);

        CategoryItemLabelGenerator generator = getItemLabelGenerator(row, 
                column);
        if (generator != null && isItemLabelVisible(row, column)) {
            drawItemLabel(g2, orientation, dataset, row, column, x, y, 
                    (value < 0.0));
        }        
                
        // collect entity and tool tip information...
        if (state.getInfo() != null) {
            EntityCollection entities = state.getEntityCollection();
            if (entities != null) {
                String tip = null;
                CategoryToolTipGenerator tipster = getToolTipGenerator(row, 
                        column);
                if (tipster != null) {
                    tip = tipster.generateToolTip(dataset, row, column);
                }
                String url = null;
                if (getItemURLGenerator(row, column) != null) {
                    url = getItemURLGenerator(row, column).generateURL(dataset,
                            row, column);
                }
                CategoryItemEntity entity = new CategoryItemEntity(
                        line.getBounds(), tip, url, dataset, row, 
                        dataset.getColumnKey(column), column);
                entities.add(entity);
            }

        }

    }

    /**
     * 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);
    }
    
    /**
     * Tests an object for equality with this instance.
     * 
     * @param obj  the object (<code>null</code> permitted).
     * 
     * @return A boolean.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof LevelRenderer)) {
            return false;
        }
        if (!super.equals(obj)) {
            return false;
        }
        LevelRenderer that = (LevelRenderer) obj;
        if (this.itemMargin != that.itemMargin) {              
            return false;
        }
        if (this.maxItemWidth != that.maxItemWidth) {
            return false;
        }
        return true;
    }

}