/* ===========================================================
 * 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.]
 *
 * -----------------
 * CategoryAxis.java
 * -----------------
 * (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
 *
 * Original Author:  David Gilbert;
 * Contributor(s):   Pady Srinivasan (patch 1217634);
 *                   Peter Kolb (patches 2497611 and 2603321);
 *
 * Changes
 * -------
 * 21-Aug-2001 : Added standard header. Fixed DOS encoding problem (DG);
 * 18-Sep-2001 : Updated header (DG);
 * 04-Dec-2001 : Changed constructors to protected, and tidied up default
 *               values (DG);
 * 19-Apr-2002 : Updated import statements (DG);
 * 05-Sep-2002 : Updated constructor for changes in Axis class (DG);
 * 06-Nov-2002 : Moved margins from the CategoryPlot class (DG);
 * 08-Nov-2002 : Moved to new package com.jrefinery.chart.axis (DG);
 * 22-Jan-2002 : Removed monolithic constructor (DG);
 * 26-Mar-2003 : Implemented Serializable (DG);
 * 09-May-2003 : Merged HorizontalCategoryAxis and VerticalCategoryAxis into
 *               this class (DG);
 * 13-Aug-2003 : Implemented Cloneable (DG);
 * 29-Oct-2003 : Added workaround for font alignment in PDF output (DG);
 * 05-Nov-2003 : Fixed serialization bug (DG);
 * 26-Nov-2003 : Added category label offset (DG);
 * 06-Jan-2004 : Moved axis line attributes to Axis class, rationalised
 *               category label position attributes (DG);
 * 07-Jan-2004 : Added new implementation for linewrapping of category
 *               labels (DG);
 * 17-Feb-2004 : Moved deprecated code to bottom of source file (DG);
 * 10-Mar-2004 : Changed Dimension --> Dimension2D in text classes (DG);
 * 16-Mar-2004 : Added support for tooltips on category labels (DG);
 * 01-Apr-2004 : Changed java.awt.geom.Dimension2D to org.jfree.ui.Size2D
 *               because of JDK bug 4976448 which persists on JDK 1.3.1 (DG);
 * 03-Sep-2004 : Added 'maxCategoryLabelLines' attribute (DG);
 * 04-Oct-2004 : Renamed ShapeUtils --> ShapeUtilities (DG);
 * 11-Jan-2005 : Removed deprecated methods in preparation for 1.0.0
 *               release (DG);
 * 21-Jan-2005 : Modified return type for RectangleAnchor.coordinates()
 *               method (DG);
 * 21-Apr-2005 : Replaced Insets with RectangleInsets (DG);
 * 26-Apr-2005 : Removed LOGGER (DG);
 * 08-Jun-2005 : Fixed bug in axis layout (DG);
 * 22-Nov-2005 : Added a method to access the tool tip text for a category
 *               label (DG);
 * 23-Nov-2005 : Added per-category font and paint options - see patch
 *               1217634 (DG);
 * ------------- JFreeChart 1.0.x ---------------------------------------------
 * 11-Jan-2006 : Fixed null pointer exception in drawCategoryLabels - see bug
 *               1403043 (DG);
 * 18-Aug-2006 : Fix for bug drawing category labels, thanks to Adriaan
 *               Joubert (1277726) (DG);
 * 02-Oct-2006 : Updated category label entity (DG);
 * 30-Oct-2006 : Updated refreshTicks() method to account for possibility of
 *               multiple domain axes (DG);
 * 07-Mar-2007 : Fixed bug in axis label positioning (DG);
 * 27-Sep-2007 : Added getCategorySeriesMiddle() method (DG);
 * 21-Nov-2007 : Fixed performance bug noted by FindBugs in the
 *               equalPaintMaps() method (DG);
 * 23-Apr-2008 : Fixed bug 1942059, bad use of insets in
 *               calculateTextBlockWidth() (DG);
 * 26-Jun-2008 : Added new getCategoryMiddle() method (DG);
 * 27-Oct-2008 : Set font on Graphics2D when creating category labels (DG);
 * 14-Jan-2009 : Added new variant of getCategorySeriesMiddle() to make it
 *               simpler for renderers with hidden series (PK);
 * 19-Mar-2009 : Added entity support - see patch 2603321 by Peter Kolb (DG);
 * 16-Apr-2009 : Added tick mark drawing (DG);
 *
 */

package org.jfree.chart.axis;

import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.Paint;
import java.awt.Shape;
import java.awt.geom.Line2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.jfree.chart.entity.CategoryLabelEntity;
import org.jfree.chart.entity.EntityCollection;
import org.jfree.chart.event.AxisChangeEvent;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.Plot;
import org.jfree.chart.plot.PlotRenderingInfo;
import org.jfree.data.category.CategoryDataset;
import org.jfree.io.SerialUtilities;
import org.jfree.text.G2TextMeasurer;
import org.jfree.text.TextBlock;
import org.jfree.text.TextUtilities;
import org.jfree.ui.RectangleAnchor;
import org.jfree.ui.RectangleEdge;
import org.jfree.ui.RectangleInsets;
import org.jfree.ui.Size2D;
import org.jfree.util.ObjectUtilities;
import org.jfree.util.PaintUtilities;
import org.jfree.util.ShapeUtilities;

/**
 * An axis that displays categories.
 */
public class CategoryAxis extends Axis implements Cloneable, Serializable {

    /** For serialization. */
    private static final long serialVersionUID = 5886554608114265863L;

    /**
     * The default margin for the axis (used for both lower and upper margins).
     */
    public static final double DEFAULT_AXIS_MARGIN = 0.05;

    /**
     * The default margin between categories (a percentage of the overall axis
     * length).
     */
    public static final double DEFAULT_CATEGORY_MARGIN = 0.20;

    /** The amount of space reserved at the start of the axis. */
    private double lowerMargin;

    /** The amount of space reserved at the end of the axis. */
    private double upperMargin;

    /** The amount of space reserved between categories. */
    private double categoryMargin;

    /** The maximum number of lines for category labels. */
    private int maximumCategoryLabelLines;

    /**
     * A ratio that is multiplied by the width of one category to determine the
     * maximum label width.
     */
    private float maximumCategoryLabelWidthRatio;

    /** The category label offset. */
    private int categoryLabelPositionOffset;

    /**
     * A structure defining the category label positions for each axis
     * location.
     */
    private CategoryLabelPositions categoryLabelPositions;

    /** Storage for tick label font overrides (if any). */
    private Map tickLabelFontMap;

    /** Storage for tick label paint overrides (if any). */
    private transient Map tickLabelPaintMap;

    /** Storage for the category label tooltips (if any). */
    private Map categoryLabelToolTips;

    /**
     * Creates a new category axis with no label.
     */
    public CategoryAxis() {
        this(null);
    }

    /**
     * Constructs a category axis, using default values where necessary.
     *
     * @param label  the axis label (<code>null</code> permitted).
     */
    public CategoryAxis(String label) {

        super(label);

        this.lowerMargin = DEFAULT_AXIS_MARGIN;
        this.upperMargin = DEFAULT_AXIS_MARGIN;
        this.categoryMargin = DEFAULT_CATEGORY_MARGIN;
        this.maximumCategoryLabelLines = 1;
        this.maximumCategoryLabelWidthRatio = 0.0f;

        this.categoryLabelPositionOffset = 4;
        this.categoryLabelPositions = CategoryLabelPositions.STANDARD;
        this.tickLabelFontMap = new HashMap();
        this.tickLabelPaintMap = new HashMap();
        this.categoryLabelToolTips = new HashMap();

    }

    /**
     * Returns the lower margin for the axis.
     *
     * @return The margin.
     *
     * @see #getUpperMargin()
     * @see #setLowerMargin(double)
     */
    public double getLowerMargin() {
        return this.lowerMargin;
    }

    /**
     * Sets the lower margin for the axis and sends an {@link AxisChangeEvent}
     * to all registered listeners.
     *
     * @param margin  the margin as a percentage of the axis length (for
     *                example, 0.05 is five percent).
     *
     * @see #getLowerMargin()
     */
    public void setLowerMargin(double margin) {
        this.lowerMargin = margin;
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the upper margin for the axis.
     *
     * @return The margin.
     *
     * @see #getLowerMargin()
     * @see #setUpperMargin(double)
     */
    public double getUpperMargin() {
        return this.upperMargin;
    }

    /**
     * Sets the upper margin for the axis and sends an {@link AxisChangeEvent}
     * to all registered listeners.
     *
     * @param margin  the margin as a percentage of the axis length (for
     *                example, 0.05 is five percent).
     *
     * @see #getUpperMargin()
     */
    public void setUpperMargin(double margin) {
        this.upperMargin = margin;
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the category margin.
     *
     * @return The margin.
     *
     * @see #setCategoryMargin(double)
     */
    public double getCategoryMargin() {
        return this.categoryMargin;
    }

    /**
     * Sets the category margin and sends an {@link AxisChangeEvent} to all
     * registered listeners.  The overall category margin is distributed over
     * N-1 gaps, where N is the number of categories on the axis.
     *
     * @param margin  the margin as a percentage of the axis length (for
     *                example, 0.05 is five percent).
     *
     * @see #getCategoryMargin()
     */
    public void setCategoryMargin(double margin) {
        this.categoryMargin = margin;
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the maximum number of lines to use for each category label.
     *
     * @return The maximum number of lines.
     *
     * @see #setMaximumCategoryLabelLines(int)
     */
    public int getMaximumCategoryLabelLines() {
        return this.maximumCategoryLabelLines;
    }

    /**
     * Sets the maximum number of lines to use for each category label and
     * sends an {@link AxisChangeEvent} to all registered listeners.
     *
     * @param lines  the maximum number of lines.
     *
     * @see #getMaximumCategoryLabelLines()
     */
    public void setMaximumCategoryLabelLines(int lines) {
        this.maximumCategoryLabelLines = lines;
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the category label width ratio.
     *
     * @return The ratio.
     *
     * @see #setMaximumCategoryLabelWidthRatio(float)
     */
    public float getMaximumCategoryLabelWidthRatio() {
        return this.maximumCategoryLabelWidthRatio;
    }

    /**
     * Sets the maximum category label width ratio and sends an
     * {@link AxisChangeEvent} to all registered listeners.
     *
     * @param ratio  the ratio.
     *
     * @see #getMaximumCategoryLabelWidthRatio()
     */
    public void setMaximumCategoryLabelWidthRatio(float ratio) {
        this.maximumCategoryLabelWidthRatio = ratio;
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the offset between the axis and the category labels (before
     * label positioning is taken into account).
     *
     * @return The offset (in Java2D units).
     *
     * @see #setCategoryLabelPositionOffset(int)
     */
    public int getCategoryLabelPositionOffset() {
        return this.categoryLabelPositionOffset;
    }

    /**
     * Sets the offset between the axis and the category labels (before label
     * positioning is taken into account).
     *
     * @param offset  the offset (in Java2D units).
     *
     * @see #getCategoryLabelPositionOffset()
     */
    public void setCategoryLabelPositionOffset(int offset) {
        this.categoryLabelPositionOffset = offset;
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the category label position specification (this contains label
     * positioning info for all four possible axis locations).
     *
     * @return The positions (never <code>null</code>).
     *
     * @see #setCategoryLabelPositions(CategoryLabelPositions)
     */
    public CategoryLabelPositions getCategoryLabelPositions() {
        return this.categoryLabelPositions;
    }

    /**
     * Sets the category label position specification for the axis and sends an
     * {@link AxisChangeEvent} to all registered listeners.
     *
     * @param positions  the positions (<code>null</code> not permitted).
     *
     * @see #getCategoryLabelPositions()
     */
    public void setCategoryLabelPositions(CategoryLabelPositions positions) {
        if (positions == null) {
            throw new IllegalArgumentException("Null 'positions' argument.");
        }
        this.categoryLabelPositions = positions;
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the font for the tick label for the given category.
     *
     * @param category  the category (<code>null</code> not permitted).
     *
     * @return The font (never <code>null</code>).
     *
     * @see #setTickLabelFont(Comparable, Font)
     */
    public Font getTickLabelFont(Comparable category) {
        if (category == null) {
            throw new IllegalArgumentException("Null 'category' argument.");
        }
        Font result = (Font) this.tickLabelFontMap.get(category);
        // if there is no specific font, use the general one...
        if (result == null) {
            result = getTickLabelFont();
        }
        return result;
    }

    /**
     * Sets the font for the tick label for the specified category and sends
     * an {@link AxisChangeEvent} to all registered listeners.
     *
     * @param category  the category (<code>null</code> not permitted).
     * @param font  the font (<code>null</code> permitted).
     *
     * @see #getTickLabelFont(Comparable)
     */
    public void setTickLabelFont(Comparable category, Font font) {
        if (category == null) {
            throw new IllegalArgumentException("Null 'category' argument.");
        }
        if (font == null) {
            this.tickLabelFontMap.remove(category);
        }
        else {
            this.tickLabelFontMap.put(category, font);
        }
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the paint for the tick label for the given category.
     *
     * @param category  the category (<code>null</code> not permitted).
     *
     * @return The paint (never <code>null</code>).
     *
     * @see #setTickLabelPaint(Paint)
     */
    public Paint getTickLabelPaint(Comparable category) {
        if (category == null) {
            throw new IllegalArgumentException("Null 'category' argument.");
        }
        Paint result = (Paint) this.tickLabelPaintMap.get(category);
        // if there is no specific paint, use the general one...
        if (result == null) {
            result = getTickLabelPaint();
        }
        return result;
    }

    /**
     * Sets the paint for the tick label for the specified category and sends
     * an {@link AxisChangeEvent} to all registered listeners.
     *
     * @param category  the category (<code>null</code> not permitted).
     * @param paint  the paint (<code>null</code> permitted).
     *
     * @see #getTickLabelPaint(Comparable)
     */
    public void setTickLabelPaint(Comparable category, Paint paint) {
        if (category == null) {
            throw new IllegalArgumentException("Null 'category' argument.");
        }
        if (paint == null) {
            this.tickLabelPaintMap.remove(category);
        }
        else {
            this.tickLabelPaintMap.put(category, paint);
        }
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Adds a tooltip to the specified category and sends an
     * {@link AxisChangeEvent} to all registered listeners.
     *
     * @param category  the category (<code>null<code> not permitted).
     * @param tooltip  the tooltip text (<code>null</code> permitted).
     *
     * @see #removeCategoryLabelToolTip(Comparable)
     */
    public void addCategoryLabelToolTip(Comparable category, String tooltip) {
        if (category == null) {
            throw new IllegalArgumentException("Null 'category' argument.");
        }
        this.categoryLabelToolTips.put(category, tooltip);
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the tool tip text for the label belonging to the specified
     * category.
     *
     * @param category  the category (<code>null</code> not permitted).
     *
     * @return The tool tip text (possibly <code>null</code>).
     *
     * @see #addCategoryLabelToolTip(Comparable, String)
     * @see #removeCategoryLabelToolTip(Comparable)
     */
    public String getCategoryLabelToolTip(Comparable category) {
        if (category == null) {
            throw new IllegalArgumentException("Null 'category' argument.");
        }
        return (String) this.categoryLabelToolTips.get(category);
    }

    /**
     * Removes the tooltip for the specified category and sends an
     * {@link AxisChangeEvent} to all registered listeners.
     *
     * @param category  the category (<code>null<code> not permitted).
     *
     * @see #addCategoryLabelToolTip(Comparable, String)
     * @see #clearCategoryLabelToolTips()
     */
    public void removeCategoryLabelToolTip(Comparable category) {
        if (category == null) {
            throw new IllegalArgumentException("Null 'category' argument.");
        }
        this.categoryLabelToolTips.remove(category);
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Clears the category label tooltips and sends an {@link AxisChangeEvent}
     * to all registered listeners.
     *
     * @see #addCategoryLabelToolTip(Comparable, String)
     * @see #removeCategoryLabelToolTip(Comparable)
     */
    public void clearCategoryLabelToolTips() {
        this.categoryLabelToolTips.clear();
        notifyListeners(new AxisChangeEvent(this));
    }

    /**
     * Returns the Java 2D coordinate for a category.
     *
     * @param anchor  the anchor point.
     * @param category  the category index.
     * @param categoryCount  the category count.
     * @param area  the data area.
     * @param edge  the location of the axis.
     *
     * @return The coordinate.
     */
    public double getCategoryJava2DCoordinate(CategoryAnchor anchor,
                                              int category,
                                              int categoryCount,
                                              Rectangle2D area,
                                              RectangleEdge edge) {

        double result = 0.0;
        if (anchor == CategoryAnchor.START) {
            result = getCategoryStart(category, categoryCount, area, edge);
        }
        else if (anchor == CategoryAnchor.MIDDLE) {
            result = getCategoryMiddle(category, categoryCount, area, edge);
        }
        else if (anchor == CategoryAnchor.END) {
            result = getCategoryEnd(category, categoryCount, area, edge);
        }
        return result;

    }

    /**
     * Returns the starting coordinate for the specified category.
     *
     * @param category  the category.
     * @param categoryCount  the number of categories.
     * @param area  the data area.
     * @param edge  the axis location.
     *
     * @return The coordinate.
     *
     * @see #getCategoryMiddle(int, int, Rectangle2D, RectangleEdge)
     * @see #getCategoryEnd(int, int, Rectangle2D, RectangleEdge)
     */
    public double getCategoryStart(int category, int categoryCount,
                                   Rectangle2D area,
                                   RectangleEdge edge) {

        double result = 0.0;
        if ((edge == RectangleEdge.TOP) || (edge == RectangleEdge.BOTTOM)) {
            result = area.getX() + area.getWidth() * getLowerMargin();
        }
        else if ((edge == RectangleEdge.LEFT)
                || (edge == RectangleEdge.RIGHT)) {
            result = area.getMinY() + area.getHeight() * getLowerMargin();
        }

        double categorySize = calculateCategorySize(categoryCount, area, edge);
        double categoryGapWidth = calculateCategoryGapSize(categoryCount, area,
                edge);

        result = result + category * (categorySize + categoryGapWidth);
        return result;

    }

    /**
     * Returns the middle coordinate for the specified category.
     *
     * @param category  the category.
     * @param categoryCount  the number of categories.
     * @param area  the data area.
     * @param edge  the axis location.
     *
     * @return The coordinate.
     *
     * @see #getCategoryStart(int, int, Rectangle2D, RectangleEdge)
     * @see #getCategoryEnd(int, int, Rectangle2D, RectangleEdge)
     */
    public double getCategoryMiddle(int category, int categoryCount,
                                    Rectangle2D area, RectangleEdge edge) {

        if (category < 0 || category >= categoryCount) {
            throw new IllegalArgumentException("Invalid category index: "
                    + category);
        }
        return getCategoryStart(category, categoryCount, area, edge)
               + calculateCategorySize(categoryCount, area, edge) / 2;

    }

    /**
     * Returns the end coordinate for the specified category.
     *
     * @param category  the category.
     * @param categoryCount  the number of categories.
     * @param area  the data area.
     * @param edge  the axis location.
     *
     * @return The coordinate.
     *
     * @see #getCategoryStart(int, int, Rectangle2D, RectangleEdge)
     * @see #getCategoryMiddle(int, int, Rectangle2D, RectangleEdge)
     */
    public double getCategoryEnd(int category, int categoryCount,
                                 Rectangle2D area, RectangleEdge edge) {

        return getCategoryStart(category, categoryCount, area, edge)
               + calculateCategorySize(categoryCount, area, edge);

    }

    /**
     * A convenience method that returns the axis coordinate for the centre of
     * a category.
     *
     * @param category  the category key (<code>null</code> not permitted).
     * @param categories  the categories (<code>null</code> not permitted).
     * @param area  the data area (<code>null</code> not permitted).
     * @param edge  the edge along which the axis lies (<code>null</code> not
     *     permitted).
     *
     * @return The centre coordinate.
     *
     * @since 1.0.11
     *
     * @see #getCategorySeriesMiddle(Comparable, Comparable, CategoryDataset,
     *     double, Rectangle2D, RectangleEdge)
     */
    public double getCategoryMiddle(Comparable category,
            List categories, Rectangle2D area, RectangleEdge edge) {
        if (categories == null) {
            throw new IllegalArgumentException("Null 'categories' argument.");
        }
        int categoryIndex = categories.indexOf(category);
        int categoryCount = categories.size();
        return getCategoryMiddle(categoryIndex, categoryCount, area, edge);
    }

    /**
     * Returns the middle coordinate (in Java2D space) for a series within a
     * category.
     *
     * @param category  the category (<code>null</code> not permitted).
     * @param seriesKey  the series key (<code>null</code> not permitted).
     * @param dataset  the dataset (<code>null</code> not permitted).
     * @param itemMargin  the item margin (0.0 <= itemMargin < 1.0);
     * @param area  the area (<code>null</code> not permitted).
     * @param edge  the edge (<code>null</code> not permitted).
     *
     * @return The coordinate in Java2D space.
     *
     * @since 1.0.7
     */
    public double getCategorySeriesMiddle(Comparable category,
            Comparable seriesKey, CategoryDataset dataset, double itemMargin,
            Rectangle2D area, RectangleEdge edge) {

        int categoryIndex = dataset.getColumnIndex(category);
        int categoryCount = dataset.getColumnCount();
        int seriesIndex = dataset.getRowIndex(seriesKey);
        int seriesCount = dataset.getRowCount();
        double start = getCategoryStart(categoryIndex, categoryCount, area,
                edge);
        double end = getCategoryEnd(categoryIndex, categoryCount, area, edge);
        double width = end - start;
        if (seriesCount == 1) {
            return start + width / 2.0;
        }
        else {
            double gap = (width * itemMargin) / (seriesCount - 1);
            double ww = (width * (1 - itemMargin)) / seriesCount;
            return start + (seriesIndex * (ww + gap)) + ww / 2.0;
        }
    }

    /**
     * Returns the middle coordinate (in Java2D space) for a series within a
     * category.
     *
     * @param categoryIndex  the category index.
     * @param categoryCount  the category count.
     * @param seriesIndex the series index.
     * @param seriesCount the series count.
     * @param itemMargin  the item margin (0.0 <= itemMargin < 1.0);
     * @param area  the area (<code>null</code> not permitted).
     * @param edge  the edge (<code>null</code> not permitted).
     *
     * @return The coordinate in Java2D space.
     *
     * @since 1.0.13
     */
    public double getCategorySeriesMiddle(int categoryIndex, int categoryCount,
            int seriesIndex, int seriesCount, double itemMargin,
            Rectangle2D area, RectangleEdge edge) {

        double start = getCategoryStart(categoryIndex, categoryCount, area,
                edge);
        double end = getCategoryEnd(categoryIndex, categoryCount, area, edge);
        double width = end - start;
        if (seriesCount == 1) {
            return start + width / 2.0;
        }
        else {
            double gap = (width * itemMargin) / (seriesCount - 1);
            double ww = (width * (1 - itemMargin)) / seriesCount;
            return start + (seriesIndex * (ww + gap)) + ww / 2.0;
        }
    }

    /**
     * Calculates the size (width or height, depending on the location of the
     * axis) of a category.
     *
     * @param categoryCount  the number of categories.
     * @param area  the area within which the categories will be drawn.
     * @param edge  the axis location.
     *
     * @return The category size.
     */
    protected double calculateCategorySize(int categoryCount, Rectangle2D area,
                                           RectangleEdge edge) {

        double result = 0.0;
        double available = 0.0;

        if ((edge == RectangleEdge.TOP) || (edge == RectangleEdge.BOTTOM)) {
            available = area.getWidth();
        }
        else if ((edge == RectangleEdge.LEFT)
                || (edge == RectangleEdge.RIGHT)) {
            available = area.getHeight();
        }
        if (categoryCount > 1) {
            result = available * (1 - getLowerMargin() - getUpperMargin()
                     - getCategoryMargin());
            result = result / categoryCount;
        }
        else {
            result = available * (1 - getLowerMargin() - getUpperMargin());
        }
        return result;

    }

    /**
     * Calculates the size (width or height, depending on the location of the
     * axis) of a category gap.
     *
     * @param categoryCount  the number of categories.
     * @param area  the area within which the categories will be drawn.
     * @param edge  the axis location.
     *
     * @return The category gap width.
     */
    protected double calculateCategoryGapSize(int categoryCount,
                                              Rectangle2D area,
                                              RectangleEdge edge) {

        double result = 0.0;
        double available = 0.0;

        if ((edge == RectangleEdge.TOP) || (edge == RectangleEdge.BOTTOM)) {
            available = area.getWidth();
        }
        else if ((edge == RectangleEdge.LEFT)
                || (edge == RectangleEdge.RIGHT)) {
            available = area.getHeight();
        }

        if (categoryCount > 1) {
            result = available * getCategoryMargin() / (categoryCount - 1);
        }

        return result;

    }

    /**
     * Estimates the space required for the axis, given a specific drawing area.
     *
     * @param g2  the graphics device (used to obtain font information).
     * @param plot  the plot that the axis belongs to.
     * @param plotArea  the area within which the axis should be drawn.
     * @param edge  the axis location (top or bottom).
     * @param space  the space already reserved.
     *
     * @return The space required to draw the axis.
     */
    public AxisSpace reserveSpace(Graphics2D g2, Plot plot,
                                  Rectangle2D plotArea,
                                  RectangleEdge edge, AxisSpace space) {

        // create a new space object if one wasn't supplied...
        if (space == null) {
            space = new AxisSpace();
        }

        // if the axis is not visible, no additional space is required...
        if (!isVisible()) {
            return space;
        }

        // calculate the max size of the tick labels (if visible)...
        double tickLabelHeight = 0.0;
        double tickLabelWidth = 0.0;
        if (isTickLabelsVisible()) {
            g2.setFont(getTickLabelFont());
            AxisState state = new AxisState();
            // we call refresh ticks just to get the maximum width or height
            refreshTicks(g2, state, plotArea, edge);
            if (edge == RectangleEdge.TOP) {
                tickLabelHeight = state.getMax();
            }
            else if (edge == RectangleEdge.BOTTOM) {
                tickLabelHeight = state.getMax();
            }
            else if (edge == RectangleEdge.LEFT) {
                tickLabelWidth = state.getMax();
            }
            else if (edge == RectangleEdge.RIGHT) {
                tickLabelWidth = state.getMax();
            }
        }

        // get the axis label size and update the space object...
        Rectangle2D labelEnclosure = getLabelEnclosure(g2, edge);
        double labelHeight = 0.0;
        double labelWidth = 0.0;
        if (RectangleEdge.isTopOrBottom(edge)) {
            labelHeight = labelEnclosure.getHeight();
            space.add(labelHeight + tickLabelHeight
                    + this.categoryLabelPositionOffset, edge);
        }
        else if (RectangleEdge.isLeftOrRight(edge)) {
            labelWidth = labelEnclosure.getWidth();
            space.add(labelWidth + tickLabelWidth
                    + this.categoryLabelPositionOffset, edge);
        }
        return space;

    }

    /**
     * Configures the axis against the current plot.
     */
    public void configure() {
        // nothing required
    }

    /**
     * Draws the axis on a Java 2D graphics device (such as the screen or a
     * printer).
     *
     * @param g2  the graphics device (<code>null</code> not permitted).
     * @param cursor  the cursor location.
     * @param plotArea  the area within which the axis should be drawn
     *                  (<code>null</code> not permitted).
     * @param dataArea  the area within which the plot is being drawn
     *                  (<code>null</code> not permitted).
     * @param edge  the location of the axis (<code>null</code> not permitted).
     * @param plotState  collects information about the plot
     *                   (<code>null</code> permitted).
     *
     * @return The axis state (never <code>null</code>).
     */
    public AxisState draw(Graphics2D g2, double cursor, Rectangle2D plotArea,
            Rectangle2D dataArea, RectangleEdge edge,
            PlotRenderingInfo plotState) {

        // if the axis is not visible, don't draw it...
        if (!isVisible()) {
            return new AxisState(cursor);
        }

        if (isAxisLineVisible()) {
            drawAxisLine(g2, cursor, dataArea, edge);
        }
        AxisState state = new AxisState(cursor);
        if (isTickMarksVisible()) {
            drawTickMarks(g2, cursor, dataArea, edge, state);
        }

        // draw the category labels and axis label
        state = drawCategoryLabels(g2, plotArea, dataArea, edge, state,
                plotState);
        state = drawLabel(getLabel(), g2, plotArea, dataArea, edge, state);
        createAndAddEntity(cursor, state, dataArea, edge, plotState);
        return state;

    }

    /**
     * Draws the category labels and returns the updated axis state.
     *
     * @param g2  the graphics device (<code>null</code> not permitted).
     * @param dataArea  the area inside the axes (<code>null</code> not
     *                  permitted).
     * @param edge  the axis location (<code>null</code> not permitted).
     * @param state  the axis state (<code>null</code> not permitted).
     * @param plotState  collects information about the plot (<code>null</code>
     *                   permitted).
     *
     * @return The updated axis state (never <code>null</code>).
     *
     * @deprecated Use {@link #drawCategoryLabels(Graphics2D, Rectangle2D,
     *     Rectangle2D, RectangleEdge, AxisState, PlotRenderingInfo)}.
     */
    protected AxisState drawCategoryLabels(Graphics2D g2,
                                           Rectangle2D dataArea,
                                           RectangleEdge edge,
                                           AxisState state,
                                           PlotRenderingInfo plotState) {

        // this method is deprecated because we really need the plotArea
        // when drawing the labels - see bug 1277726
        return drawCategoryLabels(g2, dataArea, dataArea, edge, state,
                plotState);
    }

    /**
     * Draws the category labels and returns the updated axis state.
     *
     * @param g2  the graphics device (<code>null</code> not permitted).
     * @param plotArea  the plot area (<code>null</code> not permitted).
     * @param dataArea  the area inside the axes (<code>null</code> not
     *                  permitted).
     * @param edge  the axis location (<code>null</code> not permitted).
     * @param state  the axis state (<code>null</code> not permitted).
     * @param plotState  collects information about the plot (<code>null</code>
     *                   permitted).
     *
     * @return The updated axis state (never <code>null</code>).
     */
    protected AxisState drawCategoryLabels(Graphics2D g2,
                                           Rectangle2D plotArea,
                                           Rectangle2D dataArea,
                                           RectangleEdge edge,
                                           AxisState state,
                                           PlotRenderingInfo plotState) {

        if (state == null) {
            throw new IllegalArgumentException("Null 'state' argument.");
        }

        if (isTickLabelsVisible()) {
            List ticks = refreshTicks(g2, state, plotArea, edge);
            state.setTicks(ticks);

            int categoryIndex = 0;
            Iterator iterator = ticks.iterator();
            while (iterator.hasNext()) {

                CategoryTick tick = (CategoryTick) iterator.next();
                g2.setFont(getTickLabelFont(tick.getCategory()));
                g2.setPaint(getTickLabelPaint(tick.getCategory()));

                CategoryLabelPosition position
                        = this.categoryLabelPositions.getLabelPosition(edge);
                double x0 = 0.0;
                double x1 = 0.0;
                double y0 = 0.0;
                double y1 = 0.0;
                if (edge == RectangleEdge.TOP) {
                    x0 = getCategoryStart(categoryIndex, ticks.size(),
                            dataArea, edge);
                    x1 = getCategoryEnd(categoryIndex, ticks.size(), dataArea,
                            edge);
                    y1 = state.getCursor() - this.categoryLabelPositionOffset;
                    y0 = y1 - state.getMax();
                }
                else if (edge == RectangleEdge.BOTTOM) {
                    x0 = getCategoryStart(categoryIndex, ticks.size(),
                            dataArea, edge);
                    x1 = getCategoryEnd(categoryIndex, ticks.size(), dataArea,
                            edge);
                    y0 = state.getCursor() + this.categoryLabelPositionOffset;
                    y1 = y0 + state.getMax();
                }
                else if (edge == RectangleEdge.LEFT) {
                    y0 = getCategoryStart(categoryIndex, ticks.size(),
                            dataArea, edge);
                    y1 = getCategoryEnd(categoryIndex, ticks.size(), dataArea,
                            edge);
                    x1 = state.getCursor() - this.categoryLabelPositionOffset;
                    x0 = x1 - state.getMax();
                }
                else if (edge == RectangleEdge.RIGHT) {
                    y0 = getCategoryStart(categoryIndex, ticks.size(),
                            dataArea, edge);
                    y1 = getCategoryEnd(categoryIndex, ticks.size(), dataArea,
                            edge);
                    x0 = state.getCursor() + this.categoryLabelPositionOffset;
                    x1 = x0 - state.getMax();
                }
                Rectangle2D area = new Rectangle2D.Double(x0, y0, (x1 - x0),
                        (y1 - y0));
                Point2D anchorPoint = RectangleAnchor.coordinates(area,
                        position.getCategoryAnchor());
                TextBlock block = tick.getLabel();
                block.draw(g2, (float) anchorPoint.getX(),
                        (float) anchorPoint.getY(), position.getLabelAnchor(),
                        (float) anchorPoint.getX(), (float) anchorPoint.getY(),
                        position.getAngle());
                Shape bounds = block.calculateBounds(g2,
                        (float) anchorPoint.getX(), (float) anchorPoint.getY(),
                        position.getLabelAnchor(), (float) anchorPoint.getX(),
                        (float) anchorPoint.getY(), position.getAngle());
                if (plotState != null && plotState.getOwner() != null) {
                    EntityCollection entities
                            = plotState.getOwner().getEntityCollection();
                    if (entities != null) {
                        String tooltip = getCategoryLabelToolTip(
                                tick.getCategory());
                        entities.add(new CategoryLabelEntity(tick.getCategory(),
                                bounds, tooltip, null));
                    }
                }
                categoryIndex++;
            }

            if (edge.equals(RectangleEdge.TOP)) {
                double h = state.getMax() + this.categoryLabelPositionOffset;
                state.cursorUp(h);
            }
            else if (edge.equals(RectangleEdge.BOTTOM)) {
                double h = state.getMax() + this.categoryLabelPositionOffset;
                state.cursorDown(h);
            }
            else if (edge == RectangleEdge.LEFT) {
                double w = state.getMax() + this.categoryLabelPositionOffset;
                state.cursorLeft(w);
            }
            else if (edge == RectangleEdge.RIGHT) {
                double w = state.getMax() + this.categoryLabelPositionOffset;
                state.cursorRight(w);
            }
        }
        return state;
    }

    /**
     * Creates a temporary list of ticks that can be used when drawing the axis.
     *
     * @param g2  the graphics device (used to get font measurements).
     * @param state  the axis state.
     * @param dataArea  the area inside the axes.
     * @param edge  the location of the axis.
     *
     * @return A list of ticks.
     */
    public List refreshTicks(Graphics2D g2,
                             AxisState state,
                             Rectangle2D dataArea,
                             RectangleEdge edge) {

        List ticks = new java.util.ArrayList();

        // sanity check for data area...
        if (dataArea.getHeight() <= 0.0 || dataArea.getWidth() < 0.0) {
            return ticks;
        }

        CategoryPlot plot = (CategoryPlot) getPlot();
        List categories = plot.getCategoriesForAxis(this);
        double max = 0.0;

        if (categories != null) {
            CategoryLabelPosition position
                    = this.categoryLabelPositions.getLabelPosition(edge);
            float r = this.maximumCategoryLabelWidthRatio;
            if (r <= 0.0) {
                r = position.getWidthRatio();
            }

            float l = 0.0f;
            if (position.getWidthType() == CategoryLabelWidthType.CATEGORY) {
                l = (float) calculateCategorySize(categories.size(), dataArea,
                        edge);
            }
            else {
                if (RectangleEdge.isLeftOrRight(edge)) {
                    l = (float) dataArea.getWidth();
                }
                else {
                    l = (float) dataArea.getHeight();
                }
            }
            int categoryIndex = 0;
            Iterator iterator = categories.iterator();
            while (iterator.hasNext()) {
                Comparable category = (Comparable) iterator.next();
                g2.setFont(getTickLabelFont(category));
                TextBlock label = createLabel(category, l * r, edge, g2);
                if (edge == RectangleEdge.TOP || edge == RectangleEdge.BOTTOM) {
                    max = Math.max(max, calculateTextBlockHeight(label,
                            position, g2));
                }
                else if (edge == RectangleEdge.LEFT
                        || edge == RectangleEdge.RIGHT) {
                    max = Math.max(max, calculateTextBlockWidth(label,
                            position, g2));
                }
                Tick tick = new CategoryTick(category, label,
                        position.getLabelAnchor(),
                        position.getRotationAnchor(), position.getAngle());
                ticks.add(tick);
                categoryIndex = categoryIndex + 1;
            }
        }
        state.setMax(max);
        return ticks;

    }

    /**
     * Draws the tick marks.
     *
     * @since 1.0.13
     */
    public void drawTickMarks(Graphics2D g2, double cursor,
            Rectangle2D dataArea, RectangleEdge edge, AxisState state) {

        Plot p = getPlot();
        if (p == null) {
            return;
        }
        CategoryPlot plot = (CategoryPlot) p;
        double il = getTickMarkInsideLength();
        double ol = getTickMarkOutsideLength();
        Line2D line = new Line2D.Double();
        List categories = plot.getCategoriesForAxis(this);
        g2.setPaint(getTickMarkPaint());
        g2.setStroke(getTickMarkStroke());
        if (edge.equals(RectangleEdge.TOP)) {
            Iterator iterator = categories.iterator();
            while (iterator.hasNext()) {
                Comparable key = (Comparable) iterator.next();
                double x = getCategoryMiddle(key, categories, dataArea, edge);
                line.setLine(x, cursor, x, cursor + il);
                g2.draw(line);
                line.setLine(x, cursor, x, cursor - ol);
                g2.draw(line);
            }
            state.cursorUp(ol);
        }
        else if (edge.equals(RectangleEdge.BOTTOM)) {
            Iterator iterator = categories.iterator();
            while (iterator.hasNext()) {
                Comparable key = (Comparable) iterator.next();
                double x = getCategoryMiddle(key, categories, dataArea, edge);
                line.setLine(x, cursor, x, cursor - il);
                g2.draw(line);
                line.setLine(x, cursor, x, cursor + ol);
                g2.draw(line);
            }
            state.cursorDown(ol);
        }
        else if (edge.equals(RectangleEdge.LEFT)) {
            Iterator iterator = categories.iterator();
            while (iterator.hasNext()) {
                Comparable key = (Comparable) iterator.next();
                double y = getCategoryMiddle(key, categories, dataArea, edge);
                line.setLine(cursor, y, cursor + il, y);
                g2.draw(line);
                line.setLine(cursor, y, cursor - ol, y);
                g2.draw(line);
            }
            state.cursorLeft(ol);
        }
        else if (edge.equals(RectangleEdge.RIGHT)) {
            Iterator iterator = categories.iterator();
            while (iterator.hasNext()) {
                Comparable key = (Comparable) iterator.next();
                double y = getCategoryMiddle(key, categories, dataArea, edge);
                line.setLine(cursor, y, cursor - il, y);
                g2.draw(line);
                line.setLine(cursor, y, cursor + ol, y);
                g2.draw(line);
            }
            state.cursorRight(ol);
        }
    }

    /**
     * Creates a label.
     *
     * @param category  the category.
     * @param width  the available width.
     * @param edge  the edge on which the axis appears.
     * @param g2  the graphics device.
     *
     * @return A label.
     */
    protected TextBlock createLabel(Comparable category, float width,
                                    RectangleEdge edge, Graphics2D g2) {
        TextBlock label = TextUtilities.createTextBlock(category.toString(),
                getTickLabelFont(category), getTickLabelPaint(category), width,
                this.maximumCategoryLabelLines, new G2TextMeasurer(g2));
        return label;
    }

    /**
     * A utility method for determining the width of a text block.
     *
     * @param block  the text block.
     * @param position  the position.
     * @param g2  the graphics device.
     *
     * @return The width.
     */
    protected double calculateTextBlockWidth(TextBlock block,
            CategoryLabelPosition position, Graphics2D g2) {

        RectangleInsets insets = getTickLabelInsets();
        Size2D size = block.calculateDimensions(g2);
        Rectangle2D box = new Rectangle2D.Double(0.0, 0.0, size.getWidth(),
                size.getHeight());
        Shape rotatedBox = ShapeUtilities.rotateShape(box, position.getAngle(),
                0.0f, 0.0f);
        double w = rotatedBox.getBounds2D().getWidth() + insets.getLeft()
                + insets.getRight();
        return w;

    }

    /**
     * A utility method for determining the height of a text block.
     *
     * @param block  the text block.
     * @param position  the label position.
     * @param g2  the graphics device.
     *
     * @return The height.
     */
    protected double calculateTextBlockHeight(TextBlock block,
                                              CategoryLabelPosition position,
                                              Graphics2D g2) {

        RectangleInsets insets = getTickLabelInsets();
        Size2D size = block.calculateDimensions(g2);
        Rectangle2D box = new Rectangle2D.Double(0.0, 0.0, size.getWidth(),
                size.getHeight());
        Shape rotatedBox = ShapeUtilities.rotateShape(box, position.getAngle(),
                0.0f, 0.0f);
        double h = rotatedBox.getBounds2D().getHeight()
                   + insets.getTop() + insets.getBottom();
        return h;

    }

    /**
     * Creates a clone of the axis.
     *
     * @return A clone.
     *
     * @throws CloneNotSupportedException if some component of the axis does
     *         not support cloning.
     */
    public Object clone() throws CloneNotSupportedException {
        CategoryAxis clone = (CategoryAxis) super.clone();
        clone.tickLabelFontMap = new HashMap(this.tickLabelFontMap);
        clone.tickLabelPaintMap = new HashMap(this.tickLabelPaintMap);
        clone.categoryLabelToolTips = new HashMap(this.categoryLabelToolTips);
        return clone;
    }

    /**
     * Tests this axis 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 CategoryAxis)) {
            return false;
        }
        if (!super.equals(obj)) {
            return false;
        }
        CategoryAxis that = (CategoryAxis) obj;
        if (that.lowerMargin != this.lowerMargin) {
            return false;
        }
        if (that.upperMargin != this.upperMargin) {
            return false;
        }
        if (that.categoryMargin != this.categoryMargin) {
            return false;
        }
        if (that.maximumCategoryLabelWidthRatio
                != this.maximumCategoryLabelWidthRatio) {
            return false;
        }
        if (that.categoryLabelPositionOffset
                != this.categoryLabelPositionOffset) {
            return false;
        }
        if (!ObjectUtilities.equal(that.categoryLabelPositions,
                this.categoryLabelPositions)) {
            return false;
        }
        if (!ObjectUtilities.equal(that.categoryLabelToolTips,
                this.categoryLabelToolTips)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.tickLabelFontMap,
                that.tickLabelFontMap)) {
            return false;
        }
        if (!equalPaintMaps(this.tickLabelPaintMap, that.tickLabelPaintMap)) {
            return false;
        }
        return true;
    }

    /**
     * Returns a hash code for this object.
     *
     * @return A hash code.
     */
    public int hashCode() {
        if (getLabel() != null) {
            return getLabel().hashCode();
        }
        else {
            return 0;
        }
    }

    /**
     * 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();
        writePaintMap(this.tickLabelPaintMap, 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.tickLabelPaintMap = readPaintMap(stream);
    }

    /**
     * Reads a <code>Map</code> of (<code>Comparable</code>, <code>Paint</code>)
     * elements from a stream.
     *
     * @param in  the input stream.
     *
     * @return The map.
     *
     * @throws IOException
     * @throws ClassNotFoundException
     *
     * @see #writePaintMap(Map, ObjectOutputStream)
     */
    private Map readPaintMap(ObjectInputStream in)
            throws IOException, ClassNotFoundException {
        boolean isNull = in.readBoolean();
        if (isNull) {
            return null;
        }
        Map result = new HashMap();
        int count = in.readInt();
        for (int i = 0; i < count; i++) {
            Comparable category = (Comparable) in.readObject();
            Paint paint = SerialUtilities.readPaint(in);
            result.put(category, paint);
        }
        return result;
    }

    /**
     * Writes a map of (<code>Comparable</code>, <code>Paint</code>)
     * elements to a stream.
     *
     * @param map  the map (<code>null</code> permitted).
     *
     * @param out
     * @throws IOException
     *
     * @see #readPaintMap(ObjectInputStream)
     */
    private void writePaintMap(Map map, ObjectOutputStream out)
            throws IOException {
        if (map == null) {
            out.writeBoolean(true);
        }
        else {
            out.writeBoolean(false);
            Set keys = map.keySet();
            int count = keys.size();
            out.writeInt(count);
            Iterator iterator = keys.iterator();
            while (iterator.hasNext()) {
                Comparable key = (Comparable) iterator.next();
                out.writeObject(key);
                SerialUtilities.writePaint((Paint) map.get(key), out);
            }
        }
    }

    /**
     * Tests two maps containing (<code>Comparable</code>, <code>Paint</code>)
     * elements for equality.
     *
     * @param map1  the first map (<code>null</code> not permitted).
     * @param map2  the second map (<code>null</code> not permitted).
     *
     * @return A boolean.
     */
    private boolean equalPaintMaps(Map map1, Map map2) {
        if (map1.size() != map2.size()) {
            return false;
        }
        Set entries = map1.entrySet();
        Iterator iterator = entries.iterator();
        while (iterator.hasNext()) {
            Map.Entry entry = (Map.Entry) iterator.next();
            Paint p1 = (Paint) entry.getValue();
            Paint p2 = (Paint) map2.get(entry.getKey());
            if (!PaintUtilities.equal(p1, p2)) {
                return false;
            }
        }
        return true;
    }

}
