001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
006     *
007     * Project Info:  http://www.jfree.org/jfreechart/index.html
008     *
009     * This library is free software; you can redistribute it and/or modify it 
010     * under the terms of the GNU Lesser General Public License as published by 
011     * the Free Software Foundation; either version 2.1 of the License, or 
012     * (at your option) any later version.
013     *
014     * This library is distributed in the hope that it will be useful, but 
015     * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
016     * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
017     * License for more details.
018     *
019     * You should have received a copy of the GNU Lesser General Public
020     * License along with this library; if not, write to the Free Software
021     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
022     * USA.  
023     *
024     * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
025     * in the United States and other countries.]
026     *
027     * ---------------
028     * SymbolAxis.java
029     * ---------------
030     * (C) Copyright 2002-2007, by Anthony Boulestreau and Contributors.
031     *
032     * Original Author:  Anthony Boulestreau;
033     * Contributor(s):   David Gilbert (for Object Refinery Limited);
034     *
035     *
036     * Changes
037     * -------
038     * 29-Mar-2002 : First version (AB);
039     * 19-Apr-2002 : Updated formatting and import statements (DG);
040     * 21-Jun-2002 : Make change to use the class TickUnit - remove valueToString() 
041     *               method and add SymbolicTickUnit (AB);
042     * 25-Jun-2002 : Removed redundant code (DG);
043     * 25-Jul-2002 : Changed order of parameters in ValueAxis constructor (DG);
044     * 05-Sep-2002 : Updated constructor to reflect changes in the Axis class (DG);
045     * 08-Nov-2002 : Moved to new package com.jrefinery.chart.axis (DG);
046     * 14-Feb-2003 : Added back missing constructor code (DG);
047     * 26-Mar-2003 : Implemented Serializable (DG);
048     * 14-May-2003 : Renamed HorizontalSymbolicAxis --> SymbolicAxis and merged in
049     *               VerticalSymbolicAxis (DG);
050     * 12-Aug-2003 : Fixed bug where refreshTicks() method has different signature 
051     *               to super class (DG);
052     * 29-Oct-2003 : Added workaround for font alignment in PDF output (DG);
053     * 02-Nov-2003 : Added code to avoid overlapping labels (MR);
054     * 07-Nov-2003 : Modified to use new tick classes (DG);
055     * 18-Nov-2003 : Fixed bug where symbols are not being displayed on the 
056     *               axis (DG);
057     * 24-Nov-2003 : Added fix for gridlines on zooming (bug id 834643) (DG);
058     * 21-Jan-2004 : Update for renamed method in ValueAxis (DG);
059     * 11-Mar-2004 : Modified the way the background grid color is being drawn, see
060     *               this thread:
061     *               http://www.jfree.org/phpBB2/viewtopic.php?p=22973 (DG);
062     * 16-Mar-2004 : Added plotState to draw() method (DG);
063     * 07-Apr-2004 : Modified string bounds calculation (DG);
064     * 28-Mar-2005 : Renamed autoRangeIncludesZero() --> getAutoRangeIncludesZero()
065     *               and autoRangeStickyZero() --> getAutoRangeStickyZero() (DG);
066     * 05-Jul-2005 : Fixed signature on refreshTicks() method - see bug report
067     *               1232264 (DG);
068     * 06-Jul-2005 : Renamed SymbolicAxis --> SymbolAxis, added equals() method, 
069     *               renamed getSymbolicValue() --> getSymbols(), renamed 
070     *               symbolicGridPaint --> gridBandPaint, fixed serialization of 
071     *               gridBandPaint, renamed symbolicGridLinesVisible --> 
072     *               gridBandsVisible, eliminated symbolicGridLineList (DG);
073     * ------------- JFREECHART 1.0.x ---------------------------------------------
074     * 02-Feb-2007 : Removed author tags all over JFreeChart sources (DG);
075     * 28-Feb-2007 : Fixed bug 1669302 (tick label overlap) (DG);
076     * 25-Jul-2007 : Added new field for alternate grid band paint (DG);
077     * 
078     */
079    
080    package org.jfree.chart.axis;
081    
082    import java.awt.BasicStroke;
083    import java.awt.Color;
084    import java.awt.Font;
085    import java.awt.Graphics2D;
086    import java.awt.Paint;
087    import java.awt.Shape;
088    import java.awt.Stroke;
089    import java.awt.geom.Rectangle2D;
090    import java.io.IOException;
091    import java.io.ObjectInputStream;
092    import java.io.ObjectOutputStream;
093    import java.io.Serializable;
094    import java.text.NumberFormat;
095    import java.util.Arrays;
096    import java.util.Iterator;
097    import java.util.List;
098    
099    import org.jfree.chart.event.AxisChangeEvent;
100    import org.jfree.chart.plot.Plot;
101    import org.jfree.chart.plot.PlotRenderingInfo;
102    import org.jfree.chart.plot.ValueAxisPlot;
103    import org.jfree.data.Range;
104    import org.jfree.io.SerialUtilities;
105    import org.jfree.text.TextUtilities;
106    import org.jfree.ui.RectangleEdge;
107    import org.jfree.ui.TextAnchor;
108    import org.jfree.util.PaintUtilities;
109    
110    /**
111     * A standard linear value axis that replaces integer values with symbols.
112     */
113    public class SymbolAxis extends NumberAxis implements Serializable {
114    
115        /** For serialization. */
116        private static final long serialVersionUID = 7216330468770619716L;
117        
118        /** The default grid band paint. */
119        public static final Paint DEFAULT_GRID_BAND_PAINT 
120                = new Color(232, 234, 232, 128);
121    
122        /**
123         * The default paint for alternate grid bands.
124         * 
125         * @since 1.0.7
126         */
127        public static final Paint DEFAULT_GRID_BAND_ALTERNATE_PAINT
128                = new Color(0, 0, 0, 0);  // transparent
129        
130        /** The list of symbols to display instead of the numeric values. */
131        private List symbols;
132    
133        /** Flag that indicates whether or not grid bands are visible. */
134        private boolean gridBandsVisible;
135    
136        /** The paint used to color the grid bands (if the bands are visible). */
137        private transient Paint gridBandPaint;
138        
139        /** 
140         * The paint used to fill the alternate grid bands.
141         * 
142         * @since 1.0.7
143         */
144        private transient Paint gridBandAlternatePaint;
145    
146        /**
147         * Constructs a symbol axis, using default attribute values where 
148         * necessary.
149         *
150         * @param label  the axis label (<code>null</code> permitted).
151         * @param sv  the list of symbols to display instead of the numeric
152         *            values.
153         */
154        public SymbolAxis(String label, String[] sv) {
155            super(label);
156            this.symbols = Arrays.asList(sv);
157            this.gridBandsVisible = true;
158            this.gridBandPaint = DEFAULT_GRID_BAND_PAINT;
159            this.gridBandAlternatePaint = DEFAULT_GRID_BAND_ALTERNATE_PAINT;
160            setAutoTickUnitSelection(false, false);
161            setAutoRangeStickyZero(false);
162    
163        }
164    
165        /**
166         * Returns an array of the symbols for the axis.
167         *
168         * @return The symbols.
169         */
170        public String[] getSymbols() {
171            String[] result = new String[this.symbols.size()];
172            result = (String[]) this.symbols.toArray(result);
173            return result;
174        }
175    
176        /**
177         * Returns <code>true</code> if the grid bands are showing, and
178         * <code>false</code> otherwise.
179         *
180         * @return <code>true</code> if the grid bands are showing, and 
181         *         <code>false</code> otherwise.
182         *         
183         * @see #setGridBandsVisible(boolean)
184         */
185        public boolean isGridBandsVisible() {
186            return this.gridBandsVisible;
187        }
188    
189        /**
190         * Sets the visibility of the grid bands and notifies registered
191         * listeners that the axis has been modified.
192         *
193         * @param flag  the new setting.
194         * 
195         * @see #isGridBandsVisible()
196         */
197        public void setGridBandsVisible(boolean flag) {
198            if (this.gridBandsVisible != flag) {
199                this.gridBandsVisible = flag;
200                notifyListeners(new AxisChangeEvent(this));
201            }
202        }
203    
204        /**
205         * Returns the paint used to color the grid bands.
206         *
207         * @return The grid band paint (never <code>null</code>).
208         * 
209         * @see #setGridBandPaint(Paint)
210         * @see #isGridBandsVisible()
211         */
212        public Paint getGridBandPaint() {
213            return this.gridBandPaint;
214        }
215    
216        /**
217         * Sets the grid band paint and sends an {@link AxisChangeEvent} to 
218         * all registered listeners.
219         * 
220         * @param paint  the paint (<code>null</code> not permitted).
221         * 
222         * @see #getGridBandPaint()
223         */
224        public void setGridBandPaint(Paint paint) {
225            if (paint == null) {
226                throw new IllegalArgumentException("Null 'paint' argument.");
227            }
228            this.gridBandPaint = paint;
229            notifyListeners(new AxisChangeEvent(this));
230        }
231    
232        /**
233         * Returns the paint used for alternate grid bands.
234         * 
235         * @return The paint (never <code>null</code>).
236         * 
237         * @see #setGridBandAlternatePaint(Paint)
238         * @see #getGridBandPaint()
239         * 
240         * @since 1.0.7
241         */
242        public Paint getGridBandAlternatePaint() {
243            return this.gridBandAlternatePaint;
244        }
245        
246        /**
247         * Sets the paint used for alternate grid bands and sends a 
248         * {@link AxisChangeEvent} to all registered listeners.
249         * 
250         * @param paint  the paint (<code>null</code> not permitted).
251         * 
252         * @see #getGridBandAlternatePaint()
253         * @see #setGridBandPaint(Paint)
254         * 
255         * @since 1.0.7
256         */
257        public void setGridBandAlternatePaint(Paint paint) {
258            if (paint == null) {
259                throw new IllegalArgumentException("Null 'paint' argument.");
260            }
261            this.gridBandAlternatePaint = paint;
262            notifyListeners(new AxisChangeEvent(this));
263        }
264        
265        /**
266         * This operation is not supported by this axis.
267         *
268         * @param g2  the graphics device.
269         * @param dataArea  the area in which the plot and axes should be drawn.
270         * @param edge  the edge along which the axis is drawn.
271         */
272        protected void selectAutoTickUnit(Graphics2D g2, Rectangle2D dataArea, 
273                                          RectangleEdge edge) {
274            throw new UnsupportedOperationException();
275        }
276    
277        /**
278         * Draws the axis on a Java 2D graphics device (such as the screen or a 
279         * printer).
280         *
281         * @param g2  the graphics device (<code>null</code> not permitted).
282         * @param cursor  the cursor location.
283         * @param plotArea  the area within which the plot and axes should be drawn
284         *                  (<code>null</code> not permitted).
285         * @param dataArea  the area within which the data should be drawn 
286         *                  (<code>null</code> not permitted).
287         * @param edge  the axis location (<code>null</code> not permitted).
288         * @param plotState  collects information about the plot 
289         *                   (<code>null</code> permitted).
290         * 
291         * @return The axis state (never <code>null</code>).
292         */
293        public AxisState draw(Graphics2D g2, 
294                              double cursor,
295                              Rectangle2D plotArea, 
296                              Rectangle2D dataArea, 
297                              RectangleEdge edge,
298                              PlotRenderingInfo plotState) {
299    
300            AxisState info = new AxisState(cursor);
301            if (isVisible()) {
302                info = super.draw(g2, cursor, plotArea, dataArea, edge, plotState);
303            }
304            if (this.gridBandsVisible) {
305                drawGridBands(g2, plotArea, dataArea, edge, info.getTicks());
306            }
307            return info;
308    
309        }
310    
311        /**
312         * Draws the grid bands.  Alternate bands are colored using 
313         * <CODE>gridBandPaint<CODE> (<CODE>DEFAULT_GRID_BAND_PAINT</CODE> by 
314         * default).
315         *
316         * @param g2  the graphics device.
317         * @param plotArea  the area within which the chart should be drawn.
318         * @param dataArea  the area within which the plot should be drawn (a 
319         *                  subset of the drawArea).
320         * @param edge  the axis location.
321         * @param ticks  the ticks.
322         */
323        protected void drawGridBands(Graphics2D g2,
324                                     Rectangle2D plotArea, 
325                                     Rectangle2D dataArea,
326                                     RectangleEdge edge, 
327                                     List ticks) {
328    
329            Shape savedClip = g2.getClip();
330            g2.clip(dataArea);
331            if (RectangleEdge.isTopOrBottom(edge)) {
332                drawGridBandsHorizontal(g2, plotArea, dataArea, true, ticks);
333            }
334            else if (RectangleEdge.isLeftOrRight(edge)) {
335                drawGridBandsVertical(g2, plotArea, dataArea, true, ticks);
336            }
337            g2.setClip(savedClip);
338    
339        }
340    
341        /**
342         * Draws the grid bands for the axis when it is at the top or bottom of 
343         * the plot.
344         *
345         * @param g2  the graphics device.
346         * @param plotArea  the area within which the chart should be drawn.
347         * @param dataArea  the area within which the plot should be drawn
348         *                  (a subset of the drawArea).
349         * @param firstGridBandIsDark  True: the first grid band takes the
350         *                             color of <CODE>gridBandPaint<CODE>.
351         *                             False: the second grid band takes the 
352         *                             color of <CODE>gridBandPaint<CODE>.
353         * @param ticks  the ticks.
354         */
355        protected void drawGridBandsHorizontal(Graphics2D g2,
356                                               Rectangle2D plotArea, 
357                                               Rectangle2D dataArea,
358                                               boolean firstGridBandIsDark, 
359                                               List ticks) {
360    
361            boolean currentGridBandIsDark = firstGridBandIsDark;
362            double yy = dataArea.getY();
363            double xx1, xx2;
364    
365            //gets the outline stroke width of the plot
366            double outlineStrokeWidth;
367            if (getPlot().getOutlineStroke() !=  null) {
368                outlineStrokeWidth 
369                    = ((BasicStroke) getPlot().getOutlineStroke()).getLineWidth();
370            }
371            else {
372                outlineStrokeWidth = 1d;
373            }
374    
375            Iterator iterator = ticks.iterator();
376            ValueTick tick;
377            Rectangle2D band;
378            while (iterator.hasNext()) {
379                tick = (ValueTick) iterator.next();
380                xx1 = valueToJava2D(tick.getValue() - 0.5d, dataArea, 
381                        RectangleEdge.BOTTOM);
382                xx2 = valueToJava2D(tick.getValue() + 0.5d, dataArea, 
383                        RectangleEdge.BOTTOM);
384                if (currentGridBandIsDark) {
385                    g2.setPaint(this.gridBandPaint);
386                }
387                else {
388                    g2.setPaint(Color.white);
389                }
390                band = new Rectangle2D.Double(xx1, yy + outlineStrokeWidth, 
391                    xx2 - xx1, dataArea.getMaxY() - yy - outlineStrokeWidth);
392                g2.fill(band);
393                currentGridBandIsDark = !currentGridBandIsDark;
394            }
395            g2.setPaintMode();
396        }
397    
398        /**
399         * Draws the grid bands for the axis when it is at the top or bottom of 
400         * the plot.
401         *
402         * @param g2  the graphics device.
403         * @param drawArea  the area within which the chart should be drawn.
404         * @param plotArea  the area within which the plot should be drawn (a
405         *                  subset of the drawArea).
406         * @param firstGridBandIsDark  True: the first grid band takes the
407         *                             color of <CODE>gridBandPaint<CODE>.
408         *                             False: the second grid band takes the 
409         *                             color of <CODE>gridBandPaint<CODE>.
410         * @param ticks  a list of ticks.
411         */
412        protected void drawGridBandsVertical(Graphics2D g2, 
413                                             Rectangle2D drawArea,
414                                             Rectangle2D plotArea, 
415                                             boolean firstGridBandIsDark,
416                                             List ticks) {
417    
418            boolean currentGridBandIsDark = firstGridBandIsDark;
419            double xx = plotArea.getX();
420            double yy1, yy2;
421    
422            //gets the outline stroke width of the plot
423            double outlineStrokeWidth;
424            Stroke outlineStroke = getPlot().getOutlineStroke();
425            if (outlineStroke != null && outlineStroke instanceof BasicStroke) {
426                outlineStrokeWidth = ((BasicStroke) outlineStroke).getLineWidth();
427            }
428            else {
429                outlineStrokeWidth = 1d;
430            }
431    
432            Iterator iterator = ticks.iterator();
433            ValueTick tick;
434            Rectangle2D band;
435            while (iterator.hasNext()) {
436                tick = (ValueTick) iterator.next();
437                yy1 = valueToJava2D(tick.getValue() + 0.5d, plotArea, 
438                        RectangleEdge.LEFT);
439                yy2 = valueToJava2D(tick.getValue() - 0.5d, plotArea, 
440                        RectangleEdge.LEFT);
441                if (currentGridBandIsDark) {
442                    g2.setPaint(this.gridBandPaint);
443                }
444                else {
445                    g2.setPaint(Color.white);
446                }
447                band = new Rectangle2D.Double(xx + outlineStrokeWidth, yy1, 
448                        plotArea.getMaxX() - xx - outlineStrokeWidth, yy2 - yy1);
449                g2.fill(band);
450                currentGridBandIsDark = !currentGridBandIsDark;
451            }
452            g2.setPaintMode();
453        }
454    
455        /**
456         * Rescales the axis to ensure that all data is visible.
457         */
458        protected void autoAdjustRange() {
459    
460            Plot plot = getPlot();
461            if (plot == null) {
462                return;  // no plot, no data
463            }
464    
465            if (plot instanceof ValueAxisPlot) {
466    
467                // ensure that all the symbols are displayed
468                double upper = this.symbols.size() - 1;
469                double lower = 0;
470                double range = upper - lower;
471    
472                // ensure the autorange is at least <minRange> in size...
473                double minRange = getAutoRangeMinimumSize();
474                if (range < minRange) {
475                    upper = (upper + lower + minRange) / 2;
476                    lower = (upper + lower - minRange) / 2;
477                }
478    
479                // this ensure that the grid bands will be displayed correctly.
480                double upperMargin = 0.5;
481                double lowerMargin = 0.5;
482    
483                if (getAutoRangeIncludesZero()) {
484                    if (getAutoRangeStickyZero()) {
485                        if (upper <= 0.0) {
486                            upper = 0.0;
487                        }
488                        else {
489                            upper = upper + upperMargin;
490                        }
491                        if (lower >= 0.0) {
492                            lower = 0.0;
493                        }
494                        else {
495                            lower = lower - lowerMargin;
496                        }
497                    }
498                    else {
499                        upper = Math.max(0.0, upper + upperMargin);
500                        lower = Math.min(0.0, lower - lowerMargin);
501                    }
502                }
503                else {
504                    if (getAutoRangeStickyZero()) {
505                        if (upper <= 0.0) {
506                            upper = Math.min(0.0, upper + upperMargin);
507                        }
508                        else {
509                            upper = upper + upperMargin * range;
510                        }
511                        if (lower >= 0.0) {
512                            lower = Math.max(0.0, lower - lowerMargin);
513                        }
514                        else {
515                            lower = lower - lowerMargin;
516                        }
517                    }
518                    else {
519                        upper = upper + upperMargin;
520                        lower = lower - lowerMargin;
521                    }
522                }
523    
524                setRange(new Range(lower, upper), false, false);
525    
526            }
527    
528        }
529    
530        /**
531         * Calculates the positions of the tick labels for the axis, storing the 
532         * results in the tick label list (ready for drawing).
533         *
534         * @param g2  the graphics device.
535         * @param state  the axis state.
536         * @param dataArea  the area in which the data should be drawn.
537         * @param edge  the location of the axis.
538         * 
539         * @return A list of ticks.
540         */
541        public List refreshTicks(Graphics2D g2, 
542                                 AxisState state,
543                                 Rectangle2D dataArea,
544                                 RectangleEdge edge) {
545            List ticks = null;
546            if (RectangleEdge.isTopOrBottom(edge)) {
547                ticks = refreshTicksHorizontal(g2, dataArea, edge);
548            }
549            else if (RectangleEdge.isLeftOrRight(edge)) {
550                ticks = refreshTicksVertical(g2, dataArea, edge);
551            }
552            return ticks;
553        }
554    
555        /**
556         * Calculates the positions of the tick labels for the axis, storing the 
557         * results in the tick label list (ready for drawing).
558         *
559         * @param g2  the graphics device.
560         * @param dataArea  the area in which the data should be drawn.
561         * @param edge  the location of the axis.
562         * 
563         * @return The ticks.
564         */
565        protected List refreshTicksHorizontal(Graphics2D g2,
566                                              Rectangle2D dataArea,
567                                              RectangleEdge edge) {
568    
569            List ticks = new java.util.ArrayList();
570    
571            Font tickLabelFont = getTickLabelFont();
572            g2.setFont(tickLabelFont);
573    
574            double size = getTickUnit().getSize();
575            int count = calculateVisibleTickCount();
576            double lowestTickValue = calculateLowestVisibleTickValue();
577    
578            double previousDrawnTickLabelPos = 0.0;         
579            double previousDrawnTickLabelLength = 0.0;              
580    
581            if (count <= ValueAxis.MAXIMUM_TICK_COUNT) {
582                for (int i = 0; i < count; i++) {
583                    double currentTickValue = lowestTickValue + (i * size);
584                    double xx = valueToJava2D(currentTickValue, dataArea, edge);
585                    String tickLabel;
586                    NumberFormat formatter = getNumberFormatOverride();
587                    if (formatter != null) {
588                        tickLabel = formatter.format(currentTickValue);
589                    }
590                    else {
591                        tickLabel = valueToString(currentTickValue);
592                    }
593                    
594                    // avoid to draw overlapping tick labels
595                    Rectangle2D bounds = TextUtilities.getTextBounds(tickLabel, g2, 
596                            g2.getFontMetrics());
597                    double tickLabelLength = isVerticalTickLabels() 
598                            ? bounds.getHeight() : bounds.getWidth();
599                    boolean tickLabelsOverlapping = false;
600                    if (i > 0) {
601                        double avgTickLabelLength = (previousDrawnTickLabelLength 
602                                + tickLabelLength) / 2.0;
603                        if (Math.abs(xx - previousDrawnTickLabelPos) 
604                                < avgTickLabelLength) {
605                            tickLabelsOverlapping = true;
606                        }
607                    }
608                    if (tickLabelsOverlapping) {
609                        tickLabel = ""; // don't draw this tick label
610                    }
611                    else {
612                        // remember these values for next comparison
613                        previousDrawnTickLabelPos = xx;
614                        previousDrawnTickLabelLength = tickLabelLength;         
615                    } 
616                    
617                    TextAnchor anchor = null;
618                    TextAnchor rotationAnchor = null;
619                    double angle = 0.0;
620                    if (isVerticalTickLabels()) {
621                        anchor = TextAnchor.CENTER_RIGHT;
622                        rotationAnchor = TextAnchor.CENTER_RIGHT;
623                        if (edge == RectangleEdge.TOP) {
624                            angle = Math.PI / 2.0;
625                        }
626                        else {
627                            angle = -Math.PI / 2.0;
628                        }
629                    }
630                    else {
631                        if (edge == RectangleEdge.TOP) {
632                            anchor = TextAnchor.BOTTOM_CENTER;
633                            rotationAnchor = TextAnchor.BOTTOM_CENTER;
634                        }
635                        else {
636                            anchor = TextAnchor.TOP_CENTER;
637                            rotationAnchor = TextAnchor.TOP_CENTER;
638                        }
639                    }
640                    Tick tick = new NumberTick(new Double(currentTickValue), 
641                            tickLabel, anchor, rotationAnchor, angle);
642                    ticks.add(tick);
643                }
644            }
645            return ticks;
646    
647        }
648    
649        /**
650         * Calculates the positions of the tick labels for the axis, storing the 
651         * results in the tick label list (ready for drawing).
652         *
653         * @param g2  the graphics device.
654         * @param dataArea  the area in which the plot should be drawn.
655         * @param edge  the location of the axis.
656         * 
657         * @return The ticks.
658         */
659        protected List refreshTicksVertical(Graphics2D g2,
660                                            Rectangle2D dataArea,
661                                            RectangleEdge edge) {
662    
663            List ticks = new java.util.ArrayList();
664    
665            Font tickLabelFont = getTickLabelFont();
666            g2.setFont(tickLabelFont);
667    
668            double size = getTickUnit().getSize();
669            int count = calculateVisibleTickCount();
670            double lowestTickValue = calculateLowestVisibleTickValue();
671    
672            double previousDrawnTickLabelPos = 0.0;         
673            double previousDrawnTickLabelLength = 0.0;              
674    
675            if (count <= ValueAxis.MAXIMUM_TICK_COUNT) {
676                for (int i = 0; i < count; i++) {
677                    double currentTickValue = lowestTickValue + (i * size);
678                    double yy = valueToJava2D(currentTickValue, dataArea, edge);
679                    String tickLabel;
680                    NumberFormat formatter = getNumberFormatOverride();
681                    if (formatter != null) {
682                        tickLabel = formatter.format(currentTickValue);
683                    }
684                    else {
685                        tickLabel = valueToString(currentTickValue);
686                    }
687    
688                    // avoid to draw overlapping tick labels
689                    Rectangle2D bounds = TextUtilities.getTextBounds(tickLabel, g2,
690                            g2.getFontMetrics());
691                    double tickLabelLength = isVerticalTickLabels() 
692                        ? bounds.getWidth() : bounds.getHeight();
693                    boolean tickLabelsOverlapping = false;
694                    if (i > 0) {
695                        double avgTickLabelLength = (previousDrawnTickLabelLength 
696                                + tickLabelLength) / 2.0;
697                        if (Math.abs(yy - previousDrawnTickLabelPos) 
698                                < avgTickLabelLength) {
699                            tickLabelsOverlapping = true;    
700                        }
701                    }
702                    if (tickLabelsOverlapping) {
703                        tickLabel = ""; // don't draw this tick label
704                    }
705                    else {
706                        // remember these values for next comparison
707                        previousDrawnTickLabelPos = yy;
708                        previousDrawnTickLabelLength = tickLabelLength;         
709                    }
710                    
711                    TextAnchor anchor = null;
712                    TextAnchor rotationAnchor = null;
713                    double angle = 0.0;
714                    if (isVerticalTickLabels()) {
715                        anchor = TextAnchor.BOTTOM_CENTER;
716                        rotationAnchor = TextAnchor.BOTTOM_CENTER;
717                        if (edge == RectangleEdge.LEFT) {
718                            angle = -Math.PI / 2.0;
719                        }
720                        else {
721                            angle = Math.PI / 2.0;
722                        }                    
723                    }
724                    else {
725                        if (edge == RectangleEdge.LEFT) {
726                            anchor = TextAnchor.CENTER_RIGHT;
727                            rotationAnchor = TextAnchor.CENTER_RIGHT;
728                        }
729                        else {
730                            anchor = TextAnchor.CENTER_LEFT;
731                            rotationAnchor = TextAnchor.CENTER_LEFT;
732                        }
733                    }
734                    Tick tick = new NumberTick(new Double(currentTickValue), 
735                            tickLabel, anchor, rotationAnchor, angle);
736                    ticks.add(tick);
737                }
738            }
739            return ticks;
740            
741        }
742    
743        /**
744         * Converts a value to a string, using the list of symbols.
745         *
746         * @param value  value to convert.
747         *
748         * @return The symbol.
749         */
750        public String valueToString(double value) {
751            String strToReturn;
752            try {
753                strToReturn = (String) this.symbols.get((int) value);
754            }
755            catch (IndexOutOfBoundsException  ex) {
756                strToReturn = "";
757            }
758            return strToReturn;
759        }
760    
761        /**
762         * Tests this axis for equality with an arbitrary object.
763         * 
764         * @param obj  the object (<code>null</code> permitted).
765         * 
766         * @return A boolean.
767         */
768        public boolean equals(Object obj) {
769            if (obj == this) {
770                return true;
771            }
772            if (!(obj instanceof SymbolAxis)) {
773                return false;
774            }
775            SymbolAxis that = (SymbolAxis) obj;
776            if (!this.symbols.equals(that.symbols)) {
777                return false;
778            }
779            if (this.gridBandsVisible != that.gridBandsVisible) {
780                return false;
781            }
782            if (!PaintUtilities.equal(this.gridBandPaint, that.gridBandPaint)) {
783                return false;
784            }
785            if (!PaintUtilities.equal(this.gridBandAlternatePaint, 
786                    that.gridBandAlternatePaint)) {
787                return false;
788            }
789            return super.equals(obj);
790        }
791        
792        /**
793         * Provides serialization support.
794         *
795         * @param stream  the output stream.
796         *
797         * @throws IOException  if there is an I/O error.
798         */
799        private void writeObject(ObjectOutputStream stream) throws IOException {
800            stream.defaultWriteObject();
801            SerialUtilities.writePaint(this.gridBandPaint, stream);
802            SerialUtilities.writePaint(this.gridBandAlternatePaint, stream);
803        }
804    
805        /**
806         * Provides serialization support.
807         *
808         * @param stream  the input stream.
809         *
810         * @throws IOException  if there is an I/O error.
811         * @throws ClassNotFoundException  if there is a classpath problem.
812         */
813        private void readObject(ObjectInputStream stream) 
814            throws IOException, ClassNotFoundException {
815            stream.defaultReadObject();
816            this.gridBandPaint = SerialUtilities.readPaint(stream);
817            this.gridBandAlternatePaint = SerialUtilities.readPaint(stream);
818        }
819    
820    }