Java > Open Source Codes > org > jfree > chart > axis > DateAxis


1 /* ===========================================================
2  * JFreeChart : a free chart library for the Java(tm) platform
3  * ===========================================================
4  *
5  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
6  *
7  * Project Info: http://www.jfree.org/jfreechart/index.html
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public License
20  * along with this library; if not, write to the Free Software Foundation,
21  * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
22  *
23  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
24  * in the United States and other countries.]
25  *
26  * -------------
27  * DateAxis.java
28  * -------------
29  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
30  *
31  * Original Author: David Gilbert;
32  * Contributor(s): Jonathan Nash;
33  * David Li;
34  * Michael Rauch;
35  * Bill Kelemen;
36  * Pawel Pabis;
37  *
38  * $Id: DateAxis.java,v 1.17 2005/05/19 13:58:11 mungady Exp $
39  *
40  * Changes (from 23-Jun-2001)
41  * --------------------------
42  * 23-Jun-2001 : Modified to work with null data source (DG);
43  * 18-Sep-2001 : Updated header (DG);
44  * 27-Nov-2001 : Changed constructors from public to protected, updated Javadoc
45  * comments (DG);
46  * 16-Jan-2002 : Added an optional crosshair, based on the implementation by
47  * Jonathan Nash (DG);
48  * 26-Feb-2002 : Updated import statements (DG);
49  * 22-Apr-2002 : Added a setRange() method (DG);
50  * 25-Jun-2002 : Removed redundant local variable (DG);
51  * 25-Jul-2002 : Changed order of parameters in ValueAxis constructor (DG);
52  * 21-Aug-2002 : The setTickUnit() method now turns off auto-tick unit
53  * selection (fix for bug id 528885) (DG);
54  * 05-Sep-2002 : Updated the constructors to reflect changes in the Axis
55  * class (DG);
56  * 18-Sep-2002 : Fixed errors reported by Checkstyle (DG);
57  * 25-Sep-2002 : Added new setRange() methods, and deprecated
58  * setAxisRange() (DG);
59  * 04-Oct-2002 : Changed auto tick selection to parallel number axis
60  * classes (DG);
61  * 24-Oct-2002 : Added a date format override (DG);
62  * 08-Nov-2002 : Moved to new package com.jrefinery.chart.axis (DG);
63  * 14-Jan-2003 : Changed autoRangeMinimumSize from Number --> double, moved
64  * crosshair settings to the plot (DG);
65  * 15-Jan-2003 : Removed anchor date (DG);
66  * 20-Jan-2003 : Removed unnecessary constructors (DG);
67  * 26-Mar-2003 : Implemented Serializable (DG);
68  * 02-May-2003 : Added additional units to createStandardDateTickUnits()
69  * method, as suggested by mhilpert in bug report 723187 (DG);
70  * 13-May-2003 : Merged HorizontalDateAxis and VerticalDateAxis (DG);
71  * 24-May-2003 : Added support for underlying timeline for
72  * SegmentedTimeline (BK);
73  * 16-Jul-2003 : Applied patch from Pawel Pabis to fix overlapping dates (DG);
74  * 22-Jul-2003 : Applied patch from Pawel Pabis for monthly ticks (DG);
75  * 25-Jul-2003 : Fixed bug 777561 and 777586 (DG);
76  * 13-Aug-2003 : Implemented Cloneable and added equals() method (DG);
77  * 02-Sep-2003 : Fixes for bug report 790506 (DG);
78  * 04-Sep-2003 : Fixed tick label alignment when axis appears at the top (DG);
79  * 10-Sep-2003 : Fixes for segmented timeline (DG);
80  * 17-Sep-2003 : Fixed a layout bug when multiple domain axes are used (DG);
81  * 29-Oct-2003 : Added workaround for font alignment in PDF output (DG);
82  * 07-Nov-2003 : Modified to use new tick classes (DG);
83  * 12-Nov-2003 : Modified tick labelling to use roll unit from DateTickUnit
84  * when a calculated tick value is hidden (which can occur in
85  * segmented date axes) (DG);
86  * 24-Nov-2003 : Fixed some problems with the auto tick unit selection, and
87  * fixed bug 846277 (labels missing for inverted axis) (DG);
88  * 30-Dec-2003 : Fixed bug in refreshTicksHorizontal() when start of time unit
89  * (ex. 1st of month) was hidden, causing infinite loop (BK);
90  * 13-Jan-2004 : Fixed bug in previousStandardDate() method (fix by Richard
91  * Wardle) (DG);
92  * 21-Jan-2004 : Renamed translateJava2DToValue --> java2DToValue, and
93  * translateValueToJava2D --> valueToJava2D (DG);
94  * 12-Mar-2004 : Fixed bug where date format override is ignored for vertical
95  * axis (DG);
96  * 16-Mar-2004 : Added plotState to draw() method (DG);
97  * 07-Apr-2004 : Changed string width calculation (DG);
98  * 21-Apr-2004 : Fixed bug in estimateMaximumTickLabelWidth() method (bug id
99  * 939148) (DG);
100  * 11-Jan-2005 : Removed deprecated methods in preparation for 1.0.0
101  * release (DG);
102  * 13-Jan-2005 : Fixed bug (see
103  * http://www.jfree.org/forum/viewtopic.php?t=11330) (DG);
104  * 21-Apr-2005 : Replaced Insets with RectangleInsets, removed redundant
105  * argument from selectAutoTickUnit() (DG);
106  *
107  */
108
109 package org.jfree.chart.axis;
110
111 import java.awt.Font ;
112 import java.awt.FontMetrics ;
113 import java.awt.Graphics2D ;
114 import java.awt.font.FontRenderContext ;
115 import java.awt.font.LineMetrics ;
116 import java.awt.geom.Rectangle2D ;
117 import java.io.Serializable ;
118 import java.text.DateFormat ;
119 import java.text.SimpleDateFormat ;
120 import java.util.Calendar ;
121 import java.util.Date ;
122 import java.util.List ;
123 import java.util.TimeZone ;
124
125 import org.jfree.chart.event.AxisChangeEvent;
126 import org.jfree.chart.plot.Plot;
127 import org.jfree.chart.plot.PlotRenderingInfo;
128 import org.jfree.chart.plot.ValueAxisPlot;
129 import org.jfree.data.Range;
130 import org.jfree.data.time.DateRange;
131 import org.jfree.data.time.Month;
132 import org.jfree.data.time.RegularTimePeriod;
133 import org.jfree.data.time.Year;
134 import org.jfree.ui.RectangleEdge;
135 import org.jfree.ui.RectangleInsets;
136 import org.jfree.ui.TextAnchor;
137 import org.jfree.util.ObjectUtilities;
138
139 /**
140  * The base class for axes that display dates. You will find it easier to
141  * understand how this axis works if you bear in mind that it really
142  * displays/measures integer (or long) data, where the integers are
143  * milliseconds since midnight, 1-Jan-1970. When displaying tick labels, the
144  * millisecond values are converted back to dates using a
145  * <code>DateFormat</code> instance.
146  * <P>
147  * You can also create a {@link org.jfree.chart.axis.Timeline} and supply in
148  * the constructor to create an axis that only contains certain domain values.
149  * For example, this allows you to create a date axis that only contains
150  * working days.
151  */
152 public class DateAxis extends ValueAxis implements Cloneable , Serializable {
153
154     /** For serialization. */
155     private static final long serialVersionUID = -1013460999649007604L;
156     
157     /** The default axis range. */
158     public static final DateRange DEFAULT_DATE_RANGE = new DateRange();
159
160     /** The default minimum auto range size. */
161     public static final double
162         DEFAULT_AUTO_RANGE_MINIMUM_SIZE_IN_MILLISECONDS = 2.0;
163
164     /** The default date tick unit. */
165     public static final DateTickUnit DEFAULT_DATE_TICK_UNIT
166         = new DateTickUnit(DateTickUnit.DAY, 1, new SimpleDateFormat ());
167
168     /** The default anchor date. */
169     public static final Date DEFAULT_ANCHOR_DATE = new Date ();
170
171     /** The current tick unit. */
172     private DateTickUnit tickUnit;
173
174     /** The override date format. */
175     private DateFormat dateFormatOverride;
176
177     /**
178      * Tick marks can be displayed at the start or the middle of the time
179      * period.
180      */
181     private DateTickMarkPosition tickMarkPosition = DateTickMarkPosition.START;
182
183     /**
184      * A timeline that includes all milliseconds (as defined by
185      * <code>java.util.Date</code>) in the real time line.
186      */
187     private static class DefaultTimeline implements Timeline, Serializable {
188
189         /**
190          * Converts a millisecond into a timeline value.
191          *
192          * @param millisecond the millisecond.
193          *
194          * @return The timeline value.
195          */
196         public long toTimelineValue(long millisecond) {
197             return millisecond;
198         }
199
200         /**
201          * Converts a date into a timeline value.
202          *
203          * @param date the domain value.
204          *
205          * @return The timeline value.
206          */
207         public long toTimelineValue(Date date) {
208             return date.getTime();
209         }
210
211         /**
212          * Converts a timeline value into a millisecond (as encoded by
213          * <code>java.util.Date</code>).
214          *
215          * @param value the value.
216          *
217          * @return The millisecond.
218          */
219         public long toMillisecond(long value) {
220             return value;
221         }
222
223         /**
224          * Returns <code>true</code> if the timeline includes the specified
225          * domain value.
226          *
227          * @param millisecond the millisecond.
228          *
229          * @return <code>true</code>.
230          */
231         public boolean containsDomainValue(long millisecond) {
232             return true;
233         }
234
235         /**
236          * Returns <code>true</code> if the timeline includes the specified
237          * domain value.
238          *
239          * @param date the date.
240          *
241          * @return <code>true</code>.
242          */
243         public boolean containsDomainValue(Date date) {
244             return true;
245         }
246
247         /**
248          * Returns <code>true</code> if the timeline includes the specified
249          * domain value range.
250          *
251          * @param from the start value.
252          * @param to the end value.
253          *
254          * @return <code>true</code>.
255          */
256         public boolean containsDomainRange(long from, long to) {
257             return true;
258         }
259
260         /**
261          * Returns <code>true</code> if the timeline includes the specified
262          * domain value range.
263          *
264          * @param from the start date.
265          * @param to the end date.
266          *
267          * @return <code>true</code>.
268          */
269         public boolean containsDomainRange(Date from, Date to) {
270             return true;
271         }
272
273         /**
274          * Tests an object for equality with this instance.
275          *
276          * @param object the object.
277          *
278          * @return A boolean.
279          */
280         public boolean equals(Object object) {
281
282             if (object == null) {
283                 return false;
284             }
285
286             if (object == this) {
287                 return true;
288             }
289
290             if (object instanceof DefaultTimeline) {
291                 return true;
292             }
293
294             return false;
295
296         }
297     }
298
299     /** A static default timeline shared by all standard DateAxis */
300     private static final Timeline DEFAULT_TIMELINE = new DefaultTimeline();
301
302     /** The time zone for the axis. */
303     private TimeZone timeZone;
304     
305     /** Our underlying timeline. */
306     private Timeline timeline;
307
308     /**
309      * Creates a date axis with no label.
310      */
311     public DateAxis() {
312         this(null);
313     }
314
315     /**
316      * Creates a date axis with the specified label.
317      *
318      * @param label the axis label (<code>null</code> permitted).
319      */
320     public DateAxis(String label) {
321         this(label, TimeZone.getDefault());
322     }
323
324     /**
325      * Creates a date axis. A timeline is specified for the axis. This allows
326      * special transformations to occur between a domain of values and the
327      * values included in the axis.
328      *
329      * @see org.jfree.chart.axis.SegmentedTimeline
330      *
331      * @param label the axis label (<code>null</code> permitted).
332      * @param zone the time zone.
333      */
334     public DateAxis(String label, TimeZone zone) {
335         super(label, DateAxis.createStandardDateTickUnits(zone));
336         setTickUnit(DateAxis.DEFAULT_DATE_TICK_UNIT, false, false);
337         setAutoRangeMinimumSize(
338             DEFAULT_AUTO_RANGE_MINIMUM_SIZE_IN_MILLISECONDS
339         );
340         setRange(DEFAULT_DATE_RANGE, false, false);
341         this.dateFormatOverride = null;
342         this.timeZone = zone;
343         this.timeline = DEFAULT_TIMELINE;
344     }
345
346     /**
347      * Returns the underlying timeline used by this axis.
348      *
349      * @return The timeline.
350      */
351     public Timeline getTimeline() {
352         return this.timeline;
353     }
354
355     /**
356      * Sets the underlying timeline to use for this axis.
357      * <P>
358      * If the timeline is changed, an {@link AxisChangeEvent} is sent to all
359      * registered listeners.
360      *
361      * @param timeline the timeline.
362      */
363     public void setTimeline(Timeline timeline) {
364         if (this.timeline != timeline) {
365             this.timeline = timeline;
366             notifyListeners(new AxisChangeEvent(this));
367         }
368     }
369
370     /**
371      * Returns the tick unit for the axis.
372      *
373      * @return The tick unit (possibly <code>null</code>).
374      */
375     public DateTickUnit getTickUnit() {
376         return this.tickUnit;
377     }
378
379     /**
380      * Sets the tick unit for the axis. The auto-tick-unit-selection flag is
381      * set to <code>false</code>, and registered listeners are notified that
382      * the axis has been changed.
383      *
384      * @param unit the tick unit.
385      */
386     public void setTickUnit(DateTickUnit unit) {
387         setTickUnit(unit, true, true);
388     }
389
390     /**
391      * Sets the tick unit attribute without any other side effects.
392      *
393      * @param unit the new tick unit.
394      * @param notify notify registered listeners?
395      * @param turnOffAutoSelection turn off auto selection?
396      */
397     public void setTickUnit(DateTickUnit unit, boolean notify,
398                             boolean turnOffAutoSelection) {
399
400         this.tickUnit = unit;
401         if (turnOffAutoSelection) {
402             setAutoTickUnitSelection(false, false);
403         }
404         if (notify) {
405             notifyListeners(new AxisChangeEvent(this));
406         }
407
408     }
409
410     /**
411      * Returns the date format override. If this is non-null, then it will be
412      * used to format the dates on the axis.
413      *
414      * @return The formatter (possibly <code>null</code>).
415      */
416     public DateFormat getDateFormatOverride() {
417         return this.dateFormatOverride;
418     }
419
420     /**
421      * Sets the date format override. If this is non-null, then it will be
422      * used to format the dates on the axis.
423      *
424      * @param formatter the date formatter (<code>null</code> permitted).
425      */
426     public void setDateFormatOverride(DateFormat formatter) {
427         this.dateFormatOverride = formatter;
428         notifyListeners(new AxisChangeEvent(this));
429     }
430
431     /**
432      * Sets the upper and lower bounds for the axis and sends an
433      * {@link AxisChangeEvent} to all registered listeners. As a side-effect,
434      * the auto-range flag is set to false.
435      *
436      * @param range the new range (<code>null</code> not permitted).
437      */
438     public void setRange(Range range) {
439         setRange(range, true, true);
440     }
441
442     /**
443      * Sets the range for the axis, if requested, sends an
444      * {@link AxisChangeEvent} to all registered listeners. As a side-effect,
445      * the auto-range flag is set to <code>false</code> (optional).
446      *
447      * @param range the range (<code>null</code> not permitted).
448      * @param turnOffAutoRange a flag that controls whether or not the auto
449      * range is turned off.
450      * @param notify a flag that controls whether or not listeners are
451      * notified.
452      */
453     public void setRange(Range range, boolean turnOffAutoRange,
454                          boolean notify) {
455         if (range == null) {
456             throw new IllegalArgumentException ("Null 'range' argument.");
457         }
458         // usually the range will be a DateRange, but if it isn't do a
459 // conversion...
460 if (!(range instanceof DateRange)) {
461             range = new DateRange(range);
462         }
463         super.setRange(range, turnOffAutoRange, notify);
464     }
465
466     /**
467      * Sets the axis range and sends an {@link AxisChangeEvent} to all
468      * registered listeners.
469      *
470      * @param lower the lower bound for the axis.
471      * @param upper the upper bound for the axis.
472      */
473     public void setRange(Date lower, Date upper) {
474         if (lower.getTime() >= upper.getTime()) {
475             throw new IllegalArgumentException ("Requires 'lower' < 'upper'.");
476         }
477         setRange(new DateRange(lower, upper));
478     }
479
480     /**
481      * Sets the axis range and sends an {@link AxisChangeEvent} to all
482      * registered listeners.
483      *
484      * @param lower the lower bound for the axis.
485      * @param upper the upper bound for the axis.
486      */
487     public void setRange(double lower, double upper) {
488         if (lower >= upper) {
489             throw new IllegalArgumentException ("Requires 'lower' < 'upper'.");
490         }
491         setRange(new DateRange(lower, upper));
492     }
493
494     /**
495      * Returns the earliest date visible on the axis.
496      *
497      * @return The date.
498      */
499     public Date getMinimumDate() {
500
501         Date result = null;
502
503         Range range = getRange();
504         if (range instanceof DateRange) {
505             DateRange r = (DateRange) range;
506             result = r.getLowerDate();
507         }
508         else {
509             result = new Date ((long) range.getLowerBound());
510         }
511
512         return result;
513
514     }
515
516     /**
517      * Sets the minimum date visible on the axis and sends an
518      * {@link AxisChangeEvent} to all registered listeners.
519      *
520      * @param date the date (<code>null</code> not permitted).
521      */
522     public void setMinimumDate(Date date) {
523         setRange(new DateRange(date, getMaximumDate()), true, false);
524         notifyListeners(new AxisChangeEvent(this));
525     }
526
527     /**
528      * Returns the latest date visible on the axis.
529      *
530      * @return The date.
531      */
532     public Date getMaximumDate() {
533
534         Date result = null;
535         Range range = getRange();
536         if (range instanceof DateRange) {
537             DateRange r = (DateRange) range;
538             result = r.getUpperDate();
539         }
540         else {
541             result = new Date ((long) range.getUpperBound());
542         }
543         return result;
544
545     }
546
547     /**
548      * Sets the maximum date visible on the axis. An {@link AxisChangeEvent}
549      * is sent to all registered listeners.
550      *
551      * @param maximumDate the date (<code>null</code> not permitted).
552      */
553     public void setMaximumDate(Date maximumDate) {
554         setRange(new DateRange(getMinimumDate(), maximumDate), true, false);
555         notifyListeners(new AxisChangeEvent(this));
556     }
557
558     /**
559      * Returns the tick mark position (start, middle or end of the time period).
560      *
561      * @return The position (never <code>null</code>).
562      */
563     public DateTickMarkPosition getTickMarkPosition() {
564         return this.tickMarkPosition;
565     }
566
567     /**
568      * Sets the tick mark position (start, middle or end of the time period)
569      * and sends an {@link AxisChangeEvent} to all registered listeners.
570      *
571      * @param position the position (<code>null</code> not permitted).
572      */
573     public void setTickMarkPosition(DateTickMarkPosition position) {
574         if (position == null) {
575             throw new IllegalArgumentException ("Null 'position' argument.");
576         }
577         this.tickMarkPosition = position;
578         notifyListeners(new AxisChangeEvent(this));
579     }
580
581     /**
582      * Configures the axis to work with the specified plot. If the axis has
583      * auto-scaling, then sets the maximum and minimum values.
584      */
585     public void configure() {
586         if (isAutoRange()) {
587             autoAdjustRange();
588         }
589     }
590
591     /**
592      * Returns <code>true</code> if the axis hides this value, and
593      * <code>false</code> otherwise.
594      *
595      * @param millis the data value.
596      *
597      * @return A value.
598      */
599     public boolean isHiddenValue(long millis) {
600         return (!this.timeline.containsDomainValue(new Date (millis)));
601     }
602
603     /**
604      * Translates the data value to the display coordinates (Java 2D User Space)
605      * of the chart.
606      *
607      * @param value the date to be plotted.
608      * @param area the rectangle (in Java2D space) where the data is to be
609      * plotted.
610      * @param edge the axis location.
611      *
612      * @return The coordinate corresponding to the supplied data value.
613      */
614     public double valueToJava2D(double value, Rectangle2D area,
615                                 RectangleEdge edge) {
616         
617         value = this.timeline.toTimelineValue((long) value);
618
619         DateRange range = (DateRange) getRange();
620         double axisMin = this.timeline.toTimelineValue(range.getLowerDate());
621         double axisMax = this.timeline.toTimelineValue(range.getUpperDate());
622         double result = 0.0;
623         if (RectangleEdge.isTopOrBottom(edge)) {
624             double minX = area.getX();
625             double maxX = area.getMaxX();
626             if (isInverted()) {
627                 result = maxX + ((value - axisMin) / (axisMax - axisMin))
628                          * (minX - maxX);
629             }
630             else {
631                 result = minX + ((value - axisMin) / (axisMax - axisMin))
632                          * (maxX - minX);
633             }
634         }
635         else if (RectangleEdge.isLeftOrRight(edge)) {
636             double minY = area.getMinY();
637             double maxY = area.getMaxY();
638             if (isInverted()) {
639                 result = minY + (((value - axisMin) / (axisMax - axisMin))
640                          * (maxY - minY));
641             }
642             else {
643                 result = maxY - (((value - axisMin) / (axisMax - axisMin))
644                          * (maxY - minY));
645             }
646         }
647         return result;
648
649     }
650
651     /**
652      * Translates a date to Java2D coordinates, based on the range displayed by
653      * this axis for the specified data area.
654      *
655      * @param date the date.
656      * @param area the rectangle (in Java2D space) where the data is to be
657      * plotted.
658      * @param edge the axis location.
659      *
660      * @return The coordinate corresponding to the supplied date.
661      */
662     public double dateToJava2D(Date date, Rectangle2D area,
663                                RectangleEdge edge) {
664         double value = date.getTime();
665         return valueToJava2D(value, area, edge);
666     }
667
668     /**
669      * Translates a Java2D coordinate into the corresponding data value. To
670      * perform this translation, you need to know the area used for plotting
671      * data, and which edge the axis is located on.
672      *
673      * @param java2DValue the coordinate in Java2D space.
674      * @param area the rectangle (in Java2D space) where the data is to be
675      * plotted.
676      * @param edge the axis location.
677      *
678      * @return A data value.
679      */
680     public double java2DToValue(double java2DValue, Rectangle2D area,
681                                 RectangleEdge edge) {
682         
683         DateRange range = (DateRange) getRange();
684         double axisMin = this.timeline.toTimelineValue(range.getLowerDate());
685         double axisMax = this.timeline.toTimelineValue(range.getUpperDate());
686
687         double min = 0.0;
688         double max = 0.0;
689         if (RectangleEdge.isTopOrBottom(edge)) {
690             min = area.getX();
691             max = area.getMaxX();
692         }
693         else if (RectangleEdge.isLeftOrRight(edge)) {
694             min = area.getMaxY();
695             max = area.getY();
696         }
697
698         double result;
699         if (isInverted()) {
700              result = axisMax - ((java2DValue - min) / (max - min)
701                       * (axisMax - axisMin));
702         }
703         else {
704              result = axisMin + ((java2DValue - min) / (max - min)
705                       * (axisMax - axisMin));
706         }
707
708         return this.timeline.toMillisecond((long) result);
709     }
710
711     /**
712      * Calculates the value of the lowest visible tick on the axis.
713      *
714      * @param unit date unit to use.
715      *
716      * @return The value of the lowest visible tick on the axis.
717      */
718     public Date calculateLowestVisibleTickValue(DateTickUnit unit) {
719         return nextStandardDate(getMinimumDate(), unit);
720     }
721
722     /**
723      * Calculates the value of the highest visible tick on the axis.
724      *
725      * @param unit date unit to use.
726      *
727      * @return The value of the highest visible tick on the axis.
728      */
729     public Date calculateHighestVisibleTickValue(DateTickUnit unit) {
730         return previousStandardDate(getMaximumDate(), unit);
731     }
732
733     /**
734      * Returns the previous "standard" date, for a given date and tick unit.
735      *
736      * @param date the reference date.
737      * @param unit the tick unit.
738      *
739      * @return The previous "standard" date.
740      */
741     protected Date previousStandardDate(Date date, DateTickUnit unit) {
742
743         int milliseconds;
744         int seconds;
745         int minutes;
746         int hours;
747         int days;
748         int months;
749         int years;
750
751         Calendar calendar = Calendar.getInstance(this.timeZone);
752         calendar.setTime(date);
753         int count = unit.getCount();
754         int current = calendar.get(unit.getCalendarField());
755         int value = count * (current / count);
756
757         switch (unit.getUnit()) {
758
759             case (DateTickUnit.MILLISECOND) :
760                 years = calendar.get(Calendar.YEAR);
761                 months = calendar.get(Calendar.MONTH);
762                 days = calendar.get(Calendar.DATE);
763                 hours = calendar.get(Calendar.HOUR_OF_DAY);
764                 minutes = calendar.get(Calendar.MINUTE);
765                 seconds = calendar.get(Calendar.SECOND);
766                 calendar.set(years, months, days, hours, minutes, seconds);
767                 calendar.set(Calendar.MILLISECOND, value);
768                 return calendar.getTime();
769
770             case (DateTickUnit.SECOND) :
771                 years = calendar.get(Calendar.YEAR);
772                 months = calendar.get(Calendar.MONTH);
773                 days = calendar.get(Calendar.DATE);
774                 hours = calendar.get(Calendar.HOUR_OF_DAY);
775                 minutes = calendar.get(Calendar.MINUTE);
776                 if (this.tickMarkPosition == DateTickMarkPosition.START) {
777                     milliseconds = 0;
778                 }
779                 else if (this.tickMarkPosition == DateTickMarkPosition.MIDDLE) {
780                     milliseconds = 500;
781                 }
782                 else {
783                     milliseconds = 999;
784                 }
785                 calendar.set(Calendar.MILLISECOND, milliseconds);
786                 calendar.set(years, months, days, hours, minutes, value);
787                 return calendar.getTime();
788
789             case (DateTickUnit.MINUTE) :
790                 years = calendar.get(Calendar.YEAR);
791                 months = calendar.get(Calendar.MONTH);
792                 days = calendar.get(Calendar.DATE);
793                 hours = calendar.get(Calendar.HOUR_OF_DAY);
794                 if (this.tickMarkPosition == DateTickMarkPosition.START) {
795                     seconds = 0;
796                 }
797                 else if (this.tickMarkPosition == DateTickMarkPosition.MIDDLE) {
798                     seconds = 30;
799                 }
800                 else {
801                     seconds = 59;
802                 }
803                 calendar.clear(Calendar.MILLISECOND);
804                 calendar.set(years, months, days, hours, value, seconds);
805                 return calendar.getTime();
806
807             case (DateTickUnit.HOUR) :
808                 years = calendar.get(Calendar.YEAR);
809                 months = calendar.get(Calendar.MONTH);
810                 days = calendar.get(Calendar.DATE);
811                 if (this.tickMarkPosition == DateTickMarkPosition.START) {
812                     minutes = 0;
813                     seconds = 0;
814                 }
815                 else if (this.tickMarkPosition == DateTickMarkPosition.MIDDLE) {
816                     minutes = 30;
817                     seconds = 0;
818                 }
819                 else {
820                     minutes = 59;
821                     seconds = 59;
822                 }
823                 calendar.clear(Calendar.MILLISECOND);
824                 calendar.set(years, months, days, value, minutes, seconds);
825                 return calendar.getTime();
826
827             case (DateTickUnit.DAY) :
828                 years = calendar.get(Calendar.YEAR);
829                 months = calendar.get(Calendar.MONTH);
830                 if (this.tickMarkPosition == DateTickMarkPosition.START) {
831                     hours = 0;
832                     minutes = 0;
833                     seconds = 0;
834                 }
835                 else if (this.tickMarkPosition == DateTickMarkPosition.MIDDLE) {
836                     hours = 12;
837                     minutes = 0;
838                     seconds = 0;
839                 }
840                 else {
841                     hours = 23;
842                     minutes = 59;
843                     seconds = 59;
844                 }
845                 calendar.clear(Calendar.MILLISECOND);
846                 calendar.set(years, months, value, hours, 0, 0);
847                 // long result = calendar.getTimeInMillis();
848 // won't work with JDK 1.3
849 long result = calendar.getTime().getTime();
850                 if (result > date.getTime()) {
851                     calendar.set(years, months, value - 1, hours, 0, 0);
852                 }
853                 return calendar.getTime();
854
855             case (DateTickUnit.MONTH) :
856                 years = calendar.get(Calendar.YEAR);
857                 calendar.clear(Calendar.MILLISECOND);
858                 calendar.set(years, value, 1, 0, 0, 0);
859                 Month month = new Month(calendar.getTime());
860                 Date standardDate = calculateDateForPosition(
861                     month, this.tickMarkPosition
862                 );
863                 long millis = standardDate.getTime();
864                 if (millis > date.getTime()) {
865                     month = (Month) month.previous();
866                     standardDate = calculateDateForPosition(
867                         month, this.tickMarkPosition
868                     );
869                 }
870                 return standardDate;
871
872             case(DateTickUnit.YEAR) :
873                 if (this.tickMarkPosition == DateTickMarkPosition.START) {
874                     months = 0;
875                     days = 1;
876                 }
877                 else if (this.tickMarkPosition == DateTickMarkPosition.MIDDLE) {
878                     months = 6;
879                     days = 1;
880                 }
881                 else {
882                     months = 11;
883                     days = 31;
884                 }
885                 calendar.clear(Calendar.MILLISECOND);
886                 calendar.set(value, months, days, 0, 0,