001 /* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2008, 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 * StandardTickUnitSource.java
029 * ---------------------------
030 * (C) Copyright 2003-2008, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * Changes
036 * -------
037 * 23-Sep-2003 : Version 1 (DG);
038 * 25-Oct-2007 : Implemented Serializable and equals() method (DG);
039 *
040 */
041
042 package org.jfree.chart.axis;
043
044 import java.io.Serializable;
045 import java.text.DecimalFormat;
046
047 /**
048 * A source that can used by the {@link NumberAxis} class to obtain a
049 * suitable {@link TickUnit}. Instances of this class are {@link Serializable}
050 * from version 1.0.7 onwards. Cloning is not supported, because instances
051 * are immutable.
052 */
053 public class StandardTickUnitSource implements TickUnitSource, Serializable {
054
055 /** Constant for log(10.0). */
056 private static final double LOG_10_VALUE = Math.log(10.0);
057
058 /**
059 * Default constructor.
060 */
061 public StandardTickUnitSource() {
062 super();
063 }
064
065 /**
066 * Returns a tick unit that is larger than the supplied unit.
067 *
068 * @param unit the unit (<code>null</code> not permitted).
069 *
070 * @return A tick unit that is larger than the supplied unit.
071 */
072 public TickUnit getLargerTickUnit(TickUnit unit) {
073 double x = unit.getSize();
074 double log = Math.log(x) / LOG_10_VALUE;
075 double higher = Math.ceil(log);
076 return new NumberTickUnit(Math.pow(10, higher),
077 new DecimalFormat("0.0E0"));
078 }
079
080 /**
081 * Returns the tick unit in the collection that is greater than or equal
082 * to (in size) the specified unit.
083 *
084 * @param unit the unit (<code>null</code> not permitted).
085 *
086 * @return A unit from the collection.
087 */
088 public TickUnit getCeilingTickUnit(TickUnit unit) {
089 return getLargerTickUnit(unit);
090 }
091
092 /**
093 * Returns the tick unit in the collection that is greater than or equal
094 * to the specified size.
095 *
096 * @param size the size.
097 *
098 * @return A unit from the collection.
099 */
100 public TickUnit getCeilingTickUnit(double size) {
101 double log = Math.log(size) / LOG_10_VALUE;
102 double higher = Math.ceil(log);
103 return new NumberTickUnit(Math.pow(10, higher),
104 new DecimalFormat("0.0E0"));
105 }
106
107 /**
108 * Tests this instance for equality with an arbitrary object.
109 *
110 * @param obj the object (<code>null</code> permitted).
111 *
112 * @return A boolean.
113 */
114 public boolean equals(Object obj) {
115 if (obj == this) {
116 return true;
117 }
118 return (obj instanceof StandardTickUnitSource);
119 }
120
121 /**
122 * Returns a hash code for this instance.
123 *
124 * @return A hash code.
125 */
126 public int hashCode() {
127 return 0;
128 }
129
130 }