001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-present, by David Gilbert 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 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * ---------------------------
028 * StandardTickUnitSource.java
029 * ---------------------------
030 * (C) Copyright 2003-present, by David Gilbert.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.chart.axis;
038
039import java.io.Serializable;
040import java.text.DecimalFormat;
041
042/**
043 * A source that can used by the {@link NumberAxis} class to obtain a
044 * suitable {@link TickUnit}.  Instances of this class are {@link Serializable}
045 * from version 1.0.7 onwards.  Cloning is not supported, because instances
046 * are immutable.
047 */
048public class StandardTickUnitSource implements TickUnitSource, Serializable {
049
050    /** Constant for log(10.0). */
051    private static final double LOG_10_VALUE = Math.log(10.0);
052
053    /**
054     * Default constructor.
055     */
056    public StandardTickUnitSource() {
057        super();
058    }
059
060    /**
061     * Returns a tick unit that is larger than the supplied unit.
062     *
063     * @param unit  the unit ({@code null} not permitted).
064     *
065     * @return A tick unit that is larger than the supplied unit.
066     */
067    @Override
068    public TickUnit getLargerTickUnit(TickUnit unit) {
069        double x = unit.getSize();
070        double log = Math.log(x) / LOG_10_VALUE;
071        double higher = Math.ceil(log);
072        return new NumberTickUnit(Math.pow(10, higher),
073                new DecimalFormat("0.0E0"));
074    }
075
076    /**
077     * Returns the tick unit in the collection that is greater than or equal
078     * to (in size) the specified unit.
079     *
080     * @param unit  the unit ({@code null} not permitted).
081     *
082     * @return A unit from the collection.
083     */
084    @Override
085    public TickUnit getCeilingTickUnit(TickUnit unit) {
086        return getLargerTickUnit(unit);
087    }
088
089    /**
090     * Returns the tick unit in the collection that is greater than or equal
091     * to the specified size.
092     *
093     * @param size  the size.
094     *
095     * @return A unit from the collection.
096     */
097    @Override
098    public TickUnit getCeilingTickUnit(double size) {
099        double log = Math.log(size) / LOG_10_VALUE;
100        double higher = Math.ceil(log);
101        return new NumberTickUnit(Math.pow(10, higher),
102                new DecimalFormat("0.0E0"));
103    }
104
105    /**
106     * Tests this instance for equality with an arbitrary object.
107     *
108     * @param obj  the object ({@code null} permitted).
109     *
110     * @return A boolean.
111     */
112    @Override
113    public boolean equals(Object obj) {
114        if (obj == this) {
115            return true;
116        }
117        return (obj instanceof StandardTickUnitSource);
118    }
119
120    /**
121     * Returns a hash code for this instance.
122     *
123     * @return A hash code.
124     */
125    @Override
126    public int hashCode() {
127        return 0;
128    }
129
130}