001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2013, 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 * [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 2003-2008, 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
042package org.jfree.chart.axis;
043
044import java.io.Serializable;
045import 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 */
053public 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    @Override
073    public TickUnit getLargerTickUnit(TickUnit unit) {
074        double x = unit.getSize();
075        double log = Math.log(x) / LOG_10_VALUE;
076        double higher = Math.ceil(log);
077        return new NumberTickUnit(Math.pow(10, higher),
078                new DecimalFormat("0.0E0"));
079    }
080
081    /**
082     * Returns the tick unit in the collection that is greater than or equal
083     * to (in size) the specified unit.
084     *
085     * @param unit  the unit (<code>null</code> not permitted).
086     *
087     * @return A unit from the collection.
088     */
089    @Override
090    public TickUnit getCeilingTickUnit(TickUnit unit) {
091        return getLargerTickUnit(unit);
092    }
093
094    /**
095     * Returns the tick unit in the collection that is greater than or equal
096     * to the specified size.
097     *
098     * @param size  the size.
099     *
100     * @return A unit from the collection.
101     */
102    @Override
103    public TickUnit getCeilingTickUnit(double size) {
104        double log = Math.log(size) / LOG_10_VALUE;
105        double higher = Math.ceil(log);
106        return new NumberTickUnit(Math.pow(10, higher),
107                new DecimalFormat("0.0E0"));
108    }
109
110    /**
111     * Tests this instance for equality with an arbitrary object.
112     *
113     * @param obj  the object (<code>null</code> permitted).
114     *
115     * @return A boolean.
116     */
117    @Override
118    public boolean equals(Object obj) {
119        if (obj == this) {
120            return true;
121        }
122        return (obj instanceof StandardTickUnitSource);
123    }
124
125    /**
126     * Returns a hash code for this instance.
127     *
128     * @return A hash code.
129     */
130    @Override
131    public int hashCode() {
132        return 0;
133    }
134
135}