    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     * StandardTickUnitSource.java
    029     * ---------------------------
    030     * (C) Copyright 2003-2007, 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    }