001    /* ===========================================================
002     * JFreeChart : a free chart library for the Java(tm) platform
003     * ===========================================================
004     *
005     * (C) Copyright 2000-2005, 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, 2004, by Object Refinery Limited.
031     *
032     * Original Author:  David Gilbert (for Object Refinery Limited);
033     * Contributor(s):   -;
034     *
035     * $Id: StandardTickUnitSource.java,v 1.2.2.1 2005/10/25 20:37:34 mungady Exp $
036     *
037     * Changes
038     * -------
039     * 23-Sep-2003 : Version 1 (DG);
040     *
041     */
042    
043    package org.jfree.chart.axis;
044    
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}.
050     *
051     */
052    public class StandardTickUnitSource implements TickUnitSource {
053    
054        /** Constant for log(10.0). */
055        private static final double LOG_10_VALUE = Math.log(10.0);
056        
057        /**
058         * Returns a tick unit that is larger than the supplied unit.
059         *
060         * @param unit   the unit.
061         *
062         * @return A tick unit that is larger than the supplied unit.
063         */
064        public TickUnit getLargerTickUnit(TickUnit unit) {
065            double x = unit.getSize();
066            double log = Math.log(x) / LOG_10_VALUE;
067            double higher = Math.ceil(log);
068            return new NumberTickUnit(
069                Math.pow(10, higher), new DecimalFormat("0.0E0")
070            );
071        }
072    
073        /**
074         * Returns the tick unit in the collection that is greater than or equal
075         * to (in size) the specified unit.
076         *
077         * @param unit  the unit.
078         *
079         * @return A unit from the collection.
080         */
081        public TickUnit getCeilingTickUnit(TickUnit unit) {
082            return getLargerTickUnit(unit);
083        }
084    
085        /**
086         * Returns the tick unit in the collection that is greater than or equal
087         * to the specified size.
088         *
089         * @param size  the size.
090         *
091         * @return A unit from the collection.
092         */
093        public TickUnit getCeilingTickUnit(double size) {
094            double log = Math.log(size) / LOG_10_VALUE;
095            double higher = Math.ceil(log);
096            return new NumberTickUnit(
097                Math.pow(10, higher), new DecimalFormat("0.0E0")
098            );
099        }
100        
101    }