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 1.2.2.2 2006/01/27 13:53:28 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 public class StandardTickUnitSource implements TickUnitSource {
052
053 /** Constant for log(10.0). */
054 private static final double LOG_10_VALUE = Math.log(10.0);
055
056 /**
057 * Returns a tick unit that is larger than the supplied unit.
058 *
059 * @param unit the unit (<code>null</code> not permitted).
060 *
061 * @return A tick unit that is larger than the supplied unit.
062 */
063 public TickUnit getLargerTickUnit(TickUnit unit) {
064 double x = unit.getSize();
065 double log = Math.log(x) / LOG_10_VALUE;
066 double higher = Math.ceil(log);
067 return new NumberTickUnit(Math.pow(10, higher),
068 new DecimalFormat("0.0E0"));
069 }
070
071 /**
072 * Returns the tick unit in the collection that is greater than or equal
073 * to (in size) the specified unit.
074 *
075 * @param unit the unit (<code>null</code> not permitted).
076 *
077 * @return A unit from the collection.
078 */
079 public TickUnit getCeilingTickUnit(TickUnit unit) {
080 return getLargerTickUnit(unit);
081 }
082
083 /**
084 * Returns the tick unit in the collection that is greater than or equal
085 * to the specified size.
086 *
087 * @param size the size.
088 *
089 * @return A unit from the collection.
090 */
091 public TickUnit getCeilingTickUnit(double size) {
092 double log = Math.log(size) / LOG_10_VALUE;
093 double higher = Math.ceil(log);
094 return new NumberTickUnit(Math.pow(10, higher),
095 new DecimalFormat("0.0E0"));
096 }
097
098 }