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 }