Source for org.jfree.chart.axis.StandardTickUnitSource

   1: /* ===========================================================
   2:  * JFreeChart : a free chart library for the Java(tm) platform
   3:  * ===========================================================
   4:  *
   5:  * (C) Copyright 2000-2007, by Object Refinery Limited and Contributors.
   6:  *
   7:  * Project Info:  http://www.jfree.org/jfreechart/index.html
   8:  *
   9:  * This library is free software; you can redistribute it and/or modify it 
  10:  * under the terms of the GNU Lesser General Public License as published by 
  11:  * the Free Software Foundation; either version 2.1 of the License, or 
  12:  * (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but 
  15:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
  16:  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
  17:  * License for more details.
  18:  *
  19:  * You should have received a copy of the GNU Lesser General Public
  20:  * License along with this library; if not, write to the Free Software
  21:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
  22:  * USA.  
  23:  *
  24:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
  25:  * in the United States and other countries.]
  26:  *
  27:  * ---------------------------
  28:  * StandardTickUnitSource.java
  29:  * ---------------------------
  30:  * (C) Copyright 2003-2007, by Object Refinery Limited.
  31:  *
  32:  * Original Author:  David Gilbert (for Object Refinery Limited);
  33:  * Contributor(s):   -;
  34:  *
  35:  * Changes
  36:  * -------
  37:  * 23-Sep-2003 : Version 1 (DG);
  38:  * 25-Oct-2007 : Implemented Serializable and equals() method (DG);
  39:  *
  40:  */
  41: 
  42: package org.jfree.chart.axis;
  43: 
  44: import java.io.Serializable;
  45: import java.text.DecimalFormat;
  46: 
  47: /**
  48:  * A source that can used by the {@link NumberAxis} class to obtain a
  49:  * suitable {@link TickUnit}.  Instances of this class are {@link Serializable}
  50:  * from version 1.0.7 onwards.  Cloning is not supported, because instances
  51:  * are immutable.
  52:  */
  53: public class StandardTickUnitSource implements TickUnitSource, Serializable {
  54: 
  55:     /** Constant for log(10.0). */
  56:     private static final double LOG_10_VALUE = Math.log(10.0);
  57:     
  58:     /**
  59:      * Default constructor.
  60:      */
  61:     public StandardTickUnitSource() {
  62:         super();
  63:     }
  64:     
  65:     /**
  66:      * Returns a tick unit that is larger than the supplied unit.
  67:      *
  68:      * @param unit  the unit (<code>null</code> not permitted).
  69:      *
  70:      * @return A tick unit that is larger than the supplied unit.
  71:      */
  72:     public TickUnit getLargerTickUnit(TickUnit unit) {
  73:         double x = unit.getSize();
  74:         double log = Math.log(x) / LOG_10_VALUE;
  75:         double higher = Math.ceil(log);
  76:         return new NumberTickUnit(Math.pow(10, higher), 
  77:                 new DecimalFormat("0.0E0"));
  78:     }
  79: 
  80:     /**
  81:      * Returns the tick unit in the collection that is greater than or equal
  82:      * to (in size) the specified unit.
  83:      *
  84:      * @param unit  the unit (<code>null</code> not permitted).
  85:      *
  86:      * @return A unit from the collection.
  87:      */
  88:     public TickUnit getCeilingTickUnit(TickUnit unit) {
  89:         return getLargerTickUnit(unit);
  90:     }
  91: 
  92:     /**
  93:      * Returns the tick unit in the collection that is greater than or equal
  94:      * to the specified size.
  95:      *
  96:      * @param size  the size.
  97:      *
  98:      * @return A unit from the collection.
  99:      */
 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: }