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 * HashUtilities.java
029 * ------------------
030 * (C) Copyright 2006, 2007, by Object Refinery Limited;
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * $Id: HashUtilities.java,v 1.1.2.2 2007/03/06 16:00:44 mungady Exp $
036 *
037 * Changes
038 * -------
039 * 03-Oct-2006 : Version 1 (DG);
040 * 06-Mar-2007 : Fix for hashCodeForDoubleArray() method (DG);
041 *
042 */
043
044 package org.jfree.chart;
045
046 import java.awt.GradientPaint;
047 import java.awt.Paint;
048
049 /**
050 * Some utility methods for calculating hash codes.
051 *
052 * @since 1.0.3
053 */
054 public class HashUtilities {
055
056 /**
057 * Returns a hash code for a <code>Paint</code> instance. If
058 * <code>p</code> is <code>null</code>, this method returns zero.
059 *
060 * @param p the paint (<code>null</code> permitted).
061 *
062 * @return The hash code.
063 */
064 public static int hashCodeForPaint(Paint p) {
065 if (p == null)
066 return 0;
067 int result = 0;
068 // handle GradientPaint as a special case
069 if (p instanceof GradientPaint) {
070 GradientPaint gp = (GradientPaint) p;
071 result = 193;
072 result = 37 * result + gp.getColor1().hashCode();
073 result = 37 * result + gp.getPoint1().hashCode();
074 result = 37 * result + gp.getColor2().hashCode();
075 result = 37 * result + gp.getPoint2().hashCode();
076 }
077 else {
078 // we assume that all other Paint instances implement equals() and
079 // hashCode()...of course that might not be true, but what can we
080 // do about it?
081 result = p.hashCode();
082 }
083 return result;
084 }
085
086 /**
087 * Returns a hash code for a <code>double[]</code> instance. If the array
088 * is <code>null</code>, this method returns zero.
089 *
090 * @param a the array (<code>null</code> permitted).
091 *
092 * @return The hash code.
093 */
094 public static int hashCodeForDoubleArray(double[] a) {
095 if (a == null) {
096 return 0;
097 }
098 int result = 193;
099 long temp;
100 for (int i = 0; i < a.length; i++) {
101 temp = Double.doubleToLongBits(a[i]);
102 result = 29 * result + (int) (temp ^ (temp >>> 32));
103 }
104 return result;
105 }
106
107 }