001 /* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2009, 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 * GrayPaintScale.java
029 * -------------------
030 * (C) Copyright 2006-2009, by Object Refinery Limited.
031 *
032 * Original Author: David Gilbert (for Object Refinery Limited);
033 * Contributor(s): -;
034 *
035 * Changes
036 * -------
037 * 05-Jul-2006 : Version 1 (DG);
038 * 31-Jan-2007 : Renamed min and max to lowerBound and upperBound (DG);
039 * 26-Sep-2007 : Fixed bug 1767315, problem in getPaint() method (DG);
040 * 29-Jan-2009 : Added alpha transparency field and hashCode() method (DG);
041 *
042 */
043
044 package org.jfree.chart.renderer;
045
046 import java.awt.Color;
047 import java.awt.Paint;
048 import java.io.Serializable;
049
050 import org.jfree.chart.HashUtilities;
051 import org.jfree.util.PublicCloneable;
052
053 /**
054 * A paint scale that returns shades of gray.
055 *
056 * @since 1.0.4
057 */
058 public class GrayPaintScale
059 implements PaintScale, PublicCloneable, Serializable {
060
061 /** The lower bound. */
062 private double lowerBound;
063
064 /** The upper bound. */
065 private double upperBound;
066
067 /**
068 * The alpha transparency (0-255).
069 *
070 * @since 1.0.13
071 */
072 private int alpha;
073
074 /**
075 * Creates a new <code>GrayPaintScale</code> instance with default values.
076 */
077 public GrayPaintScale() {
078 this(0.0, 1.0);
079 }
080
081 /**
082 * Creates a new paint scale for values in the specified range.
083 *
084 * @param lowerBound the lower bound.
085 * @param upperBound the upper bound.
086 *
087 * @throws IllegalArgumentException if <code>lowerBound</code> is not
088 * less than <code>upperBound</code>.
089 */
090 public GrayPaintScale(double lowerBound, double upperBound) {
091 this(lowerBound, upperBound, 255);
092 }
093
094 /**
095 * Creates a new paint scale for values in the specified range.
096 *
097 * @param lowerBound the lower bound.
098 * @param upperBound the upper bound.
099 * @param alpha the alpha transparency (0-255).
100 *
101 * @throws IllegalArgumentException if <code>lowerBound</code> is not
102 * less than <code>upperBound</code>, or <code>alpha</code> is not in
103 * the range 0 to 255.
104 *
105 * @since 1.0.13
106 */
107 public GrayPaintScale(double lowerBound, double upperBound, int alpha) {
108 if (lowerBound >= upperBound) {
109 throw new IllegalArgumentException(
110 "Requires lowerBound < upperBound.");
111 }
112 if (alpha < 0 || alpha > 255) {
113 throw new IllegalArgumentException(
114 "Requires alpha in the range 0 to 255.");
115
116 }
117 this.lowerBound = lowerBound;
118 this.upperBound = upperBound;
119 this.alpha = alpha;
120 }
121
122 /**
123 * Returns the lower bound.
124 *
125 * @return The lower bound.
126 *
127 * @see #getUpperBound()
128 */
129 public double getLowerBound() {
130 return this.lowerBound;
131 }
132
133 /**
134 * Returns the upper bound.
135 *
136 * @return The upper bound.
137 *
138 * @see #getLowerBound()
139 */
140 public double getUpperBound() {
141 return this.upperBound;
142 }
143
144 /**
145 * Returns the alpha transparency that was specified in the constructor.
146 *
147 * @return The alpha transparency (in the range 0 to 255).
148 *
149 * @since 1.0.13
150 */
151 public int getAlpha() {
152 return this.alpha;
153 }
154
155 /**
156 * Returns a paint for the specified value.
157 *
158 * @param value the value (must be within the range specified by the
159 * lower and upper bounds for the scale).
160 *
161 * @return A paint for the specified value.
162 */
163 public Paint getPaint(double value) {
164 double v = Math.max(value, this.lowerBound);
165 v = Math.min(v, this.upperBound);
166 int g = (int) ((v - this.lowerBound) / (this.upperBound
167 - this.lowerBound) * 255.0);
168 // FIXME: it probably makes sense to allocate an array of 256 Colors
169 // and lazily populate this array...
170 return new Color(g, g, g, this.alpha);
171 }
172
173 /**
174 * Tests this <code>GrayPaintScale</code> instance for equality with an
175 * arbitrary object. This method returns <code>true</code> if and only
176 * if:
177 * <ul>
178 * <li><code>obj</code> is not <code>null</code>;</li>
179 * <li><code>obj</code> is an instance of <code>GrayPaintScale</code>;</li>
180 * </ul>
181 *
182 * @param obj the object (<code>null</code> permitted).
183 *
184 * @return A boolean.
185 */
186 public boolean equals(Object obj) {
187 if (obj == this) {
188 return true;
189 }
190 if (!(obj instanceof GrayPaintScale)) {
191 return false;
192 }
193 GrayPaintScale that = (GrayPaintScale) obj;
194 if (this.lowerBound != that.lowerBound) {
195 return false;
196 }
197 if (this.upperBound != that.upperBound) {
198 return false;
199 }
200 if (this.alpha != that.alpha) {
201 return false;
202 }
203 return true;
204 }
205
206 /**
207 * Returns a hash code for this instance.
208 *
209 * @return A hash code.
210 */
211 public int hashCode() {
212 int hash = 7;
213 hash = HashUtilities.hashCode(hash, this.lowerBound);
214 hash = HashUtilities.hashCode(hash, this.upperBound);
215 hash = 43 * hash + this.alpha;
216 return hash;
217 }
218
219 /**
220 * Returns a clone of this <code>GrayPaintScale</code> instance.
221 *
222 * @return A clone.
223 *
224 * @throws CloneNotSupportedException if there is a problem cloning this
225 * instance.
226 */
227 public Object clone() throws CloneNotSupportedException {
228 return super.clone();
229 }
230
231 }