001 /* AlphaComposite.java -- provides a context for performing alpha compositing
002 Copyright (C) 2002, 2005, 2006 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt;
040
041 import gnu.java.awt.java2d.AlphaCompositeContext;
042
043 import java.awt.image.ColorModel;
044 import java.util.LinkedHashMap;
045 import java.util.Map;
046
047 /**
048 *
049 * @author Eric Blake (ebb9@email.byu.edu)
050 * @see Composite
051 * @see CompositeContext
052 * @since 1.3
053 * @status updated to 1.4 except for createContext, needs documentation
054 */
055 public final class AlphaComposite implements Composite
056 {
057 /** Map Long to AlphaComposites. See getInstance for details. */
058 private static final LinkedHashMap cache = new LinkedHashMap(11, 0.75f, true)
059 {
060 /** The largest the alpha composite cache can grow. */
061 private static final int MAX_CACHE_SIZE = 2048;
062
063 /** Prune stale entries. */
064 protected boolean removeEldestEntry(Map.Entry eldest)
065 {
066 return size() > MAX_CACHE_SIZE;
067 }
068 };
069
070 public static final int CLEAR = 1;
071 public static final int SRC = 2;
072 public static final int DST = 9;
073 public static final int SRC_OVER = 3;
074 public static final int DST_OVER = 4;
075 public static final int SRC_IN = 5;
076 public static final int DST_IN = 6;
077 public static final int SRC_OUT = 7;
078 public static final int DST_OUT = 8;
079 public static final int SRC_ATOP = 10;
080 public static final int DST_ATOP = 11;
081 public static final int XOR = 12;
082 public static final AlphaComposite Clear = getInstance(CLEAR);
083 public static final AlphaComposite Src = getInstance(SRC);
084 public static final AlphaComposite Dst = getInstance(DST);
085 public static final AlphaComposite SrcOver = getInstance(SRC_OVER);
086 public static final AlphaComposite DstOver = getInstance(DST_OVER);
087 public static final AlphaComposite SrcIn = getInstance(SRC_IN);
088 public static final AlphaComposite DstIn = getInstance(DST_IN);
089 public static final AlphaComposite SrcOut = getInstance(SRC_OUT);
090 public static final AlphaComposite DstOut = getInstance(DST_OUT);
091 public static final AlphaComposite SrcAtop = getInstance(SRC_ATOP);
092 public static final AlphaComposite DstAtop = getInstance(DST_ATOP);
093 public static final AlphaComposite Xor = getInstance(XOR);
094
095 private final int rule;
096 private final float alpha;
097 private AlphaComposite(int rule, float alpha)
098 {
099 this.rule = rule;
100 this.alpha = alpha;
101 }
102
103 /**
104 * Creates an AlphaComposite object with the specified rule.
105 *
106 * @param rule The compositing rule.
107 *
108 * @exception IllegalArgumentException If rule is not one of the following:
109 * CLEAR, SRC, DST, SRC_OVER, DST_OVER, SRC_IN, DST_IN, SRC_OUT, DST_OUT,
110 * SRC_ATOP, DST_ATOP, or XOR.
111 */
112 public static AlphaComposite getInstance(int rule)
113 {
114 return getInstance(rule, 1);
115 }
116
117 /**
118 * Creates an AlphaComposite object with the specified rule and the constant
119 * alpha to multiply with the alpha of the source. The source is multiplied
120 * with the specified alpha before being composited with the destination.
121 *
122 * @param rule The compositing rule.
123 *
124 * @exception IllegalArgumentException If rule is not one of the following:
125 * CLEAR, SRC, DST, SRC_OVER, DST_OVER, SRC_IN, DST_IN, SRC_OUT, DST_OUT,
126 * SRC_ATOP, DST_ATOP, or XOR.
127 */
128 public static AlphaComposite getInstance(int rule, float alpha)
129 {
130 if (rule < CLEAR || rule > XOR || ! (alpha >= 0 && alpha <= 1))
131 throw new IllegalArgumentException();
132 // This long is guaranteed unique for all valid alpha composites.
133 Long l = new Long(rule + Double.doubleToLongBits(alpha));
134 AlphaComposite a = (AlphaComposite) cache.get(l);
135 if (a == null)
136 {
137 a = new AlphaComposite(rule, alpha);
138 cache.put(l, a);
139 }
140 return a;
141 }
142
143 /**
144 * Creates a {@link CompositeContext} that can be used to perform
145 * compositing operations according to this AlphaComposite settings.
146 *
147 * @param srcColorModel the color model of the source raster
148 * @param dstColorModel the color model of the destination raster
149 * @param hints the rendering hints to use
150 *
151 * @return a {@link CompositeContext} that can be used to perform
152 * compositing operations according to this AlphaComposite settings
153 */
154 public CompositeContext createContext(ColorModel srcColorModel,
155 ColorModel dstColorModel,
156 RenderingHints hints)
157 {
158 return new AlphaCompositeContext(this, srcColorModel, dstColorModel);
159 }
160
161 /**
162 * Return an <code>AlphaComposite</code> similar to <code>this</code>,
163 * that uses the specified rule. If <code>rule</code> is the same as
164 * <code>this.rule</code>, then <code>this</code> is returned.
165 *
166 * @since 1.6
167 */
168 public AlphaComposite derive(int rule)
169 {
170 if (this.rule == rule)
171 return this;
172 else
173 return AlphaComposite.getInstance(rule, this.getAlpha());
174 }
175
176 /**
177 * Return an <code>AlphaComposite</code> similar to <code>this</code>,
178 * that uses the specified <code>alpha</code>.
179 *
180 * If <code>alph</code> is the same as <code>this.alpha</code>,
181 * then <code>this</code> is returned.
182 *
183 * @since 1.6
184 */
185 public AlphaComposite derive(float alpha)
186 {
187 if (this.getAlpha() == alpha)
188 return this;
189 else
190 return AlphaComposite.getInstance(this.getRule(), alpha);
191 }
192
193 public float getAlpha()
194 {
195 return alpha;
196 }
197
198 public int getRule()
199 {
200 return rule;
201 }
202
203 public int hashCode()
204 {
205 return 31 * Float.floatToIntBits(alpha) + rule;
206 }
207
208 public boolean equals(Object o)
209 {
210 if (! (o instanceof AlphaComposite))
211 return false;
212 AlphaComposite a = (AlphaComposite) o;
213 return rule == a.rule && alpha == a.alpha;
214 }
215 } // class AlphaComposite