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1: /* AlphaComposite.java -- provides a context for performing alpha compositing 2: Copyright (C) 2002, 2005, 2006 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package java.awt; 40: 41: import gnu.java.awt.java2d.AlphaCompositeContext; 42: 43: import java.awt.image.ColorModel; 44: import java.util.LinkedHashMap; 45: import java.util.Map; 46: 47: /** 48: * 49: * @author Eric Blake (ebb9@email.byu.edu) 50: * @see Composite 51: * @see CompositeContext 52: * @since 1.3 53: * @status updated to 1.4 except for createContext, needs documentation 54: */ 55: public final class AlphaComposite implements Composite 56: { 57: /** Map Long to AlphaComposites. See getInstance for details. */ 58: private static final LinkedHashMap cache = new LinkedHashMap(11, 0.75f, true) 59: { 60: /** The largest the alpha composite cache can grow. */ 61: private static final int MAX_CACHE_SIZE = 2048; 62: 63: /** Prune stale entries. */ 64: protected boolean removeEldestEntry(Map.Entry eldest) 65: { 66: return size() > MAX_CACHE_SIZE; 67: } 68: }; 69: 70: public static final int CLEAR = 1; 71: public static final int SRC = 2; 72: public static final int DST = 9; 73: public static final int SRC_OVER = 3; 74: public static final int DST_OVER = 4; 75: public static final int SRC_IN = 5; 76: public static final int DST_IN = 6; 77: public static final int SRC_OUT = 7; 78: public static final int DST_OUT = 8; 79: public static final int SRC_ATOP = 10; 80: public static final int DST_ATOP = 11; 81: public static final int XOR = 12; 82: public static final AlphaComposite Clear = getInstance(CLEAR); 83: public static final AlphaComposite Src = getInstance(SRC); 84: public static final AlphaComposite Dst = getInstance(DST); 85: public static final AlphaComposite SrcOver = getInstance(SRC_OVER); 86: public static final AlphaComposite DstOver = getInstance(DST_OVER); 87: public static final AlphaComposite SrcIn = getInstance(SRC_IN); 88: public static final AlphaComposite DstIn = getInstance(DST_IN); 89: public static final AlphaComposite SrcOut = getInstance(SRC_OUT); 90: public static final AlphaComposite DstOut = getInstance(DST_OUT); 91: public static final AlphaComposite SrcAtop = getInstance(SRC_ATOP); 92: public static final AlphaComposite DstAtop = getInstance(DST_ATOP); 93: public static final AlphaComposite Xor = getInstance(XOR); 94: 95: private final int rule; 96: private final float alpha; 97: private AlphaComposite(int rule, float alpha) 98: { 99: 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