libjava/classpath/java/awt/AlphaComposite.java

   1 /* AlphaComposite.java -- provides a context for performing alpha compositing
   2    Copyright (C) 2002, 2005  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     {   // XXX - FIXME Use Map.Entry, not just Entry as gcj 3.1 workaround.
  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   public float getAlpha()
 162   {
 163     return alpha;
 164   }
 165   public int getRule()
 166   {
 167     return rule;
 168   }
 169   public int hashCode()
 170   {
 171     return 31 * Float.floatToIntBits(alpha) + rule;
 172   }
 173   public boolean equals(Object o)
 174   {
 175     if (! (o instanceof AlphaComposite))
 176       return false;
 177     AlphaComposite a = (AlphaComposite) o;
 178     return rule == a.rule && alpha == a.alpha;
 179   }
 180 } // class AlphaComposite