gomp-20050608-branch/libjava/classpath/java/awt/image/LookupTable.java

   1 /* LookupTable.java -- Java class for a pixel translation table.
   2    Copyright (C) 2004, 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.image;
  40
  41 /**
  42  * LookupTable represents translation arrays for pixel values.  It wraps one
  43  * or more data arrays for each layer (or component) in an image, such as
  44  * Alpha, R, G, and B.  When doing translation, the offset is subtracted from
  45  * the pixel values to allow a subset of an array to be used.
  46  *
  47  * @see ByteLookupTable
  48  * @see ShortLookupTable
  49  *
  50  * @author Jerry Quinn (jlquinn@optonline.net)
  51  * @version 1.0
  52  */
  53 public abstract class LookupTable
  54 {
  55   // Not protected since that's part of the public API.
  56   int offset;
  57   int numComponents;
  58
  59   /**
  60    * Creates a new <code>LookupTable</code> instance.
  61    *
  62    * If numComponents is 1, the same translation table is used for all pixel
  63    * components.
  64    *
  65    * @param offset Offset to be subtracted.
  66    * @param numComponents Number of image components.
  67    * @exception IllegalArgumentException if offset < 0 or numComponents < 1.
  68    */
  69   protected LookupTable(int offset, int numComponents)
  70     throws IllegalArgumentException
  71   {
  72     if (offset < 0 || numComponents < 1)
  73       throw new IllegalArgumentException();
  74     this.offset = offset;
  75     this.numComponents = numComponents;
  76   }
  77
  78   /** Return the number of components. */
  79   public int getNumComponents()
  80   {
  81     return numComponents;
  82   }
  83
  84   /** Return the offset. */
  85   public int getOffset()
  86   {
  87     return offset;
  88   }
  89
  90
  91   /**
  92    * Return translated values for a pixel.
  93    *
  94    * For each value in the pixel src, use the value minus offset as an index
  95    * in the component array and copy the value there to the output for the
  96    * component.  If dest is null, the output is a new array, otherwise the
  97    * translated values are written to dest.  Dest can be the same array as
  98    * src.
  99    *
 100    * For example, if the pixel src is [2, 4, 3], and offset is 1, the output
 101    * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the
 102    * translation arrays.
 103    *
 104    * @param src Component values of a pixel.
 105    * @param dest Destination array for values, or null.
 106    * @return Translated values for the pixel.
 107    */
 108   public abstract int[] lookupPixel(int[] src, int[] dest);
 109 }