Source for java.awt.image.LookupTable

   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: }