001    /* LookupTable.java -- Java class for a pixel translation table.
002       Copyright (C) 2004, 2005  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.image;
040    
041    /**
042     * LookupTable represents translation arrays for pixel values.  It wraps one
043     * or more data arrays for each layer (or component) in an image, such as
044     * Alpha, R, G, and B.  When doing translation, the offset is subtracted from
045     * the pixel values to allow a subset of an array to be used.
046     *
047     * @see ByteLookupTable
048     * @see ShortLookupTable
049     *
050     * @author Jerry Quinn (jlquinn@optonline.net)
051     * @version 1.0
052     */
053    public abstract class LookupTable
054    {
055      // Not protected since that's part of the public API.
056      int offset;
057      int numComponents;
058    
059      /**
060       * Creates a new <code>LookupTable</code> instance.
061       *
062       * If numComponents is 1, the same translation table is used for all pixel
063       * components.
064       *
065       * @param offset Offset to be subtracted.
066       * @param numComponents Number of image components.
067       * @exception IllegalArgumentException if offset < 0 or numComponents < 1.
068       */
069      protected LookupTable(int offset, int numComponents)
070        throws IllegalArgumentException
071      {
072        if (offset < 0 || numComponents < 1)
073          throw new IllegalArgumentException();
074        this.offset = offset;
075        this.numComponents = numComponents;
076      }
077    
078      /** Return the number of components. */
079      public int getNumComponents()
080      {
081        return numComponents;
082      }
083    
084      /** Return the offset. */
085      public int getOffset()
086      {
087        return offset;
088      }
089    
090    
091      /**
092       * Return translated values for a pixel.
093       *
094       * For each value in the pixel src, use the value minus offset as an index
095       * in the component array and copy the value there to the output for the
096       * component.  If dest is null, the output is a new array, otherwise the
097       * translated values are written to dest.  Dest can be the same array as
098       * src.
099       *
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    }