001    /* ByteLookupTable.java -- Java class for a pixel translation table.
002       Copyright (C) 2004, 2005, 2006,  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     * ByteLookupTable represents translation arrays for pixel values.  It wraps
043     * one 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     * @author Jerry Quinn (jlquinn@optonline.net)
048     * @version 1.0
049     */
050    public class ByteLookupTable extends LookupTable
051    {
052      // Array of translation tables.
053      private byte data[][];
054    
055      /**
056       * Creates a new <code>ByteLookupTable</code> instance.
057       *
058       * Offset is subtracted from pixel values when looking up in the translation
059       * tables.  If data.length is one, the same table is applied to all pixel
060       * components.
061       * 
062       * @param offset Offset to be subtracted.
063       * @param data Array of lookup tables (<code>null</code> not permitted).
064       * @exception IllegalArgumentException if offset &lt; 0 or data.length &lt; 1.
065       */
066      public ByteLookupTable(int offset, byte[][] data)
067        throws IllegalArgumentException
068      {
069        super(offset, data.length);
070        
071        // tests show that Sun's implementation creates a new array to store the
072        // references from the incoming 'data' array - not sure why, but we'll 
073        // match that behaviour just in case it matters...
074        this.data = new byte[data.length][];
075        for (int i = 0; i < data.length; i++)
076          this.data[i] = data[i];
077      }
078    
079      /**
080       * Creates a new <code>ByteLookupTable</code> instance.
081       *
082       * Offset is subtracted from pixel values when looking up in the translation
083       * table.  The same table is applied to all pixel components.
084       * 
085       * @param offset Offset to be subtracted.
086       * @param data Lookup table for all components (<code>null</code> not 
087       *     permitted).
088       * @exception IllegalArgumentException if offset &lt; 0.
089       */
090      public ByteLookupTable(int offset, byte[] data)
091        throws IllegalArgumentException
092      {
093        super(offset, 1);
094        if (data == null)
095          throw new NullPointerException("Null 'data' argument.");
096        this.data = new byte[][] {data};
097      }
098    
099      /**
100       * Return the lookup tables.
101       *
102       * @return the tables
103       */
104      public final byte[][] getTable()
105      {
106        return data;
107      }
108    
109      /**
110       * Return translated values for a pixel.
111       *
112       * For each value in the pixel src, use the value minus offset as an index
113       * in the component array and copy the value there to the output for the
114       * component.  If dest is null, the output is a new array, otherwise the
115       * translated values are written to dest.  Dest can be the same array as
116       * src.
117       *
118       * For example, if the pixel src is [2, 4, 3], and offset is 1, the output
119       * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the
120       * translation arrays.
121       *
122       * @param src Component values of a pixel.
123       * @param dst Destination array for values, or null.
124       * @return Translated values for the pixel.
125       */
126      public int[] lookupPixel(int[] src, int[] dst)
127        throws ArrayIndexOutOfBoundsException
128      {
129        if (dst == null)
130          dst = new int[src.length];
131    
132        if (data.length == 1)
133          for (int i=0; i < src.length; i++)
134            dst[i] = data[0][src[i] - offset];
135        else
136          for (int i=0; i < src.length; i++)
137            dst[i] = data[i][src[i] - offset];
138          
139        return dst;
140      }
141    
142      /**
143       * Return translated values for a pixel.
144       *
145       * For each value in the pixel src, use the value minus offset as an index
146       * in the component array and copy the value there to the output for the
147       * component.  If dest is null, the output is a new array, otherwise the
148       * translated values are written to dest.  Dest can be the same array as
149       * src.
150       *
151       * For example, if the pixel src is [2, 4, 3], and offset is 1, the output
152       * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the
153       * translation arrays.
154       *
155       * @param src Component values of a pixel.
156       * @param dst Destination array for values, or null.
157       * @return Translated values for the pixel.
158       */
159      public byte[] lookupPixel(byte[] src, byte[] dst)
160        throws ArrayIndexOutOfBoundsException
161      {
162        if (dst == null)
163          dst = new byte[src.length];
164    
165        if (data.length == 1)
166          for (int i=0; i < src.length; i++)
167            dst[i] = data[0][((int)src[i]) - offset];
168        else
169          for (int i=0; i < src.length; i++)
170            dst[i] = data[i][((int)src[i]) - offset];
171          
172        return dst;
173    
174      }
175    }