001/* ShortLookupTable.java -- Java class for a pixel translation table.
002   Copyright (C) 2004, 2005, 2006,  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.awt.image;
040
041/**
042 * ShortLookupTable 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 */
050public class ShortLookupTable extends LookupTable
051{
052  // Array of translation tables.
053  private short data[][];
054
055  /**
056   * Creates a new <code>ShortLookupTable</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.
064   * @exception IllegalArgumentException if offset &lt; 0 or data.length &lt; 1.
065   */
066  public ShortLookupTable(int offset, short[][] 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 short[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>ShortLookupTable</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 ShortLookupTable(int offset, short[] data)
091    throws IllegalArgumentException
092  {
093    super(offset, 1);
094    if (data == null)
095      throw new NullPointerException("Null 'data' argument.");
096    this.data = new short[][] {data};
097  }
098
099  /**
100   * Return the lookup tables.  This is a reference to the actual table, so
101   * modifying the contents of the returned array will modify the lookup table.
102   *
103   * @return The lookup table.
104   */
105  public final short[][] getTable()
106  {
107    return data;
108  }
109
110  /**
111   * Return translated values for a pixel.
112   *
113   * For each value in the pixel src, use the value minus offset as an index
114   * in the component array and copy the value there to the output for the
115   * component.  If dest is null, the output is a new array, otherwise the
116   * translated values are written to dest.  Dest can be the same array as
117   * src.
118   *
119   * For example, if the pixel src is [2, 4, 3], and offset is 1, the output
120   * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the
121   * translation arrays.
122   *
123   * @param src Component values of a pixel.
124   * @param dst Destination array for values, or null.
125   * @return Translated values for the pixel.
126   */
127  public int[] lookupPixel(int[] src, int[] dst)
128    throws ArrayIndexOutOfBoundsException
129  {
130    if (dst == null)
131      dst = new int[src.length];
132
133    if (data.length == 1)
134      for (int i = 0; i < src.length; i++)
135        dst[i] = data[0][src[i] - offset];
136    else
137      for (int i = 0; i < src.length; i++)
138        dst[i] = data[i][src[i] - offset];
139
140    return dst;
141  }
142
143  /**
144   * Return translated values for a pixel.
145   *
146   * For each value in the pixel src, use the value minus offset as an index
147   * in the component array and copy the value there to the output for the
148   * component.  If dest is null, the output is a new array, otherwise the
149   * translated values are written to dest.  Dest can be the same array as
150   * src.
151   *
152   * For example, if the pixel src is [2, 4, 3], and offset is 1, the output
153   * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the
154   * translation arrays.
155   *
156   * @param src Component values of a pixel.
157   * @param dst Destination array for values, or null.
158   * @return Translated values for the pixel.
159   *
160   */
161  public short[] lookupPixel(short[] src, short[] dst)
162    throws ArrayIndexOutOfBoundsException
163  {
164    if (dst == null)
165      dst = new short[src.length];
166
167    if (data.length == 1)
168      for (int i = 0; i < src.length; i++)
169        dst[i] = data[0][((int) src[i]) - offset];
170    else
171      for (int i = 0; i < src.length; i++)
172        dst[i] = data[i][((int) src[i]) - offset];
173
174    return dst;
175
176  }
177}