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
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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.
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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
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031 independent module, the terms and conditions of the license of that
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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 < 0 or data.length < 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 < 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 }