001 /*
002 * Copyright 2007 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package javax.imageio.plugins.jpeg;
027
028 import java.util.Arrays;
029
030 /**
031 * A class encapsulating a single JPEG Huffman table.
032 * Fields are provided for the "standard" tables taken
033 * from Annex K of the JPEG specification.
034 * These are the tables used as defaults.
035 * <p>
036 * For more information about the operation of the standard JPEG plug-in,
037 * see the <A HREF="../../metadata/doc-files/jpeg_metadata.html">JPEG
038 * metadata format specification and usage notes</A>
039 */
040
041 public class JPEGHuffmanTable {
042
043 /* The data for the publically defined tables, as specified in ITU T.81
044 * JPEG specification section K3.3 and used in the IJG library.
045 */
046 private static final short[] StdDCLuminanceLengths = { 0x00, 0x01,
047 0x05, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00,
048 0x00, 0x00, 0x00, 0x00, };
049
050 private static final short[] StdDCLuminanceValues = { 0x00, 0x01,
051 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, };
052
053 private static final short[] StdDCChrominanceLengths = { 0x00,
054 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
055 0x00, 0x00, 0x00, 0x00, 0x00, };
056
057 private static final short[] StdDCChrominanceValues = { 0x00, 0x01,
058 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, };
059
060 private static final short[] StdACLuminanceLengths = { 0x00, 0x02,
061 0x01, 0x03, 0x03, 0x02, 0x04, 0x03, 0x05, 0x05, 0x04, 0x04,
062 0x00, 0x00, 0x01, 0x7d, };
063
064 private static final short[] StdACLuminanceValues = { 0x01, 0x02,
065 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 0x21, 0x31, 0x41, 0x06,
066 0x13, 0x51, 0x61, 0x07, 0x22, 0x71, 0x14, 0x32, 0x81, 0x91,
067 0xa1, 0x08, 0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
068 0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16, 0x17, 0x18,
069 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x34, 0x35,
070 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47,
071 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
072 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x73,
073 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x83, 0x84, 0x85,
074 0x86, 0x87, 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
075 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
076 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8,
077 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9,
078 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
079 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
080 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, };
081
082 private static final short[] StdACChrominanceLengths = { 0x00,
083 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04, 0x07, 0x05, 0x04,
084 0x04, 0x00, 0x01, 0x02, 0x77, };
085
086 private static final short[] StdACChrominanceValues = { 0x00, 0x01,
087 0x02, 0x03, 0x11, 0x04, 0x05, 0x21, 0x31, 0x06, 0x12, 0x41,
088 0x51, 0x07, 0x61, 0x71, 0x13, 0x22, 0x32, 0x81, 0x08, 0x14,
089 0x42, 0x91, 0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
090 0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34, 0xe1, 0x25,
091 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26, 0x27, 0x28, 0x29, 0x2a,
092 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46,
093 0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
094 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a,
095 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x82, 0x83,
096 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94,
097 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
098 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
099 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
100 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8,
101 0xd9, 0xda, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
102 0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, };
103
104 /**
105 * The standard DC luminance Huffman table.
106 */
107 public static final JPEGHuffmanTable StdDCLuminance = new JPEGHuffmanTable(
108 StdDCLuminanceLengths, StdDCLuminanceValues, false);
109
110 /**
111 * The standard DC chrominance Huffman table.
112 */
113 public static final JPEGHuffmanTable StdDCChrominance = new JPEGHuffmanTable(
114 StdDCChrominanceLengths, StdDCChrominanceValues, false);
115
116 /**
117 * The standard AC luminance Huffman table.
118 */
119 public static final JPEGHuffmanTable StdACLuminance = new JPEGHuffmanTable(
120 StdACLuminanceLengths, StdACLuminanceValues, false);
121
122 /**
123 * The standard AC chrominance Huffman table.
124 */
125 public static final JPEGHuffmanTable StdACChrominance = new JPEGHuffmanTable(
126 StdACChrominanceLengths, StdACChrominanceValues, false);
127
128 private short[] lengths;
129 private short[] values;
130
131 /**
132 * Creates a Huffman table and initializes it. The input arrays are copied.
133 * The arrays must describe a possible Huffman table.
134 * For example, 3 codes cannot be expressed with a single bit.
135 *
136 * @param lengths an array of {@code short}s where <code>lengths[k]</code>
137 * is equal to the number of values with corresponding codes of
138 * length <code>k + 1</code> bits.
139 * @param values an array of shorts containing the values in
140 * order of increasing code length.
141 * @throws IllegalArgumentException if <code>lengths</code> or
142 * <code>values</code> are null, the length of <code>lengths</code> is
143 * greater than 16, the length of <code>values</code> is greater than 256,
144 * if any value in <code>lengths</code> or <code>values</code> is less
145 * than zero, or if the arrays do not describe a valid Huffman table.
146 */
147 public JPEGHuffmanTable(short[] lengths, short[] values) {
148 if (lengths == null || values == null || lengths.length == 0
149 || values.length == 0 || lengths.length > 16
150 || values.length > 256) {
151 throw new IllegalArgumentException(
152 "Illegal lengths or values");
153 }
154 for (int i = 0; i < lengths.length; i++) {
155 if (lengths[i] < 0) {
156 throw new IllegalArgumentException("lengths[" + i
157 + "] < 0");
158 }
159 }
160 for (int i = 0; i < values.length; i++) {
161 if (values[i] < 0) {
162 throw new IllegalArgumentException("values[" + i
163 + "] < 0");
164 }
165 }
166 this .lengths = Arrays.copyOf(lengths, lengths.length);
167 this .values = Arrays.copyOf(values, values.length);
168 validate();
169 }
170
171 private void validate() {
172 int sumOfLengths = 0;
173 for (int i = 0; i < lengths.length; i++) {
174 sumOfLengths += lengths[i];
175 }
176 if (sumOfLengths != values.length) {
177 throw new IllegalArgumentException(
178 "lengths do not correspond "
179 + "to length of value table");
180 }
181 }
182
183 /* Internal version which avoids the overhead of copying and checking */
184 private JPEGHuffmanTable(short[] lengths, short[] values,
185 boolean copy) {
186 if (copy) {
187 this .lengths = Arrays.copyOf(lengths, lengths.length);
188 this .values = Arrays.copyOf(values, values.length);
189 } else {
190 this .lengths = lengths;
191 this .values = values;
192 }
193 }
194
195 /**
196 * Returns an array of <code>short</code>s containing the number of values
197 * for each length in the Huffman table. The returned array is a copy.
198 *
199 * @return a <code>short</code> array where <code>array[k-1]</code>
200 * is equal to the number of values in the table of length <code>k</code>.
201 * @see #getValues
202 */
203 public short[] getLengths() {
204 return Arrays.copyOf(lengths, lengths.length);
205 }
206
207 /**
208 * Returns an array of <code>short</code>s containing the values arranged
209 * by increasing length of their corresponding codes.
210 * The interpretation of the array is dependent on the values returned
211 * from <code>getLengths</code>. The returned array is a copy.
212 *
213 * @return a <code>short</code> array of values.
214 * @see #getLengths
215 */
216 public short[] getValues() {
217 return Arrays.copyOf(values, values.length);
218 }
219
220 /**
221 * Returns a {@code String} representing this Huffman table.
222 * @return a {@code String} representing this Huffman table.
223 */
224 public String toString() {
225 String ls = System.getProperty("line.separator", "\n");
226 StringBuilder sb = new StringBuilder("JPEGHuffmanTable");
227 sb.append(ls).append("lengths:");
228 for (int i = 0; i < lengths.length; i++) {
229 sb.append(" ").append(lengths[i]);
230 }
231 sb.append(ls).append("values:");
232 for (int i = 0; i < values.length; i++) {
233 sb.append(" ").append(values[i]);
234 }
235 return sb.toString();
236 }
237 }
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