1/* 2 * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package javax.imageio.plugins.jpeg; 27 28import java.util.Arrays; 29 30/** 31 * A class encapsulating a single JPEG Huffman table. 32 * Fields are provided for the "standard" tables taken 33 * from Annex K of the JPEG specification. 34 * These are the tables used as defaults. 35 * <p> 36 * For more information about the operation of the standard JPEG plug-in, 37 * see the <A HREF="../../metadata/doc-files/jpeg_metadata.html">JPEG 38 * metadata format specification and usage notes</A> 39 */ 40 41public class JPEGHuffmanTable { 42 43 /* The data for the publically defined tables, as specified in ITU T.81 44 * JPEG specification section K3.3 and used in the IJG library. 45 */ 46 private static final short[] StdDCLuminanceLengths = { 47 0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01, 48 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 49 }; 50 51 private static final short[] StdDCLuminanceValues = { 52 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 53 0x08, 0x09, 0x0a, 0x0b, 54 }; 55 56 private static final short[] StdDCChrominanceLengths = { 57 0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 58 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 59 }; 60 61 private static final short[] StdDCChrominanceValues = { 62 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 63 0x08, 0x09, 0x0a, 0x0b, 64 }; 65 66 private static final short[] StdACLuminanceLengths = { 67 0x00, 0x02, 0x01, 0x03, 0x03, 0x02, 0x04, 0x03, 68 0x05, 0x05, 0x04, 0x04, 0x00, 0x00, 0x01, 0x7d, 69 }; 70 71 private static final short[] StdACLuminanceValues = { 72 0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 73 0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07, 74 0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08, 75 0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0, 76 0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16, 77 0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28, 78 0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 79 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 80 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 81 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 82 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 83 0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 84 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 85 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 86 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 87 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 88 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 89 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2, 90 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 91 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 92 0xf9, 0xfa, 93 }; 94 95 private static final short[] StdACChrominanceLengths = { 96 0x00, 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04, 97 0x07, 0x05, 0x04, 0x04, 0x00, 0x01, 0x02, 0x77, 98 }; 99 100 private static final short[] StdACChrominanceValues = { 101 0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21, 102 0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71, 103 0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91, 104 0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0, 105 0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34, 106 0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26, 107 0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38, 108 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 109 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 110 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 111 0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 112 0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 113 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 114 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 115 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 116 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 117 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 118 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 119 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 120 0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 121 0xf9, 0xfa, 122 }; 123 124 /** 125 * The standard DC luminance Huffman table. 126 */ 127 public static final JPEGHuffmanTable 128 StdDCLuminance = new JPEGHuffmanTable(StdDCLuminanceLengths, 129 StdDCLuminanceValues, false); 130 131 /** 132 * The standard DC chrominance Huffman table. 133 */ 134 public static final JPEGHuffmanTable 135 StdDCChrominance = new JPEGHuffmanTable(StdDCChrominanceLengths, 136 StdDCChrominanceValues, false); 137 138 /** 139 * The standard AC luminance Huffman table. 140 */ 141 public static final JPEGHuffmanTable 142 StdACLuminance = new JPEGHuffmanTable(StdACLuminanceLengths, 143 StdACLuminanceValues, false); 144 145 /** 146 * The standard AC chrominance Huffman table. 147 */ 148 public static final JPEGHuffmanTable 149 StdACChrominance = new JPEGHuffmanTable(StdACChrominanceLengths, 150 StdACChrominanceValues, false); 151 152 private short[] lengths; 153 private short[] values; 154 155 /** 156 * Creates a Huffman table and initializes it. The input arrays are copied. 157 * The arrays must describe a possible Huffman table. 158 * For example, 3 codes cannot be expressed with a single bit. 159 * 160 * @param lengths an array of {@code short}s where {@code lengths[k]} 161 * is equal to the number of values with corresponding codes of 162 * length {@code k + 1} bits. 163 * @param values an array of shorts containing the values in 164 * order of increasing code length. 165 * @throws IllegalArgumentException if {@code lengths} or 166 * {@code values} are null, the length of {@code lengths} is 167 * greater than 16, the length of {@code values} is greater than 256, 168 * if any value in {@code lengths} or {@code values} is less 169 * than zero, or if the arrays do not describe a valid Huffman table. 170 */ 171 public JPEGHuffmanTable(short[] lengths, short[] values) { 172 if (lengths == null || values == null || 173 lengths.length == 0 || values.length == 0 || 174 lengths.length > 16 || values.length > 256) { 175 throw new IllegalArgumentException("Illegal lengths or values"); 176 } 177 for (int i = 0; i<lengths.length; i++) { 178 if (lengths[i] < 0) { 179 throw new IllegalArgumentException("lengths["+i+"] < 0"); 180 } 181 } 182 for (int i = 0; i<values.length; i++) { 183 if (values[i] < 0) { 184 throw new IllegalArgumentException("values["+i+"] < 0"); 185 } 186 } 187 this.lengths = Arrays.copyOf(lengths, lengths.length); 188 this.values = Arrays.copyOf(values, values.length); 189 validate(); 190 } 191 192 private void validate() { 193 int sumOfLengths = 0; 194 for (int i=0; i<lengths.length; i++) { 195 sumOfLengths += lengths[i]; 196 } 197 if (sumOfLengths != values.length) { 198 throw new IllegalArgumentException("lengths do not correspond " + 199 "to length of value table"); 200 } 201 } 202 203 /* Internal version which avoids the overhead of copying and checking */ 204 private JPEGHuffmanTable(short[] lengths, short[] values, boolean copy) { 205 if (copy) { 206 this.lengths = Arrays.copyOf(lengths, lengths.length); 207 this.values = Arrays.copyOf(values, values.length); 208 } else { 209 this.lengths = lengths; 210 this.values = values; 211 } 212 } 213 214 /** 215 * Returns an array of {@code short}s containing the number of values 216 * for each length in the Huffman table. The returned array is a copy. 217 * 218 * @return a {@code short} array where {@code array[k-1]} 219 * is equal to the number of values in the table of length {@code k}. 220 * @see #getValues 221 */ 222 public short[] getLengths() { 223 return Arrays.copyOf(lengths, lengths.length); 224 } 225 226 /** 227 * Returns an array of {@code short}s containing the values arranged 228 * by increasing length of their corresponding codes. 229 * The interpretation of the array is dependent on the values returned 230 * from {@code getLengths}. The returned array is a copy. 231 * 232 * @return a {@code short} array of values. 233 * @see #getLengths 234 */ 235 public short[] getValues() { 236 return Arrays.copyOf(values, values.length); 237 } 238 239 /** 240 * Returns a {@code String} representing this Huffman table. 241 * @return a {@code String} representing this Huffman table. 242 */ 243 public String toString() { 244 String ls = System.getProperty("line.separator", "\n"); 245 StringBuilder sb = new StringBuilder("JPEGHuffmanTable"); 246 sb.append(ls).append("lengths:"); 247 for (int i=0; i<lengths.length; i++) { 248 sb.append(" ").append(lengths[i]); 249 } 250 sb.append(ls).append("values:"); 251 for (int i=0; i<values.length; i++) { 252 sb.append(" ").append(values[i]); 253 } 254 return sb.toString(); 255 } 256} 257