/*
* @(#)JPEGHuffmanTable.java 1.13 03/12/19
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
/**********************************************************************
**********************************************************************
**********************************************************************
*** COPYRIGHT (c) 1997-1998 Eastman Kodak Company. ***
*** As an unpublished work pursuant to Title 17 of the United ***
*** States Code. All rights reserved. ***
**********************************************************************
**********************************************************************
**********************************************************************/
package javax.imageio.plugins.jpeg;
/**
* A class encapsulating a single JPEG Huffman table. Fields are
* provided for the "standard" tables from taken from Annex K of the
* JPEG specification. These are the tables used as defaults.
* This class differs from the old unsupported
* com.sun.image.codec.jpeg.JPEGHuffmanTable in two ways:
* <ol>
* <li>The lengths arrays for this class do not contain an ignored 0th
* entry. The lengths array in a JPEG stream does not contain an extra
* entry, and this class is used to represent the contents of a JPEG
* stream.
* </li>
* <li>The old class incorrectly referred to Huffman "symbols", while
* expecting an array of values to be encoded. This class has a
* <code>getValues</code> method instead of a <code>getSymbols</code>
* method.
* </li>
* </ol>
*
* <p>
* For more information about the operation of the built-in JPEG plug-ins,
* see the <A HREF="../../metadata/doc-files/jpeg_metadata.html">JPEG
* metadata format specification and usage notes</A>.
*
* @version 0.5
*/
public class JPEGHuffmanTable {
/**
* The maximum number of symbol lengths
* (max symbol length in bits = 16).
*/
private static final int HUFF_MAX_LEN = 16;
/** The maximum number of values. */
private static final int HUFF_MAX_VALS = 256;
/** lengths[k-1] = number of symbols with length k bits. */
private short lengths[] = null;
/** Values in order of increasing length of the corresponding symbols. */
private short values[] = null;
/** The standard DC luminance Huffman table. */
public static final JPEGHuffmanTable StdDCLuminance =
new JPEGHuffmanTable();
static {
short lengths[] = {
0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 };
short values[] = {
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
StdDCLuminance.lengths = lengths;
StdDCLuminance.values = values;
StdDCLuminance.checkTable();
}
/** The standard DC chrominance Huffman table. */
public static final JPEGHuffmanTable StdDCChrominance =
new JPEGHuffmanTable();
static {
short lengths[] = {
0, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0 };
short values[] = {
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
StdDCChrominance.lengths = lengths;
StdDCChrominance.values = values;
StdDCChrominance.checkTable();
}
/** The standard AC luminance Huffman table. */
public static final JPEGHuffmanTable StdACLuminance =
new JPEGHuffmanTable();
static {
short lengths[] = {
0, 2, 1, 3, 3, 2, 4, 3, 5, 5, 4, 4, 0, 0, 1, 0x7d };
short values[] = {
0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
0xf9, 0xfa };
StdACLuminance.lengths = lengths;
StdACLuminance.values = values;
StdACLuminance.checkTable();
}
/** The standard AC chrominance Huffman table. */
public static final JPEGHuffmanTable StdACChrominance =
new JPEGHuffmanTable();
static {
short lengths[] = {
0, 2, 1, 2, 4, 4, 3, 4, 7, 5, 4, 4, 0, 1, 2, 0x77 };
short values[] = {
0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
0xf9, 0xfa };
StdACChrominance.lengths = lengths;
StdACChrominance.values = values;
StdACChrominance.checkTable();
}
/**
* Private constructor used to construct the Standard Huffman tables
*/
private JPEGHuffmanTable() {}
/**
* Creates a Huffman table and initializes it. The input arrays
* are copied. The arrays must describe a possible Huffman table.
* For example, 3 codes cannot be expressed with a single bit.
*
* @param lengths an array of <code>short</code>s where
* <code>lengths[k]</code> is equal to the number of values with
* corresponding codes of length <code>k + 1</code> bits.
* @param values an array of <code>short</code>s containing the
* values in order of increasing code length.
*
* @exception IllegalArgumentException if <code>lengths</code> or
* <code>values</code> are <code>null</code>, the length of
* <code>lengths</code> is greater than 16, the length of
* <code>values</code> is greater than 256, if any value in
* <code>lengths</code> or <code>values</code> is less than zero,
* or if the arrays do not describe a valid Huffman table.
*/
public JPEGHuffmanTable(short[] lengths, short[] values) {
if (lengths == null) {
throw new IllegalArgumentException("lengths array is null!");
}
if (values == null) {
throw new IllegalArgumentException("values array is null!");
}
if (lengths.length > HUFF_MAX_LEN) {
throw new IllegalArgumentException("lengths array is too long!");
}
if (values.length > HUFF_MAX_VALS) {
throw new IllegalArgumentException("values array is too long");
}
for (int i = 1; i < lengths.length; i++) {
if (lengths[i] < 0) {
throw new IllegalArgumentException
("Values in lengths array must be non-negative.");
}
}
for (int i = 0; i < values.length; i++) {
if (values[i] < 0) {
throw new IllegalArgumentException
("Values in values array must be non-negative.");
}
}
this.lengths = (short[])lengths.clone();
this.values = (short[])values.clone();
checkTable();
}
/**
* This checks that the table they gave us isn't 'illegal' It
* checks that the symbol length counts are possible, and that
* they gave us at least enough values for the symbol length
* counts. Eventually this might check that there aren't duplicate
* values.
*/
private void checkTable() {
int numVals = 2;
int sum = 0;
for (int i = 0; i < lengths.length; i++) {
sum += lengths[i];
numVals -= lengths[i];
numVals *= 2;
}
if (numVals < 0) {
throw new IllegalArgumentException
("Invalid Huffman table provided, lengths are incorrect.");
}
if (sum != values.length) {
throw new IllegalArgumentException
("Invalid Huffman table provided, sum of lengths != values.");
}
}
/**
* Return an array of <code>short</code>s containing the number of
* values for each length in the Huffman table. The returned
* array is a copy.
*
* @return a <code>short</code> array where <code>array[k-1]</code>
* is equal to the number of values in the table of length
* <code>k</code>.
*
* @see #getValues
*/
public short[] getLengths() {
return (short[])lengths.clone();
}
/**
* Return an array of <code>short</code>s containing the
* values arranged by increasing length of their corresponding
* codes. The interpretation of
* the array is dependent on the values returned from
* <code>getLengths</code>. The returned array is a copy.
*
* @return a <code>short</code> array of values.
*
* @see #getLengths
*/
public short[] getValues() {
return (short[])values.clone();
}
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("JPEGHuffmanTable:\nlengths:");
for (int i = 0; i< lengths.length; i++) {
sb.append(' ').append(lengths[i]);
}
sb.append("\nvalues:");
for (int i = 0; i< values.length; i++) {
sb.append(' ').append(values[i]);
}
return sb.toString();
}
}
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