org.jpedal.sun.LZWDecoder Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of OpenViewerFX Show documentation
Show all versions of OpenViewerFX Show documentation
An Open Source JavaFX PDF Viewer
/*
* Copyright (c) 2001 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* -Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* -Redistribution in binary form must reproduct the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
* IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
* NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE
* LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
* LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
* INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
* CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
* OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that Software is not designed,licensed or intended for use in
* the design, construction, operation or maintenance of any nuclear facility.
*
* Adapted from the codecs TIFFLZWDecoder for itext
* LZWDecoder.java
*/
package org.jpedal.sun;
import java.io.IOException;
import java.io.OutputStream;
import org.jpedal.utils.LogWriter;
/**
* A class for performing LZW decoding.
*
*
*/
public class LZWDecoder {
byte stringTable[][];
byte data[];
OutputStream uncompData;
int tableIndex, bitsToGet = 9;
int bytePointer;
int nextData;
int nextBits;
boolean earlyChange;
final int[] andTable = {
511,
1023,
2047,
4095
};
public LZWDecoder() {
}
/**
* Method to decode LZW compressed data.
*
* @param data The compressed data.
* @param uncompData Array to return the uncompressed data in.
* @param earlyChange Default should be true. RE: PDF spec EarlyChange
*/
public void decode(final byte[] data, final OutputStream uncompData, final boolean earlyChange) {
if(data[0] == (byte)0x00 && data[1] == (byte)0x01) {
throw new RuntimeException("LZW flavour not supported.");
}
initializeStringTable();
this.data = data;
this.uncompData = uncompData;
this.earlyChange = earlyChange;
// Initialize pointers
bytePointer = 0;
nextData = 0;
nextBits = 0;
int code, oldCode = 0;
byte string[];
while ((code = getNextCode()) != 257) {
if (code == 256) {
initializeStringTable();
code = getNextCode();
if (code == 257) {
break;
}
writeString(stringTable[code]);
oldCode = code;
} else {
if (code < tableIndex) {
string = stringTable[code];
writeString(string);
addStringToTable(stringTable[oldCode], string[0]);
oldCode = code;
} else {
string = stringTable[oldCode];
string = composeString(string, string[0]);
writeString(string);
addStringToTable(string);
oldCode = code;
}
}
}
}
/**
* Initialize the string table.
*/
public void initializeStringTable() {
stringTable = new byte[8192][];
for (int i=0; i<256; i++) {
stringTable[i] = new byte[1];
stringTable[i][0] = (byte)i;
}
tableIndex = 258;
bitsToGet = 9;
}
/**
* Write out the string just uncompressed.
*/
public void writeString(final byte[] string) {
try {
uncompData.write(string);
}
catch (final IOException e) {
LogWriter.writeLog("Exception "+e+" with LZW decoder");
}
}
/**
* Add a new string to the string table.
*/
public void addStringToTable(final byte[] oldString, final byte newString) {
final int length = oldString.length;
final byte[] string = new byte[length + 1];
System.arraycopy(oldString, 0, string, 0, length);
string[length] = newString;
addStringToTable(string);
}
/**
* Add a new string to the string table.
*/
public void addStringToTable(final byte[] string) {
if(earlyChange) {
stringTable[tableIndex++] = string;
}
if (tableIndex == 511) {
bitsToGet = 10;
} else if (tableIndex == 1023) {
bitsToGet = 11;
} else if (tableIndex == 2047) {
bitsToGet = 12;
}
if(!earlyChange) {
stringTable[tableIndex++] = string;
}
}
/**
* Append newString to the end of oldString.
*/
public static byte[] composeString(final byte[] oldString, final byte newString) {
final int length = oldString.length;
final byte[] string = new byte[length + 1];
System.arraycopy(oldString, 0, string, 0, length);
string[length] = newString;
return string;
}
// Returns the next 9, 10, 11 or 12 bits
public int getNextCode() {
// Attempt to get the next code. The exception is caught to make
// this robust to cases wherein the EndOfInformation code has been
// omitted from a strip. Examples of such cases have been observed
// in practice.
try {
nextData = (nextData << 8) | (data[bytePointer++] & 0xff);
nextBits += 8;
if (nextBits < bitsToGet) {
nextData = (nextData << 8) | (data[bytePointer++] & 0xff);
nextBits += 8;
}
final int code =
(nextData >> (nextBits - bitsToGet)) & andTable[bitsToGet-9];
nextBits -= bitsToGet;
return code;
} catch(final ArrayIndexOutOfBoundsException e) {
// Strip not terminated as expected: return EndOfInformation code.
LogWriter.writeLog("LZW value out of bounds "+e);
return 257;
}
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy