Package com.twelvemonkeys.imageio.plugins.tiff

Class LZWDecoder

java.lang.Object

com.twelvemonkeys.imageio.plugins.tiff.LZWDecoder

All Implemented Interfaces:

Decoder

Direct Known Subclasses:

LZWDecoder.LZWCompatibilityDecoder, LZWDecoder.LZWSpecDecoder

abstract class LZWDecoder
extends java.lang.Object
implements Decoder

Lempel–Ziv–Welch (LZW) decompression. LZW is a universal loss-less data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. Inspired by libTiff's LZW decompression.

Version:

$Id: LZWDecoder.java,v 1.0 08.05.12 21:11 haraldk Exp$

See Also:

LZW (Wikipedia)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	LZWDecoder.LZWCompatibilityDecoder
(package private) static class	LZWDecoder.LZWSpecDecoder
(package private) static class	LZWDecoder.LZWString

Field Summary

Fields

Modifier and Type	Field	Description
(package private) int	bitMask
(package private) int	bitsPerCode
(package private) static int	CLEAR_CODE	Clear: Re-initialize tables.
(package private) boolean	eofReached
(package private) static int	EOI_CODE	End of Information.
private static int	MAX_BITS
private int	maxCode
private int	maxString
private static int	MIN_BITS
(package private) int	nextBits
(package private) int	nextData
private int	oldCode
private LZWDecoder.LZWString[]	table
private static int	TABLE_SIZE
private int	tableLength

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	LZWDecoder(int tableSize)

Method Summary

Modifier and Type	Method	Description
private void	addStringToTable(LZWDecoder.LZWString string)
private static int	bitmaskFor(int bits)
static Decoder	create(boolean oldBitReversedStream)
int	decode(java.io.InputStream stream, java.nio.ByteBuffer buffer)	Decodes up to buffer.length bytes from the given input stream, into the given buffer.
protected abstract int	getNextCode(java.io.InputStream stream)
private void	init()
private boolean	isInTable(int code)
(package private) static boolean	isOldBitReversedStream(java.io.InputStream stream)
protected abstract int	maxCode()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CLEAR_CODE

static final int CLEAR_CODE

Clear: Re-initialize tables.

See Also:

Constant Field Values

EOI_CODE

static final int EOI_CODE

End of Information.

See Also:

Constant Field Values

MIN_BITS

private static final int MIN_BITS

See Also:

Constant Field Values

MAX_BITS

private static final int MAX_BITS

See Also:

Constant Field Values

TABLE_SIZE

private static final int TABLE_SIZE

See Also:

Constant Field Values

table

private final LZWDecoder.LZWString[] table

tableLength

private int tableLength

bitsPerCode

int bitsPerCode

oldCode

private int oldCode

maxCode

private int maxCode

bitMask

int bitMask

maxString

private int maxString

eofReached

boolean eofReached

nextData

int nextData

nextBits

int nextBits

Constructor Detail

LZWDecoder

protected LZWDecoder(int tableSize)

Method Detail

bitmaskFor

private static int bitmaskFor(int bits)

init

private void init()

decode

public int decode(java.io.InputStream stream,
                  java.nio.ByteBuffer buffer)
           throws java.io.IOException

Description copied from interface: Decoder

Decodes up to buffer.length bytes from the given input stream, into the given buffer.

Specified by:

decode in interface Decoder

Parameters:

stream - the input stream to decode data from

buffer - buffer to store the read data

Returns:

the total number of bytes read into the buffer, or 0 if there is no more data because the end of the stream has been reached.

Throws:

DecodeException - if encoded data is corrupt.

java.io.IOException - if an I/O error occurs.

java.io.EOFException - if a premature end-of-file is encountered.

addStringToTable

private void addStringToTable(LZWDecoder.LZWString string)
                       throws java.io.IOException

Throws:

java.io.IOException

maxCode

protected abstract int maxCode()

isInTable

private boolean isInTable(int code)

getNextCode

protected abstract int getNextCode(java.io.InputStream stream)
                            throws java.io.IOException

Throws:

java.io.IOException

isOldBitReversedStream

static boolean isOldBitReversedStream(java.io.InputStream stream)
                               throws java.io.IOException

Throws:

java.io.IOException

create

public static Decoder create(boolean oldBitReversedStream)