decaf::util::zip::Deflater Class Reference

This class compresses data using the DEFLATE algorithm (see specification). More...

#include <src/main/decaf/util/zip/Deflater.h>

Public Member Functions
	Deflater (int level, bool nowrap=false)
	Creates a new compressor using the specified compression level.
	Deflater ()
	Creates a new compressor with the default compression level.
virtual	~Deflater ()
void	setInput (const unsigned char *buffer, int size, int offset, int length)
	Sets input data for compression.
void	setInput (const std::vector< unsigned char > &buffer, int offset, int length)
	Sets input data for compression.
void	setInput (const std::vector< unsigned char > &buffer)
	Sets input data for compression.
void	setDictionary (const unsigned char *buffer, int size, int offset, int length)
	Sets preset dictionary for compression.
void	setDictionary (const std::vector< unsigned char > &buffer, int offset, int length)
	Sets preset dictionary for compression.
void	setDictionary (const std::vector< unsigned char > &buffer)
	Sets preset dictionary for compression.
void	setStrategy (int strategy)
	Sets the compression strategy to the specified value.
void	setLevel (int level)
	Sets the compression level to the specified value.
bool	needsInput () const
void	finish ()
	When called, indicates that compression should end with the current contents of the input buffer.
bool	finished () const
int	deflate (unsigned char *buffer, int size, int offset, int length)
	Fills specified buffer with compressed data.
int	deflate (std::vector< unsigned char > &buffer, int offset, int length)
	Fills specified buffer with compressed data.
int	deflate (std::vector< unsigned char > &buffer)
	Fills specified buffer with compressed data.
long long	getAdler () const
long long	getBytesRead () const
long long	getBytesWritten () const
void	reset ()
	Resets deflater so that a new set of input data can be processed.
void	end ()
	Closes the compressor and discards any unprocessed input.
Static Public Attributes
static const int	BEST_SPEED
	Compression level for fastest compression.
static const int	BEST_COMPRESSION
	Compression level for best compression.
static const int	DEFAULT_COMPRESSION
	Default compression level.
static const int	DEFLATED
	Compression method for the deflate algorithm (the only one currently supported).
static const int	NO_COMPRESSION
	Compression level for no compression.
static const int	FILTERED
	Compression strategy best used for data consisting mostly of small values with a somewhat random distribution.
static const int	HUFFMAN_ONLY
	Compression strategy for Huffman coding only.
static const int	DEFAULT_STRATEGY
	Default compression strategy.

Detailed Description

This class compresses data using the DEFLATE algorithm (see specification).

Basically this class is part of the API to the stream based ZLIB compression library and is used as such by DeflaterOutputStream and its descendants.

The typical usage of a Deflater instance outside this package consists of a specific call to one of its constructors before being passed to an instance of DeflaterOutputStream.

See also:: DeflaterOutputStream; Inflater

Since:: 1.0

Constructor & Destructor Documentation

decaf::util::zip::Deflater::Deflater	(	int	level,
		bool	nowrap = `false`
	)

Creates a new compressor using the specified compression level.

If 'nowrap' is true then the ZLIB header and checksum fields will not be used in order to support the compression format used in both GZIP and PKZIP.

Parameters:

	level	The compression level to use (0-9).
	nowrap	If true uses GZip compatible compression (defaults to false).

decaf::util::zip::Deflater::Deflater ( )

Creates a new compressor with the default compression level.

Compressed data will be generated in ZLIB format.

virtual decaf::util::zip::Deflater::~Deflater ( ) [virtual]

Member Function Documentation

int decaf::util::zip::Deflater::deflate ( std::vector< unsigned char > & buffer )

Fills specified buffer with compressed data.

Returns actual number of bytes of compressed data. A return value of 0 indicates that needsInput() should be called in order to determine if more input data is required.

Parameters:

buffer

The Buffer to write the compressed data to.

Returns:: the actual number of bytes of compressed data.

Exceptions:

IllegalStateException

if in the end state.

int decaf::util::zip::Deflater::deflate	(	std::vector< unsigned char > &	buffer,
		int	offset,
		int	length
	)

Fills specified buffer with compressed data.

Returns actual number of bytes of compressed data. A return value of 0 indicates that needsInput() should be called in order to determine if more input data is required.

Parameters:

	buffer	The Buffer to write the compressed data to.
	offset	The position in the Buffer to start writing at.
	length	The maximum number of byte of data to write.

Returns:: the actual number of bytes of compressed data.

Exceptions:

	IndexOutOfBoundsException	if the offset + length > size of the buffer.
	IllegalStateException	if in the end state.

int decaf::util::zip::Deflater::deflate	(	unsigned char *	buffer,
		int	size,
		int	offset,
		int	length
	)

Fills specified buffer with compressed data.

Returns actual number of bytes of compressed data. A return value of 0 indicates that needsInput() should be called in order to determine if more input data is required.

Parameters:

	buffer	The Buffer to write the compressed data to.
	size	The size of the passed buffer.
	offset	The position in the Buffer to start writing at.
	length	The maximum number of byte of data to write.

Returns:: the actual number of bytes of compressed data.

Exceptions:

	NullPointerException	if buffer is NULL.
	IndexOutOfBoundsException	if the offset + length > size of the buffer.
	IllegalStateException	if in the end state.

void decaf::util::zip::Deflater::end ( )

Closes the compressor and discards any unprocessed input.

This method should be called when the compressor is no longer being used, but will also be called automatically by the destructor. Once this method is called, the behavior of the Deflater object is undefined.

void decaf::util::zip::Deflater::finish ( )

When called, indicates that compression should end with the current contents of the input buffer.

bool decaf::util::zip::Deflater::finished ( ) const

Returns:: true if the end of the compressed data output stream has been reached.

long long decaf::util::zip::Deflater::getAdler ( ) const

Returns:: the ADLER-32 value of the uncompressed data.

Exceptions:

IllegalStateException

if in the end state.

long long decaf::util::zip::Deflater::getBytesRead ( ) const

Returns:: the total number of uncompressed bytes input so far.

Exceptions:

IllegalStateException

if in the end state.

long long decaf::util::zip::Deflater::getBytesWritten ( ) const

Returns:: the total number of compressed bytes output so far.

Exceptions:

IllegalStateException

if in the end state.

bool decaf::util::zip::Deflater::needsInput ( ) const

Returns:: true if the input data buffer is empty and setInput() should be called in order to provide more input

void decaf::util::zip::Deflater::reset ( )

Resets deflater so that a new set of input data can be processed.

Keeps current compression level and strategy settings.

Exceptions:

IllegalStateException

if in the end state.

void decaf::util::zip::Deflater::setDictionary ( const std::vector< unsigned char > & buffer )

Sets preset dictionary for compression.

A preset dictionary is used when the history buffer can be predetermined. When the data is later uncompressed with Inflater.inflate(), Inflater.getAdler() can be called in order to get the Adler-32 value of the dictionary required for decompression.

Parameters:

buffer

The buffer containing the preset dictionary.

Exceptions:

IllegalStateException

if in the end state.

void decaf::util::zip::Deflater::setDictionary	(	const std::vector< unsigned char > &	buffer,
		int	offset,
		int	length
	)

Sets preset dictionary for compression.

A preset dictionary is used when the history buffer can be predetermined. When the data is later uncompressed with Inflater.inflate(), Inflater.getAdler() can be called in order to get the Adler-32 value of the dictionary required for decompression.

Parameters:

	buffer	The buffer containing the preset dictionary.
	offset	The position in the Buffer to start reading from.
	length	The number of bytes to read from the input buffer.

Exceptions:

	IndexOutOfBoundsException	if the offset + length > size of the buffer.
	IllegalStateException	if in the end state.

void decaf::util::zip::Deflater::setDictionary	(	const unsigned char *	buffer,
		int	size,
		int	offset,
		int	length
	)

Sets preset dictionary for compression.

A preset dictionary is used when the history buffer can be predetermined. When the data is later uncompressed with Inflater.inflate(), Inflater.getAdler() can be called in order to get the Adler-32 value of the dictionary required for decompression.

Parameters:

	buffer	The buffer containing the preset dictionary.
	size	The size of the passed dictionary buffer.
	offset	The position in the Buffer to start reading from.
	length	The number of bytes to read from the input buffer.

Exceptions:

	NullPointerException	if buffer is NULL.
	IndexOutOfBoundsException	if the offset + length > size of the buffer.
	IllegalStateException	if in the end state.

void decaf::util::zip::Deflater::setInput ( const std::vector< unsigned char > & buffer )

Sets input data for compression.

This should be called whenever needsInput() returns true indicating that more input data is required.

Parameters:

buffer

The Buffer to read in for compression.

Exceptions:

IllegalStateException

if in the end state.

void decaf::util::zip::Deflater::setInput	(	const std::vector< unsigned char > &	buffer,
		int	offset,
		int	length
	)

Sets input data for compression.

This should be called whenever needsInput() returns true indicating that more input data is required.

Parameters:

	buffer	The Buffer to read in for compression.
	offset	The position in the Buffer to start reading from.
	length	The number of bytes to read from the input buffer.

Exceptions:

	IndexOutOfBoundsException	if the offset + length > size of the buffer.
	IllegalStateException	if in the end state.

void decaf::util::zip::Deflater::setInput	(	const unsigned char *	buffer,
		int	size,
		int	offset,
		int	length
	)

Sets input data for compression.

This should be called whenever needsInput() returns true indicating that more input data is required.

Parameters:

	buffer	The Buffer to read in for compression.
	size	The size in bytes of the buffer passed.
	offset	The position in the Buffer to start reading from.
	length	The number of bytes to read from the input buffer.

Exceptions:

	NullPointerException	if buffer is NULL.
	IndexOutOfBoundsException	if the offset + length > size of the buffer.
	IllegalStateException	if in the end state.