CZipCompressor Class Reference

#include <ZipCompressor.h>

Inheritance diagram for CZipCompressor:


Public Types
enum	CompressionLevel { levelDefault = -1, levelStore = 0, levelFastest = 1, levelBest = 9 }
enum	CompressionMethod { methodStore = 0, methodDeflate = 8, methodBzip2 = 12, methodWinZipAes = 99 }
enum	CompressorType { typeDeflate = 1, typeBzip2 }
typedef CZipArray< COffsetsPair * >	CZipOffsetsPairsArray
Public Member Functions
virtual bool	CanProcess (WORD uMethod)=0
virtual void	Compress (const void *pBuffer, DWORD uSize)=0
virtual DWORD	Decompress (void *pBuffer, DWORD uSize)=0
virtual void	FinishCompression (bool bAfterException)
virtual void	FinishDecompression (bool bAfterException)
virtual const COptions *	GetOptions () const
virtual void	InitCompression (int iLevel, CZipFileHeader pFile, CZipCryptograph pCryptograph)
virtual void	InitDecompression (CZipFileHeader pFile, CZipCryptograph pCryptograph)
bool	PrepareForSeek (CZipFileHeader pCurrentFile, COffsetsPair pPair)
void	UpdateOptions (const COptionsMap &optionsMap)
Static Public Member Functions
static CZipCompressor *	CreateCompressor (WORD uMethod, CZipStorage *pStorage)
static bool	IsCompressionSupported (WORD uCompressionMethod)
Public Attributes
ZIP_SIZE_TYPE	m_uComprLeft
	The number of bytes left to compress.
DWORD	m_uCrc32
	The CRC32 file checksum.
ZIP_SIZE_TYPE	m_uUncomprLeft
	The number of bytes left to decompress.
Protected Member Functions
virtual int	ConvertInternalError (int iErr) const
	CZipCompressor (CZipStorage *pStorage)
void	FlushWriteBuffer ()
void	InitBuffer ()
void	ReleaseBuffer ()
void	ThrowError (int iErr, bool bInternal=false)
void	UpdateCrc (const void *pBuffer, DWORD uSize)
void	UpdateFileCrc (const void *pBuffer, DWORD uSize)
virtual void	UpdateOptions (const COptions *pOptions)
Protected Attributes
CZipAutoBuffer	m_pBuffer
	A buffer that receives compressed data or provides data for decompression.
CZipCryptograph *	m_pCryptograph
	Current cryptograph.
CZipFileHeader *	m_pFile
	The file header being compressed or decompressed.
CZipStorage *	m_pStorage
	The current storage object.
Classes
class	COffsetsArray
struct	COffsetsPair
struct	COptions
class	COptionsMap

Detailed Description

A base class for compressors used in compression and decompression of data.

Member Enumeration Documentation

enum CZipCompressor::CompressionLevel

The compression level.

Enumerator:

levelDefault	The default compression level (equals 6 for deflate).
levelStore	No compression used. Data is stored.
levelFastest	The fastest compression. The compression ratio is the lowest (apart from levelStore).
levelBest	The highest compression ratio. It's usually the slowest.

enum CZipCompressor::CompressionMethod

The compression method.

Enumerator:

methodStore	A file is stored, not compressed.
methodDeflate	The deflate compression method.
methodBzip2	A file is compressed using the bzip2 algorithm. See also: Compressing Data
methodWinZipAes	This value means that WinZip AES encryption is used. The original compression method is stored in a WinZip extra field. It is only an informational value - you cannot set it as a compression method. The ZipArchive Library handles this value internally. See also: Encryption Methods: How to Best Protect Your Data

enum CZipCompressor::CompressorType

The type of a compressor.

Enumerator:

typeDeflate	Deflate compression (default in zip archives).
typeBzip2	Bzip2 compression.

Constructor & Destructor Documentation

CZipCompressor::CZipCompressor ( CZipStorage * pStorage ) [inline, protected]

Initializes a new instance of the CZipCompressor class.

Parameters:

pStorage

The current storage object.

Member Function Documentation

virtual bool CZipCompressor::CanProcess ( WORD uMethod ) [pure virtual]

Returns the value indicating, if the current CZipCompressor object supports the given compression method.

Parameters:

uMethod

The compression method. Can be one of the CompressionMethod values.

Returns:: true, if the compression method is supported; false otherwise.

Implemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

virtual void CZipCompressor::Compress	(	const void *	pBuffer,
		DWORD	uSize
	)			`[pure virtual]`

Compresses the given data.

Parameters:

	pBuffer	The buffer that holds the data to compress.
	uSize	The size of pBuffer.

See also:: InitCompression
FinishCompression

Implemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

virtual int CZipCompressor::ConvertInternalError ( int iErr ) const [inline, protected, virtual]

Converts internal error code of the compressor to the ZipArchive Library error code.

Parameters:

iErr

An internal error code.

Returns:: A ZipArchive Library error code.

Reimplemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

static CZipCompressor* CZipCompressor::CreateCompressor	(	WORD	uMethod,
		CZipStorage *	pStorage
	)			`[static]`

A factory method that creates an appropriate compressor for the given compression method.

Parameters:

	uMethod	The compression method to create a compressor for. Can be one of CompressionMethod values.
	pStorage	The current storage object.

virtual DWORD CZipCompressor::Decompress	(	void *	pBuffer,
		DWORD	uSize
	)			`[pure virtual]`

Decompresses the given data.

Parameters:

	pBuffer	The buffer that receives the decompressed data.
	uSize	The size of pBuffer.

Returns:: The number of bytes decompressed and written to pBuffer.

Note:: This method should be called repeatedly until it returns 0.

See also:: InitDecompression
FinishDecompression

Implemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

virtual void CZipCompressor::FinishCompression ( bool bAfterException ) [inline, virtual]

The method called at the end of the compression process.

Parameters:

bAfterException Set to true, if an exception occurred before or to false otherwise.

See also:: InitCompression
Compress

Reimplemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

virtual void CZipCompressor::FinishDecompression ( bool bAfterException ) [inline, virtual]

The method called at the end of the decompression process.

Parameters:

bAfterException Set to true, if an exception occurred before or to false otherwise.

See also:: InitDecompression
Decompress

Reimplemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

void CZipCompressor::FlushWriteBuffer ( ) [inline, protected]

Flushes data in the buffer into the storage, encrypting the data if needed.

Note:: Throws exceptions.

virtual const COptions* CZipCompressor::GetOptions ( ) const [inline, virtual]

Returns the current options of the compressor.

Returns:: The current options for the compressor.

See also:

Compressing Data

CZipArchive::SetCompressionOptions

UpdateOptions

Reimplemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

void CZipCompressor::InitBuffer ( ) [protected]

Initializes the internal buffer.

See also:: ReleaseBuffer

virtual void CZipCompressor::InitCompression	(	int	iLevel,
		CZipFileHeader *	pFile,
		CZipCryptograph *	pCryptograph
	)			`[inline, virtual]`

The method called when a new file is opened for compression.

Parameters:

	iLevel	The compression level.
	pFile	The file being compressed.
	pCryptograph	The current CZipCryptograph. Can be `NULL`, if no encryption is used.

See also:: Compress
FinishCompression

Reimplemented in ZipArchiveLib::CDeflateCompressor, and ZipArchiveLib::CBzip2Compressor.

virtual void CZipCompressor::InitDecompression	(	CZipFileHeader *	pFile,
		CZipCryptograph *	pCryptograph
	)			`[inline, virtual]`

The method called when a new file is opened for extraction.

Parameters:

	pFile	The file being extracted.
	pCryptograph	The current CZipCryptograph. Can be `NULL`, if no decryption is used.

See also:: Decompress
FinishDecompression

Reimplemented in ZipArchiveLib::CDeflateCompressor, ZipArchiveLib::CBaseLibCompressor, and ZipArchiveLib::CBzip2Compressor.

static bool CZipCompressor::IsCompressionSupported ( WORD uCompressionMethod ) [inline, static]

Returns the value indicating whether the given compression method is supported by the ZipArchive Library.

Parameters:

uCompressionMethod

The compression method. Can be one of the CompressionMethod values.

Returns:: true, if the compression method is supported, false otherwise.

bool CZipCompressor::PrepareForSeek	(	CZipFileHeader *	pCurrentFile,
		COffsetsPair *	pPair
	)

Prepares the compressor for the seeking operation.

Parameters:

	pCurrentFile	The currently opened file.
	pPair	The offsets pair describing the seek location.

See also:: Creating Seekable Compressed Data

void CZipCompressor::ReleaseBuffer ( ) [inline, protected]

Releases the internal buffer.

See also:: InitBuffer

void CZipCompressor::ThrowError	(	int	iErr,
		bool	bInternal = `false`
	)			`[inline, protected]`

Throws an exception with a given error code.

Parameters:

	iErr	An error code.
	bInternal	`true`, if iErr is an internal error code and needs a conversion to the ZipArchive Library error code; `false` otherwise.