Library: Foundation
Package: Streams
Header: Poco/DeflatingStream.h
Description
This is the streambuf class used by DeflatingInputStream and DeflatingOutputStream. The actual work is delegated to zlib (see http://zlib.net). Both zlib (deflate) streams and gzip streams are supported. Output streams should always call close() to ensure proper completion of compression. A compression level (0 to 9) can be specified in the constructor.
Inheritance
Direct Base Classes: BufferedStreamBuf
All Base Classes: BufferedStreamBuf
Member Summary
Member Functions: close, readFromDevice, sync, writeToDevice
Enumerations
CompressionLevel
Constants for compression levels. Note to maintainers: These must be kept in sync with the constants defined by zlib.
DEFAULT_COMPRESSION = - 1
NO_COMPRESSION = 0
BEST_SPEED = 1
BEST_COMPRESSION = 9
StreamType
Create a zlib header, use Adler-32 checksum.
Create a gzip header, use CRC-32 checksum.
Constructors
DeflatingStreamBuf
DeflatingStreamBuf(
std::istream & istr,
StreamType type,
int level
);
Creates a DeflatingStreamBuf for compressing data read from the given input stream.
DeflatingStreamBuf
DeflatingStreamBuf(
std::istream & istr,
int windowBits,
int level
);
Creates a DeflatingStreamBuf for compressing data read from the given input stream.
Please refer to the zlib documentation of deflateInit2() for a description of the windowBits parameter.
DeflatingStreamBuf
DeflatingStreamBuf(
std::ostream & ostr,
StreamType type,
int level
);
Creates a DeflatingStreamBuf for compressing data passed through and forwarding it to the given output stream.
DeflatingStreamBuf
DeflatingStreamBuf(
std::ostream & ostr,
int windowBits,
int level
);
Creates a DeflatingStreamBuf for compressing data passed through and forwarding it to the given output stream.
Please refer to the zlib documentation of deflateInit2() for a description of the windowBits parameter.
Destructor
~DeflatingStreamBuf
Destroys the DeflatingStreamBuf.
Member Functions
close
int close();
Finishes up the stream.
Must be called when deflating to an output stream.
readFromDevice 
int readFromDevice(
char * buffer,
std::streamsize length
);
sync 
virtual int sync();
writeToDevice
int writeToDevice(
const char * buffer,
std::streamsize length
);