zlib compression filter for input streams More...

Inheritance diagram for DcmZLibInputFilter:

Public Member Functions
	DcmZLibInputFilter ()
	default constructor

virtual	~DcmZLibInputFilter ()
	destructor

virtual OFBool	good () const
	returns the status of the producer. More...

virtual OFCondition	status () const
	returns the status of the producer as an OFCondition object. More...

virtual OFBool	eos ()
	returns true if the producer is at the end of stream. More...

virtual offile_off_t	avail ()
	returns the minimum number of bytes that can be read with the next call to read(). More...

virtual offile_off_t	read (void *buf, offile_off_t buflen)
	reads as many bytes as possible into the given block. More...

virtual offile_off_t	skip (offile_off_t skiplen)
	skips over the given number of bytes (or less) More...

virtual void	putback (offile_off_t num)
	resets the stream to the position by the given number of bytes. More...

virtual void	append (DcmProducer &producer)
	determines the producer from which the filter is supposed to read it's input. More...

Public Member Functions inherited from DcmInputFilter
virtual	~DcmInputFilter ()
	destructor

Public Member Functions inherited from DcmProducer
virtual	~DcmProducer ()
	destructor

Private Member Functions
	DcmZLibInputFilter (const DcmZLibInputFilter &)
	private unimplemented copy constructor

DcmZLibInputFilter &	operator= (const DcmZLibInputFilter &)
	private unimplemented copy assignment operator

offile_off_t	fillInputBuffer ()
	reads data from the producer into the input ring buffer until the input ring buffer becomes full or the producer suspends More...

offile_off_t	decompress (const void *buf, offile_off_t buflen)
	decompress data into the given output block until complete or no more input is available in the input ring buffer. More...

void	fillOutputBuffer ()
	reads and decompresses data from the producer until the producer suspends or the output ring buffer becomes full.

void	flushOutputBuffer ()
	writes the content of the output ring buffer to the next filter stage until the output ring buffer becomes empty or the next filter stage becomes full

offile_off_t	fillInputBuffer (const void *buf, offile_off_t buflen)
	copies as much of the given block of data as possible in the input ring buffer More...

void	compressInputBuffer (OFBool finalize)
	feed data from the input ring buffer to the compression codec until complete or the output ring buffer becomes full. More...

Private Attributes
DcmProducer *	current_
	pointer to producer from which compressed input is read

z_streamp	zstream_
	pointer to struct z_stream object containing the zlib status

OFCondition	status_
	status

OFBool	eos_
	true if the zlib object has reported Z_STREAM_END

unsigned char *	inputBuf_
	input ring buffer

offile_off_t	inputBufStart_
	offset of first byte in input ring buffer

offile_off_t	inputBufCount_
	number of bytes in input ring buffer

unsigned char *	outputBuf_
	output ring buffer

offile_off_t	outputBufStart_
	offset of first byte in output ring buffer

offile_off_t	outputBufCount_
	number of bytes available for read in output ring buffer

offile_off_t	outputBufPutback_
	number of putback bytes in output ring buffer

OFBool	padded_
	flag indicating whether or not a pad byte has been appended to the input stream

Detailed Description

zlib compression filter for input streams

Remarks: this class is only available if DCMTK is compiled with ZLIB support enabled.

Member Function Documentation

◆ append()

virtual void DcmZLibInputFilter::append ( DcmProducer & producer )

virtual

determines the producer from which the filter is supposed to read it's input.

Once a producer for the input filter has been defined, it cannot be changed anymore during the lifetime of the object.

Parameters

producer reference to producer, must not be circular chain

Implements DcmInputFilter.

◆ avail()

virtual offile_off_t DcmZLibInputFilter::avail ( )

virtual

returns the minimum number of bytes that can be read with the next call to read().

The DcmObject read methods rely on avail to return a value > 0 if there is no I/O suspension since certain data such as tag and length are only read "en bloc", i.e. all or nothing.

Returns: minimum of data available in producer

Implements DcmProducer.

◆ compressInputBuffer()

void DcmZLibInputFilter::compressInputBuffer ( OFBool finalize )

private

feed data from the input ring buffer to the compression codec until complete or the output ring buffer becomes full.

Does not flush the output ring buffer.

Parameters

finalize true if the content of the input ring buffer constitutes the end of the input stream, i.e. the compression codec should be forced to flush its internal state.

◆ decompress()

offile_off_t DcmZLibInputFilter::decompress	(	const void *	buf,
		offile_off_t	buflen
	)

private

decompress data into the given output block until complete or no more input is available in the input ring buffer.

does not re-fill the input ring buffer from the producer.

Parameters

buf	pointer to input data
buflen	number of bytes in buf

Returns: number of bytes processed

◆ eos()

virtual OFBool DcmZLibInputFilter::eos ( )

virtual

returns true if the producer is at the end of stream.

Returns: true if end of stream, false otherwise

Implements DcmProducer.

◆ fillInputBuffer() [1/2]

offile_off_t DcmZLibInputFilter::fillInputBuffer ( )

private

reads data from the producer into the input ring buffer until the input ring buffer becomes full or the producer suspends

Returns: number of bytes added to input buffer

◆ fillInputBuffer() [2/2]

offile_off_t DcmZLibInputFilter::fillInputBuffer	(	const void *	buf,
		offile_off_t	buflen
	)

private

copies as much of the given block of data as possible in the input ring buffer

Parameters

buf	pointer to input data
buflen	number of bytes in buf

Returns: number of bytes copied to input ring buffer

◆ good()

virtual OFBool DcmZLibInputFilter::good ( ) const

virtual

returns the status of the producer.

Unless the status is good, the producer will not permit any operation.

Returns: status, true if good

Implements DcmProducer.

◆ putback()

virtual void DcmZLibInputFilter::putback ( offile_off_t num )

virtual

resets the stream to the position by the given number of bytes.

Parameters

num	number of bytes to putback. If the putback operation fails, the producer status becomes bad.

Implements DcmProducer.

◆ read()

virtual offile_off_t DcmZLibInputFilter::read	(	void *	buf,
		offile_off_t	buflen
	)

virtual

reads as many bytes as possible into the given block.

Parameters

buf	pointer to memory block, must not be NULL
buflen	length of memory block

Returns: number of bytes actually read.

Implements DcmProducer.

◆ skip()

virtual offile_off_t DcmZLibInputFilter::skip ( offile_off_t skiplen )

virtual

skips over the given number of bytes (or less)

Parameters

skiplen number of bytes to skip

Returns: number of bytes actually skipped.

Implements DcmProducer.

◆ status()

virtual OFCondition DcmZLibInputFilter::status ( ) const

virtual

returns the status of the producer as an OFCondition object.

Unless the status is good, the producer will not permit any operation.

Returns: status, EC_Normal if good

Implements DcmProducer.

The documentation for this class was generated from the following file:

dcmdata/include/dcmtk/dcmdata/dcistrmz.h

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Member Function Documentation

◆ append()

◆ avail()

◆ compressInputBuffer()

◆ decompress()

◆ eos()

◆ fillInputBuffer() [1/2]

◆ fillInputBuffer() [2/2]

◆ good()

◆ putback()

◆ read()

◆ skip()

◆ status()