DcmZLibInputFilter Class Reference

zlib compression filter for input streams More...

Inheritance diagram for DcmZLibInputFilter:

List of all members.

Public Member Functions
	DcmZLibInputFilter ()
	default constructor
virtual	~DcmZLibInputFilter ()
	destructor
virtual OFBool	good () const
	returns the status of the producer.
virtual OFCondition	status () const
	returns the status of the producer as an OFCondition object.
virtual OFBool	eos () const
	returns true if the producer is at the end of stream.
virtual Uint32	avail () const
	returns the minimum number of bytes that can be read with the next call to read().
virtual Uint32	read (void *buf, Uint32 buflen)
	reads as many bytes as possible into the given block.
virtual Uint32	skip (Uint32 skiplen)
	skips over the given number of bytes (or less)
virtual void	putback (Uint32 num)
	resets the stream to the position by the given number of bytes.
virtual void	append (DcmProducer &producer)
	determines the producer from which the filter is supposed to read it's input.
Private Member Functions
	DcmZLibInputFilter (const DcmZLibInputFilter &)
	private unimplemented copy constructor
DcmZLibInputFilter &	operator= (const DcmZLibInputFilter &)
	private unimplemented copy assignment operator
Uint32	fillInputBuffer ()
	reads data from the producer into the input ring buffer until the input ring buffer becomes full or the producer suspends
Uint32	decompress (const void *buf, Uint32 buflen)
	decompress data into the given output block until complete or no more input is available in the input ring buffer.
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
Uint32	fillInputBuffer (const void *buf, Uint32 buflen)
	copies as much of the given block of data as possible in the input ring buffer
void	compressInputBuffer (OFBool finalize)
	feed data from the input ring buffer to the compression codec until complete or the output ring buffer becomes full.
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
Uint32	inputBufStart_
	offset of first byte in input ring buffer
Uint32	inputBufCount_
	number of bytes in input ring buffer
unsigned char *	outputBuf_
	output ring buffer
Uint32	outputBufStart_
	offset of first byte in output ring buffer
Uint32	outputBufCount_
	number of bytes available for read in output ring buffer
Uint32	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

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Detailed Description

zlib compression filter for input streams

Definition at line 56 of file dcistrmz.h.

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Member Function Documentation

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.

virtual Uint32 DcmZLibInputFilter::avail (   )  const [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.

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.

Uint32 DcmZLibInputFilter::decompress (  const void *  buf, Uint32  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 number  of bytes in buf Returns: number of bytes processed

virtual OFBool DcmZLibInputFilter::eos (   )  const [virtual]

returns true if the producer is at the end of stream. Returns: true if end of stream, false otherwise Implements DcmProducer.

Uint32 DcmZLibInputFilter::fillInputBuffer (  const void *  buf, Uint32  buflen )  [private]

copies as much of the given block of data as possible in the input ring buffer Parameters: buf  pointer to input data number  of bytes in buf Returns: number of bytes copied to input ring buffer

Uint32 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

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.

virtual void DcmZLibInputFilter::putback (  Uint32  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.

virtual Uint32 DcmZLibInputFilter::read (  void *  buf, Uint32  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.

virtual Uint32 DcmZLibInputFilter::skip (  Uint32  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.

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.

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

• dcmdata/include/dcmtk/dcmdata/dcistrmz.h

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