DcmZLibOutputFilter Class Reference

zlib compression filter for output streams More...

Inheritance diagram for DcmZLibOutputFilter:

DcmOutputFilter DcmConsumer List of all members.

Public Member Functions

 DcmZLibOutputFilter ()
 default constructor
virtual ~DcmZLibOutputFilter ()
 destructor
virtual OFBool good () const
 returns the status of the consumer.
virtual OFCondition status () const
 returns the status of the consumer as an OFCondition object.
virtual OFBool isFlushed () const
 returns true if the consumer is flushed, i.e.
virtual Uint32 avail () const
 returns the minimum number of bytes that can be written with the next call to write().
virtual Uint32 write (const void *buf, Uint32 buflen)
 processes as many bytes as possible from the given input block.
virtual void flush ()
 instructs the consumer to flush its internal content until either the consumer becomes "flushed" or I/O suspension occurs.
virtual void append (DcmConsumer &consumer)
 determines the consumer to which the filter is supposed to write it's output.

Private Member Functions

 DcmZLibOutputFilter (const DcmZLibOutputFilter &)
 private unimplemented copy constructor
DcmZLibOutputFilter & operator= (const DcmZLibOutputFilter &)
 private unimplemented copy assignment operator
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 compress (const void *buf, Uint32 buflen, OFBool finalize)
 feed data from the given block of data to the compression codec until complete or the output ring buffer 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

DcmConsumer * current_
 pointer to consumer to which compressed output is written
z_streamp zstream_
 pointer to struct z_stream object containing the zlib status
OFCondition status_
 status
OFBool flushed_
 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 in output ring buffer

Detailed Description

zlib compression filter for output streams

Definition at line 55 of file dcostrmz.h.

Member Function Documentation

virtual void DcmZLibOutputFilter::append (  DcmConsumer &  consumer  )  [virtual]
 

determines the consumer to which the filter is supposed to write it's output.

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

Parameters:
consumer reference to consumer, must not be circular chain

Implements DcmOutputFilter.

virtual Uint32 DcmZLibOutputFilter::avail (   )  const [virtual]
 

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

The DcmObject write 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 written "en bloc", i.e. all or nothing.

Returns:
minimum of space available in consumer

Implements DcmConsumer.

Uint32 DcmZLibOutputFilter::compress (  const void *  buf,
Uint32  buflen,
OFBool  finalize
)  [private]
 

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

Does not flush the output ring buffer.

Parameters:
buf pointer to input data
number of bytes in buf
finalize true if the current block of data constitutes the end of the input stream, i.e. the compression codec should be forced to flush its internal state.
Returns:
number of bytes processed

void DcmZLibOutputFilter::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 DcmZLibOutputFilter::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

virtual void DcmZLibOutputFilter::flush (   )  [virtual]
 

instructs the consumer to flush its internal content until either the consumer becomes "flushed" or I/O suspension occurs.

After a call to flush(), a call to write() will produce undefined behaviour.

Implements DcmConsumer.

virtual OFBool DcmZLibOutputFilter::good (   )  const [virtual]
 

returns the status of the consumer.

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

Returns:
status, true if good

Implements DcmConsumer.

virtual OFBool DcmZLibOutputFilter::isFlushed (   )  const [virtual]
 

returns true if the consumer is flushed, i.e.

has no more data pending in it's internal state that needs to be flushed before the stream is closed.

Returns:
true if consumer is flushed, false otherwise

Implements DcmConsumer.

virtual OFCondition DcmZLibOutputFilter::status (   )  const [virtual]
 

returns the status of the consumer as an OFCondition object.

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

Returns:
status, EC_Normal if good

Implements DcmConsumer.

virtual Uint32 DcmZLibOutputFilter::write (  const void *  buf,
Uint32  buflen
)  [virtual]
 

processes as many bytes as possible from the given input block.

Parameters:
buf pointer to memory block, must not be NULL
buflen length of memory block
Returns:
number of bytes actually processed.

Implements DcmConsumer.

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

Generated on 20 Dec 2005 for OFFIS DCMTK Version 3.5.4 by Doxygen 1.4.5