TStreamFilter Class Reference

#include <s32buf.h>

class TStreamFilter : public MStreamBuf

Inherits from

TStreamFilter
- MStreamBuf

Public Member Enumerations
enum	anonymous { EAttached }

Protected Member Functions
	TStreamFilter()
void	Committed()
virtual IMPORT_C TInt	DoReadL(TAny *, TInt)
virtual IMPORT_C void	DoRelease()
virtual IMPORT_C void	DoSynchL()
virtual IMPORT_C void	DoWriteL(const TAny *, TInt)
IMPORT_C void	EmitL(const TAny *, TInt)
TBool	IsCommitted()
void	Set(MStreamBuf *, TInt)

Inherited Enumerations
	MStreamBuf:TRead
	MStreamBuf:TWrite

Inherited Functions
	MStreamBuf::Close()
	MStreamBuf::MStreamBuf()
	MStreamBuf::PushL()
	MStreamBuf::Read(TDes8 &,TInt,TRequestStatus &)
	MStreamBuf::Read(TDes8 &,TRequestStatus &)
	MStreamBuf::ReadL(MStreamInput &)
	MStreamBuf::ReadL(MStreamInput &,TInt)
	MStreamBuf::ReadL(MStreamInput &,TStreamTransfer)
	MStreamBuf::ReadL(TAny *,TInt)
	MStreamBuf::ReadL(TDes8 &,TInt,TRequestStatus &)
	MStreamBuf::ReadL(TDes8 &,TRequestStatus &)
	MStreamBuf::Release()
	MStreamBuf::SeekL(TMark,TStreamLocation,TInt)
	MStreamBuf::SeekL(TMark,TStreamPos)
	MStreamBuf::SeekL(TRead,TInt)
	MStreamBuf::SeekL(TRead,TStreamLocation,TInt)
	MStreamBuf::SeekL(TWrite,TInt)
	MStreamBuf::SeekL(TWrite,TStreamLocation,TInt)
	MStreamBuf::SizeL()const
	MStreamBuf::Synch()
	MStreamBuf::SynchL()
	MStreamBuf::TellL(TRead)const
	MStreamBuf::TellL(TWrite)const
	MStreamBuf::Write(const TDesC8 &,TInt,TRequestStatus &)
	MStreamBuf::Write(const TDesC8 &,TRequestStatus &)
	MStreamBuf::WriteL(MStreamOutput &)
	MStreamBuf::WriteL(MStreamOutput &,TInt)
	MStreamBuf::WriteL(MStreamOutput &,TStreamTransfer)
	MStreamBuf::WriteL(const TAny *,TInt)
	MStreamBuf::WriteL(const TDesC8 &,TInt,TRequestStatus &)
	MStreamBuf::WriteL(const TDesC8 &,TRequestStatus &)

Inherited Type Definitions
	MStreamBuf::TMark

Detailed Description

Interface to a stream filter.

A stream filter is an object that allows stream data to be filtered after retrieval from a host or filtered before being written to a host.

The class is abstract and a derived class must be defined an implemented.

Member Enumeration Documentation

Enum anonymous

Enumerator	Value	Description
EAttached	0x10

Constructor & Destructor Documentation

TStreamFilter ( )

IMPORT_C

TStreamFilter

(

)

[protected]

Constructs an empty stream filter object.

Member Function Documentation

Committed ( )

void

Committed

(

)

[protected, inline]

Flags the streamed data as committed.

DoReadL ( TAny *, TInt )

IMPORT_C TInt	DoReadL	(	TAny *	aPtr,
			TInt	aMaxLength
		)	[protected, virtual]

Reimplemented from MStreamBuf::DoReadL(TAny *,TInt)

Reads data from the host stream through the filter into the specified memory location.

In debug mode: the filter must be in read mode, otherwise the function raises a STORE-Stream 10 panic.

In debug mode, a host stream must have been set before calling this function, otherwise it raises a STORE-Stream 0 panic.

Parameters
aPtr	A pointer to the target memory location for the filtered data.
aMaxLength	The maximum number of bytes to be read. In debug mode: if this value is negative then the function raises a STORE-Stream 1 panic; if this value is zero, then the function raises a STORE-Stream 3 panic.

Return Value: The number of bytes read.

DoRelease ( )

IMPORT_C void

DoRelease

(

)

[protected, virtual]

Reimplemented from MStreamBuf::DoRelease()

Frees the host stream's resources.

DoSynchL ( )

IMPORT_C void

DoSynchL

(

)

[protected, virtual]

Reimplemented from MStreamBuf::DoSynchL()

Synchronizes the host's intermediate buffer with its stream, leaving if any error occurs.

DoWriteL ( const TAny *, TInt )

IMPORT_C void	DoWriteL	(	const TAny *	aPtr,
			TInt	aLength
		)	[protected, virtual]

Reimplemented from MStreamBuf::DoWriteL(const TAny *,TInt)

Writes data to the host stream through the filter from the specified memory location.

In debug mode: the filter must be in write mode, otherwise the function raises a STORE-Stream 11 panic.

In debug mode, a host stream must have been set before calling this function, otherwise it raises a STORE-Stream 0 panic.

Parameters
aPtr	A pointer to the source memory location.
aLength	The number of bytes to be written. In debug mode: if this value is negative then the function raises a STORE-Stream 1 panic; if this value is zero, then the function raises a STORE-Stream 7 panic.

EmitL ( const TAny *, TInt )

IMPORT_C void	EmitL	(	const TAny *	aPtr,
			TInt	aLength
		)	[protected]

Writes data from the specified memory location directly to the host without filtering.

This is useful for sending any final data, when flushing the filter as part of DoSynchL().

In debug mode: the filter must be in write mode, otherwise the function raises a STORE-Stream 11 panic.

In debug mode, a host stream must have been set before calling this function, otherwise it raises a STORE-Stream 0 panic.

Parameters
aPtr	A pointer to the memory location from which data is to be written to the host stream.
aLength	The number of bytes to be written.

IsCommitted ( )

TBool

IsCommitted

(

)

const [protected, inline]

Tests whether the streamed data is committed.

Return Value: True, if streamed data is committed; false, otherwise.

Set ( MStreamBuf *, TInt )

void	Set	(	MStreamBuf *	aHost,
			TInt	aMode
		)	[protected, inline]

Sets up the filter to use the specified host for streamed data.

Taking ownership of the host stream buffer means that calls to SynchL() propagate to the host buffer after the filter has flushed its data, and that when the filter is released it also releases the host buffer.

Parameters
aHost	The host for the streamed data - a stream buffer.
aMode	The mode in which the stream buffer is to be used. It can be used in either read or write modes, represented by ERead and EWrite, but not both at the same time. In debug mode, setting both raises a STORE-Stream 18 panic. In addition, specify EAttached to indicate that the filter should take ownership of the host stream buffer.