Class TBufBuf

TBufBuf

Support

Supported from 5.0

Description

A stream buffer that uses a dynamic buffer for its implementation.

A stream of this type is used by RBufWriteStream and RBufReadStream objects. It also has intermediate buffering capabilities.

This is a seekable stream buffer.

There are three write modes:

• insert mode - inserts new data into the buffer at the offset passed to Set()

• overwrite mode - replaces the data in the buffer starting at the offset passed to Set(). Once the end of the buffer is reached, it is automatically extended as more data is written. This is the default mode.

• truncate mode - truncates the buffer to the offset passed to Set() before data is written, extending the buffer. When writing, the buffer size as reported by CBufBase::Size() may be larger than the data written to the stream. To synchronise the buffer's reported size with the stream, call the MStreamBuf::SynchL() function.

Note that this object never takes ownership of the dynamic buffer, the CBufBase type object.

Derivation

MStreamBuf A stream buffer that provides a generic I/O interface for streamed data TBufBuf A stream buffer that uses a dynamic buffer for its implementation TStreamBuf Adds buffering capabilities to a stream buffer

Defined in TBufBuf:
(Anonymous), EInsert, ETruncate, Set(), TBufBuf()

Inherited from MStreamBuf:
SeekL(), Close(), DoRelease(), DoSeekL(), DoSynchL(), ERead, EWrite, PushL(), Read(), ReadL(), Release(), SeekL(), SizeL(), Synch(), SynchL(), TMark, TRead, TWrite, TellL(), Write(), WriteL()

Inherited from TStreamBuf:
Avail(), DoReadL(), DoWriteL(), End(), OverflowL(), Ptr(), SetBuf(), SetEnd(), SetPtr(), TArea, UnderflowL()

See also:

• RBufWriteStream
• RBufReadStream
• CBufBase::Size()
• MStreamBuf::SynchL()

TBufBuf();

Description

Constructs an empty object.

Call Set() before using the object.

void Set(CBufBase& aBuf,TInt aPos,TInt aMode=ERead|EWrite);

Description

Sets up the stream to use the specified dynamic buffer.

Parameters

CBufBase& aBuf The dynamic buffer that hosts the stream and that also acts as the intermediate buffer. TInt aPos The offset within the dynamic buffer where the stream starts. TInt aMode The mode in which the stream is to be used. It can be used in either or both read and write modes, represented by ERead and EWrite. In addition, specify TBufBuf::EInsert to imply insert mode; specify TBufBuf::ETruncate to imply truncate mode. If neither TBufBuf::EInsert nor TBufBuf::ETruncate are specified, then overwrite mode is implied. Both TBufBuf::EInsert and TBufBuf::ETruncate imply EWrite.

See also:

• CBufBase
• MStreamBuf::TRead
• MStreamBuf::TWrite

n/a

Description

Defines the insert and truncate mode bit values used by the mode parameter in Set().

ETruncate Write mode is truncate. EInsert Write mode is insert.