COleStreamFile Class
Represents a stream of data (IStream) in a compound file as part of OLE Structured Storage.
Syntax
class COleStreamFile : public CFile
Members
Public Constructors
| Name | Description |
|---|---|
| COleStreamFile::COleStreamFile | Constructs a COleStreamFile object. |
Public Methods
| Name | Description |
|---|---|
| COleStreamFile::Attach | Associates a stream with the object. |
| COleStreamFile::CreateMemoryStream | Creates a stream from global memory and associates it with the object. |
| COleStreamFile::CreateStream | Creates a stream and associates it with the object. |
| COleStreamFile::Detach | Disassociates the stream from the object. |
| COleStreamFile::GetStream | Returns the current stream. |
| COleStreamFile::OpenStream | Safely opens a stream and associates it with the object. |
Remarks
An IStorage object must exist before the stream can be opened or created unless it is a memory stream.
COleStreamFile objects are manipulated exactly like CFile objects.
For more information about manipulating streams and storages, see the article Containers: Compound Files..
For more information, see IStream and IStorage in the Windows SDK.
Inheritance Hierarchy
COleStreamFile
Requirements
Header: afxole.h
COleStreamFile::Attach
Associates the supplied OLE stream with the COleStreamFile object.
void Attach(LPSTREAM lpStream);
Parameters
lpStream
Points to the OLE stream (IStream) to be associated with the object. Cannot be NULL.
Remarks
The object must not already be associated with an OLE stream.
For more information, see IStream in the Windows SDK.
COleStreamFile::COleStreamFile
Creates a COleStreamFile object.
COleStreamFile(LPSTREAM lpStream = NULL);
Parameters
lpStream
Pointer to the OLE stream to be associated with the object.
Remarks
If lpStream is NULL, the object is not associated with an OLE stream, otherwise, the object is associated with the supplied OLE stream.
For more information, see IStream in the Windows SDK.
COleStreamFile::CreateMemoryStream
Safely creates a new stream out of global, shared memory where a failure is a normal, expected condition.
BOOL CreateMemoryStream(CFileException* pError = NULL);
Parameters
pError
Points to a CFileException object or NULL that indicates the completion status of the create operation. Supply this parameter if you want to monitor possible exceptions generated by attempting to create the stream.
Return Value
Nonzero if the stream is created successfully; otherwise 0.
Remarks
The memory is allocated by the OLE subsystem.
For more information, see CreateStreamOnHGlobal in the Windows SDK.
COleStreamFile::CreateStream
Safely creates a new stream in the supplied storage object where a failure is a normal, expected condition.
BOOL CreateStream(
LPSTORAGE lpStorage,
LPCTSTR lpszStreamName,
DWORD nOpenFlags = modeReadWrite|shareExclusive|modeCreate,
CFileException* pError = NULL);
Parameters
lpStorage
Points to the OLE storage object that contains the stream to be created. Cannot be NULL.
lpszStreamName
Name of the stream to be created. Cannot be NULL.
nOpenFlags
Access mode to use when opening the stream. Exclusive, read/write, and create modes are used by default. For a complete list of the available modes, see CFile::CFile.
pError
Points to a CFileException object or NULL. Supply this parameter if you want to monitor possible exceptions generated by attempting to create the stream.
Return Value
Nonzero if the stream is created successfully; otherwise 0.
Remarks
A file exception will be thrown if the open fails and pError is not NULL.
For more information, see IStorage::CreateStream in the Windows SDK.
COleStreamFile::Detach
Disassociates the stream from the object without closing the stream.
LPSTREAM Detach();
Return Value
A pointer to the stream (IStream) that was associated with the object.
Remarks
The stream must be closed in some other fashion before the program terminates.
For more information, see IStream in the Windows SDK.
COleStreamFile::GetStream
Call this function to return a pointer to current stream.
IStream* GetStream() const;
Return Value
A pointer to the current stream interface ( IStream).
COleStreamFile::OpenStream
Opens an existing stream.
BOOL OpenStream(
LPSTORAGE lpStorage,
LPCTSTR lpszStreamName,
DWORD nOpenFlags = modeReadWrite|shareExclusive,
CFileException* pError = NULL);
Parameters
lpStorage
Points to the OLE storage object that contains the stream to be opened. Cannot be NULL.
lpszStreamName
Name of the stream to be opened. Cannot be NULL.
nOpenFlags
Access mode to use when opening the stream. Exclusive and read/write modes are used by default. For the complete list of the available modes, see CFile::CFile.
pError
Points to a CFileException object or NULL. Supply this parameter if you want to monitor possible exceptions generated by attempting to open the stream.
Return Value
Nonzero if the stream is opened successfully; otherwise 0.
Remarks
A file exception will be thrown if the open fails and pError is not NULL.
For more information, see IStorage::OpenStream in the Windows SDK.