OleConvertOLESTREAMToIStorage
Converts the
specified object from the OLE 1 storage model to an OLE 2 structured storage
object without specifying presentation data. This is one of several
compatibility functions.
WINOLEAPI OleConvertOLESTREAMToIStorage(
|
LPOLESTREAM lpolestream, |
//Pointer to the stream where the OLE 1 storage is
written |
|
IStorage *
pstg, |
//Pointer to OLE 2 storage object |
|
const DVTARGETDEVICE * ptd |
//Pointer to target device |
|
); |
|
Parameters
lpolestream
[in] Pointer
to a stream that contains the persistent representation of the object in the
OLE 1 storage format.
pstg
[out] Pointer
to the IStorage interface on the OLE 2 structured storage object.
ptd
[in] Pointer
to the DVTARGETDEVICE
structure specifying the target device for which the OLE 1 object is rendered.
Return Values
This function
supports the standard return value E_INVALIDARG, as well as the following:
S_OK
The object
was successfully converted.
CONVERT10_S_NO_PRESENTATION
The object
either has no presentation data or uses native data for its presentation.
DV_E_DVTARGETDEVICE
or DV_E_DVTARGETDEVICE_SIZE
Invalid value
for ptd.
Remarks
This function
converts an OLE 1 object to an OLE 2 structured storage object. You can use
this function to update OLE 1 objects to OLE 2 objects when a new version of
the object application supports OLE 2.
On entry, the
lpolestm parameter should be created and positioned just as it would be
for an OleLoadFromStream
function call. On exit, the lpolestm parameter is positioned just as it
would be on exit from an OleLoadFromStream function, and the pstg
parameter contains the uncommitted persistent representation of the OLE 2
storage object.
For OLE 1
objects that use native data for their presentation, the OleConvertOLESTREAMToIStorage
function returns CONVERT10_S_NO_PRESENTATION. On receiving this return value,
callers should call IOleObject::Update to get the presentation data so
it can be written to storage.
Applications
that do not use OLE s default caching resources, but do use the conversion
resources, can use an alternate function, OleConvertOLESTREAMToIStorageEx,
which can specify which presentation data to convert. In the OleConvertOLESTREAMToIStorageEx
function, the presentation data read from the OLESTREAM structure is
passed out and the newly created OLE 2 storage object does not contain a
presentation stream.
The following
steps describe the conversion process using OleConvertOLESTREAMToIStorage:
1. Create a root IStorage object by calling the StgCreateDocfile function(..., &pstg).
2. Open the OLE 1 file (using OpenFile or
another OLE 1 technique).
3. Using the OLE 1 procedure for reading files,
read from the file until an OLE object is encountered.
4. Allocate an IStorage object from the
root IStorage created in step 1:
pstg->lpVtbl->CreateStorage(...&pStgChild);
hRes = OleConvertIStorageToOLESTREAM(polestm,
pStgChild);
hRes = OleLoad(pStgChild, &IID_IOleObject,
pClientSite, ppvObj);
5. Repeat step 3 until the file is completely
read.
See Also