OleRegEnumFormatEtc
Supplies a
pointer to an enumeration object that can be used to enumerate data formats
that an OLE object server has registered in the system registry. An object
application or object handler calls this function when it must enumerate those
formats. Developers of custom DLL object applications use this function to
emulate the behavior of the default object handler.
WINOLEAPI OleRegEnumFormatEtc(
|
REFCLSID clsid, |
//Class identifier |
|
DWORD dwDirection, |
//Value specifying data formats |
|
LPENUMFORMATETC * ppenumFormatetc |
//Indirect pointer to returned format information |
|
); |
|
Parameters
clsid
[in] CLSID of
the class whose formats are being requested.
dwDirection
[in] Whether
to enumerate formats that can be passed to IDataObject::GetData or formats that can be
passed to IDataObject::SetData. Valid values are taken from the enumeration DATADIR.
ppenumFormatetc
[out]
Indirect pointer to the IEnumFORMATETC interface on the new enumeration object.
Return Values
This function
supports the standard return value E_OUTOFMEMORY, as well as the following:
S_OK
The
enumerator was returned successfully.
REGDB_E_CLASSNOTREG
There is no
CLSID registered for the class object.
REGDB_E_READREGDB
There was an
error reading the registry.
OLE_E_REGDB_KEY
The
DataFormats/GetSet key is missing from the registry.
Remarks
Object
applications can ask OLE to create an enumeration object for FORMATETC
structures to enumerate supported data formats in one of two ways. One way is
to call OleRegEnumFormatEtc. The other is to return OLE_S_USEREG in
response to calls by the default object handler to IDataObject::EnumFormatEtc. OLE_S_USEREG instructs
the default handler to call OleRegEnumFormatEtc. Because DLL object
applications cannot return OLE_S_USEREG, they must call OleRegEnumFormatEtc
rather than delegating the job to the object handler. With the supplied IEnumFORMATETC pointer to the object, you
can call the standard enumeration object methods to do the enumeration.
The
OleRegEnumFormatEtc function and its sibling functions, OleRegGetUserType, OleRegGetMiscStatus, and OleRegEnumVerbs, provide a way for
developers of custom DLL object applications to emulate the behavior of OLE s
default object handler in getting information about objects from the registry.
By using these functions, you avoid the considerable work of writing your own,
and the pitfalls inherent in working directly in the registry. In addition, you
get future enhancements and optimizations of these functions without having to
code them yourself.
See Also