# 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

IDataObject::EnumFormatEtc, IEnumFORMATETC