ICreateDevEnum::CreateClassEnumerator method (strmif.h)

12/05/2018
2 minutes to read

The CreateClassEnumerator method creates an enumerator for a specified device category.

Syntax

HRESULT CreateClassEnumerator(
  REFCLSID     clsidDeviceClass,
  IEnumMoniker **ppEnumMoniker,
  DWORD        dwFlags
);

Parameters

clsidDeviceClass

Specifies the class identifier (CLSID) of the device category. See Filter Categories.

ppEnumMoniker

Receives a pointer to the IEnumMoniker interface. The caller must release the interface.

dwFlags

Bitwise combination of zero or more flags. If zero, the method enumerates every filter in the category. If any flags are set, the enumeration includes only filters that match the specified flags. The following flags are defined:

Flag	Description
CDEF_DEVMON_CMGR_DEVICE	Enumerate audio or video codecs, using the audio compression manager (ACM) or video compression manager (VCM).
CDEF_DEVMON_DMO	Enumerate DirectX Media Objects (DMOs).
CDEF_DEVMON_FILTER	Enumerate native DirectShow filters.
CDEF_DEVMON_PNP_DEVICE	Enumerate Plug and Play hardware devices.

Return value

Returns one of the following HRESULT values.

Return code	Description
S_OK	Success.
E_OUTOFMEMORY	Out of memory.
S_FALSE	The category specified by clsidDeviceClass does not exist or is empty.
E_POINTER	NULL pointer argument.

Remarks

If the category does not exist or is empty, the return value is S_FALSE, and the ppEnumMoniker parameter receives the value NULL. Therefore, test for the return value S_OK instead of using the SUCCEEDED macro:

C++
IEnumMoniker *pEnum = NULL; hr = pSysDevEnum->CreateClassEnumerator( CLSID_VideoCompressorCategory, &pEnum, 0); if (hr == S_OK) { // Safe to dereference pEnum. pEnum->Release(); }

Use the IEnumMoniker interface to enumerate monikers that represent the filters in the device category. Monikers support the IMoniker interface. The monikers created by CreateClassEnumerator also support the IGetCapabilitiesKey interface.

Requirements


Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	strmif.h (include Dshow.h)
Library	Strmiids.lib