Windows Dev Center

ICreateDevEnum::CreateClassEnumerator method

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

Syntax


HRESULT CreateClassEnumerator(
  [in]  REFCLSID     clsidDeviceClass,
  [out] IEnumMoniker **ppEnumMoniker,
  [in]  DWORD        dwFlags
);

Parameters

clsidDeviceClass [in]

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

ppEnumMoniker [out]

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

dwFlags [in]

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_DEVICEEnumerate audio or video codecs, using the audio compression manager (ACM) or video compression manager (VCM).
CDEF_DEVMON_DMOEnumerate DirectX Media Objects (DMOs).
CDEF_DEVMON_FILTEREnumerate native DirectShow filters.
CDEF_DEVMON_PNP_DEVICEEnumerate Plug and Play hardware devices.

 

Return value

Returns one of the following HRESULT values.

Return codeDescription
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:



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]

Header

Strmif.h (include Dshow.h)

Library

Strmiids.lib

See also

Error and Success Codes
ICreateDevEnum Interface

 

 

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