IVdsSubSystem::QueryControllers method (vdshwprv.h)
Returns an object that enumerates the online and offline controllers managed by the subsystem.
HRESULT QueryControllers( [out] IEnumVdsObject **ppEnum );
The address of an IEnumVdsObject interface pointer that can be used to enumerate the controllers in the subsystem as controller objects. For more information, see Working with Enumeration Objects. Callers must release the interface and each of the controller objects when they are no longer needed by calling the IUnknown::Release method.
This method can return standard HRESULT values, such as E_INVALIDARG or E_OUTOFMEMORY, and VDS-specific return values. It can also return converted system error codes using the HRESULT_FROM_WIN32 macro. Errors can originate from VDS itself or from the underlying VDS provider that is being used. Possible return values include the following.
||Returns the enumeration of controllers. If the subsystem has no controllers, the enumeration is empty.|
||This return value signals a software or communication problem inside a provider that caches information about the array. Use the IVdsHwProvider::Reenumerate method followed by the IVdsHwProvider::Refresh method to restore the cache.|
||The subsystem object is no longer present.|
||The subsystem is in a failed state and is unable to perform the requested operation.|
||Another operation is in progress; this operation cannot proceed until the previous operation or operations are complete.|
Use the QueryControllers method to get the number of controllers, and then count the controllers in the returned enumeration.
If the subsystem has no controllers, this method returns an empty enumeration object.
|Minimum supported client||Windows Vista [desktop apps only]|
|Minimum supported server||Windows Server 2003 [desktop apps only]|