Providing a COM Interface

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A WIA minidriver must support the IWiaMiniDrv, IStiUSD, and IUnknown interfaces to be recognized and loaded by the WIA service. The following interface identifiers should be added to the WIA driver's QueryInterface method:

  • IID_IWiaMiniDrv - the interface identifier for the IWiaMiniDrv interface, a standard WIA interface used to access WIA-specific functionality.

  • IID_IStiUSD - the interface identifier for the IStiUSD interface, a standard STI interface used to access the STI functionality of the WIA driver

  • IID_IUnknown - the interface identifier for the IUnknown interface, a standard COM interface defined in the Microsoft Windows SDK documentation.

The minidriver exports these interface identifiers in response to the WIA service calling the minidriver's QueryInterface method.

For examples of how these interfaces are implemented, see the wiascanr scanner sample minidriver files wiascanr.h, iwiaminidrv.cpp and istiusd.cpp or see the wiacam camera sample minidriver files IWiaMiniDrv.cpp and IStiUSD.cpp.