IWiaMiniDrv::drvGetCapabilities method (wiamindr_lh.h)

Article
07/21/2022

The IWiaMiniDrv::drvGetCapabilities method returns an array of events and commands that a device supports.

Syntax

HRESULT drvGetCapabilities(
  BYTE            *__MIDL__IWiaMiniDrv0048,
  LONG            __MIDL__IWiaMiniDrv0049,
  LONG            *__MIDL__IWiaMiniDrv0050,
  WIA_DEV_CAP_DRV **__MIDL__IWiaMiniDrv0051,
  LONG            *__MIDL__IWiaMiniDrv0052
);

Parameters

__MIDL__IWiaMiniDrv0048

lFlags [in]

Specifies whether the array pointed to by ppCapabilites consists of commands, or events, or both. This parameter can be either of the following flags or of both of them combined by an OR operator.

Flag	Description
WIA_DEVICE_COMMANDS	The array consists of device commands.
WIA_DEVICE_EVENTS	The array consists of device events.

__MIDL__IWiaMiniDrv0049

pWiasContext [in]

Pointer to a WIA item context.

__MIDL__IWiaMiniDrv0050

pcelt [out]

Points to a memory location that will receive the number of elements in the array pointed to by the ppCapabilities parameter.

__MIDL__IWiaMiniDrv0051

plDevErrVal [out]

Points to a memory location that will receive a status code for this method. If this method returns S_OK, the value stored will be zero. Otherwise, a minidriver-specific error code will be stored at the location pointed to by this parameter.

__MIDL__IWiaMiniDrv0052

ppCapabilities [out, optional]

Points to a memory location that will receive the address of the first element of an array of WIA_DEV_CAP_DRV structures that contain the GUIDs of events and commands that the device supports.

Return value

On success, the method should return S_OK and clear the device error value pointed to by plDevErrVal. If the method fails, it should return a standard COM error code and place a minidriver-specific error code value in the memory pointed to by plDevErrVal.

The value pointed to by plDevErrVal can be converted to a string by calling IWiaMiniDrv::drvGetDeviceErrorStr.

Remarks

The WIA service calls the minidriver method IWiaMiniDrv::drvGetCapabilities to obtain a list of hardware command capabilities and/or device events. In response to this call, a minidriver sets ppCapabilities with the address of an array of pointers to GUID data. Each GUID corresponds to an event notification or a device command supported by the imaging device. When the lFlags parameter is set to WIA_DEVICE_COMMANDS, the array of GUIDs contains device commands. When lFlags is set to WIA_DEVICE_EVENTS, the array of GUIDs contains events. If lFlags is set to WIA_DEVICE_COMMANDS | WIA_DEVICE_EVENTS, the array of GUIDs contains both events and commands, listed in that order.

The Wiadef.h header lists several predefined commands and events.

Requirements

Requirement	Value
Target Platform	Desktop
Header	wiamindr_lh.h (include Wiamindr.h)