IWiaMiniDrv::drvGetWiaFormatInfo method (wiamindr_lh.h)

Article
07/21/2022

The IWiaMiniDrv::drvGetWiaFormatInfo method finds the image formats and media types that the WIA hardware device supports.

Syntax

HRESULT drvGetWiaFormatInfo(
  BYTE            *__MIDL__IWiaMiniDrv0059,
  LONG            __MIDL__IWiaMiniDrv0060,
  LONG            *__MIDL__IWiaMiniDrv0061,
  WIA_FORMAT_INFO **__MIDL__IWiaMiniDrv0062,
  LONG            *__MIDL__IWiaMiniDrv0063
);

Parameters

__MIDL__IWiaMiniDrv0059

lFlags [in]

Reserved.

__MIDL__IWiaMiniDrv0060

pWiasContext [in]

Pointer to a WIA item context.

__MIDL__IWiaMiniDrv0061

pcelt [out]

Points to a memory location that will receive the number of items in the array pointed to by ppwfi.

__MIDL__IWiaMiniDrv0062

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__IWiaMiniDrv0063

ppwfi [out, optional]

Points to a memory location that will receive the address of the first element of an array of WIA_FORMAT_INFO structures.

Return value

On success, the method should return S_OK and clear the device error value pointed to by plDevErrVal. If this method is called for items that do not contain any data, it should return E_INVALIDARG. 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

This method creates an array of WIA_FORMAT_INFO structures that describe the media types and image formats that the WIA hardware device supports. For each element in the array, the media type can be one of TYMED_CALLBACK, TYMED_MULTIPAGE_CALLBACK, TYMED_FILE, or TYMED_MULTIPAGE_FILE. Typical values for the image format include WiaImgFmt_JPEG, and WiaImgFmt_BMP, among others. For more information, see Understanding TYMED and WIA_IPA_FILENAME_EXTENSION.

The minidriver can define a global array to hold the WIA_FORMAT_INFO structures, or it can allocate memory for the array. The WIA service will not free the allocated memory, so the minidriver should store a pointer to that memory in the driver item context. The minidriver can then free this memory in a call to IWiaMiniDrv::drvFreeDrvItemContext.

Requirements

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