wiasGetImageInformation function (wiamdef.h)

The wiasGetImageInformation function retrieves transfer context information from an item.

Syntax

HRESULT wiasGetImageInformation(
  [in]      BYTE                      *pWiasContext,
            LONG                      lFlags,
  [in, out] PMINIDRV_TRANSFER_CONTEXT pmdtc
);

Parameters

[in] pWiasContext

Pointer to a WIA item context.

lFlags

Specifies operational flags. Currently, only the following flag is defined:

[in, out] pmdtc

Pointer to a MINIDRV_TRANSFER_CONTEXT structure. Upon return, this structure contains the requested image item information.

Return value

On success, the function returns S_OK.

If the function fails, it returns a standard COM error or one of the WIA error codes.

Remarks

This function uses a MINIDRV_TRANSFER_CONTEXT structure to calculate item image and item header sizes. In addition, it can optionally fill in an image header if the image format requires a data header. The header will be copied to the buffer if the pTransferBuffer member of the MINIDRV_TRANSFER_CONTEXT structure is not NULL. When using image formats (such as JPEG) that do not have a header, the header size in the lHeaderSize member of the MINIDRV_TRANSFER_CONTEXT structure is reported as zero.

For image formats where the actual final size of the image is not known until after data acquisition, as with multipage TIFF and compressed formats, the lItemSize member of the MINIDRV_TRANSFER_CONTEXT structure is reported as zero. The lImageSize member is reported as the size, in bytes, of the uncompressed image in a single page.

If WIAS_INIT_CONTEXT is specified in the lFlags parameter, the MINIDRV_TRANSFER_CONTEXT structure pointed to by the pmdtc parameter is filled in with information derived from the item's image properties. This flag should be used when a minidriver has allocated a new context.

Requirements

See also

MINIDRV_TRANSFER_CONTEXT