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IWiaMiniDrvCallBack::MiniDrvCallback method (wiamindr_lh.h)

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The MiniDrvCallback method provides a callback method for WIA minidrivers to use during a callback data transfer.

Syntax

HRESULT MiniDrvCallback(
  [in] LONG                      lReason,
  [in] LONG                      lStatus,
  [in] LONG                      lPercentComplete,
  [in] LONG                      lOffset,
  [in] LONG                      lLength,
  [in] PMINIDRV_TRANSFER_CONTEXT pTranCtx,
  [in] LONG                      lReserved
);

Parameters

[in] lReason

Specifies a constant value that designates a callback status message. This value is used to determine the purpose of the callback, and can be one of the following values:

Message Definition
IT_MSG_DATA Indicates that the transfer buffer contains a block of data.
IT_MSG_DATA_HEADER Received before any data transfers. Indicates that the transfer buffer points to a WIA_DATA_CALLBACK_HEADER structure that defines elements of the data transfer.
IT_MSG_DEVICE_STATUS Callback contains only status information about the device.
IT_MSG_FILE_PREVIEW_DATA Indicates preview data is being transferred to the application.
IT_MSG_FILE_PREVIEW_DATA_HEADER Indicates a header is being transferred to the application, prior to the preview data being transferred.
IT_MSG_NEW_PAGE Indicates that the data transfer of a page is complete, and a new page is being sent.
IT_MSG_STATUS Callback contains only status information about the transfer.
IT_MSG_TERMINATION Indicates that the data transfer is complete.

[in] lStatus

Specifies the status of the transfer. This parameter is a bitwise OR of the following values:

Status Definition
IT_STATUS_TRANSFER_FROM_DEVICE Transferring data from device.
IT_STATUS_PROCESSING_DATA Device and/or minidriver are processing the data.
IT_STATUS_TRANSFER_TO_CLIENT Transferring data from the minidriver to the WIA service.

[in] lPercentComplete

Specifies the current percentage of data transferred.

[in] lOffset

Specifies the current offset (in bytes) into the transfer buffer from the beginning of the buffer.

[in] lLength

Specifies the number of bytes contained in the transfer.

[in] pTranCtx

Points to a MINIDRV_TRANSFER_CONTEXT structure containing the data transfer values.

[in] lReserved

Reserved. Set to zero.

Return value

If the method succeeds, it returns S_OK. If the callback is canceled by the client application, the method returns S_FALSE. If the method fails, it returns a standard COM error code.

Remarks

The percent complete values are sent directly from the driver. The WIA service does not adjust the values.

IT_MSG_FILE_PREVIEW_DATA_HEADER is for out-of-band-data. This allows the application doing a file transfer to display the banded data. This is useful for scroll-fed scanners that have an unknown length and no preview scan. The information reported in this message should be treated the same as IT_MSG_DATA_HEADER. If a driver supports this message, it can supply preview data during its file transfer.

Requirements

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

See also

IWiaMiniDrvCallBack

MINIDRV_TRANSFER_CONTEXT