Mapping for a legacy application and Windows Vista driver

Important

This article contains information that applies to obsolete Windows operating systems.

This section explains how Windows Vista transfer messages and data flow are mapped to legacy transfer messages and data flow when a legacy application needs to work with a Windows Vista driver.

Callback Transfers

This table shows the mapping of a Windows Vista driver's callback transfer messages to the message sent to a legacy application.

Windows Vista driver message	Legacy application message (after compatibility layer conversion)
WIA_TRANSFER_MSG_STATUS	IT_MSG_STATUS
WIA_TRANSFER_MSG_ERROR	Ignored.
WIA_TRANSFER_MSG_END_OF_STREAM	Ignored. This message always goes along with a call to IWiaTransferCallback::GetNextStream. To avoid duplicate messages, this message is implemented in the GetNextStream implementation instead.
WIA_TRANSFER_MSG_END_OF_TRANSFER	IT_MSG_TERMINATION (WIA_TRANSFER_MSG_END_OF_TRANSFER is not sent by the driver).
WIA_TRANSFER_MSG_DEVICE_STATUS	If hrErrorStatus == WIA_STATUS_WARMING_UP, the compatibility layer sends IT_MSG_STATUS with IT_STATUS_TRANSFER_FROM_DEVICE in order to provide some status to an application as well as giving a Windows Vista application the possibility to cancel the transfer.
WIA_TRANSFER_MSG_NEW_PAGE	Ignored. Should never be sent by a Windows Vista driver in this case, since we call into the Windows Vista driver with TYMED_FILE.
IWiaTransferCallback::GetNextStream	First page: IT_MSG_DATA_HEADER Subsequent pages: IT_MSG_NEW_PAGE
IStream::Write	IT_MSG_DATA

File Transfers

This table shows the mapping of a Windows Vista driver's file transfer messages to the message sent to a legacy application.

Windows Vista driver message	Legacy application message (after compatibility layer conversion)
WIA_TRANSFER_MSG_STATUS	IT_MSG_STATUS
WIA_TRANSFER_MSG_ERROR	Ignored.
WIA_TRANSFER_MSG_END_OF_STREAM	Ignored. This message always goes along with a call to IWiaTransferCallback::GetNextStream. To avoid duplicate messages, this message is implemented in the GetNextStream implementation instead.
WIA_TRANSFER_MSG_END_OF_TRANSFER	IT_MSG_TERMINATION (WIA_TRANSFER_MSG_END_OF_TRANSFER is not sent by the driver).
WIA_TRANSFER_MSG_DEVICE_STATUS	If hrErrorStatus == WIA_STATUS_WARMING_UP, IT_MSG_STATUS is sent with IT_STATUS_TRANSFER_FROM_DEVICE in order to provide some status to an application as well as giving a Windows Vista application the possibility to cancel the transfer.
WIA_TRANSFER_MSG_NEW_PAGE	This behavior is somewhat different from a multi-page file transfer today because wiasWritePageBufToFile never sends IT_MSG_NEW_PAGE.
IWiaTransferCallback::GetNextStream	First page: IT_MSG_FILE_PREVIEW_DATA_HEADER Subsequent pages: Error (the WIA_ERROR_GENERAL_ERROR is passed back to driver). IWiaTransferCallback::GetNextStream should only be called once because you can only transfer one page with TYMED_FILE and during a TYMED_MULTIPAGE_FILE transfer, the Windows Vista driver should only call GetNextStream once because all the pages should go into the same stream.
IStream::Write	No message sent. In case of file transfers, the compatibility layer does not convert any of the data that the driver (image processing filter) writes into legacy transfer messages. Rather, the data is simply written into a file that is returned to the user at the end of the transfer.

For more information on the legacy transfer messages see the IWiaMiniDrvCallBack Interface.

For more information on the TYMED constants, see Understanding TYMED.