IWiaDataTransfer::idtGetBandedData method (wia_xp.h)
The IWiaDataTransfer::idtGetBandedData method transfers a band of data from a hardware device to an application. For efficiency, applications retrieve data from Windows Image Acquisition (WIA) hardware devices in successive bands.
HRESULT idtGetBandedData( [in] PWIA_DATA_TRANSFER_INFO pWiaDataTransInfo, [in] IWiaDataCallback *pIWiaDataCallback );
Pointer to the WIA_DATA_TRANSFER_INFO structure.
This method can return any one of the following values:
|E_INVALIDARG||One or more parameters to this method contain invalid data.|
|E_OUTOFMEMORY||This method cannot allocate enough memory to complete its operation.|
|E_UNEXPECTED||An unknown error occurred.|
|S_FALSE||The application canceled the operation.|
|S_OK||The image was successfully acquired.|
|STG_E_MEDIUMFULL||The storage medium the application is using to acquire the image is full.|
|WIA_S_NO_DEVICE_AVAILABLE||There are no WIA hardware devices attached to the user's computer.|
This method will return a value specified in Error Codes, or a standard COM error if it fails for any reason other than those specified in the preceding table.
The IWiaDataTransfer::idtGetBandedData method allocates a section of memory to transfer data without requiring an extra data copy through the Component Object Model/Remote Procedure Call (COM/RPC) marshalling layer. This memory section is shared between the application and the hardware device's item tree.
Optionally, the application can pass in a pointer to a block of memory that IWiaDataTransfer::idtGetBandedData will use as its shared section. The application passes this handle by storing the pointer in the ulSection member of the WIA_DATA_TRANSFER_INFO structure prior to calling IWiaDataTransfer::idtGetBandedData.
Applications can improve performance by using double buffering. To do this, applications must set the bDoubleBuffer member of the WIA_DATA_TRANSFER_INFO structure to TRUE. The IWiaDataTransfer::idtGetBandedData method will divide the data buffer in half. When one half of the buffer is full, IWiaDataTransfer::idtGetBandedData will send a notification to the application using the IWiaDataCallback pointer passed in through the pIWiaDataCallback parameter. While the application is retrieving the data from the full half of the buffer, the device driver can fill the other half with data.
The format of the data transfer is determined by the values of the item's WIA_IPA_FORMAT and WIA_IPA_TYMED properties. The application sets these properties with calls to the IWiaPropertyStorage::WriteMultiple method.
|Minimum supported client||Windows 2000 Professional, Windows XP [desktop apps only]|
|Minimum supported server||Windows Server 2003 [desktop apps only]|
|Header||wia_xp.h (include Wia.h)|