Ejemplo: Aplicación que usa un filtro de segmentación

En el ejemplo de código siguiente se muestra cómo una aplicación sencilla podría usar el filtro de segmentación. Para mayor claridad, se ha omitido el código de comprobación de errores, así como el código para liberar y liberar punteros de interfaz y memoria.

IWiaSegmentationFilter *pWiaSegmentationFilter = NULL;
IWiaTransferCallback *pMyWiaTransferCallback = NULL;
IWiaTransfer  *pWiaTransfer = NULL;

...

pWiaItem2->QueryInterface(IID_IWiaTransfer, (void**)&pWiaTransfer);

pMyWiaTransferCallback = new MyWiaTransferCallback();


//
// Do preview scan.
//    
pWiaTransfer->Download(lFlags, pMyWiaTransferCallback);

//
// If an application changes any properties in pWiaItem2, it
// should call IWiaPropertyStorage::GetPropertyStream on
// that item to save its property settings (so they can be
// restored) before calling IWiaSegmentationFilter::DetectRegions.
//

if (ReadPropertyLong(WIA_IPS_SEGMENTATION_FILTER, &lUseSegFilter) &&
    (lUseSegFilter == WIA_USE_SEGMENTATION_FILTER)
{
    bstrSegmentation = SysAllocStr(WIA_SEGMENTATION_FILTER_STR);

    pWiaItem2->GetExtension(bstrSegmentation,
                            IID_IWiaSegmentationFilter,
                           (void**)& pWiaSegmentationFilter);

//
// m_pInputStream is a pointer to the IStream that the application's
// implementation of MyWiaTransferCallback::GetNextStream
// returns.
//
// Note: If the application has changed any properties into
// pWiaItem2 since the call to Download, it must now restore
// these properties with IWiaPropertyStorage::SetPropertyStream.
//

//
// The application is responsible for resetting m_pInputStream
// before calling DetectRegions!
//
    LARGE_INTEGER  ul = {0};

    m_pInputStream->Seek(ul, STREAM_SEEK_SET, NULL);

    pWiaSegmentationFilter->DetectRegions(m_pInputStream,
                                          pWiaItem2);

   ...
}

//
// Display the subregions to the users (if segmentation was
// supported) and let them pick the images they want to scan,
// as well as change the properties in the child items

//
// For each child item, pChildItem, do the following ( alternatively,
// do a folder acquisition on pWiaItem2).
//
IWiaTransfer  *pWiaTransferChild= NULL;

pChildItem->QueryInterface(IID_IWiaTransfer,
                           (void**)& pWiaTransferChild);

pWiaTransferChild->Download(lFlags, pMyWiaTransferCallback);