Exemple : Application utilisant un filtre de segmentation

L’exemple de code suivant montre comment une application simple peut utiliser le filtre de segmentation. Pour plus de clarté, le code de vérification des erreurs a été omis, ainsi que le code pour libérer et libérer les pointeurs d’interface et la mémoire.

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);