Pergunta
I'm new to WIA. I somehow managed to get a device listing, select my device and enumerate this device for an image item. But now, when I try to transfer an image, I'm stuck. If I use the root item for data transfer pWiaDataTransfer->idtGetData
returns a HRESULT of 0x8000FFFF (E_UNEXPECTED), if I use the image item (there are only two items 'root' and 'top' on my device) it fails when I obtain the storage interface. I thought maybe I needed to obtain the storage interface from 'root' and the data transfer interface from 'top' but that also fails (when I try to obtain the data transfer interface). I then get 0x80004002 (E_NOINTERFACE - No such interface supported.). Here is the code:
HRESULT TransferWiaItem( IWiaItem *pWiaItem, IWiaItem *pWiaItem2 )
{
IWiaPropertyStorage *pWiaPropertyStorage = NULL;
HRESULT hr = pWiaItem->QueryInterface( IID_IWiaPropertyStorage, (void**)&pWiaPropertyStorage );
if( SUCCEEDED( hr ) )
{
PROPSPEC PropSpec[2] = {0};
PROPVARIANT PropVariant[2] = {0};
const ULONG c_nPropCount = sizeof(PropVariant)/sizeof(PropVariant[0]);
GUID guidOutputFormat = WiaImgFmt_BMP;
PropSpec[0].ulKind = PRSPEC_PROPID;
PropSpec[0].propid = WIA_IPA_FORMAT;
PropSpec[1].ulKind = PRSPEC_PROPID;
PropSpec[1].propid = WIA_IPA_TYMED;
PropVariant[0].vt = VT_CLSID;
PropVariant[0].puuid = &guidOutputFormat;
PropVariant[1].vt = VT_I4;
PropVariant[1].lVal = TYMED_FILE;
hr = pWiaPropertyStorage->WriteMultiple( c_nPropCount, PropSpec, PropVariant, WIA_IPA_FIRST );
if( SUCCEEDED( hr ) )
{
IWiaDataTransfer *pWiaDataTransfer = NULL;
hr = pWiaItem2->QueryInterface( IID_IWiaDataTransfer, (void**)&pWiaDataTransfer );
if( SUCCEEDED( hr ) )
{
CWiaDataCallback *pCallback = new CWiaDataCallback;
if( pCallback )
{
IWiaDataCallback *pWiaDataCallback = NULL;
hr = pCallback->QueryInterface( IID_IWiaDataCallback, (void**)&pWiaDataCallback );
if( SUCCEEDED( hr ) )
{
STGMEDIUM stgMedium = {0};
stgMedium.tymed = TYMED_FILE;
hr = pWiaDataTransfer->idtGetData( &stgMedium, pWiaDataCallback );
...
Where pWiaItem
is the 'root' item and pWiaItem2
is the 'top' item.
Anybody have a clue what is going on here?
Solução
The solution is to enumerate the items of the 'root' WiaItem
in the local context again. I did this in an init method and stored the pointer to the 'top', somehow it seemed so that it got invalidated and the HRESULT did not reflect that. After I changed the code, so that the 'top' WiaItem
gets identified right before I use it, everything went fine.