PWINBIO_IDENTIFY_CALLBACK callback function (winbio.h)
The PWINBIO_IDENTIFY_CALLBACK function is called by the Windows Biometric Framework to return results from the asynchronous WinBioIdentifyWithCallback function. The client application must implement this function.
- Implement a PWINBIO_ASYNC_COMPLETION_CALLBACK function to receive notice when the operation completes.
- Call the WinBioAsyncOpenSession function. Pass the address of your callback in the CallbackRoutine parameter. Pass WINBIO_ASYNC_NOTIFY_CALLBACK in the NotificationMethod parameter. Retrieve an asynchronous session handle.
- Use the asynchronous session handle to call WinBioIdentify. When the operation finishes, the Windows Biometric Framework will allocate and initialize a WINBIO_ASYNC_RESULT structure with the results and invoke your callback with a pointer to the results structure.
- Call WinBioFree from your callback implementation to release the WINBIO_ASYNC_RESULT structure after you have finished using it.
Syntax
PWINBIO_IDENTIFY_CALLBACK PwinbioIdentifyCallback;
void PwinbioIdentifyCallback(
[in, optional] PVOID IdentifyCallbackContext,
[in] HRESULT OperationStatus,
[in] WINBIO_UNIT_ID UnitId,
[in] WINBIO_IDENTITY *Identity,
[in] WINBIO_BIOMETRIC_SUBTYPE SubFactor,
[in] WINBIO_REJECT_DETAIL RejectDetail
)
{...}
Parameters
[in, optional] IdentifyCallbackContext
Pointer to a buffer defined by the application and passed to the IdentifyCallbackContext parameter of the WinBioIdentifyWithCallback function. The buffer is not modified by the framework or the biometric unit. Your application can use the data to help it determine what actions to perform or to maintain additional information about the biometric capture.
[in] OperationStatus
Error code returned by the capture operation.
[in] UnitId
Biometric unit ID number.
[in] Identity
A WINBIO_IDENTITY structure that receives the GUID or SID of the user providing the biometric sample.
[in] SubFactor
A WINBIO_BIOMETRIC_SUBTYPE value that receives the sub-factor associated with the biometric sample. See the Remarks section for more details.
[in] RejectDetail
Additional information about the failure, if any, to perform the operation. For more information, see Remarks.
Return value
None
Remarks
Currently, the Windows Biometric Framework supports only fingerprint readers. Therefore, if an operation fails and returns additional information in a WINBIO_REJECT_DETAIL constant, it will be one of the following values:
- WINBIO_FP_TOO_HIGH
- WINBIO_FP_TOO_LOW
- WINBIO_FP_TOO_LEFT
- WINBIO_FP_TOO_RIGHT
- WINBIO_FP_TOO_FAST
- WINBIO_FP_TOO_SLOW
- WINBIO_FP_POOR_QUALITY
- WINBIO_FP_TOO_SKEWED
- WINBIO_FP_TOO_SHORT
- WINBIO_FP_MERGE_FAILURE
Examples
The following code example calls WinBioIdentifyWithCallback to identify a user from a biometric scan. WinBioIdentifyWithCallback is an asynchronous function that configures the biometric subsystem to process biometric input on another thread. Output from the biometric subsystem is then sent to a custom callback function named IdentifyCallback. Link to the Winbio.lib static library and include the following header files:
- Windows.h
- Stdio.h
- Conio.h
- Winbio.h
HRESULT IdentifyWithCallback(BOOL bCancel)
{
// Declare variables.
HRESULT hr = S_OK;
WINBIO_SESSION_HANDLE sessionHandle = NULL;
// Connect to the system pool.
hr = WinBioOpenSession(
WINBIO_TYPE_FINGERPRINT, // Service provider
WINBIO_POOL_SYSTEM, // Pool type
WINBIO_FLAG_DEFAULT, // Configuration and access
NULL, // Array of biometric unit IDs
0, // Count of biometric unit IDs
WINBIO_DB_DEFAULT, // Database ID
&sessionHandle // [out] Session handle
);
if (FAILED(hr))
{
wprintf_s(L"\n WinBioOpenSession failed. hr = 0x%x\n", hr);
goto e_Exit;
}
// Call WinBioIdentifyWithCallback. The method is asynchronous
// and returns immediately.
wprintf_s(L"\n Calling WinBioIdentifyWithCallback");
wprintf_s(L"\n Swipe the sensor ...\n");
hr = WinBioIdentifyWithCallback(
sessionHandle, // Open biometric session
IdentifyCallback, // Callback function
NULL // Optional context
);
if (FAILED(hr))
{
wprintf_s(L"\n WinBioIdentifyWithCallback failed. hr = 0x%x\n", hr);
goto e_Exit;
}
// Cancel user identification if the bCancel flag is set.
if (bCancel)
{
wprintf_s(L"\n Starting CANCEL timer...\n");
Sleep( 7000 );
wprintf_s(L"\n Calling WinBioCancel\n");
hr = WinBioCancel( sessionHandle );
if (FAILED(hr))
{
wprintf_s(L"\n WinBioCancel failed. hr = 0x%x\n", hr);
goto e_Exit;
}
}
// Wait for the asynchronous identification process to complete
// or be canceled.
hr = WinBioWait( sessionHandle );
if (FAILED(hr))
{
wprintf_s(L"\n WinBioWait failed. hr = 0x%x\n", hr);
}
e_Exit:
if (sessionHandle != NULL)
{
wprintf_s(L"\n Closing the session.\n");
hr = WinBioCloseSession(sessionHandle);
if (FAILED(hr))
{
wprintf_s(L"\n WinBioCloseSession failed. hr = 0x%x\n", hr);
}
sessionHandle = NULL;
}
wprintf_s(L"\n Hit any key to exit...");
_getch();
return hr;
}
//------------------------------------------------------------------------
// The following function is the callback for WinBioIdentifyWithCallback.
// The function filters the response from the biometric subsystem and
// writes a result to the console window.
//
VOID CALLBACK IdentifyCallback(
__in_opt PVOID IdentifyCallbackContext,
__in HRESULT OperationStatus,
__in WINBIO_UNIT_ID UnitId,
__in WINBIO_IDENTITY *Identity,
__in WINBIO_BIOMETRIC_SUBTYPE SubFactor,
__in WINBIO_REJECT_DETAIL RejectDetail
)
{
UNREFERENCED_PARAMETER(IdentifyCallbackContext);
UNREFERENCED_PARAMETER(Identity);
wprintf_s(L"\n IdentifyCallback executing");
wprintf_s(L"\n Swipe processed for unit ID %d\n", UnitId);
// The attempt to process the fingerprint failed.
if (FAILED(OperationStatus))
{
if (OperationStatus == WINBIO_E_UNKNOWN_ID)
{
wprintf_s(L"\n Unknown identity.\n");
}
else if (OperationStatus == WINBIO_E_BAD_CAPTURE)
{
wprintf_s(L"\n Bad capture; reason: %d\n", RejectDetail);
}
else
{
wprintf_s(L"IdentifyCallback failed.");
wprintf_s(L"OperationStatus = 0x%x\n", OperationStatus);
}
}
// Processing succeeded and the finger swiped is written
// to the console window.
else
{
wprintf_s(L"\n The following finger was used:");
switch (SubFactor)
{
case WINBIO_SUBTYPE_NO_INFORMATION:
wprintf_s(L"\n No information\n");
break;
case WINBIO_ANSI_381_POS_RH_THUMB:
wprintf_s(L"\n RH thumb\n");
break;
case WINBIO_ANSI_381_POS_RH_INDEX_FINGER:
wprintf_s(L"\n RH index finger\n");
break;
case WINBIO_ANSI_381_POS_RH_MIDDLE_FINGER:
wprintf_s(L"\n RH middle finger\n");
break;
case WINBIO_ANSI_381_POS_RH_RING_FINGER:
wprintf_s(L"\n RH ring finger\n");
break;
case WINBIO_ANSI_381_POS_RH_LITTLE_FINGER:
wprintf_s(L"\n RH little finger\n");
break;
case WINBIO_ANSI_381_POS_LH_THUMB:
wprintf_s(L"\n LH thumb\n");
break;
case WINBIO_ANSI_381_POS_LH_INDEX_FINGER:
wprintf_s(L"\n LH index finger\n");
break;
case WINBIO_ANSI_381_POS_LH_MIDDLE_FINGER:
wprintf_s(L"\n LH middle finger\n");
break;
case WINBIO_ANSI_381_POS_LH_RING_FINGER:
wprintf_s(L"\n LH ring finger\n");
break;
case WINBIO_ANSI_381_POS_LH_LITTLE_FINGER:
wprintf_s(L"\n LH little finger\n");
break;
case WINBIO_SUBTYPE_ANY:
wprintf_s(L"\n Any finger\n");
break;
default:
break;
}
}
}
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 7 [desktop apps only] |
| Minimum supported server | Windows Server 2008 R2 [desktop apps only] |
| Target Platform | Windows |
| Header | winbio.h |