WinBioEnrollDiscard function (winbio.h)
Ends the enrollment sequence and discards a pending biometric template. Starting with Windows 10, build 1607, this function is available to use with a mobile image.
Syntax
HRESULT WinBioEnrollDiscard(
[in] WINBIO_SESSION_HANDLE SessionHandle
);
Parameters
[in] SessionHandle
A WINBIO_SESSION_HANDLE value that identifies an open biometric session. Open a synchronous session handle by calling WinBioOpenSession. Open an asynchronous session handle by calling WinBioAsyncOpenSession.
Return value
If the function succeeds, it returns S_OK. If the function fails, it returns an HRESULT value that indicates the error. Possible values include, but are not limited to, those in the following table. For a list of common error codes, see Common HRESULT Values.
| Return code | Description |
|---|---|
|
The caller does not have permission to enroll. |
|
The session handle is not valid. |
|
The biometric unit is in use and is locked. |
Remarks
You can use this function to allow a user to stop an enrollment sequence before saving a biometric template to the template database.
To use WinBioEnrollDiscard synchronously, call the function with a session handle created by calling WinBioOpenSession. The function blocks until the operation completes or an error is encountered.
To use WinBioEnrollDiscard asynchronously, call the function with a session handle created by calling WinBioAsyncOpenSession. The framework allocates a WINBIO_ASYNC_RESULT structure and uses it to return information about operation success or failure. The WINBIO_ASYNC_RESULT structure is returned to the application callback or to the application message queue, depending on the value you set in the NotificationMethod parameter of the WinBioAsyncOpenSession function:
- If you choose to receive completion notices by using a callback, you must implement a PWINBIO_ASYNC_COMPLETION_CALLBACK function and set the NotificationMethod parameter to WINBIO_ASYNC_NOTIFY_CALLBACK.
- If you choose to receive completion notices by using the application message queue, you must set the NotificationMethod parameter to WINBIO_ASYNC_NOTIFY_MESSAGE. The framework returns a WINBIO_ASYNC_RESULT pointer to the LPARAM field of the window message.
Examples
The following function enrolls a biometric template in the system pool. You can pass a Boolean value to the function which enables you to discard an enrollment by calling WinBioEnrollDiscard. Link to the Winbio.lib static library and include the following header files:
- Windows.h
- Stdio.h
- Conio.h
- Winbio.h
HRESULT EnrollSysPool(
BOOL discardEnrollment,
WINBIO_BIOMETRIC_SUBTYPE subFactor)
{
HRESULT hr = S_OK;
WINBIO_IDENTITY identity = {0};
WINBIO_SESSION_HANDLE sessionHandle = NULL;
WINBIO_UNIT_ID unitId = 0;
WINBIO_REJECT_DETAIL rejectDetail = 0;
BOOLEAN isNewTemplate = TRUE;
// 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
NULL, // Database ID
&sessionHandle // [out] Session handle
);
if (FAILED(hr))
{
wprintf_s(L"\n WinBioOpenSession failed. ");
wprintf_s(L"hr = 0x%x\n", hr);
goto e_Exit;
}
// Locate a sensor.
wprintf_s(L"\n Swipe your finger on the sensor...\n");
hr = WinBioLocateSensor( sessionHandle, &unitId);
if (FAILED(hr))
{
wprintf_s(L"\n WinBioLocateSensor failed. hr = 0x%x\n", hr);
goto e_Exit;
}
// Begin the enrollment sequence.
wprintf_s(L"\n Starting enrollment sequence...\n");
hr = WinBioEnrollBegin(
sessionHandle, // Handle to open biometric session
subFactor, // Finger to create template for
unitId // Biometric unit ID
);
if (FAILED(hr))
{
wprintf_s(L"\n WinBioEnrollBegin failed. hr = 0x%x\n", hr);
goto e_Exit;
}
// Capture enrollment information by swiping the sensor with
// the finger identified by the subFactor argument in the
// WinBioEnrollBegin function.
for (int swipeCount = 1;; ++swipeCount)
{
wprintf_s(L"\n Swipe the sensor to capture %s sample.",
(swipeCount == 1)?L"the first":L"another");
hr = WinBioEnrollCapture(
sessionHandle, // Handle to open biometric session
&rejectDetail // [out] Failure information
);
wprintf_s(L"\n Sample %d captured from unit number %d.",
swipeCount,
unitId);
if (hr == WINBIO_I_MORE_DATA)
{
wprintf_s(L"\n More data required.\n");
continue;
}
if (FAILED(hr))
{
if (hr == WINBIO_E_BAD_CAPTURE)
{
wprintf_s(L"\n Error: Bad capture; reason: %d",
rejectDetail);
continue;
}
else
{
wprintf_s(L"\n WinBioEnrollCapture failed. hr = 0x%x", hr);
goto e_Exit;
}
}
else
{
wprintf_s(L"\n Template completed.\n");
break;
}
}
// Discard the enrollment if the appropriate flag is set.
// Commit the enrollment if it is not discarded.
if (discardEnrollment == TRUE)
{
wprintf_s(L"\n Discarding enrollment...\n\n");
hr = WinBioEnrollDiscard( sessionHandle );
if (FAILED(hr))
{
wprintf_s(L"\n WinBioLocateSensor failed. hr = 0x%x\n", hr);
}
goto e_Exit;
}
else
{
wprintf_s(L"\n Committing enrollment...\n");
hr = WinBioEnrollCommit(
sessionHandle, // Handle to open biometric session
&identity, // WINBIO_IDENTITY object for the user
&isNewTemplate); // Is this a new template
if (FAILED(hr))
{
wprintf_s(L"\n WinBioEnrollCommit failed. hr = 0x%x\n", hr);
goto e_Exit;
}
}
e_Exit:
if (sessionHandle != NULL)
{
WinBioCloseSession(sessionHandle);
sessionHandle = NULL;
}
wprintf_s(L" Press any key to continue...");
_getch();
return hr;
}
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 (include Winbio.h) |
| Library | Winbio.lib |
| DLL | Winbio.dll |