WinBioEnrollCapture function (winbio.h)

Article
10/13/2021

Captures a biometric sample and adds it to a template. Starting with Windows 10, build 1607, this function is available to use with a mobile image.

Syntax

HRESULT WinBioEnrollCapture(
  [in]            WINBIO_SESSION_HANDLE SessionHandle,
  [out, optional] WINBIO_REJECT_DETAIL  *RejectDetail
);

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.

[out, optional] RejectDetail

A pointer to a ULONG value that contains additional information the failure to capture a biometric sample. If the capture succeeded, this parameter is set to zero. The following values are defined for fingerprint capture:

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

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
E_ACCESSDENIED	The calling account is not allowed to perform enrollment.
E_HANDLE	The session handle is not valid.
E_POINTER	The pointer specified by the RejectDetail parameter cannot be NULL.
WINBIO_E_BAD_CAPTURE	The sample could not be captured. Use the RejectDetail value for more information.
WINBIO_E_LOCK_VIOLATION	The biometric unit is in use and is locked.
WINBIO_I_MORE_DATA	The matching engine requires one or more additional samples to generate a reliable template. You should update instructions to the user to submit more samples and call WinBioEnrollCapture again.

Remarks

Any application that enrolls by using a biometric unit in the system pool must have window focus when it calls WinBioEnrollBegin. If it does not, the call blocks until the application acquires window focus and the user has provided a biometric sample. We recommend, therefore, that your application not call WinBioEnrollBegin until it has acquired focus. The manner in which you acquire focus depends on the type of application you are writing. For example, if you are creating a GUI application you can implement a message handler that captures a WM_ACTIVATE, WM_SETFOCUS, or other appropriate message. If you are writing a CUI application, call GetConsoleWindow to retrieve a handle to the console window and pass that handle to the SetForegroundWindow function to force the console window into the foreground and assign it focus. If your application is running in a detached process and has no window or is a Windows service, use WinBioAcquireFocus and WinBioReleaseFocus to manually control focus.

To use WinBioEnrollCapture 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 WinBioEnrollCapture 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. If the operation is unsuccessful, the framework returns WINBIO_REJECT_DETAIL information in a nested EnrollCapture structure. 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.

To prevent memory leaks, you must call WinBioFree from your callback implementation to release the WINBIO_ASYNC_RESULT structure after you have finished using it.

Windows 7: You can perform this operation asynchronously by using the WinBioEnrollCaptureWithCallback function. The function verifies the input arguments and returns immediately. If the input arguments are not valid, the function returns an error code. Otherwise, the framework starts the operation on another thread. When the asynchronous operation completes or encounters an error, the framework sends the results to the PWINBIO_ENROLL_CAPTURE_CALLBACK function implemented by your application.

Examples

The following function enrolls a biometric template in the system pool by calling WinBioEnrollCapture. 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