WinBioEnrollCaptureWithCallback function

Asynchronously captures a biometric sample and adds it to a template. The function returns immediately to the caller, performs enrollment on a separate thread, and calls into an application-defined callback function to update operation status.

Important  

We recommend that, beginning with Windows 8, you no longer use this function to start an asynchronous operation. Instead, do the following:

  • 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 WinBioEnrollCapture. 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


HRESULT WINAPI WinBioEnrollCaptureWithCallback(
  _In_     WINBIO_SESSION_HANDLE           SessionHandle,
  _In_     PWINBIO_ENROLL_CAPTURE_CALLBACK EnrollCallback,
  _In_opt_ PVOID                           EnrollCallbackContext
);

Parameters

SessionHandle [in]

A WINBIO_SESSION_HANDLE value that identifies an open biometric session.

EnrollCallback [in]

Address of a callback function that will be called by the WinBioEnrollCaptureWithCallback function when the capture operation succeeds or fails. You must create the callback.

EnrollCallbackContext [in, optional]

Pointer to an optional application-defined structure that is passed to the EnrollCallbackContext parameter of the callback function. This structure can contain any data that the custom callback function is designed to handle.

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 codeDescription
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 EnrollCallback parameter cannot be NULL.

 

Remarks

If the SessionHandle parameter refers to the system sensor pool, the callback function will not be called until the application acquires window focus and the user has provided a biometric sample. 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.

Examples

The following code example enrolls a fingerprint asynchronously by calling WinBioEnrollCaptureWithCallback and passing a pointer to a custom callback function. The callback function, EnrollCaptureCallback, is also shown. Link to the Winbio.lib static library.


//------------------------------------------------------------------------
// EnrollSystemPoolWithCallback.cpp : console application entry point.
//

#include <windows.h>
#include <stdio.h>
#include <conio.h>
#include <winbio.h>


//------------------------------------------------------------------------
// Forward declarations.
//
HRESULT EnrollSysPoolWithCallback(
                      BOOL bCancel,
                      BOOL bDiscard,
                      WINBIO_BIOMETRIC_SUBTYPE subFactor);

VOID CALLBACK EnrollCaptureCallback(
                      __in_opt PVOID EnrollCallbackContext,
                      __in HRESULT OperationStatus,
                      __in WINBIO_REJECT_DETAIL RejectDetail);

typedef struct _ENROLL_CALLBACK_CONTEXT {
    WINBIO_SESSION_HANDLE SessionHandle;
    WINBIO_UNIT_ID UnitId;
    WINBIO_BIOMETRIC_SUBTYPE SubFactor;
} ENROLL_CALLBACK_CONTEXT, *PENROLL_CALLBACK_CONTEXT;

//------------------------------------------------------------------------
int wmain()
{
    HRESULT hr = S_OK;

    hr = EnrollSysPoolWithCallback(
                      FALSE, 
                      FALSE, 
                      WINBIO_ANSI_381_POS_RH_INDEX_FINGER);

    return 0;
}

//------------------------------------------------------------------------
// The following function enrolls a user's fingerprint in the system pool.
// The function calls WinBioEnrollCaptureWithCallback and waits for the
// asynchronous enrollment process to be completed or canceled.
//
HRESULT EnrollSysPoolWithCallback(
                      BOOL bCancel,
                      BOOL bDiscard,
                      WINBIO_BIOMETRIC_SUBTYPE subFactor)
{
    // Declare variables
    HRESULT hr = S_OK;
    WINBIO_IDENTITY identity = {0};
    WINBIO_SESSION_HANDLE sessionHandle = NULL;
    WINBIO_UNIT_ID unitId = 0;
    BOOLEAN isNewTemplate = TRUE;
    ENROLL_CALLBACK_CONTEXT callbackContext = {0};

    // 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 WinBioEnumBiometricUnits failed. ");
        wprintf_s(L"hr = 0x%x\n", hr);
        goto e_Exit;
    }

    // Locate the sensor.
    wprintf_s(L"\n Swipe your finger to locate 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. 
    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;
    }

    // Set up the custom callback context structure.
    callbackContext.SessionHandle = sessionHandle;
    callbackContext.UnitId = unitId;
    callbackContext.SubFactor = subFactor;

    // Call WinBioEnrollCaptureWithCallback. This is an asynchronous
    // method that returns immediately.
    hr = WinBioEnrollCaptureWithCallback(
            sessionHandle,          // Handle to open biometric session
            EnrollCaptureCallback,  // Callback function
            &callbackContext        // Pointer to the custom context
            );
    if (FAILED(hr))
    {
        wprintf_s(L"\n WinBioEnrollCaptureWithCallback failed. ");
        wprintf_s(L"hr = 0x%x\n", hr);
        goto e_Exit;
    }
    wprintf_s(L"\n Swipe the sensor with the appropriate finger...\n");

    // Cancel the enrollment 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 enrollment process to complete
    // or be canceled.
    hr = WinBioWait( sessionHandle );
    if (FAILED(hr))
    {
        wprintf_s(L"\n WinBioWait failed. hr = 0x%x\n", hr);
    }

    // Discard the enrollment if the bDiscard flag is set.
    // Commit the enrollment if the flag is not set.
    if (bDiscard)
    {
        wprintf_s(L"\n Discarding enrollment...\n");
        hr = WinBioEnrollDiscard( sessionHandle );
        if (FAILED(hr))
        {
            wprintf_s(L"\n WinBioLocateSensor failed. ");
            wprintf_s(L"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"\n Press any key to exit...");
    _getch();

    return hr;
}

//------------------------------------------------------------------------
// The following function is the callback for the Windows Biometric
// Framework WinBioEnrollCaptureWithCallback() function. 
//
VOID CALLBACK EnrollCaptureCallback(
    __in_opt PVOID EnrollCallbackContext,
    __in HRESULT OperationStatus,
    __in WINBIO_REJECT_DETAIL RejectDetail
    )
{
    // Declare variables.
    HRESULT hr = S_OK; 
    static SIZE_T swipeCount = 1;

    PENROLL_CALLBACK_CONTEXT callbackContext = 
        (PENROLL_CALLBACK_CONTEXT)EnrollCallbackContext;

    wprintf_s(L"\n EnrollCaptureCallback executing\n");
    wprintf_s(L"\n Sample %d captured", swipeCount++);

    // The capture was not acceptable or the enrollment operation
    // failed.
    if (FAILED(OperationStatus))
    {
        if (OperationStatus == WINBIO_E_BAD_CAPTURE)
        {
            wprintf_s(L"\n Bad capture; reason: %d\n", RejectDetail);
            wprintf_s(L"\n Swipe your finger to capture another sample.\n");

            // Try again.
            hr = WinBioEnrollCaptureWithCallback(
                    callbackContext->SessionHandle, // Open session handle
                    EnrollCaptureCallback,          // Callback function
                    EnrollCallbackContext           // Callback context
                    );
            if (FAILED(hr))
            {
                wprintf_s(L"WinBioEnrollCaptureWithCallback failed.");
                wprintf_s(L"hr = 0x%x\n", hr);
            }
        }
        else
        {
            wprintf_s(L"EnrollCaptureCallback failed.");
            wprintf_s(L"OperationStatus = 0x%x\n", OperationStatus);
        }
        goto e_Exit;
    }

    // The enrollment operation requires more fingerprint swipes.
    // This is normal and depends on your hardware. Typically, at least
    // three swipes are required.
    if (OperationStatus == WINBIO_I_MORE_DATA)
    {
        wprintf_s(L"\n More data required.");
        wprintf_s(L"\n Swipe your finger on the sensor again.");

        hr = WinBioEnrollCaptureWithCallback(
                callbackContext->SessionHandle,
                EnrollCaptureCallback,
                EnrollCallbackContext
                );
        if (FAILED(hr))
        {
            wprintf_s(L"WinBioEnrollCaptureWithCallback failed. ");
            wprintf_s(L"hr = 0x%x\n", hr);
        }
        goto e_Exit;
    }

    wprintf_s(L"\n Template completed\n");

e_Exit:

    return;
}



Requirements

Minimum supported client

Windows 7 [desktop apps only]

Minimum supported server

Windows Server 2008 R2 [desktop apps only]

Header

Winbio.h (include Winbio.h)

Library

Winbio.lib

DLL

Winbio.dll

See also

WinBioAcquireFocus
WinBioEnrollBegin
WinBioEnrollCapture
WinBioEnrollCommit
WinBioEnrollDiscard
WinBioReleaseFocus

 

 

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