PIBIO_ENGINE_DISCARD_ENROLLMENT_FN callback function (winbio_adapter.h)

Article
02/22/2024

Called by the Windows Biometric Framework to delete intermediate enrollment state information from the pipeline.

Syntax

PIBIO_ENGINE_DISCARD_ENROLLMENT_FN PibioEngineDiscardEnrollmentFn;

HRESULT PibioEngineDiscardEnrollmentFn(
  [in, out] PWINBIO_PIPELINE Pipeline
)
{...}

Parameters

[in, out] Pipeline

Pointer to a WINBIO_PIPELINE structure associated with the biometric unit performing the operation.

Return value

If the function succeeds, it returns S_OK. If the function fails, it must return the following HRESULT value to indicate the error.

Return code	Description
E_POINTER	The Pipeline parameter cannot be NULL.

Remarks

Your implementation of this function should not save information in the biometric unit database.

Examples

The following pseudocode shows one possible implementation of this function. The example does not compile. You must adapt it to suit your purpose.

//////////////////////////////////////////////////////////////////////////////////////////
//
// EngineAdapterDiscardEnrollment
//
// Purpose:
//      Deletes intermediate enrollment state information from the pipeline.
//
// Parameters:
//      Pipeline  - Pointer to a WINBIO_PIPELINE structure associated 
//                  with the biometric unit performing the operation
// 
static HRESULT
WINAPI
EngineAdapterDiscardEnrollment(
    __inout PWINBIO_PIPELINE Pipeline
    )
{
    HRESULT hr = S_OK;

    // Verify that the Pipeline parameter is not NULL.
    if (!ARGUMENT_PRESENT(Pipeline))
    {
        hr = E_POINTER;
        goto cleanup;
    }

    // Retrieve the context from the pipeline.
    PWINBIO_ENGINE_CONTEXT context = 
           (PWINBIO_ENGINE_CONTEXT)Pipeline->EngineContext;

    // Return if an enrollment is not in progress. This example assumes that 
    // an enrollment object is part of your engine context structure.
    if (context->Enrollment.InProgress != TRUE)
    {
        hr = WINBIO_E_INVALID_DEVICE_STATE;
        goto cleanup;
    }


    // Call a custom function (_AdapterDestroyEnrollmentTemplate) to release
    // any objects attached to the enrollment object.
    _AdapterDestroyEnrollmentTemplate(
        context,
        &context->Enrollment
        );

    // If the _AdapterDestroyEnrollmentTemplate function does not reset the
    // InProgress data member, reset it here.
    context->Enrollment.InProgress = FALSE;

cleanup:

    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_adapter.h (include Winbio_adapter.h)

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