SensorAdapterCancel

SensorAdapterCancel function

Called by the Windows Biometric Framework to cancel all pending sensor operations.

Syntax


HRESULT WINAPI SensorAdapterCancel(
  _Inout_ PWINBIO_PIPELINE Pipeline
);

Parameters

Pipeline [in, out]

Pointer to the 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 one of the following HRESULT values to indicate the error.

Return codeDescription
E_POINTER

The Pipeline argument cannot be NULL.

WINBIO_E_INVALID_DEVICE_STATE

The SensorHandle member of the WINBIO_PIPELINE structure pointed to by the Pipeline argument is set to INVALID_HANDLE_VALUE.

 

Remarks

Your implementation of this function should not wait for pending operations to complete.

If the sensor has no pending operations when this function is called, your implementation must return S_OK without changing the state of the pipeline.

Examples

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


//////////////////////////////////////////////////////////////////////////////////////////
//
// SensorAdapterCancel
//
// Purpose:
//      Cancels all pending sensor operations.
//      
// Parameters:
//      Pipeline -  Pointer to a WINBIO_PIPELINE structure associated with 
//                  the biometric unit.
//
static HRESULT
WINAPI
SensorAdapterCancel(
    __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;
    }

    // Validate the current sensor state.
    if (Pipeline->SensorHandle == INVALID_HANDLE_VALUE)
    {
        return WINBIO_E_INVALID_DEVICE_STATE;
    }

    // Cancel all I/O to the sensor handle.
    if (!CancelIoEx(Pipeline->SensorHandle, NULL))
    {
        hr = _SensorAdapterGetHresultFromWin32(GetLastError());
    }

    return hr;
}


Requirements

Minimum supported client

Windows 7 [desktop apps only]

Minimum supported server

Windows Server 2008 R2 [desktop apps only]

Header

Winbio_adapter.h (include Winbio_adapter.h)

See also

Plug-in Functions

 

 

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