PIBIO_ENGINE_NOTIFY_POWER_CHANGE_FN callback function (winbio_adapter.h)

Called by the Windows Biometric Framework when the computer is ready to enter a low-power state or when the computer has been awakened from a low-power state. The purpose of this function is to enable the adapter to respond to transitions in the computer power state.

Syntax

PIBIO_ENGINE_NOTIFY_POWER_CHANGE_FN PibioEngineNotifyPowerChangeFn;

HRESULT PibioEngineNotifyPowerChangeFn(
  [in, out] PWINBIO_PIPELINE Pipeline,
  [in]      ULONG PowerEventType
)
{...}

Parameters

[in, out] Pipeline

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

[in] PowerEventType

Indicates the nature of the change. It can be one of the following values:

• PBT_APMSUSPEND

The system is entering a low-power state.

• PBT_APMRESUMEAUTOMATIC

The system is returning from a low-power state.

• PBT_APMPOWERSTATUSCHANGE

The status of the system's power source is changing (e.g. the system has switched from battery to line power, or the battery is getting low).

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.

Remarks

When it receives a PBT_APMPOWERSTATUSCHANGE event, the adapter should call the Microsoft Win32GetSystemPowerStatus API to determine the new power status.

The biometric framework calls this adapter entry point asynchronously in the context of an arbitrary thread. It is the responsibility of the adapter to synchronize processing of this call with any other work it may be doing.

Requirements

See also

GetSystemPowerStatus

PBT_APMPOWERSTATUSCHANGE