WM_POWERBROADCAST Overview  Group

The WM_POWERBROADCAST message is sent to an application to notify it of power-management events.

dwPowerEvent = (DWORD) wParam;
dwData = (DWORD) lParam;
 

Parameters

dwPowerEvent

Event notification message. This parameter can be one of the following values:

Value	Meaning
PBT_APMBATTERYLOW	Battery power is low.
PBT_APMOEMEVENT	OEM-defined event occurred.
PBT_APMPOWERSTATUSCHANGE	Power status has changed.
PBT_APMQUERYSUSPEND	Request for permission to suspend.
PBT_APMQUERYSUSPENDFAILED	Suspension request denied.
PBT_APMRESUMECRITICAL	Operation resuming after critical suspension.
PBT_APMRESUMESUSPEND	Operation resuming after suspension.
PBT_APMSUSPEND	System is suspending operation.

dwData

Function-specific data. For most messages, this parameter is reserved and not used.

However, if wParam is one of the resume notifications (PBT_APMRESUME*), the lParam parameter can specify the PBTF_APMRESUMEFROMFAILURE flag. This flag indicates that a suspend operation failed after the PBT_APMSUSPEND message was sent.

Return Values

Return TRUE to grant a request.

Return BROADCAST_QUERY_DENY to deny a request.