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.