PBT_APMSUSPEND event

Applies to: desktop apps only

Notifies applications that the computer is about to enter a suspended state. This event is typically broadcast when all applications and installable drivers have returned TRUE to a previous PBT_APMQUERYSUSPEND event.

A window receives this event through the WM_POWERBROADCAST message. The wParam and lParam parameters are set as described following.

LRESULT 
CALLBACK 
WindowProc( HWND hwnd,      // handle to window
            UINT uMsg,      // WM_POWERBROADCAST
            WPARAM wParam,  // PBT_APMSUSPEND
            LPARAM lParam); // zero

Parameters

hwnd

A handle to window.

uMsg

Value	Meaning
WM_POWERBROADCAST 536 (0x218)	Message identifier.

 

wParam

Value	Meaning
PBT_APMSUSPEND 4 (0x4)	Event identifier.

 

lParam

Reserved; must be zero.

Return value

No return value.

Remarks

An application should process this event by completing all tasks necessary to save data. This event may also be broadcast, without a prior PBT_APMQUERYSUSPEND event, if an application or device driver uses the SetSystemPowerState function to force suspension.

The system allows approximately two seconds for an application to handle this notification. If an application is still performing operations after its time allotment has expired, the system may interrupt the application.

Windows Server 2003 and Windows XP:  Applications are allowed up to 20 seconds to respond to the PBT_APMSUSPEND event.

Requirements

See also

System Sleep Criteria

System Wake-up Events

Power Management Events

PBT_APMQUERYSUSPEND

SetSystemPowerState

WM_POWERBROADCAST

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Build date: 2/7/2012