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Turn on/off monitor

, 24 Jul 2005
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Sets the state of the display.

Introduction

The SendMessage function is useful to handle monitor states - the display is going to low power, the display is being shut off and the display is turned on.

Code explanation

While using SendMessage function, you have to set four parameters:

  • hWnd

    Handle to the window whose window procedure will receive the message. If you don't want to bother creating a window to send the message to, you can send the message to all top level windows (HWND_BROADCAST) or you can use GetDesktopWindow function sending the message to the desktop window.

  • Msg

    Specifies the message to be sent (WM_SYSCOMMAND).

  • wParam

    Specifies additional message-specific information (SC_MONITORPOWER).

  • lParam
    • 1 - the display is going to low power.
    • 2 - the display is being shut off.
    • -1 - the display is being turned on (undocumented value).
// Turn off monitor
Sleep(500); // Eliminate user's interaction for 500 ms
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 2);

// Turn on monitor
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) -1);

// Low power monitor
Sleep(500); // Eliminate user's interaction for 500 ms
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, (LPARAM) 1);

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Dalibor Drzik
Web Developer
Slovakia Slovakia
Wink | ;-)

Comments and Discussions

 
AnswerRe: FYI PinmemberDalibor Drzik4-Apr-07 7:29 
QuestionAnd how to turn off harddisk? Pinmemberandreasm8211-Jun-06 1:26 
QuestionDetect monitor changes? PinmemberJudge423-Apr-06 8:43 
AnswerRe: Detect monitor changes? PinmemberDalibor Drzik24-Apr-06 3:11 
GeneralGood Job! PinmemberJohn R. Shaw16-Mar-06 16:46 
AnswerRe: Good Job! PinmemberDalibor Drzik17-Mar-06 2:08 
QuestionHow to turn off monitor Pinmemberuyencpham16-Dec-05 10:56 
AnswerRe: How to turn off monitor PinmemberDalibor Drzik18-Dec-05 4:05 
GeneralI tried using C# but it wont work , where i am missing PinmemberLalit N Dubey16-Aug-05 1:38 
GeneralRe: I tried using C# but it wont work , where i am missing PinmemberOMalleyW16-Aug-05 3:12 
GeneralRe: I tried using C# but it wont work , where i am missing PinmemberLalit N Dubey16-Aug-05 18:48 
GeneralRe: I tried using C# but it wont work , where i am missing PinmemberDalibor Drzik18-Aug-05 2:29 
GeneralExcellent - but i need it in VB PinsussAnonymous4-Aug-05 5:59 
GeneralRe: Excellent - but i need it in VB PinsussAnonymous4-Aug-05 6:21 
GeneralRe: Excellent - but i need it in VB PinsussAnonymous4-Aug-05 14:02 
GeneralRe: Excellent - but i need it in VB PinsussAnonymous4-Aug-05 14:36 
GeneralRe: Excellent - but i need it in VB Pinsusscodephoenix1-Oct-05 17:29 
GeneralRe: Excellent - but i need it in VB Pinmemberuyencpham16-Dec-05 11:13 
GeneralI had no idea... PinmemberTom Archer25-Jul-05 6:35 
GeneralRe: I had no idea... PinmemberTed Ferenc25-Jul-05 12:33 
GeneralRe: I had no idea... PinmemberTom Archer25-Jul-05 13:07 
GeneralRe: I had no idea... PinmemberDalibor Drzik26-Jul-05 5:35 
GeneralRe: I had no idea... PinmemberDalibor Drzik26-Jul-05 5:29 
GeneralGreat PinmemberDanila Korablin25-Jul-05 6:09 
GeneralRe: Great PinmemberDalibor Drzik26-Jul-05 5:25 

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