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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

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About the Author

Dalibor Drzik
Web Developer
Slovakia Slovakia
Wink | ;-)

Comments and Discussions

 
QuestionShall it stay countinously? Pinmemberthamizhinpan15-Oct-07 7:57 
AnswerRe: Shall it stay countinously? PinmemberDalibor Drzik16-Oct-07 1:39 
GeneralRe: Shall it stay countinously? Pinmemberkingmax_00718-Nov-07 20:09 

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