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Get monitor state

Posted on 2004-10-08
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Last Modified: 2010-04-05
Hello.

Is it possible to get the state of the monitor (turned on/off, standby)? If so, how do I do it?

The WMI (Windows Management Instrumentation) Win32_DesktopMonitor class (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/wmisdk/wmi/win32_desktopmonitor.asp) contains the information I need (Availability), but the Win32_DesktopMonitor class does not update real time.

Are there any other way to get this information?

Thanks in advance.

/Snebal
0
Comment
Question by:Michael G
10 Comments
 
LVL 12

Expert Comment

by:Ivanov_G
ID: 12266053
You can handle WM_SYSCOMMAND. When monitor is being turned on/off the wParams is SC_MONITORPOWER      ...
0
 

Author Comment

by:Michael G
ID: 12269569
Thank you for your comment.

I have the following code which can tell me when powersafe gets activated, but it doesn't react if I turn off my monitor !?

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;

  private
  protected
    procedure WMSysCommand(var Message : TWMSysCommand ); Message WM_SYSCOMMAND;
    { Private declarations }
  public

    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.WMSysCommand(var Message : TWMSysCommand);
// Intercept screen saver or power monitor message and do something ...
begin
  if (Message.CmdType and $FFF0 = SC_SCREENSAVE) or
     (Message.CmdType and $FFF0 = SC_MONITORPOWER) then
   begin
     memo1.Lines.Add(datetimetostr(now)+ ': Powersafe activated or monitor power off')
  end;
  inherited; // let the message thru'
end; {WMSysCommand}

end.
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LVL 12

Expert Comment

by:Ivanov_G
ID: 12270926
Yep, I know about this. I couldn't make it work with monitor turned off...
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Author Comment

by:Michael G
ID: 12271123
So it's not possible to detect if you turn off your monitor !?
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LVL 17

Expert Comment

by:Wim ten Brink
ID: 12271996
Maybe some smarter monitors will signal the system that the monitor is turned off, but afaik, this is extremely uncommon. Many laptops will keep track of the monitor state of the LCD screen but I don't think this information is sent to the system. It's just used to turn off the monitor when you close the lid of the laptop.
0
 

Author Comment

by:Michael G
ID: 12865770
I never really solved the problem, but found a more or less working workaround.

I use a WMSysCommand, see below, to detect if powersave is activated, and then I use a global keyboard/mouse hook to detect user input that takes the monitor out of powersaving.

procedure TForm1.WMSysCommand(var Message : TWMSysCommand);
// Intercept screen saver or power monitor message and do something ...
begin
  if  (Message.CmdType and $FFF0 = SC_SCREENSAVE) or(Message.CmdType and
$FFF0 = SC_MONITORPOWER) then begin

    memo1.Lines.Add(datetimetostr(now)+ ': powersave')
  end; {if}
  inherited; // let the message thru'
end; {WMSysCommand}
0
 

Author Comment

by:Michael G
ID: 13343683
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