How do I detect a Lock This Computer command from a WPF application?

Question

Would prefer an answer in C#, .Net 3.5 using WPF (Windows Forms also okay)

I have an application that is essentially a toolbar window or tray icon. It needs to detect if a user locks his/her workstation and walks away in order to update the person's status in a centralized system.

I can detect a session switch or a logout easily enough, using the SystemEvents, but I cannot for the life of me figure out how to detect or receive an event on Lock.

Thanks for any assistance.

See http://stackoverflow.com/questions/44980/how-can-i-programmatically-determine-if-my-workstation-is-locked — Abhijit, Mar 16 '09 at 23:51

score 46 · Accepted Answer · edited Jan 26 '10 at 09:43

When you handle the Microsoft.Win32.SystemEvents.SessionSwitch event (which it sounds like you're already doing to detect logout), check to see if the Reason is SessionSwitchReason.SessionLock:

 using Microsoft.Win32;
 // ...
 // Somewhere in your startup, add your event handler:
    SystemEvents.SessionSwitch += 
       new SessionSwitchEventHandler(SystemEvents_SessionSwitch);
 // ...

 void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)
 {
     switch(e.Reason)
     {
         // ...
         case SessionSwitchReason.SessionLock:
            // Do whatever you need to do for a lock
            // ...
         break;
         case SessionSwitchReason.SessionUnlock:
            // Do whatever you need to do for an unlock
            // ...
         break;
         // ...
     }
 }

score 2 · Answer 2 · edited Mar 01 '19 at 12:37

2

You need to P/Invoke WTSRegisterSessionNotification.

edited Mar 01 '19 at 12:37

Mikael Dúi Bolinder

2,080
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answered Mar 16 '09 at 23:42

BC.

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2

Is there a reason to do this instead of handling the SystemEvents.SessionSwitch? – Daniel LeCheminant Mar 17 '09 at 00:04
4

Only if you're unaware of SessionSwitch. I was until now. – BC. Mar 17 '09 at 00:20

score 1 · Answer 3 · answered Mar 16 '09 at 23:43

1

Here is something from CodeProject.

http://www.codeproject.com/KB/vb/DetectWindowslockunlock.aspx

answered Mar 16 '09 at 23:43

Daniel A. White

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How do I detect a Lock This Computer command from a WPF application?

3 Answers3

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