Checking for workstation lock/unlock change with c#

Question

DUPLICATE: How can I programmatically determine if my workstation is locked?

How can I detect (during runtime) when a Windows user has locked their screen (Windows+L) and unlocked it again. I know I could globally track keyboard input, but is it possible to check such thing with environment variables?

The answers to this question might provide a starting point for you. http://stackoverflow.com/questions/44980 — Timothy Carter, Mar 02 '09 at 18:56

Ben S · Answer 1 · 2009-03-02T19:03:23.767

20

A SessionSwitch event may be your best bet for this. Check the SessionSwitchReason passed through the SessionSwitchEventArgs to find out what kind of switch it is and react appropriately.

edited Mar 02 '09 at 19:03

answered Mar 02 '09 at 18:55

Ben S

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score 3 · Accepted Answer · answered Mar 02 '09 at 18:58

3

You can get this notification via a WM_WTSSESSION_CHANGE message. You must notify Windows that you want to receive these messages via WTSRegisterSessionNotification and unregister with WTSUnRegisterSessionNotification.

These posts should be helpful for a C# implementation.

http://pinvoke.net/default.aspx/wtsapi32.WTSRegisterSessionNotification

http://blogs.msdn.com/shawnfa/archive/2005/05/17/418891.aspx

http://bytes.com/groups/net-c/276963-trapping-when-workstation-locked

answered Mar 02 '09 at 18:58

Andrew Grant

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-1: The managed code version of this was posted before the Win32 version was... why is this even marked as the correct answer? – Powerlord Mar 02 '09 at 19:13
2

IMO, pinvoke is a last case solution when using .NET. It's better to use methods built into the Framework first. – Powerlord Mar 02 '09 at 21:18
1

I don't disagree, I just wasn't aware there was an alternative .net method. I've no idea why you cry babies see it as a reason to start downvoting though. – Andrew Grant Mar 02 '09 at 22:03

score 2 · Answer 3 · answered Dec 19 '13 at 22:21

You can use ComponentDispatcher as an alternative way to get those events.

Here's an example class to wrap that.

public class Win32Session
{
    private const int NOTIFY_FOR_THIS_SESSION = 0;
    private const int WM_WTSSESSION_CHANGE = 0x2b1;
    private const int WTS_SESSION_LOCK = 0x7;
    private const int WTS_SESSION_UNLOCK = 0x8;

    public event EventHandler MachineLocked;
    public event EventHandler MachineUnlocked;

    public Win32Session()
    {
        ComponentDispatcher.ThreadFilterMessage += ComponentDispatcher_ThreadFilterMessage;
    }

    void ComponentDispatcher_ThreadFilterMessage(ref MSG msg, ref bool handled)
    {
        if (msg.message == WM_WTSSESSION_CHANGE)
        {
            int value = msg.wParam.ToInt32();
            if (value == WTS_SESSION_LOCK)
            {
                OnMachineLocked(EventArgs.Empty);
            }
            else if (value == WTS_SESSION_UNLOCK)
            {
                OnMachineUnlocked(EventArgs.Empty);
            }
        }
    }

    protected virtual void OnMachineLocked(EventArgs e)
    {
        EventHandler temp = MachineLocked;
        if (temp != null)
        {
            temp(this, e);
        }
    }

    protected virtual void OnMachineUnlocked(EventArgs e)
    {
        EventHandler temp = MachineUnlocked;
        if (temp != null)
        {
            temp(this, e);
        }
    }
}

score -3 · Answer 4 · answered Mar 02 '09 at 19:54

-3

You absolutely don't need WM_WTSSESSION_CHANGE Just use internal WTTS apis.

answered Mar 02 '09 at 19:54

Checking for workstation lock/unlock change with c#

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