Checking for workstation lock/unlock change with c#
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03-07-2019 - |
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?
Solution
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
OTHER TIPS
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.
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);
}
}
}
You absolutely don't need WM_WTSSESSION_CHANGE Just use internal WTTS apis.