Detecting user presence

Question

What I would like to do is detect if a user is actively using a computer running Windows (2000 or later). Preferably, I would like to do this without resorting to using screensavers.

Background: We have a customer service department that sits in a hunt group and can be "Available" or not. If they are "Available" calls will be routed to their phone rather than sit in the queue. While the phone is ringing at an extension, the inbound caller hears the "ringing" sound rather than hold music. Unfortunately, we also have reps that forget to take themselves out of "Available" when they go to lunch or leave for the day.

The end result would likely be written using .NET

Any thoughts?

Answer 1

The API GetLastInputInfo() should be used for this.

Answer 2

If users lock their workstations, or if group policy forced a screen lock after some amount of idle minutes, you could use the Windows API to subscribe to the 'Session Notification' event using WTSRegisterSessionNotification and WTSUnRegisterSessionNotification. Once you ask Windows to let your application know that the session has locked, you could use that as your indication that the user is not present.

Good reading: http://support.microsoft.com/kb/310153

Example:

private const int NOTIFY_FOR_THIS_SESSION = 0x0;
private const int WM_WTSSESSION_CHANGE = 0x2B1;
private const int WTS_CONSOLE_CONNECT = 0x1;
private const int WTS_CONSOLE_DISCONNECT = 0x2;
private const int WTS_SESSION_LOCK = 0x7;
private const int WTS_SESSION_UNLOCK = 0x8;
private const int WM_DESTROY = 0x2;
private const int WM_ACTIVATEAPP = 0x1C;

// The WTSUnRegisterSessionNotification function unregisters the specified 
// window so that the specified window receives no more session-change notifications.
[DllImport("Wtsapi32.dll")]
private static extern bool WTSUnRegisterSessionNotification(IntPtr hWnd);

// The WTSRegisterSessionNotification function registers the specified 
// window to receive session-change notifications.
[DllImport("Wtsapi32.dll")]
private static extern bool WTSRegisterSessionNotification(IntPtr hWnd, Int32 dwFlags);

// The PostQuitMessage function indicates to the system that a thread 
// has made a request to quit. The PostQuitMessage function is typically used in 
// response to a WM_DESTROY message.
[DllImport("user32.dll")]
private static extern void PostQuitMessage(Int32 nExitCode);

[DllImport("user32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr PostMessage(HandleRef hwnd, int msg, int wparam, int lparam);

private void Unsubscribe() {
   if (this.Handle != IntPtr.Zero) {
      WTSUnRegisterSessionNotification(this.Handle);
   }
}

private void Subscribe() {
   if (this.Handle != IntPtr.Zero) {
      WTSRegisterSessionNotification(this.Handle, NOTIFY_FOR_THIS_SESSION);
   }
}

// override WndProc in order to catch process the Session-Notification events:
protected override void WndProc(ref Message m) {
   switch (m.Msg) {
      case WM_WTSSESSION_CHANGE:
         switch (m.WParam.ToInt32()) {
            case WTS_CONSOLE_CONNECT:
               // User-switch : Sign-on
               break;
            case WTS_CONSOLE_DISCONNECT:
               // User-switch : Sign-off
               break;
            case WTS_SESSION_LOCK:
               // Screen Lock
               break;
            case WTS_SESSION_UNLOCK:
               // Screen Unlock
               break;
            default:
               break;
         }
         break;
      default:
         break;
   }

   base.WndProc(ref m);
}