WPF: application Idle Time

Question

Hi, I need to count the idle time of my WPF application (Idle time = when no keyboard input,mouse input (movement + clicks ) had occurred ). So far I tried 2 approaches but none of them seem to be working:

1. Using the dispatcher to invoke a delegate each time it get a contextIdle priority, the problem is that binding and many other operations invoke it and thus I can't really use that.
2. using the input manager I registered to the "System.Windows.Input.InputManager.Current.PostProcessInput" event and each time it was invoked I restarted the idle time count. The second approach seemed promising but the problem is that when the mouse is over the application (it has focus) I keep getting the event.

Any Other ideas? or maybe a way to modify the 2nd solution to work?

Answer 1

Well no one seemed to answer so I continued digging and found a relatively simple solution using the OS last input + up time. the code is really simple but this solution make me do data polling which I never recommend and also instead of being in the application level it's in the OS level which is not the exact solution I needed. If someone ever opens this thread this is the code, just use GetIdleTime():

 public class IdleTimeService
{
    //Importing the Dll & declaring the neccessary funtion
    [DllImport("user32.dll")]
    private static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);


    /// <summary>
    /// return the current idle time (in ms)
    /// </summary>
    /// <returns>current idle time in ms</returns>
    public static int GetIdleTime()
    {

        //Creating the object of the structure
        LASTINPUTINFO lastone = new LASTINPUTINFO();

        //Initialising  
        lastone.cbSize = (uint)Marshal.SizeOf(lastone);
        lastone.dwTime = 0;

        int idleTime = 0;

        //To get the total time after starting the system.
        int tickCount = System.Environment.TickCount;

        //Calling the dll function and getting the last input time.
        if (GetLastInputInfo(ref lastone))
        {
            idleTime = tickCount - (int)lastone.dwTime;
            return idleTime;
        }
        else
            return 0;
    }


}