Fine tuning the Application Idle Time in Windows Mobile

Question

I am trying to detect the Idle time in a Windows Mobile application and show a Screen lock after this inactive period. This link http://blog.opennetcf.com/ctacke/2009/05/19/DetectingApplicationIdle.aspx gives a hint but I found that this works only for a single form.

How can this same code be used across an application with multiple forms. I tried implementing this code after the InitializeComponent() for each form and used the Reset() function in the form Activate and GotFocus event so that the timer is reset after the user closes the screen lock by entering a PIN number. But this does not seem to work for multiple forms and the timer is not reset but it keeps firing every minute. Even if I am working on the application the event fires up every 1 minute (as per the sample code) and this is not correct.

Can anyone suggest how to use this functionality across the entire application.

Thanks in advance for any solution.

Answer 1

What about utilizing GetIdleTime ? Seems like this, paired with a timer that wakes peroidically to check it, could detect system idle and allow you to show the screen lock.

Answer 2

We need to see your code to know what's wrong, but the method proposed in that blog entry uses an IMessageFilter implementation. That hooks into the Windows message pump, which is application-wide not a single-Form system. I use the exact same technique for application-wide idle detection in a couple of solutions and it works well.

My guess is that you have a scope issue with the IMessageFilter instance you're using. If you create it as a Form-level variable (like the sample in that blog does), when close the Form that the filter is disposed of and will no longer work. If you have multiple Forms, you need to put it somewhere else in the Model so it survives as long as the app is up.