Question

Does anyone know of a way to detect recent activity in a VB.net windows forms application?

We have a retail store where users share floor computers, the application will be on each machine and require a log in before use. I am trying to find a way to automatically close the application if it has been idle for lets say 10 minutes.

I guess I could do something similar with the current windows log on session – set a gp that logs the user out after 10 minutes of inactivity – but if there is an easy, non memory intensive way to do it in vb.net i would rather use that method

thanks

Answer 1

When the applications starts, create a handler for the Application.Idle event. Also create an object that is your 10-minute timer. The Appliation.Idle event is raised every time the event queue is empty. If you move the mouse, that raises an event. If you press a key, that raises an event. Note that you cannot use the Handles keyword with Application.Idle. Handles only works for locally decalred objects, not static objects.

Public Sub MainForm_Load(sender As Object, e As EventArgs) Handles MainForm.Load
    AddHandler System.Windows.Forms.Application.Idle, AddressOf Application_Idle
    ' TODO: Create the 10-minute timer.
End Sub

Private Sub Application_Idle(sender As Object, e As EventArgs)  
    ' TODO: Restart the 10-minute timer.
End Sub

' This assumes your TenMinuteTimer object has an Expire event.  Do what works for you instead.
Private Sub TenMinuteTimer_Expire(sender As Object, e As EventArgs) Handles TenMinuteTimer.Expire
    ' TODO: Close the application safely.
End Sub

The only issue with this is if the user starts an action that takes longer than 10 minutes, it will raise Application.Idle after TenMinuteTimer.Expire. If you expect this may happen, be sure to disable the TenMinuteTimer before executing long-running code and enable it again afterwards.