This article described code for calculating for how long a system has been idle. This is useful to do background work etc. There might be other similar articles on the web and/or CodepPoject; if you find a better way, please do let me know. The attached sample is a simple WinForms application to demonstrate the code.
I was browsing the web and encountered a couple of articles on how to calculate idle time, but they were doing it using system wide hooks. We don't want to install hooks, do we? Especially for a simple task like calculating system idle time. So, the result is this article.
Using the code
The code is very simple, just a couple of Windows API function calls.
Dim idleStruct As LASTINPUTINFO
idleStruct.cbSize = Marshal.SizeOf(idleStruct)
If GetLastInputInfo(idleStruct) Then
Dim sysIdleTime As Integer = GetTickCount() - idleStruct.dwTime
Dim totalTime As New TimeSpan(sysIdleTime * 10000)
All we need to do is create an object of the
LASTINPUTINFO structure. Before passing it as a parameter, set its size using the
Marshal.SizeOf method. The function
GetLastInputInfo is used to populate the
dwTime property of the
LASTINPUTINFO structure. If the function is successful, it returns
false. Once the
dwTime is populated, we call another function
GetTickCount; what this does is it calculates the time since the Windows session was started. And, the API declarations are as follows:
Public Structure LASTINPUTINFO
Public cbSize As Integer
Public dwTime As Integer
Public Declare Function GetLastInputInfo Lib "User32.dll" _
(ByRef lii As LASTINPUTINFO) As Boolean
Public Declare Function GetTickCount Lib "kernel32" _
Alias "GetTickCount" () As Integer
I hope this article helps my fellow developers. If you like this article, please do vote for it. And, if you find a bug or improvement, do let me know.