Input Idle Handler

A simple tools to check if user is idle or not.

How it works?

P/Invoke (Platform Invocation Services) is utilized to invoke functions from native Windows libraries directly within managed C# code. Specifically, it's used to call the GetLastInputInfo and GetLastError functions from the User32.dll and Kernel32.dll libraries, respectively.

Structure Definition:

The LASTINPUTINFO structure is defined to store information about the last input event received by the system. It contains two members:
- cbSize: Represents the size of the structure in bytes.
- dwTime: Holds the time of the last input event, measured in milliseconds.

P/Invoke Declarations:

Two functions from the Windows API are imported using Platform Invocation Services (P/Invoke):
- GetLastInputInfo: Retrieves information about the last input event.
- GetLastError: Retrieves the last-error code value for the calling thread.

GetIdleTime Method:

This method retrieves the amount of time that has elapsed since the last user input event.
It creates an instance of the LASTINPUTINFO struct, initializes its cbSize, and calls GetLastInputInfo to populate the struct with the last input information.
The method calculates the idle time by subtracting the time of the last input event from the current system time (Environment.TickCount) and returns the result in milliseconds.

GetLastInputTime Method:

This method retrieves the time (in milliseconds) of the last input event.
It follows a similar process as the GetIdleTime method, creating an instance of LASTINPUTINFO, initializing its cbSize, and calling GetLastInputInfo to populate the struct.
If GetLastInputInfo fails, it throws an exception, providing the error code returned by GetLastError.
Finally, it returns the time of the last input event stored in the dwTime member of the LASTINPUTINFO struct.

IsIdle Method:

This method checks if the system is currently idle by calling the GetLastInputTime method.
If the time of the last input event is not zero, it indicates that the system is not idle, and the method returns false.
If the time is zero, it signifies that the system is idle, and the method returns true.

Usage:

You can use the IdleHandler class to monitor user activity and implement features like auto-locking screens after a period of inactivity, tracking user session duration, or triggering background tasks based on user idle time.

How to use

You can just the function like this:

// Set the idle threshold to 5 seconds
const int idleThreshold = 5 * 1000;

if (IdleHandler.IsIdle() && IdleHandler.GetIdleTime() > idleThreshold)
{
    Console.WriteLine("User is idle");
    // Do something
}
else
{
    Console.WriteLine("Active");
    // Do something
}

KidiXDev / Input-Idle-Handler