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
}