C# Signature:

[DllImport("user32.dll")]
static extern bool GetLastInputInfo(ref LASTINPUTINFO plii);

VB Signature:

<DllImport("user32.dll")> _
Shared Function GetLastInputInfo(ByRef plii As LASTINPUTINFO) As Boolean
End Function

C++ Signature:

[DllImport("user32.dll")]
static bool GetLastInputInfo(LASTINPUTINFO* plii);

User-Defined Types:

LASTINPUTINFO

Notes:

Very useful to detect user-idle state of an application.

Minimum operating systems: Windows 2000

Tips & Tricks:

Compare to Environment.TickCount to get the time since the last user input.

Sample Code:

These samples do not take into account the rollover of the tick counter which will occur after ~50 days of uptime.

This function retrieves the time in seconds since last user input

    static int GetLastInputTime()
    {
        uint idleTime = 0;
        LASTINPUTINFO lastInputInfo = new LASTINPUTINFO();
        lastInputInfo.cbSize = Marshal.SizeOf( lastInputInfo );
        lastInputInfo.dwTime = 0;

        uint envTicks = (uint)Environment.TickCount;

        if ( GetLastInputInfo( ref lastInputInfo ) )
        {
        uint lastInputTick = lastInputInfo.dwTime;

        idleTime = envTicks - lastInputTick;
        }

        return (( idleTime > 0 ) ? ( idleTime / 1000 ) : 0);
    }

Sample Code vb.net:

This function retrieves the time in seconds since last user input

Dim idletime As Integer
Dim lastInputInf As New LASTINPUTINFO()

   Public Function GetLastInputTime() As Integer

    idletime = 0
    lastInputInf.cbSize = Marshal.SizeOf(lastInputInf)
    lastInputInf.dwTime = 0

    If GetLastInputInfo(lastInputInf) Then
        idletime = Environment.TickCount - lastInputInf.dwTime
    End If

    If idletime > 0 Then
        Return idletime / 1000
    Else : Return 0
    End If

   End Function

Sample Code C++ .net:

This function retrieves the time in seconds since last user input

public: static double getSystemIdleTime()
{                    
    int systemUptime = Environment::TickCount;
    int idleTicks = 0;
    LASTINPUTINFO lastInputInfo;
    lastInputInfo.cbSize = (UInt32)Marshal::SizeOf(lastInputInfo);
    lastInputInfo.dwTime = 0;
    if (GetLastInputInfo(&lastInputInfo))
    {        
        int lastInputTicks = (int)lastInputInfo.dwTime;
        idleTicks = systemUptime - lastInputTicks;
    }
    return (( idleTicks > 0 ) ? ( idleTicks / 1000 ) : idleTicks );
}

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