How to determine inactivity on a winform

Question

I have a winform that is displayed at the top of my application. What I would like to is have the form set to 20% opacity if it has been inactive for a certain amount of tim

Answer 1

Here is a great example using the GetLastInputInfo from the user32.dll

Answer 2

The IMessageFilter interface is good for this, it lets you see all of the mouse and keyboard messages. Enable a timer when you see one. Change the Opacity property when it ticks. Like this:

Public Class Form1
    Implements IMessageFilter

    Public Sub New()
        InitializeComponent()
        Application.AddMessageFilter(Me)
        Me.Opacity = 0.99
        Timer1.Start()
    End Sub

    Protected Overrides Sub OnFormClosed(e As FormClosedEventArgs)
        Application.RemoveMessageFilter(Me)
        MyBase.OnFormClosed(e)
    End Sub

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Timer1.Enabled = False
        Me.Opacity = 0.3
    End Sub

    Public Function PreFilterMessage(ByRef m As Message) As Boolean Implements IMessageFilter.PreFilterMessage
        '' Bump timer on mouse or keyboard messages
        If (m.Msg >= &H200 And m.Msg <= &H20E) Or (m.Msg >= &H100 And m.Msg <= &H109) Then
            Timer1.Stop()
            Timer1.Start()
            Me.Opacity = 0.99
        End If
        Return False
    End Function
End Class