How to detect if keyboard idle and how long?

[HongKongCV]

I've got an app that allows user to type in text and does an auto-search based on what the user typed. But if we do it after every key stroke, the early keystrokes lag because the search returns a lot.

So. Is there a way to determine how long ago the user last pressed a key?

[dday9]

Well if you take two(2) datetimes and add/subtract them, you will get a timespan. I think that's what you may be looking for, something like this:

Private dt As DateTime
    Private Sub TextBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyDown
        dt = DateTime.Now
    End Sub

    Private Sub TextBox1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp
        Dim ts As TimeSpan = DateTime.Now - dt
        MessageBox.Show(ts.ToString, Me.Text, MessageBoxButtons.OK, MessageBoxIcon.Information)
    End Sub

Mind you this would get annoying because for instance, me typing out quick reply, I've hit a key prob 100 times now, that would give me 100 + messagebox's. But it will getcha on the right path.

[HongKongCV]

I know how to jerry-rig a solution, I was just wondering if one was built-in.

I COULD record the datetime of the last keystroke and the last search, then fire the search if the current datetime (from a timer tick event) is more than a second after the last keystroke AND no intervening search has fired.

I could do that, but I'm hoping for a simpler way.

[dday9]

I'm hoping for a simpler way

3 lines of code isn't simple enough? Any ways... As far as I know there is no built in function. But if you do use the route I suggested, don't use a timer, just compare the timespan. If the timespan's second is > 1(or w/e) then...

[HongKongCV]

Have to use a timer to kick off the search... since the search is fired based upon INactivity, I have to have a timer fire to check for that inactivity.

[dday9]

You could use a timer, but it's not the only way. You could compare the timespan as shown above, or compare a variable based on the timer's tick. This is how it would look like if you used a timer:

Private i As Integer = 0
    Private Sub TextBox1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles TextBox1.KeyUp
        Timer1.Stop()
        MessageBox.Show("It has been " & i.ToString & " seconds since the a key was pressed.")
        If i >= 0 Then
            i = 0
            Timer1.Start()
        End If
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        i += 1

    End Sub

[MattP]

Here's an msdn article that talks about improving LINQ queries: http://msdn.microsoft.com/en-us/magazine/cc721610.aspx.

Whether you use LINQ or not you can benefit from the section that talks about performing incremental searches.

[Shaggy Hiker]

You might take a look at this link to give you other ideas about it. It's API calls, but might be more reliable:

http://dataerror.blogspot.com/2005/0...idle-time.html