.NET — Textbox control - wait till user is done typing

Question

Greetings all,

Is there a built in way to know when a user is done typing into a textbox? (Before hitting tab, Or moving the mouse) I have a database query that occ

Answer 1

I ended up trying Scott Weinstein answer although it required some deeper knowledge about threading, delegates and basic lambda syntax. And it worked pretty well. His orginal answer wasn't pure copy-paste so I had to do some playing around to get it work.

I added very little time to Thread.Sleep, since I noticed invoke method can happen twice if user is typing really quickly but with tiny random delay between some of keystrokes. You have to also add reference to WindowsBase assembly for using Dispatcher.

I use 1,5 seconds to wait user end typing.

    // use manual reset event to Q up waiting threads.
    // each new text changed event clears the Q
    // only the last changed will hit the timeout, triggering the action
    private ManualResetEvent _delayMSE;
    private Func TBDelay;
    private delegate void ActionToRunWhenUserStopstyping();

    public Form1()
    {
        InitializeComponent();

        _delayMSE = new ManualResetEvent(false);
        TBDelay = () => !_delayMSE.WaitOne(1500, false);
    }

    private void textBox1_TextChanged(object sender, EventArgs e)
    {
        _delayMSE.Set(); 

        // open the ResetEvent gate, to discard these delays    
        Thread.Sleep(20);
        // let all pending through the gate    
        _delayMSE.Reset();
        // close the gate
        TBDelay.BeginInvoke(res =>    
        {        
            // callback code        
            // check how we exited, via timeout or signal.        
            bool timedOut = TBDelay.EndInvoke(res);
            if (timedOut)
                Dispatcher.CurrentDispatcher.Invoke(
                    new ActionToRunWhenUserStopstyping(DoWhatEverYouNeed), 
                    DispatcherPriority.Input);
        }, null);
    }

    private void DoWhatEverYouNeed()
    {
        MessageBox.Show(textBox1.Text);
    }