Question

I have a TextBlock on my application. I want to update it every second to show the current time.

How should I do it? The first thing I though was to create an instance of a System.Thread.Timer and update the text…

clockTimer = new Timer(o =>
{
    Dispatcher.BeginInvoke(() =>
    {
        currentTime.Text = DateTime.Now.ToShortTimeString();
    });
}, null, 0, 1000);

But is it ok to call Dispatcher every second?

If I use a binding what will be its behavior? Is it better for performance than calling Dispatcher? (consider having several calls to Dispatcher every second and several bindings)

Answer 1

You can use a DispatcherTimer instead.

Something like this:

        DispatcherTimer dt = new DispatcherTimer();
        dt.Interval = TimeSpan.FromMilliseconds(1000);

        dt.Tick += (s, e) => { currentTime.Text = DateTime.Now.ToShortTimeString(); };

        dt.Start();

There shouldn’t be harm in doing this, just don’t hang around too long in your tick event.

Also, if you do it in binding, you’re going to have to have a timer of some sort around it to update your bound property, so, though I always favor databinding over direct manipulation of the control, it shouldn’t matter either way.