Where should I turn off a BusyIndicator in a custom control?

Question

There is a Popup in the AutoCompleteBox. I want to make a busyindicator while the popup is being populated from the filtered ItemsSource items.
I've managed to alter the template.  And in the code, I locate the BusyIndicator and turn it on when the list starts to be filtered.
But if I make the BusyIndicator not busy again, it never shows up.  Because there was never an opportunity to draw it. It needs some time on the UI thread to have it update.
Anybody have a suggestion as to what method or event listener to hook into to set the busy at the beginning of the operation and unset it at the end?

Answer 1

If you're adding these things on the UI thread then isn't it going to be busy until you stop?
I know Silverlight doesn't have the fancy wait until idle setting you get in wpf but...
You might find if you do a begininvoke from your OnPopulating
YourControl.Dispatcher.BeginInvoke ...
It's queued until everything is done.
If you're lucky.
Failing that, consider just "cheating".
Work out roughly how long your populating is likely to take.
New up a storyboard for that timespan + 1 second or whatever.
Subscribe to the completed event and dispatcher.begininvoke in there.
Your UI will be busy by the time it fires and it'll probably queue OK but even if it doesn't then it'll be about right anyhow.
Storyboard sb = new Storyboard(); sb.Duration = new TimeSpan(0, 0, 1);
sb.Completed += new EventHandler(delegate(object s, EventArgs a)
// Dispatcher.Begininvoke....
sb.Begin();
Hope that helps.
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