How to access c# WPF control in thread safe way?

Question

I've tried using the examples from MSDN for this but they seem to only be applicable to Windows Forms. For instance the method of using .InvokeRequired relies on the windows forms control, however this method isn't available for WPF controls. The Backgound worker method throws an InvalidOperationException as well -

The calling thread cannot access this object because a different thread owns it.

So how can this be done in the context of WPF?

Solution

You simply want to use the Dispatcher.Invoke method (or the asynchronous equivalent Dispatcher.BeginInvoke), which will marshal the call to the main WPF UI thread.

The DependencyObject class contains a Dispatcher property, which means all controls and other objects which inherit from this class also provide this property, in a way similar to WinForms. In addition, the Application object provides access to the dispatcher.

An example usage might be the following (in code-behind of a Window/UserControl):

this.Dispatcher.Invoke((Action)(() =>
    {
        ...
    }));

Comments

[Sebastian Gray]

Thanks, that worked perfectly. It actually looks a lot simpler in WPF than win forms, when you know what you need to do ;-)

[Noldorin]

No problem. And yeah WPF certainly does have a better threading/message pump model.