Use WPF Dispatcher to invoke event handler only when needed

After floundering a bit with the WPF Dispatcher I've come up with a simple way to make sure an event handler executes on the UI thread without paying the overhead of always invoking a delegate.

void someEvent_Handler(object sender, SomeEventEventArgs e)
{
    if (this.Dispatcher.CheckAccess())
    {
        // do work on UI thread
    }
    else
    {
        // or BeginInvoke()
        this.Dispatcher.Invoke(new Action<object, SomeEventEventArgs>(someEvent_Handler), 
            sender, e);
    }
}

This has the benefit (for me at least) of being very easy to remember. Hook up the event handler and then if there's a chance it could be called from a different thread wrap it using the pattern above. It's easier to read than an anonymous delegate and much faster than defining a specific delegate for the event in question.

I haven't tested the various methods to see which is the fastest yet… will get round to this at some point.

Comments

Daniel



Thank you! This information was very useful for me.

December 23, 2010

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