Application.DispatcherUnhandledException Event

Tonight I was trying out RikReader (a WPF rss feed reader) and enjoying the experience…love those columns that flowdocument provides on my 20" monitor!

But then I came to a blog hosted on spaces.live.com.  For some reason, one of their image files makes WPF unhappy.  We are investigating the issue, but until then, developers should be aware of how to handle these problems.

 

Saturday, Douglas Stockwell (author of RikReader) posted the issue on this post.

At first, my colleague said to use the Image.ImageFailed event…however the image we found didn’t raise that event.

 

I’ve found that one way to solve this is by listening to:

Application.DispatcherUnhandledException Event

and doing something like this:

 

    public partial class App : System.Windows.Application
    {
        protected override void OnStartup(StartupEventArgs e)
        {
            this.DispatcherUnhandledException += new System.Windows.Threading.DispatcherUnhandledExceptionEventHandler(App_DispatcherUnhandledException);
            base.OnStartup(e);
        }

        void App_DispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e)
        {

            //likely more elegant ways to do this...
            if (e.Exception.Message == "Cannot read from the stream.")
            {
                MainWindow.Background = System.Windows.Media.Brushes.Pink;
                e.Handled = true;
            }
        }
    }

[WOW, I just used Paste From Visual Studio tool in Windows Live Writer…Very nice!]