How does dispatcher work the a thread?

Question

Hi,

We have a silverlight application which uses a dispatcher and I would appreciate any help explaining what the following codes does? (unfortunately the developer who wrote the code has left).

So what we have is the following:

Public Class ABC {

private Dispatcher dispatcher;
private Thread threadRunner;

Public void ABC()
{
       threadRunner= new Thread(ThreadRunnerMethod)
                        {
                            IsBackground = true, 
                            ApartmentState = ApartmentState.STA
                        };
       threadRunner.Start();
}


private static void ThreadRunnerMethod()
{
        Dispatcher.Run();
}


Public void MainMethod()
{
   dispatcher = Dispatcher.FromThread(threadRunner);
   dispatcher.Invoke(new Action(() => 
                                 // "DO SOME WORK WITH A COM OBJECT"
                                  ));

}

}

I have some basic experience with threading but I have no idea how this all works?

JD

Answer 1

It's the equivalent of Control.Invoke in Windows Forms, basically - it's just been separated into its own object.

As I understand it, Dispatcher.Run will basically start an event loop, and you can marshall calls into that event loop using Dispatcher.Invoke. Dispatcher.FromThread finds the Dispatcher object which is responsible for a given thread - so in this case, it finds the event loop running in the new thread.

So in your code, the delegate created with the lambda expression will execute in the newly created thread.