Is Dispatcher Required in BackgroundWorker?

07-19-2009 2:53 AM |

Hi people,

I'm done reading the article "Build More Responsive Apps With The Dispatcher". That's where it says:

By using BackgroundWorker, the Dispatcher is being employed automatically to invoke cross-thread method calls.

A BackgroundWorker notifies main UI-thread when it finishes operation through its BackgroundWorker::RunWorkerCompleted event. The question is, can this event be fired in UI-thread when UI-thread is still running other functions (e.g. UpdateFrame)? Or  RunWorkerCompleted event is guaranteed to be dispatched correctly when UI-thread is not doing anything?

1    class MyPage : Page
2    {
3        // Called from within CompositionTarget.Rendering event.
4        void UpdateFrame()
5        {
6            DoTaskOne();
7            DoTaskTwo();
8            // Can  BackgroundWorker::RunWorkerCompleted be raised somewhere here?
9            DoTaskThree();
10       }
11   }
12   

Thanks in advance,
Ben.

Re: Is Dispatcher Required in BackgroundWorker?

07-19-2009 3:34 AM |

 Ben

You may be interested in the example I have posted in http://silverlight.net/forums/t/111299.aspx. As far as I can tell, the BackgroundWorker does need to directly invoke the dispatcher when creating UI elements.

Nigel 

Re: Is Dispatcher Required in BackgroundWorker?

07-19-2009 10:10 AM |

Thanks guys, that helps! This property of BackgroundWorker makes it very useful.

Nigel, I am taking a while longer to understand the codes in your example. I will have a look at it soon, thanks anyway