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How to create a task (TPL) running a STA thread?

Posted by: admin November 30, 2017 Leave a comment

Questions:

Using Thread is pretty straightforward

 Thread thread = new Thread(MethodWhichRequiresSTA);
 thread.SetApartmentState(ApartmentState.STA);  

How to accomplish the same using Tasks in a WPF application? Here is some code:

Task.Factory.StartNew
  (
    () => 
    {return "some Text";}
  )
   .ContinueWith(r => AddControlsToGrid(r.Result));  

I’m getting an InvalidOperationException with

The calling thread must be STA, because many UI components require this.

Answers:

You can use the TaskScheduler.FromCurrentSynchronizationContext Method to get a TaskScheduler for the current synchronization context (which is the WPF dispatcher when you’re running a WPF application).

Then use the ContinueWith overload that accepts a TaskScheduler:

var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

Task.Factory.StartNew(...)
            .ContinueWith(r => AddControlsToGrid(r.Result), scheduler);

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