Question

I am working with WPF. I run a thread process in the main xaml window using Dispatcher.

Then I got this error for opening another WPF to show the result of displaying a 3D image:

{“The calling thread must be STA, because many UI components require
this.”}

This is how I start a new window:

void DisplayFormThread()
{
    IResult result = _mainWindow.GetResult();
    ResultView resultView = new ResultView (result);
    resultView.Show();
}

I have tried to resolve the problem by adding this in some posts on stackoverflow but it does not help:

ThreadStart start = delegate()
{
   DispatcherOperation op = Dispatcher.CurrentDispatcher.BeginInvoke(
        new delegateNewWindow(DisplayFormThread), DispatcherPriority.Background);

        DispatcherOperationStatus status = op.Status;
                   while (status != DispatcherOperationStatus.Completed)
                   {
                            status = op.Wait(TimeSpan.FromMilliseconds(1000));
                            if (status == DispatcherOperationStatus.Aborted)
                            {
                                 // Alert Someone
                            }
                    }

       };

// Create the thread and kick it started!
Thread thread = new Thread(start);
thread.SetApartmentState(ApartmentState.STA);
thread.Start();

How can I solve the problem?

Thanks in advance.

Answer 1

The reason is that our newly created thread is not enabled to support WPF window infrastructure. In particular, it provides no support for Windows message pumping,You have to run separate dispatcher for newly created window. Here is sample for this