CODEWITHSUNDEEP
c#wpfmultithreading
537mfb
537mfb

Reputation: 1482

Wait on thread for UI activity

I have read a lot on threading but can't figure out a way to make this one work right. So it should really be obvious how to do this as it usually is with me (always missing the obvious) :p

Here's my problem (BTW, am working with WPF in C#):

I have a long running process i'm running on a separate thread while the UI stays responsinve and showing evolution. However, mid-process, i need to ask the user to confirm a value before proceeding. That's what i can't figure out, cause the window to confirm the value must be run in the UI thread and still return the value to the work thread so it can continue it's work.

So...

Long running process beeing run in work thread
Work thread waits for UI Thread
    UI thread shows the confirmation window
    User confirms/fixes value and closes the confirmation window
    UI thread sends result from confirmation window to work thread
work thread gets values from UI Thread (value was changed by user? to what?)
work thread continues long running process
Work thread gets values from confirmation window

I've already the work thread working well using ThreadPool - although am open to using threading in different ways (NET 4.5). Problem i am having is that if i send the confirmation window part to dispatcher my work thread won't wait for the results from the confirmation window. If i don't put in the dispatcher i get an exception about not beeing in an STA thread when the window constructor is called.

Any ideas welcome

Upvotes: 1

Views: 86

Answers (1)

BradleyDotNET
BradleyDotNET

Reputation: 61349

You probably don't want to block the worker thread waiting on UI (not saying you couldn't do it, but it would be messy).

A much simpler solution would be to split up your process into two threads; one that runs pre-user input, and one that runs after. You would prompt the user upon the first thread's completion (via a callback or event).

Something like (pseudo-code)

InitialThreadObject.Completed += () =>
  {
      PromptForUI();
      SecondThreadObject.Start();
  } 
InitialThreadObject.Start();

Obviously you would choose the completion notification mechanism based on your current code.

Upvotes: 1

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