Question

I am working on a WPF project where I have to import data from a lot of single files.
The actual importing of those files and the data in them is being done in a backgroundworker doWork method.
It works like a charm, does the job and updating a progress bar also works perfectly.

Now though, depending on what I encounter in those files, I occasionally need to get a decision from the User before I can proceed processing the current file.

What is the best way to open a window/dialog, getting the values set in there back into the backgroundworker.doWork method and continue processing?

Is that even possible with a backgroundworker or do I need to keep that processing logic in the main/UI thread and update the progress bar from there somehow?

I hope some of you can give me some hints or point me to other resources since I have not found much useful information for my specific problem.

Answer 1

Background worker works in a different thread. You can not invoke UI directly from a background thread. One way of achiving what you are trying to do is by using a flag and Dispatcher to invoke UI for user input

    bool WaitFor_Input = false; //flag to indicate user input status

    private void ThreadRun()
    {
        //THIS IS IN Background worker thread
        //do task
        WaitFor_Input = true;
        //ask for user input
        Dispatcher.BeginInvoke(new Action(Show_Dialogue), null);
        while (WaitFor_Input); //Background worker waits untill user input is complete
        //continue further processing
    }

    private void Show_Dialogue()
    {
        //THIS IS IN UI THREAD
        //show your dialogue box here, update data variables
        //finally set
        WaitFor_Input = false;
    }

Keeping processing logic in a background thread is actually a good idea.