Question

I have a label and canvas representing a coordinate system. In the canvas there is a node, which should change it’s place every time a calculation is made. This is done until a specific stopping criteria is meet.

I also have a label containing coordinate info for the note. I want to be able to see the node and label update on every iteration(every time the calculation is made).

I have looked a the dispatcher, but my GUI will only update when the calculations are done. Below is what I have tried doing with the Dispatcher for the label.

While(notDone = true){
//Calculations made here

Application.Current.Dispatcher.BeginInvoke(
                    DispatcherPriority.Background,
                    new Action(() => this.aLabel.Text = aString ));
}

I have been looking at solutions for similar problems and some solutions involve threads. Do I have to use threads to update my GUI?

Answer 1

Just create delegate and event for handling information changes

public delegate void SomeInfoChangeDelegate(object o);
public event SomeInfoChangeDelegate InfoChangeEvent = null;

Assign listener to event and start thread w/ calculations

InfoChangeEvent += new SomeInfoChangeDelegate(OnInfoChanged);
Thread t = new Thread(new ParameterizedThreadStart(SomeWorkerThread));
t.Start();

Make calculation thread and event listener

    void OnInfoChanged(object o)
    {
        // Update label
    }

    protected void SomeWorkerThread(object o)
    {
        int i = 0;
        while(true)
        {
            if( i % 10 == 0 )
            {
                if(InfoChangeEvent != null)
                {
                    InfoChangeEvent(i);
                }
            }
            Thread.Sleep(1000);
            i++;
        }
    }

And don’t forget to stop thread 🙂