Question

I have a windows forms program with a form MainForm. On a button press I start a code that runs (pulses) on every 0.5secs on another thread. I want to modify many things, like labels, progressbars on my MainForm, from the Pulse method. How is this possible?
So I would like to know, how to interract with variables, values, in that thread, and the MainForm. Modify each other, etc..

On foo button click, I tell my pulsator to start.
Pulsator.Initialize();

Here is the Pulsator class:

public static class Pulsator
{
    private static Thread _worker;

    public static void Initialize()
    {
        _worker = new Thread(Pulse);
        _worker.IsBackground = true;
        _worker.Start();
    }

    public static void Close()
    {
        if (_worker != null)
        {
            _worker.Abort();
            while (_worker.IsAlive || _worker.ThreadState != ThreadState.Stopped)
            {
               //closing
            }
        }
    }

    public static void Pulse()
    {
        if (_worker != null)
        {
            while (true)
            {
                SomeOtherClass.Pulse();
                Thread.Sleep(500);
            }
        }
        else
        {
            SomeOtherClass.Pulse(); // yeah I know this doesnt needed
        }
    }
}

SomeOtherClass Pulse method looks like :

    public static void Pulse()
    {
        //here I will have several values, variables, and I want to show results,
        // values on my MainForm, like:
        Random random = new Random();
        MainForm.label1.Text = random.Next(123,321).ToString(); // I hope you know what I mean
    }

Of course it’s much complicated, it’s just a silly example.

Answer 1

As others already mentioned, you have to use Control.Invoke to change the UI controls from the background thread.

Another option is to use System.ComponentModel.BackgroundWorker (it’s available in the form designer toolbox). You could then take a regular forms timer, to call the RunWorkerAsync-Method and do your background work in the DoWork event handler, which is automatically called from another thread.

From there, you can hand data back to the main thread, by calling ReportProgress. This will raise the ProgressChanged event in the main thread, where you are free to update all your UI controls.