How can I update the GUI with live results from a for loop?

Question

I am using for loop in my c# project.

I some cases I am iterating over 500,000 values - the GUI does not respond until the end of the loop.

Can I get the GUI to update inside the for loop?

for (int i = 0; i < 100000; i++)
{
    double s1 = rnd.NextDouble();
    double s2 = rnd.NextDouble();
    w = Math.Sqrt(-2 * Math.Log(s1)) * Math.Cos(2 * Math.PI * s2);
    listBox1.Items.Add(w.ToString());
}

Answer 1

The best way I have done this is by starting a thread to populate a control item with text for that you would need to call a method from inside the thread to populate the listbox and that requires a delegate method,

Declare a delegate method in your class,

delegate void SetListBoxDelg(string value);

then start a thread that will start this process of populating the listbox,

Thread t  = new Thread(StartProc);
   t.Start();

this is the thread code where you call the method to populate your listbox,

public void StartProc()
{
  for (int i = 0; i < 100000; i++)
  {
    double s1 = rnd.NextDouble();
    double s2 = rnd.NextDouble();
    w = Math.Sqrt(-2 * Math.Log(s1)) * Math.Cos(2 * Math.PI * s2);
    SetListBox(w.ToString());
  }
}

And here is the method that is called from inside of the thread,

private void SetListBox(string value)
{
  if (this.InvokeRequired)
  {
    SetListBoxDelg dlg = new SetListBoxDelg(this.SetListBox);
    this.Invoke(value);
    return;
  }
  listBox1.Items.Add(value);
}

Answer 2

Try this:

for (int i = 0; i < 100000; i++)
      {
            label.Text = i;
            double s1 = rnd.NextDouble();
            double s2 = rnd.NextDouble();
            w = Math.Sqrt(-2 * Math.Log(s1)) * Math.Cos(2 * Math.PI * s2);
            listBox1.Items.Add(w.ToString());

       }

Replace label.Text with your label's name.

Answer 3

Jason Hughes answered this above. Use the Refresh() of the control you are displaying your counter in:

for (int i = 0; i < 100000; i++)
{
    labelIteration.Text = i.ToString();
    labelIteration.Refresh();

    double s1 = rnd.NextDouble();
    double s2 = rnd.NextDouble();
    w = Math.Sqrt(-2 * Math.Log(s1)) * Math.Cos(2 * Math.PI * s2);
}

Answer 4

If it is single-threaded application you can get froze of you GUI. Try use Application.DoEvents() method in loop. For example:

for (int i = 0; i < 100000; i++)
{
    labelToShow.Text = i.ToString(); // live update of information on the GUI
    labelToShow.Invalidate();
    Application.DoEvents();

    double s1 = rnd.NextDouble();
    double s2 = rnd.NextDouble();
    w = Math.Sqrt(-2 * Math.Log(s1)) * Math.Cos(2 * Math.PI * s2);
}