How to modify UI from an another thread?

Question

Hi friends,

For testing and learning purposes, I tried to write a code which simulates some calculations. I used BackGroundWorker to avoid GUI freeze during calculation. My problem is that I want to make change in UI, for example, changing a button's text. I added it to DoWork section of my code. Consider that my operations order needs to be kept. There is runtime error says cross-thread exception. I think I have to use Invoke and Delegate for solving my problem. Please write me a code for solving this problem. I would learn from your code.

Thanks.

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            button1.Text = "processing";
            int sum = 0;
            for (int i = 0; i <= 100; i++)
            {
                Thread.Sleep(100);
                sum = sum + i;
                backgroundWorker1.ReportProgress(i);
                if (backgroundWorker1.CancellationPending)
                {
                    e.Cancel = true;
                    backgroundWorker1.ReportProgress(0);
                    return;
                }
            }
            e.Result = sum;
        }


        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
            label1.Text = e.ProgressPercentage + "%";

        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                label1.Text = "Process canceled";
            }
            else if (e.Error != null)
            {
                label1.Text = e.Error.Message;
            }
            else
            {
                label1.Text = "Result: " + e.Result.ToString();
            }

        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (!backgroundWorker1.IsBusy)
            {
                backgroundWorker1.RunWorkerAsync();
            }
            else
            {
                MessageBox.Show("Busy processing!. Please wait...");
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            if (backgroundWorker1.IsBusy)
            {
                backgroundWorker1.CancelAsync();
            }
            else
            {
                label1.Text = "No operation is running to cancel.";
            }
        }
    }