Thread and UI in WPF

Question

This is XAML with a button and 3 progress bars

TestBtn

this is the thread to update the 3 progress bars..

Thread thread = new Thread(
                                new ThreadStart(
                                    delegate()
                                    {
                                        progressBar1.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal,
                                                                                        new Action(
                                                                                            delegate()
                                                                                            {
                                                                                                int x=0;
                                                                                                while(true)
                                                                                                {

                                                                                                    x++;
                                                                                                    Thread.Sleep(50);
                                                                                                progressBar1.Value = x;
                                                                                                    if (x>100)
                                                                                                    {
                                                                                                        break;
                                                                                                    }
                                                                                                }
                                                                                                MessageBox.Show(" Complete ");
                                                                                            }
                                                                                    ));


                                        progressBar2.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal,
                                                                                        new Action(
                                                                                            delegate()
                                                                                            {
                                                                                                int y = 0;
                                                                                                while (true)
                                                                                                {
                                                                                                    Thread.Sleep(50);
                                                                                                    y = y + 2;
                                                                                                    progressBar2.Value = y;
                                                                                                    if (y > 100)
                                                                                                    {
                                                                                                        break;
                                                                                                    }
                                                                                                }
                                                                                                MessageBox.Show(" Complete ");
                                                                                            }
                                                                                    ));



                                        progressBar3.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal,
                                                                                       new Action(
                                                                                           delegate()
                                                                                           {

                                                                                               int z = 0;
                                                                                               while (true)
                                                                                               {
                                                                                                   Thread.Sleep(50);
                                                                                                   z = z + 3;
                                                                                                   progressBar3.Value = z;
                                                                                                   if (z > 100)
                                                                                                   {
                                                                                                       break;
                                                                                                   }
                                                                                               }
                                                                                               MessageBox.Show(" Complete ");
                                                                                           }
                                                                                   ));
 )
            );//end of thread

            thread.Start();

        }

when i run this, all the 3 progress bars are updated to 100 percent at last(all are reaching directly to 100 at the same time) and it is not showing any increments from 0 to 100.

What i need is a thread with 3 item , where each will update the UI at the same time.So here at the same time all these 3 progress bars have to start and they have finish according to the loop.. (When we are copying files, in the UI , copying description is changing at the same time progress bar has to be updated.I want similar to that.So i think if i can understand a small example like this, then i can sort the required one)

pls correct me, where i cam wrong. Thnks Kaja

Answer 1

You could always use a BackgroundWorker, example by Figo Fei (altered slightly):

private void button1_Click(object sender, EventArgs e)
{
    progressBar1.Maximum = 100;
    backgroundWorker1.WorkerReportsProgress = true;
    backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
    backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
    backgroundWorker1.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorker1_RunWorkerCompleted);
    backgroundWorker1.RunWorkerAsync();
}

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    // This would be the load process, where you put your Load methods into.
    // You would report progress as something loads.

    for (int i = 0; i < 100; i++)
    {
        Thread.Sleep(100);
        backgroundWorker1.ReportProgress(i); //run in back thread
    }
}

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) //call back method
{
    progressBar1.Value = e.ProgressPercentage;
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) //call back method
{
    progressBar1.Value = progressBar1.Maximum;
}

One of the lovely thing about the BackgroundWorker is that it does run all the "heavy lifting" on a worker thread, but reports back to the UI thread. So by using the above code to your own needs, you should solve your problem.