如何获取在backgroundworker wpf c# mvvm上运行的进度值

Question

I am developing wpf application using MVVM Prism. I got four views , MainWindow, ViewB, ViewC and ViewD and all are attached with their respective ViewModel. I initialized the backgroundworker at application start. see the following background worker class.

 public class BackGroundThread
    {
        public BackgroundWorker bgWrk;
        public bool stopStatus;
        public int GetPercent;

        public BackGroundThread()
        {
            bgWrk = new BackgroundWorker();

            bgWrk.RunWorkerCompleted += backgroundWorker_RunWorkerCompleted;
            bgWrk.ProgressChanged += backgroundWorker_ProgressChanged;
            bgWrk.DoWork += bw_DoWork;
            bgWrk.WorkerReportsProgress = true;

        }

        public void backgroundWorker_RunWorkerCompleted(object sender,RunWorkerCompletedEventArgs e) { 

        }

        public void backgroundWorker_ProgressChanged(object sender,ProgressChangedEventArgs e)
        {
            Overall.EverythingOk = e.ProgressPercentage.ToString();

        }

        public void bw_DoWork(object sender, DoWorkEventArgs e)
        {
            int i = 1;


            while (!stopStatus)
            {

                GetPercent = I;

                if (i == int.MaxValue)
                    i = 0;
                    i = i + 1;
            }
        }
    }

I called it from MainWindow.xaml.cs and start background worker.

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();            
        ViewModel.MainWindowsViewModel viewModel = new ViewModel.MainWindowsViewModel();
        this.DataContext = viewModel;
        BackGroundThread bgT = new BackGroundThread();
        bgT.bgWrk.RunWorkerAsync();
    }  
}

How can i call the GetPercent variable from the rest of the view? For example, when i navigate to ViewC, ViewC show the real time value using Label or TextBlock (Value is keep increasing.). Then i go to ViewB, ViewB also show real time increment of GetPercent variable.

Any help, really appreciate it.

Thanks

Answer 1

This is the best scenario to use events and delegates.In your BackGroundThread create a EventHandler and listen to that event in other class.

 public class ProgressBarEventArgs:EventArgs 
 {
        public int CompletedPercent{get;set;}
 }

public class BackgroundThread
{
    public static event EventHandler<ProgressBarEventArgs> CompletedEventHandler;

    public void backgroundWorker_ProgressChanged(object sender,ProgressChangedEventArgs e)
    {
        Overall.EverythingOk = e.ProgressPercentage.ToString();
        if (CompletedEventHandler != null)
        {
            CompletedEventHandler(sender, new ProgressBarEventArgs { CompletedPercent = e.ProgressPercentage });

        }

    }

}

You can access this value in your other view's viewmodel

    class AnotherviewModel
    {
        BackgroundThread.CompletedEventHandler+=w_ChangedEventHandler;
        void w_ChangedEventHandler(object sender, ProgressBarEventArgs e)
        {
          // get e.Percentage
        }
    }

likewise you can do this in as many classes you want.

Answer 2

Straight from the main BackgroudWorker page on MSDN
You need to make a call to worker.ReportProgress(...);

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = sender as BackgroundWorker;

    for (int i = 1; i <= 10; i++)
    {
        if (worker.CancellationPending == true)
        {
            e.Cancel = true;
            break;
        }
        else
        {
            // Perform a time consuming operation and report progress.
            System.Threading.Thread.Sleep(500);
            worker.ReportProgress(i * 10);
        }
    }
}