Question

I have got a StartCommand Class:

public class StartCommand : ICommand
{
    public void Execute(object parameter)
    {
        //Fill Listview1
        ...
        //Here I want to increase the Progressbarvalue   

        //Fill Listview2
        ...
        //Here again and so far..       
    }
}

Execute Command will be executed, when clicking the Startbutton on my MainWindow.xaml (where’s also the progressBar).

What I want now, is updating the Progressbar on these places (look at Code), while the ListViews are loading. How do I set up the Backgroundworker?

I tried something like that:

public class StartCommand : ICommand
    {
        MainWindow mainWindow;

        public StartCommand(MainWindow mainWindow)
        {
             this.mainWindow = mainWindow
        }

        public void Execute(object parameter)
        {
            //Fill Listview1
            ...
            mainWindow.backgroundWorker1.RunWorkerAsync(10);  

            //Fill Listview2
            ...
            mainWindow.backgroundWorker1.RunWorkerAsync(20);      
        }
    }

MainWindow:

public partial class MainWindow : Window
{
    BackgroundWorker backgroundWorker1;

    public MainWindow()
    {
        InitializeComponent();
        InitializeBackgroundWorker();
    }

    private void InitializeBackgroundWorker()
    {
        backgroundWorker1.DoWork +=
            new DoWorkEventHandler(backgroundWorker1_DoWork);
        backgroundWorker1.RunWorkerCompleted +=
            new RunWorkerCompletedEventHandler(
        backgroundWorker1_RunWorkerCompleted);
        backgroundWorker1.ProgressChanged +=
            new ProgressChangedEventHandler(
        backgroundWorker1_ProgressChanged);
    }


    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        BackgroundWorker worker = sender as BackgroundWorker;
        e.Result = UpdateProgressBar((int)e.Argument, worker);
    }

    private int UpdateProgressBar(int value, BackgroundWorker worker)
    {
        worker.ReportProgress(value);
        return Convert.ToInt32(progressBar.Value);
    }

    private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {

    }

    private void backgroundWorker1_ProgressChanged(object sender,ProgressChangedEventArgs e)
    {
        progressBar.Value = e.ProgressPercentage;
    }
}

}

Thats not working (This is only some Copy/Paste arrangement, cause I have no idea on how to accomplish that, working first time with Threads in WPF). But maybe u got now a better sight, of what I’m looking for..

Answer 1

You have to choose: use one background worker to load all the listviews or use multiple background workers, each filling a listview.

Currently you are trying to force the backgroundworker to start working on another job before the previous job has finished.

To fix this quickly: put all the code to load the listviews in the DoWork handler.

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    BackgroundWorker worker = sender as BackgroundWorker;
    // fill listview1
    worker.ReportProgress(percentageDone);
    // fill listview2
    worker.ReportProgress(percentageDone);
    // fill listview3
    worker.ReportProgress(percentageDone);
}

To use multiple Backgroundworkers create multiple Backgroundworkers:

var bw1 = new BackgroundWorker();
bw1.DoWork += ...;
bw1.RunAsync(...);
var bw2 = new BackgroundWorker();
bw2.DoWork += ...;
bw2.RunAsync(...);
var bw3 = new BackgroundWorker();
bw3.DoWork += ...;
bw3.RunAsync(...);