Using Indeterminate Progressbar with Backgroundworker in WPF

Question

I created a little tool for importing and converting data from one database to another. Since this takes a lot of time, I wanted to display some kind of progress for the user with a indeterminate progressbar. As long as the import is running, the progressbar should be running too. I used this site as reference : The ProgressBar control but I got trouble understanding the role of the DoWork-Method since the option for a indeterminate progressbar is set once.

I came up with a solution that works halfway, I can't stop the animation after the import's done. Could someone help me out?

XAML:

 <ProgressBar Minimum="{Binding Path=Minimum}" Maximum="100" IsIndeterminate="{Binding Path=IsIndeterminate}" Height="20" Grid.Column="2" Grid.Row="5" Grid.ColumnSpan="2"/>

ViewModel:

public void StartImportThread()
    {
        ButtonsEnabled = false;
        var th = new Thread(new ThreadStart(StartImport));
        th.IsBackground = true;
        th.Start();
    }
public void StartImport()
    {
        _threadDispatcher = Dispatcher.CurrentDispatcher;
        BackgroundWorker worker = new BackgroundWorker();
        worker.WorkerReportsProgress = true;
        worker.WorkerSupportsCancellation = true;
        worker.DoWork += worker_DoWork;
        worker.RunWorkerCompleted += worker_Complete;

        worker.RunWorkerAsync();

        // Doing Import Stuff
        worker.CancelAsync(); // Import finished
        ButtonsEnabled=true;
    }
    void worker_DoWork(object sender, DoWorkEventArgs e)
    {
       // while(true)
     //  {
          Minimum = 0;
          IsIndeterminate = true;
    //   }


    }


    private void worker_Complete(object sender, RunWorkerCompletedEventArgs e)
    {
       // if (e.Cancelled)
       // {
            IsIndeterminate = false;
            Minimum = 100;  
       // }

    }

Answer 1

Here is what works for me. RelayCommand and ViewModelBase are from MvvmLight library, the DoWorkCommand is called by a button:

        <Button Name="BtnReload" Command="{Binding DoWorkCommand}" Width="75" Height="25"/>
        <ProgressBar Minimum="{Binding Path=Minimum}" Maximum="100" IsIndeterminate="{Binding Path=IsIndeterminate}" Height="20"/>



   public class MainViewModel : ViewModelBase {

    private RelayCommand _doWorkCommand;
    private bool _isIndeterminate;
    private int _minimum;
    private Dispatcher _threadDispatcher;


    public int Minimum {
        get { return _minimum; }
        set {
            _minimum = value;
            RaisePropertyChanged(nameof(Minimum));
        }
    }

    public bool IsIndeterminate {
        get { return _isIndeterminate; }
        set {
            _isIndeterminate = value;
            RaisePropertyChanged(nameof(IsIndeterminate));
        }
    }

    public MainViewModel(IDataService dataService) {

    }

    public void StartImportThread() {
        //  ButtonsEnabled = false;
        var th = new Thread(new ThreadStart(StartImport));
        th.IsBackground = true;
        th.Start();
    }

    public void StartImport() {
        _threadDispatcher = Dispatcher.CurrentDispatcher;
        BackgroundWorker worker = new BackgroundWorker();
        worker.WorkerReportsProgress = true;
        worker.WorkerSupportsCancellation = true;
        worker.DoWork += worker_DoWork;
        worker.RunWorkerCompleted += worker_Complete;

        worker.RunWorkerAsync();

        // Doing Import Stuff
        worker.CancelAsync(); // Import finished
        //   ButtonsEnabled = true;

    }

    void worker_DoWork(object sender, DoWorkEventArgs e) {
        Minimum = 0;
        IsIndeterminate = true;
        //for (int i = 0; i < 30; i++) {
        //    Thread.Sleep(100);
        //}     
    }

    void worker_Complete(object sender, RunWorkerCompletedEventArgs e) {
        IsIndeterminate = false;
        Minimum = 100;
    }

    public RelayCommand DoWorkCommand => _doWorkCommand ??
        (_doWorkCommand = new RelayCommand(() => StartImportThread()));

}