Question

I’m trying to display a WPF Popup that will indicate some progress:

The problem is that the popup is not displayed before the Thread.Sleep completes, this is only an example, in my program I have complex IO and DB logic that needs to be executed synchronously and the progress needs to be displayed on the popup.

Here is my example code:

    private ProgressBar m_ProgressBar;

    private void buttonDoWork_Click(object sender, RoutedEventArgs e)
    {
        var progressPopup = new Popup { PopupAnimation = PopupAnimation.Fade, StaysOpen = true, Height = 150, Width = 260 };
        m_ProgressBar = new ProgressBar
                              {
                                  HorizontalAlignment = HorizontalAlignment.Stretch,
                                  VerticalAlignment = VerticalAlignment.Stretch
                              };

        progressPopup.Child = m_ProgressBar;

        progressPopup.IsOpen = true;

        Thread.Sleep(5000);
        this.m_ProgressBar.Value = 25;
        Thread.Sleep(5000);
        this.m_ProgressBar.Value = 50;
        Thread.Sleep(5000);
        this.m_ProgressBar.Value = 75;
        Thread.Sleep(5000);
        this.m_ProgressBar.Value = 100;
    } 

Update

The problem is that the logic which blocks the main thread needs to stay on the main thread, there is nothing else I can do. Is there a way to run the popup on a separate thread?

Answer 1

Use

Dispather.BeginInvoke(new Action(()=>{ this.m_ProgressBar.Value = progress; });

to update the progress bar on the UI thread.

In general you shouldn’t weave your code like this (UI and logic mixed up)

You could use the BackgroundWorker or a Task that reports progress by raising an event.

EDIT

To clarify: expose the data that changes from your ViewModel/code and raise events (PropertyChanged) so you can bind the UI to those values. That will allow you to keep UI and code separated.