为什么MahApps.Metro ShowProgressAsync对话框意外重绘？ （总是灰色的）

Question

So, I'm guessing a bit, but it looks like my Mahapps.Metro ShowProgressAsync dialog box is redrawing very quickly, so it always looks greyed out.

I have a program that is looking through a document for certain matches based on regex, and I've set up a progress bar, but the dialog just greys out the main application, and then just shows the dialog as grey (like it's loading it over and over very quickly, or freezing).

If I put some sort of stop in there, like a messagebox, then everything shows fine. I don't think my code should be redrawing the dialog every time. I thought it should only be updating the progress bar. Here's my code.

In this example code, instead of showing the logic where I add a page number to a list, I just added the number 42 over and over, just to make it shorter

    private async void RegexMatchProgressBar(Regex regex, string myText, Microsoft.Office.Interop.Word.Document myDoc)
    {
        int charCount = myDoc.Application.ActiveDocument.Characters.Count;

        var myProgressAsync = await this.ShowProgressAsync("WAIT WHILE WE DO STUFF!", "Searching...");
        myProgressAsync.Maximum = charCount;
        myProgressAsync.Minimum = 0;

        Dictionary<String, List<int>> table = new Dictionary<string, List<int>>();
        foreach (Match match in regex.Matches(myText))
        {
            if (!table.ContainsKey(match.Value))
            {
                List<int> page = new List<int>();
                page.Add(42);
                table.Add(match.Value, page);
                myProgressAsync.SetProgress((double)match.Index);

            }
        }
        myProgressAsync.SetProgress(charCount);
        await myProgressAsync.CloseAsync();
    }

Answer 1

Your Operation need to be on a different Thread:

private async void RegexMatchProgressBar(Regex regex, string myText, Microsoft.Office.Interop.Word.Document myDoc)
{
    int charCount = myDoc.Application.ActiveDocument.Characters.Count;

    var myProgressAsync = await this.ShowProgressAsync("WAIT WHILE WE DO STUFF!", "Searching...");
    myProgressAsync.Maximum = charCount;
    myProgressAsync.Minimum = 0;

    await Task.Run(() => 
    {
        Dictionary<String, List<int>> table = new Dictionary<string, List<int>>();
        foreach (Match match in regex.Matches(myText))
        {
            if (!table.ContainsKey(match.Value))
            {
                List<int> page = new List<int>();
                page.Add(42);
                table.Add(match.Value, page);
                myProgressAsync.SetProgress((double)match.Index);

            }
        }

        myProgressAsync.SetProgress(charCount);
    });

    await myProgressAsync.CloseAsync();
}

I dont know if this is intentional but this Method does a "Fire and Forget" async void . I would suggest to change the Method signature to async task to await it on the other side. Further more the Exception will be handled that way : Exception Handling