Question

I would like to achieve this:

1. Create a new window, which is just a spinning loader and some static text, and display it.
2. Do some computation on the UI thread (it has to be done there)
3. Close the loader window

Currently, when I call .Show() on the loader window, it doesnt load at all, it just hangs out as a blank window (the UI thread is blocked, which I dont want)

What can I do to enable the loader window to display its contents at the same time my computation is done?

private void CopyToClipboard(object sender, RoutedEventArgs e)
    {
        var selected = mDataGrid.SelectedItem;
        var selectedIndex = mDataGrid.SelectedIndex;
        var progressWindow = mProgressDialog.Create(this,"Copying data to clipboard");
        progressWindow.Show();
        try
        {

            mDataGrid.ClipboardCopyMode = DataGridClipboardCopyMode.IncludeHeader;
            mDataGrid.SelectionMode = DataGridSelectionMode.Extended;
            mDataGrid.SelectAllCells();  // SLOW !!!!
            ApplicationCommands.Copy.Execute(null, mDataGrid); //SLOW !!!!
        }
        catch (Exception ex)
        {
            mLog.Error("Copying to clipboard", ex);
            MessageBox.Show("Error while copying to clipboard");
        }
        finally
        {
            mDataGrid.SelectionMode = DataGridSelectionMode.Single;
            mDataGrid.UnselectAllCells();
            this.Select(selectedIndex, selected);
            progressWindow.Close();
        }
    }

Answer 1

Only thing I was able to achieve is this:

progressWindow.Show();
this.DoEvents();


public static void DoEvents(this Window _)
    {
        Application.Current.Dispatcher.Invoke(DispatcherPriority.Background,
                                              new Action(delegate { }));
    }

The “loader window” gets at least displayed, so the user knows something is happening. It usually lasts under a second, so this solution is acceptable to me.