为此您需要一个异步ShowDialog方法

public static class WindowExtensions
{
    public static async Task<bool?> ShowDialogAsync(this Window window)
    {
        await Task.Yield(); // this is the magic ;o)
        return window.ShowDialog();
    }
}

现在您可以做

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private async void Button_Click( object sender,RoutedEventArgs e )
    {
        var dialog = new WaitWindow();
        var task = WorkAsync( dialog.Progress );
        var dialogTask = dialog.ShowDialogAsync();
        await task;
        dialog.Close();
        await dialogTask;
    }

    private async Task WorkAsync( IProgress<double> progress )
    {
        for ( int i = 0; i < 100; i++ )
        {
            progress.Report( i );
            await Task.Delay( 25 ).ConfigureAwait( false );
        }
    }
}

WaitWindow类

public partial class WaitWindow : Window
{
    public WaitWindow()
    {
        InitializeComponent();

        Progress = new Progress<double>( progress => ProgressHandler( progress ) );
    }

    public IProgress<double> Progress { get; }

    private void ProgressHandler( double progress )
    {
        progressBar.Value = progress;
    }
}

我会研究IProgress T界面。

创建一个类，该类将保存您的进度信息，例如进度值，最大值，最小值（如果需要）。

public class MyProgressReport
{
    public int ProgressValue{ get; set; }
}

在类中某个位置的ReportProgress方法将获取进度报告并更新用户界面上的信息

private void ReportProgress(MyProgressReport progressReport)
{
    //your dialog window needs a property to handle progress
    //or just access its Bar.Value like you do in your example
    dialogWindow.Progress = progressReport.ProgressValue;
}

最后是显示对话框/完成工作的方法。告诉它您想使用Action做什么。

public async void ShowBusyWindow(Action<IProgress<MyProgressReport>> operation)
{
    //ReportProgress method will be called every time you want to update progress
    var progressCallback = new Progress<MyProgressReport>(ReportProgress);

    progressWindow = new Window();

    var workTask = DoWork(operation(progressCallback));
    progressWindow.ShowDialog(); //program will wait here until window is closed
    await workTask; // usually not needed since workTask will be done by the time this is hit,this is where exceptions will be thrown
}

private async Task DoWork(Action operation)
{
    //you should also check for exceptions here and close window
    await Task.Run(operation);
    //close window when done
    progressWindow.Close();
}

最后，要使用它，您只需像这样调用Show：

ShowBusyWindow((progress) => 
{
    //do work here and update progress
    var report = new MyProgressReport();

    for(int i=0; i<100; i++)
    {
        report.ProgressValue = i;
        progress.Report(report);
        Thread.Sleep(500);
    }
});

我还没有运行它（可能会出现错误），但是我使用了几乎相同的方法，在进度报告类和异常处理上有更多的属性。