當WPF中有很多UI更新時，ProgressRing會停滯不前？

Question

窗口中有一個TreeView。我想在事件中從ItemsSource加載TreeViewItems，同時顯示ProgressRing（MahApps.Metro.Controls）。

但ProgressRing總是卡住。

我使用多線程&調度過程中的ItemsSource負荷，也無法正常工作。

XAML：

... 
<Button Name="startButton" Content="Start" Click="Start"/> 
<controls:ProgressRing x:Name="p1" IsActive="False"></controls:ProgressRing> 
<TreeView x:Name="treeView1"></TreeView> 
... 

CS：

private void Start(object sender, EventArgs e) 
{ 
    TreeViewItem root = new TreeViewItem() { Header = "Root", IsExpanded = true }; 
    treeView1.Items.Add(root); 

    p1.IsActive = true; 

    Thread thread = new Thread(() => 
    { 
     // Main work 
     InitTree(root, "D:\\"); 

     startButton.Dispatcher.BeginInvoke(DispatcherPriority.ApplicationIdle, 
     (ThreadStart)delegate() { 
      p1.IsActive = false; 
     }); 
    }); 

    thread.Start(); 
} 

private void InitTree(TreeViewItem item, string dir) 
{ 
    string[] dirs = Directory.GetDirectories(dir); 

    foreach (string subdir in dirs) 
    { 
     startButton.Dispatcher.Invoke(DispatcherPriority.ApplicationIdle, 
     (ThreadStart)delegate() 
     { 
      TreeViewItem subItem = new TreeViewItem() { Header = subdir, IsExpanded= true }; 
      item.Items.Add(subItem); 
      InitTree(subItem, subdir); 
     }); 
    } 
} 

我已閱讀&嘗試：
http://msdn.microsoft.com/en-us/library/ms741870(v=vs.110).aspx
專業WPF編程，第31章多線程

Answer 1

贊GE

foreach (string subdir in dirs) 
{ 
    startButton.Dispatcher.Invoke(DispatcherPriority.ApplicationIdle, 
    (ThreadStart)delegate() 
    { 
     TreeViewItem subItem = new TreeViewItem() { Header = subdir, IsExpanded= true }; 
     item.Items.Add(subItem); 
     InitTree(subItem, subdir); 
    }); 
} 

到

​​

會更好。