c# - 当 WPF 中的大量 UI 更新时，ProgressRing 卡住了？

Question

Window 中有一个TreeView。我想在事件中从 ItemsSource 加载 TreeViewItems，同时显示 ProgressRing(MahApps.Metro.Controls)。

但是 ProgressRing 总是卡住。

我用多线程&Dispatcher进程加载ItemsSource，也不行。

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);
        });
    }
}

我读过并试过的内容:
http://msdn.microsoft.com/en-us/library/ms741870(v=vs.110).aspx
专业WPF编程，第31章多线程

Answer 1

改变

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

foreach (string subdir in dirs)
{
    TreeViewItem subItem = new TreeViewItem() { Header = subdir, IsExpanded= true };

    startButton.Dispatcher.Invoke(DispatcherPriority.ApplicationIdle,
    (ThreadStart)delegate()
    {
        item.Items.Add(subItem);
    });

    InitTree(subItem, subdir);
}

会更好。