C# 在树视图中加载一堆项目时WPF UI线程冻结_C#_.net_Wpf

C# 在树视图中加载一堆项目时WPF UI线程冻结

c# .net wpf

C# 在树视图中加载一堆项目时WPF UI线程冻结,c#,.net,wpf,C#,.net,Wpf,在过去的几个月里，我在TreeView上玩了很多，现在我开始讨论UI冻结问题。当您有大量的项，并且这些项的数据部分创建得非常快，但创建树视图项并将其可视化（必须在UI线程上完成）需要一段时间时，就会出现这种情况让我们以Shell浏览器和C:\Windows\System32目录为例。（我为此修改了解决方案。）此目录有约2500个文件和文件夹 DataItem和可视化加载是在不同的线程中实现的，但由于文件和目录信息读取速度很快，因此没有任何好处。应用程序在创建树视图项并使其可见时冻结。我试过：

在过去的几个月里，我在TreeView上玩了很多，现在我开始讨论UI冻结问题。当您有大量的项，并且这些项的数据部分创建得非常快，但创建树视图项并将其可视化（必须在UI线程上完成）需要一段时间时，就会出现这种情况

让我们以Shell浏览器和C:\Windows\System32目录为例。（我为此修改了解决方案。）此目录有约2500个文件和文件夹

DataItem和可视化加载是在不同的线程中实现的，但由于文件和目录信息读取速度很快，因此没有任何好处。应用程序在创建树视图项并使其可见时冻结。我试过：

在加载项目时，为UI线程设置不同的DispatcherPriority，例如窗口与DispatcherPriority.ContextIdle交互（我可以移动它），但随后项目的加载速度非常慢

创建并可视化块中的项目，比如一次100个项目，但没有任何好处，UI线程仍然处于冻结状态

我的目标是，应用程序将是交互式的，而加载这些项目的！目前，我只有一个办法来解决这个问题，那就是实现我自己的控制，跟踪窗口大小、滚动条位置并只加载可查看的项目，但这并不容易，我不确定最终性能是否会更好：）

也许有人知道如何使应用程序在加载一堆可视化项目时具有交互性

代码：

public partial class DemoWindow
{
    public DemoWindow()
    {
        InitializeComponent();
        this.Loaded += DemoWindow_Loaded;
    }

    private readonly object _dummyNode = null;

    delegate void LoaderDelegate(TreeViewItem tviLoad, string strPath, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem);       
    delegate void AddSubItemDelegate(TreeViewItem tviParent, IEnumerable<ItemToAdd> itemsToAdd);

    // Gets an IEnumerable for the items to load, in this sample it's either "GetFolders" or "GetDrives"
    // RUNS ON:  Background Thread
    delegate IEnumerable<ItemToAdd> DEL_GetItems(string strParent);

    void DemoWindow_Loaded(object sender, RoutedEventArgs e)
    {
        var tviRoot = new TreeViewItem();

        tviRoot.Header = "My Computer";
        tviRoot.Items.Add(_dummyNode);
        tviRoot.Expanded += OnRootExpanded;
        tviRoot.Collapsed += OnItemCollapsed;
        TreeViewItemProps.SetItemImageName(tviRoot, @"Images/Computer.png");

        foldersTree.Items.Add(tviRoot);
    }

    void OnRootExpanded(object sender, RoutedEventArgs e)
    {
        var treeViewItem = e.OriginalSource as TreeViewItem;

        StartItemLoading(treeViewItem, GetDrives, AddItem);

    }

    void OnItemCollapsed(object sender, RoutedEventArgs e)
    {
        var treeViewItem = e.OriginalSource as TreeViewItem;

        if (treeViewItem != null)
        {
            treeViewItem.Items.Clear();
            treeViewItem.Items.Add(_dummyNode);
        }

    }

    void OnFolderExpanded(object sender, RoutedEventArgs e)
    {
        var tviSender = e.OriginalSource as TreeViewItem;

        e.Handled = true;
        StartItemLoading(tviSender, GetFilesAndFolders, AddItem);
    }

    void StartItemLoading(TreeViewItem tviSender, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem)
    {
        tviSender.Items.Clear();

        LoaderDelegate actLoad = LoadSubItems;

        actLoad.BeginInvoke(tviSender, tviSender.Tag as string, actGetItems, actAddSubItem, ProcessAsyncCallback, actLoad);
    }

    void LoadSubItems(TreeViewItem tviParent, string strPath, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem)
    {
            var itemsList = actGetItems(strPath).ToList();

            Dispatcher.BeginInvoke(DispatcherPriority.Normal, actAddSubItem, tviParent, itemsList);
    }



    // Runs on Background thread.
    IEnumerable<ItemToAdd> GetFilesAndFolders(string strParent)
    {
        var list = Directory.GetDirectories(strParent).Select(itemName => new ItemToAdd() {Path = itemName, TypeOfTheItem = ItemType.Directory}).ToList();

        list.AddRange(Directory.GetFiles(strParent).Select(itemName => new ItemToAdd() {Path = itemName, TypeOfTheItem = ItemType.File}));

        return list;
    }

    // Runs on Background thread.
    IEnumerable<ItemToAdd> GetDrives(string strParent)
    {
        return (Directory.GetLogicalDrives().Select(x => new ItemToAdd(){Path = x, TypeOfTheItem = ItemType.DiscDrive}));
    }

    void AddItem(TreeViewItem tviParent, IEnumerable<ItemToAdd> itemsToAdd)
    {
        string imgPath = "";

        foreach (ItemToAdd itemToAdd in itemsToAdd)
        {
            switch (itemToAdd.TypeOfTheItem)
            {
                case ItemType.File:
                    imgPath = @"Images/File.png";
                    break;
                case ItemType.Directory:
                    imgPath = @"Images/Folder.png";
                    break;
                case ItemType.DiscDrive:
                    imgPath = @"Images/DiskDrive.png";
                    break;
            }

            if (itemToAdd.TypeOfTheItem == ItemType.Directory || itemToAdd.TypeOfTheItem == ItemType.File)
                IntAddItem(tviParent, System.IO.Path.GetFileName(itemToAdd.Path), itemToAdd.Path, imgPath);
            else
                IntAddItem(tviParent, itemToAdd.Path, itemToAdd.Path, imgPath);                 
        }            
    }

    private void IntAddItem(TreeViewItem tviParent, string strName, string strTag, string strImageName)
    {
        var tviSubItem = new TreeViewItem();
        tviSubItem.Header = strName;
        tviSubItem.Tag = strTag;
        tviSubItem.Items.Add(_dummyNode);
        tviSubItem.Expanded += OnFolderExpanded;
        tviSubItem.Collapsed += OnItemCollapsed;

        TreeViewItemProps.SetItemImageName(tviSubItem, strImageName);

        tviParent.Items.Add(tviSubItem);
    }

    private void ProcessAsyncCallback(IAsyncResult iAR)
    {
        // Call end invoke on UI thread to process any exceptions, etc.
        Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal, (Action)(() => ProcessEndInvoke(iAR)));
    }

    private void ProcessEndInvoke(IAsyncResult iAR)
    {
        try
        {
            var actInvoked = (LoaderDelegate)iAR.AsyncState;
            actInvoked.EndInvoke(iAR);
        }
        catch (Exception ex)
        {
            // Probably should check for useful inner exceptions
            MessageBox.Show(string.Format("Error in ProcessEndInvoke\r\nException:  {0}", ex.Message));
        }
    }

    private struct ItemToAdd
    {
        public string Path;
        public ItemType TypeOfTheItem;
    }

    private enum ItemType
    {
        File,
        Directory,
        DiscDrive
    }
}

public static class TreeViewItemProps
{
    public static string GetItemImageName(DependencyObject obj)
    {
        return (string)obj.GetValue(ItemImageNameProperty);
    }

    public static void SetItemImageName(DependencyObject obj, string value)
    {
        obj.SetValue(ItemImageNameProperty, value);
    }

    public static readonly DependencyProperty ItemImageNameProperty;

    static TreeViewItemProps()
    {
        ItemImageNameProperty = DependencyProperty.RegisterAttached("ItemImageName", typeof(string), typeof(TreeViewItemProps), new UIPropertyMetadata(string.Empty));
    }
}

<Window x:Class="ThreadedWpfExplorer.DemoWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:ThreadedWpfExplorer"
    Title="Threaded WPF Explorer" Height="840" Width="350" Icon="/ThreadedWpfExplorer;component/Images/Computer.png">
    <Grid>
        <TreeView x:Name="foldersTree">
            <TreeView.Resources>
                <Style TargetType="{x:Type TreeViewItem}">
                    <Setter Property="HeaderTemplate">
                        <Setter.Value>
                            <DataTemplate DataType="ContentPresenter">
                                <Grid>
                                    <StackPanel Name="spImg" Orientation="Horizontal">
                                        <Image Name="img"  
                                               Source="{Binding 
                                                           RelativeSource={RelativeSource 
                                                                            Mode=FindAncestor, 
                                                                            AncestorType={x:Type TreeViewItem}},
                                                                            Path=(local:TreeViewItemProps.ItemImageName)}" 
                                               Width="20" Height="20"  Stretch="Fill" VerticalAlignment="Center" />
                                        <TextBlock Text="{Binding}" Margin="5,0" VerticalAlignment="Center" />
                                    </StackPanel>
                                </Grid>

                            </DataTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </TreeView.Resources>
        </TreeView>
    </Grid>
</Window>

private const int rangeToAdd = 100;

void LoadSubItems(TreeViewItem tviParent, string strPath, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem)
{
    var itemsList = actGetItems(strPath).ToList();


    int index;
    for (index = 0; (index + rangeToAdd) <= itemsList.Count && rangeToAdd <= itemsList.Count; index = index + rangeToAdd)
    {
        Dispatcher.BeginInvoke(DispatcherPriority.Normal, actAddSubItem, tviParent, itemsList.GetRange(index, rangeToAdd));
    }

    if (itemsList.Count < (index + rangeToAdd) || rangeToAdd > itemsList.Count)
    {
        var itemsLeftToAdd = itemsList.Count % rangeToAdd;

        Dispatcher.BeginInvoke(DispatcherPriority.Normal, actAddSubItem, tviParent, itemsList.GetRange((rangeToAdd > itemsList.Count) ? index : index - rangeToAdd, itemsLeftToAdd));
    }
}

可以在那里找到完整的解决方案：

节目：

public partial class DemoWindow
{
    public DemoWindow()
    {
        InitializeComponent();
        this.Loaded += DemoWindow_Loaded;
    }

    private readonly object _dummyNode = null;

    delegate void LoaderDelegate(TreeViewItem tviLoad, string strPath, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem);       
    delegate void AddSubItemDelegate(TreeViewItem tviParent, IEnumerable<ItemToAdd> itemsToAdd);

    // Gets an IEnumerable for the items to load, in this sample it's either "GetFolders" or "GetDrives"
    // RUNS ON:  Background Thread
    delegate IEnumerable<ItemToAdd> DEL_GetItems(string strParent);

    void DemoWindow_Loaded(object sender, RoutedEventArgs e)
    {
        var tviRoot = new TreeViewItem();

        tviRoot.Header = "My Computer";
        tviRoot.Items.Add(_dummyNode);
        tviRoot.Expanded += OnRootExpanded;
        tviRoot.Collapsed += OnItemCollapsed;
        TreeViewItemProps.SetItemImageName(tviRoot, @"Images/Computer.png");

        foldersTree.Items.Add(tviRoot);
    }

    void OnRootExpanded(object sender, RoutedEventArgs e)
    {
        var treeViewItem = e.OriginalSource as TreeViewItem;

        StartItemLoading(treeViewItem, GetDrives, AddItem);

    }

    void OnItemCollapsed(object sender, RoutedEventArgs e)
    {
        var treeViewItem = e.OriginalSource as TreeViewItem;

        if (treeViewItem != null)
        {
            treeViewItem.Items.Clear();
            treeViewItem.Items.Add(_dummyNode);
        }

    }

    void OnFolderExpanded(object sender, RoutedEventArgs e)
    {
        var tviSender = e.OriginalSource as TreeViewItem;

        e.Handled = true;
        StartItemLoading(tviSender, GetFilesAndFolders, AddItem);
    }

    void StartItemLoading(TreeViewItem tviSender, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem)
    {
        tviSender.Items.Clear();

        LoaderDelegate actLoad = LoadSubItems;

        actLoad.BeginInvoke(tviSender, tviSender.Tag as string, actGetItems, actAddSubItem, ProcessAsyncCallback, actLoad);
    }

    void LoadSubItems(TreeViewItem tviParent, string strPath, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem)
    {
            var itemsList = actGetItems(strPath).ToList();

            Dispatcher.BeginInvoke(DispatcherPriority.Normal, actAddSubItem, tviParent, itemsList);
    }



    // Runs on Background thread.
    IEnumerable<ItemToAdd> GetFilesAndFolders(string strParent)
    {
        var list = Directory.GetDirectories(strParent).Select(itemName => new ItemToAdd() {Path = itemName, TypeOfTheItem = ItemType.Directory}).ToList();

        list.AddRange(Directory.GetFiles(strParent).Select(itemName => new ItemToAdd() {Path = itemName, TypeOfTheItem = ItemType.File}));

        return list;
    }

    // Runs on Background thread.
    IEnumerable<ItemToAdd> GetDrives(string strParent)
    {
        return (Directory.GetLogicalDrives().Select(x => new ItemToAdd(){Path = x, TypeOfTheItem = ItemType.DiscDrive}));
    }

    void AddItem(TreeViewItem tviParent, IEnumerable<ItemToAdd> itemsToAdd)
    {
        string imgPath = "";

        foreach (ItemToAdd itemToAdd in itemsToAdd)
        {
            switch (itemToAdd.TypeOfTheItem)
            {
                case ItemType.File:
                    imgPath = @"Images/File.png";
                    break;
                case ItemType.Directory:
                    imgPath = @"Images/Folder.png";
                    break;
                case ItemType.DiscDrive:
                    imgPath = @"Images/DiskDrive.png";
                    break;
            }

            if (itemToAdd.TypeOfTheItem == ItemType.Directory || itemToAdd.TypeOfTheItem == ItemType.File)
                IntAddItem(tviParent, System.IO.Path.GetFileName(itemToAdd.Path), itemToAdd.Path, imgPath);
            else
                IntAddItem(tviParent, itemToAdd.Path, itemToAdd.Path, imgPath);                 
        }            
    }

    private void IntAddItem(TreeViewItem tviParent, string strName, string strTag, string strImageName)
    {
        var tviSubItem = new TreeViewItem();
        tviSubItem.Header = strName;
        tviSubItem.Tag = strTag;
        tviSubItem.Items.Add(_dummyNode);
        tviSubItem.Expanded += OnFolderExpanded;
        tviSubItem.Collapsed += OnItemCollapsed;

        TreeViewItemProps.SetItemImageName(tviSubItem, strImageName);

        tviParent.Items.Add(tviSubItem);
    }

    private void ProcessAsyncCallback(IAsyncResult iAR)
    {
        // Call end invoke on UI thread to process any exceptions, etc.
        Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Normal, (Action)(() => ProcessEndInvoke(iAR)));
    }

    private void ProcessEndInvoke(IAsyncResult iAR)
    {
        try
        {
            var actInvoked = (LoaderDelegate)iAR.AsyncState;
            actInvoked.EndInvoke(iAR);
        }
        catch (Exception ex)
        {
            // Probably should check for useful inner exceptions
            MessageBox.Show(string.Format("Error in ProcessEndInvoke\r\nException:  {0}", ex.Message));
        }
    }

    private struct ItemToAdd
    {
        public string Path;
        public ItemType TypeOfTheItem;
    }

    private enum ItemType
    {
        File,
        Directory,
        DiscDrive
    }
}

public static class TreeViewItemProps
{
    public static string GetItemImageName(DependencyObject obj)
    {
        return (string)obj.GetValue(ItemImageNameProperty);
    }

    public static void SetItemImageName(DependencyObject obj, string value)
    {
        obj.SetValue(ItemImageNameProperty, value);
    }

    public static readonly DependencyProperty ItemImageNameProperty;

    static TreeViewItemProps()
    {
        ItemImageNameProperty = DependencyProperty.RegisterAttached("ItemImageName", typeof(string), typeof(TreeViewItemProps), new UIPropertyMetadata(string.Empty));
    }
}

<Window x:Class="ThreadedWpfExplorer.DemoWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:ThreadedWpfExplorer"
    Title="Threaded WPF Explorer" Height="840" Width="350" Icon="/ThreadedWpfExplorer;component/Images/Computer.png">
    <Grid>
        <TreeView x:Name="foldersTree">
            <TreeView.Resources>
                <Style TargetType="{x:Type TreeViewItem}">
                    <Setter Property="HeaderTemplate">
                        <Setter.Value>
                            <DataTemplate DataType="ContentPresenter">
                                <Grid>
                                    <StackPanel Name="spImg" Orientation="Horizontal">
                                        <Image Name="img"  
                                               Source="{Binding 
                                                           RelativeSource={RelativeSource 
                                                                            Mode=FindAncestor, 
                                                                            AncestorType={x:Type TreeViewItem}},
                                                                            Path=(local:TreeViewItemProps.ItemImageName)}" 
                                               Width="20" Height="20"  Stretch="Fill" VerticalAlignment="Center" />
                                        <TextBlock Text="{Binding}" Margin="5,0" VerticalAlignment="Center" />
                                    </StackPanel>
                                </Grid>

                            </DataTemplate>
                        </Setter.Value>
                    </Setter>
                </Style>
            </TreeView.Resources>
        </TreeView>
    </Grid>
</Window>

private const int rangeToAdd = 100;

void LoadSubItems(TreeViewItem tviParent, string strPath, DEL_GetItems actGetItems, AddSubItemDelegate actAddSubItem)
{
    var itemsList = actGetItems(strPath).ToList();


    int index;
    for (index = 0; (index + rangeToAdd) <= itemsList.Count && rangeToAdd <= itemsList.Count; index = index + rangeToAdd)
    {
        Dispatcher.BeginInvoke(DispatcherPriority.Normal, actAddSubItem, tviParent, itemsList.GetRange(index, rangeToAdd));
    }

    if (itemsList.Count < (index + rangeToAdd) || rangeToAdd > itemsList.Count)
    {
        var itemsLeftToAdd = itemsList.Count % rangeToAdd;

        Dispatcher.BeginInvoke(DispatcherPriority.Normal, actAddSubItem, tviParent, itemsList.GetRange((rangeToAdd > itemsList.Count) ? index : index - rangeToAdd, itemsLeftToAdd));
    }
}

公共部分类演示窗口
{
公共窗口（）
{
初始化组件（）；
this.Loaded+=DemoWindow\u Loaded；
}
私有只读对象_dummyNode=null；
委托void LoaderDelegate（TreeViewItem tviLoad、字符串strPath、DEL_GetItems actGetItems、AddSubItemDelegate actAddSubItem）；
委托void AddSubItemDelegate（TreeViewItem tviParent，IEnumerable itemsToAdd）；
//获取要加载的项的IEnumerable，在此示例中为“GetFolders”或“GetDrive”
//运行于：后台线程
委托IEnumerable DEL_GetItems（字符串strParent）；
已加载void DemoWindow_（对象发送器，路由目标）
{
var tviRoot=new TreeViewItem（）；
tviRoot.Header=“我的电脑”；
添加（_dummyNode）；
tviRoot.Expanded+=OnRootExpanded；
tviRoot.Collapsed+=OnItemCollapsed；
SetItemImageName（tviRoot，@“Images/Computer.png”）；
foldersTree.Items.Add（tviRoot）；
}
void OnRootExpanded（对象发送方，RoutedEventArgs e）
{
var treeViewItem=e.原始来源为treeViewItem；
开始加载（treeViewItem、GetDrive、AddItem）；
}
无效OnItemCollapsed（对象发送方，路由目标）
{
var treeViewItem=e.原始来源为treeViewItem；
if（treeViewItem！=null）
{
treeViewItem.Items.Clear（）；
treevieItem.Items.Add（_dummyNode）；
}
}
void OnFolderExpanded（对象发送方，路由目标）
{
var tviSender=e.原始源作为树项；
e、 已处理=正确；
开始加载（tviSender、GetFilesAndFolders、AddItem）；
}
无效开始加载（TreeViewItem tviSender、DEL_GetItems actGetItems、AddSubItems Delegate actAddSubItem）
{
tviSender.Items.Clear（）；
LoaderDelegate actLoad=加载子项；
actLoad.BeginInvoke（tviSender，tviSender.tagas字符串，actGetItems，actAddSubItem，ProcessAsyncCallback，actLoad）；
}
void LoadSubItems（树视图项tviParent、字符串strPath、DEL_GetItems actGetItems、addsubitems委托actAddSubItem）
{
var itemsList=actGetItems（strPath）.ToList（）；
Dispatcher.BeginInvoke（DispatcherPriority.Normal、actAddSubItem、tviParent、itemsList）；
}
//在后台线程上运行。
IEnumerable GetFilesAndFolders（字符串strParent）
{
var list=Directory.GetDirectories（strParent）.Select（itemName=>newitemtoadd（）{Path=itemName，typeofitem=ItemType.Directory}）.ToList（）；
AddRange（Directory.GetFiles（strParent）.Select（itemName=>newitemtoadd（）{Path=itemName，typeofitem=ItemType.File}）；
退货清单；
}
//在后台线程上运行。
IEnumerable GetDrive（字符串strParent）
{
返回（Directory.GetLogicalDrives（）.Select（x=>newitemtoadd（）{Path=x，typeofItem=ItemType.DiscDrive}））；
}
void AddItem（树视图项tviParent，IEnumerable项stoadd）
{
字符串imgPath=“”；
foreach（itemtoadditemtoadd in itemsToAdd）
{
开关（项目至项目的添加类型）
{
案例ItemType.File：
imgPath=@“Images/File.png”；
打破
案例项目类型。目录：
imgPath=@“Images/Folder.png”；
打破
case ItemType.DiscDrive：
imgPath=@“Images/DiskDrive.png”；
打破
}
if（itemToAdd.typeofitem==ItemType.Directory | | itemToAdd.typeofitem==ItemType.File）
IntAddItem（tviParent、System.IO.Path.GetFileName（itemToAdd.Path）、itemToAdd.Path、imgPath）；
其他的
IntAddItem（tviParent、itemToAdd.Path、itemToAdd.Path、imgPath）；
}            
}
私有void IntAddItem（树视图项tviParent、字符串strName、字符串strTag、字符串strImageName）
{
var tviSubItem=new TreeViewItem（）；
tviSubItem.Header=strName；
tviSubItem.Tag=strTag；
添加（_dummyNode）；
tviSubItem.Expanded+=OnFolderExpanded；
tviSubItem.Collapsed+=OnItemCollapsed；
TreeViewItemProps.SetItemImageName（tviSub