Question

我正在尝试选择TreeViewItem。现在，我可以访问包含TreeViewItem并告诉它扩展所以我可以选择它的孩子。如果它已经扩展了一切都很好，如果不是那么我运行这个代码：

EventHandler selector = new EventHandler(delegate
    {
        if (selectedDirectoryTreeItem.ItemContainerGenerator.Status == GeneratorStatus.ContainersGenerated)
        {
            TreeViewItem want = selectedDirectoryTreeItem.ItemContainerGenerator.ContainerFromItem(dirWeWantSelected) as TreeViewItem;
            if (want == null)
                return;

                want.IsSelected = true;
            // selectedDirectoryTreeItem.ItemContainerGenerator.StatusChanged -= selector;
        }
    });
selectedDirectoryTreeItem.ItemContainerGenerator.StatusChanged += selector;

所以我的问题是，为什么不选择？想要永远是空的。我正在搜寻互联网寻找另一种方法，但如果有人可以向我解释这将是很酷的

Answer 1

我个人总是发现最简单的方法是将Selected属性粘贴到我的模型对象中，然后将TreeViewItem Selected属性绑定到模型的Selected属性。这是一些代码：

模型

public class Data : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public Data()
    {
        DataItems = new List<Data>();
    }

    public string Name { get; set; }

    private bool _selected;
    public bool Selected
    {
        get { return _selected; }
        set
        {
            _selected = value;
            OnPropertyChanged("Selected");
        }
    }

    public List<Data> DataItems { get; set; }

    private void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}

XAML

<Window x:Class="WpfApplication1.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication1"
    xmlns:controls="clr-namespace:MyControls;assembly=MyControls"
    Title="Window1">  
    <Window.Resources>
        <Style x:Key="CustomTreeViewItem" TargetType="TreeViewItem">
            <Setter Property="IsSelected" Value="{Binding Path=Selected, Mode=TwoWay}" />
            <Setter Property="IsExpanded" Value="True" />
        </Style>
    </Window.Resources>
    <DockPanel Background="Transparent">   
        <TreeView x:Name="_tvTest" DockPanel.Dock="Left" ItemContainerStyle="{StaticResource CustomTreeViewItem}" Width="300" >
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate DataType="{x:Type local:Data}" ItemsSource="{Binding DataItems}">
                    <TextBlock Text="{Binding Name}" Padding="2" />
                    <HierarchicalDataTemplate.ItemTemplate>
                        <DataTemplate>
                            <TextBlock Text="{Binding Name}" Padding="2" />
                        </DataTemplate>
                    </HierarchicalDataTemplate.ItemTemplate>
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
        </TreeView>

        <Button Content="Select Random TreeView Item" Click="Button_Click" Height="50" Width="200" />
    </DockPanel>
</Window>

背后的代码

public partial class Window1 : Window
{
    private Random _random;
    private List<Data> _dataItems;

    public Window1()
    {
        InitializeComponent();
        _dataItems = Init();
        _tvTest.ItemsSource = _dataItems;
        _random = new Random(5);
    }

    private List<Data> Init()
    {
        List<Data> dataItems = new List<Data>();
        for (int i = 1; i <= 10; i++)
        {
            Data d1 = new Data();
            d1.Name = "Data:" + i.ToString();
            for (int j = 1; j <= 4; j++)
            {
                Data d2 = new Data();
                d2.Name = "Data:" + i.ToString() + j.ToString();
                d1.DataItems.Add(d2);
            }
            dataItems.Add(d1);
        }
        return dataItems;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        int index = _random.Next(0, 9);
        int subIndex = _random.Next(0, 3);

        if (subIndex == 0)
            _dataItems[index].Selected = true;
        else
            _dataItems[index].DataItems[subIndex - 1].Selected = true;
    }
}

Answer 2

在我看来，这是WPF中的一个错误，但我已多次遇到同样的问题。我从不相信ItemContainerGenerator的状态，而是在不同的线程上循环：

private void _selectTreeViewHelper(object directory) {
    TreeViewItem want = null;
    bool broke = false;  //probably some sort of wait timeout instead, but works for sake of example
    while (true) {
       Dispatcher.Invoke(new Action(delegate {
          want = selectedDirectoryTreeItem.ItemContainerGenerator.ContainerFromItem(directory) as TreeViewItem;
          if (want != null && want.IsLoaded) {
               want.IsSelected = true;
               broke = true;
          }
       }));
       if (broke) { break; }
       Thread.Sleep(100); 
    }
}

然后叫它：

var thread = new Thread(new ParameterizedThreadStart(_selectTreeViewHelper));
thread.Start(dirWeWantSelected);

痛苦我知道，但它确实有效。

Answer 3

感谢您的帮助，我明白了。好吧它无论如何都有效，但我不完全确定为什么它之前没有...如果有人能告诉我它会很可爱......我有点结合上面两个回答的元素然后加上一点点来制作这行得通。出于某种原因，无论我做什么，如果TVI（TreeViewElement）的父节点尚未展开，我就无法选择TVI（TreeViewElement），即使父TVI表示其内容已生成，并且实际上有内容我可以迭代。因此，我的解决方案是等待生成内容然后通过它们进行评估并找到我想要的内容。我真的很奇怪，因为它的内容我不能抓住一个容器。咩。我的代码可以稍微重构一下，但这里是:(完美地工作）

public void listItemClickClick(object sender, RoutedEventArgs e) 
    {
        try
        {
            UserFile fil = (UserFile)(sender as ListBoxItem).DataContext;
            MessageBox.Show("to do: download stuff");
            return;
        }
        catch (InvalidCastException)
        {
        }
        try
        {
            dirWeWantSelected = (Directory)(sender as ListBoxItem).DataContext;
        }
        catch (InvalidCastException)
        {
            MessageBox.Show("this should never happen");
        }
        selectedDirectoryTreeItem.IsExpanded = true;
        TreeViewItem want = null;
        try
        {
            want = selectedDirectoryTreeItem.ItemContainerGenerator.ContainerFromItem(dirWeWantSelected) as TreeViewItem;
        }
        catch
        {
            MessageBox.Show("weird error");
        }
        if (want != null)
        {
            want.IsSelected = true;
        }
        else
        {
            selectedDirectoryTreeItem.ItemContainerGenerator.StatusChanged += ItemContainerGenerator_StatusChanged;
        }
    }

    void ItemContainerGenerator_StatusChanged(object sender, EventArgs e)
    {
        if (selectedDirectoryTreeItem.ItemContainerGenerator.Status
            == System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated)
        {
            selectedDirectoryTreeItem.ItemContainerGenerator.StatusChanged
                -= ItemContainerGenerator_StatusChanged;
            Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Input,
                new Action(DelayedAction));
        }
    }

    void DelayedAction()
    {
        selectedDirectoryTreeItem.Items.MoveCurrentToFirst();
        Directory curr;
        do
        {
            curr = (Directory)selectedDirectoryTreeItem.Items.CurrentItem;
            if (curr.id == dirWeWantSelected.id)
            {
                curr.Selected = true;
                return;
            }
            selectedDirectoryTreeItem.Items.MoveCurrentToNext();
        }
        while (selectedDirectoryTreeItem.Items.CurrentItem != null);
    }

wpf treeview蓝调。我想选择一个项目

3 个答案: