数据绑定到WPF Treeview中的SelectedItem-Java 学习之路

212

如何检索在WPF树视图中选择的项目？我想在XAML中这样做，因为我想绑定它 .

您可能认为它是 SelectedItem 但显然不存在是只读的，因此无法使用 .

这就是我想要做的：

<TreeView ItemsSource="{Binding Path=Model.Clusters}" 
            ItemTemplate="{StaticResource ClusterTemplate}"
            SelectedItem="{Binding Path=Model.SelectedCluster}" />

我想将 SelectedItem 绑定到我的Model上的属性 .

但这给了我错误：

'SelectedItem'属性是只读的，不能通过标记设置 .

Edit: 好的，这就是我解决这个问题的方法：

<TreeView
          ItemsSource="{Binding Path=Model.Clusters}" 
          ItemTemplate="{StaticResource HoofdCLusterTemplate}"
          SelectedItemChanged="TreeView_OnSelectedItemChanged" />

在我的xaml的codebehindfile中：

private void TreeView_OnSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
    Model.SelectedCluster = (Cluster)e.NewValue;
}

19 回答

一切都很复杂......跟Caliburn Micro一起去（http://caliburnmicro.codeplex.com/）

视图：

<TreeView Micro:Message.Attach="[Event SelectedItemChanged] = [Action SetSelectedItem($this.SelectedItem)]" />

视图模型：

public void SetSelectedItem(YourNodeViewModel item) {};

回复于 2024-04-27T16:00:17+08:00

我意识到这已经接受了答案，但我把它放在一起解决问题 . 它使用与Delta的解决方案类似的想法，但不需要继承TreeView：

public class BindableSelectedItemBehavior : Behavior<TreeView>
{
    #region SelectedItem Property

    public object SelectedItem
    {
        get { return (object)GetValue(SelectedItemProperty); }
        set { SetValue(SelectedItemProperty, value); }
    }

    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register("SelectedItem", typeof(object), typeof(BindableSelectedItemBehavior), new UIPropertyMetadata(null, OnSelectedItemChanged));

    private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var item = e.NewValue as TreeViewItem;
        if (item != null)
        {
            item.SetValue(TreeViewItem.IsSelectedProperty, true);
        }
    }

    #endregion

    protected override void OnAttached()
    {
        base.OnAttached();

        this.AssociatedObject.SelectedItemChanged += OnTreeViewSelectedItemChanged;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.SelectedItemChanged -= OnTreeViewSelectedItemChanged;
        }
    }

    private void OnTreeViewSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        this.SelectedItem = e.NewValue;
    }
}

然后，您可以在XAML中使用它：

<TreeView>
    <e:Interaction.Behaviors>
        <behaviours:BindableSelectedItemBehavior SelectedItem="{Binding SelectedItem, Mode=TwoWay}" />
    </e:Interaction.Behaviors>
</TreeView>

希望它会帮助别人！

回复于 2024-04-27T16:00:17+08:00

3

此属性存在：TreeView.SelectedItem

但它只是readonly，因此您无法通过绑定分配它，只能检索它

回复于 2024-04-27T16:00:17+08:00

好吧，我找到了解决方案 . 它移动了混乱，以便MVVM工作 .

首先添加这个类：

public class ExtendedTreeView : TreeView
{
    public ExtendedTreeView()
        : base()
    {
        this.SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(___ICH);
    }

    void ___ICH(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        if (SelectedItem != null)
        {
            SetValue(SelectedItem_Property, SelectedItem);
        }
    }

    public object SelectedItem_
    {
        get { return (object)GetValue(SelectedItem_Property); }
        set { SetValue(SelectedItem_Property, value); }
    }
    public static readonly DependencyProperty SelectedItem_Property = DependencyProperty.Register("SelectedItem_", typeof(object), typeof(ExtendedTreeView), new UIPropertyMetadata(null));
}

并将其添加到您的xaml：

<local:ExtendedTreeView ItemsSource="{Binding Items}" SelectedItem_="{Binding Item, Mode=TwoWay}">
 .....
 </local:ExtendedTreeView>

回复于 2024-04-27T16:00:17+08:00

如果需要，请回答附加属性并且没有外部依赖性！

您可以创建一个可绑定的附加属性，并具有一个getter和setter：

public class TreeViewHelper
{
    private static Dictionary<DependencyObject, TreeViewSelectedItemBehavior> behaviors = new Dictionary<DependencyObject, TreeViewSelectedItemBehavior>();

    public static object GetSelectedItem(DependencyObject obj)
    {
        return (object)obj.GetValue(SelectedItemProperty);
    }

    public static void SetSelectedItem(DependencyObject obj, object value)
    {
        obj.SetValue(SelectedItemProperty, value);
    }

    // Using a DependencyProperty as the backing store for SelectedItem.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.RegisterAttached("SelectedItem", typeof(object), typeof(TreeViewHelper), new UIPropertyMetadata(null, SelectedItemChanged));

    private static void SelectedItemChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
    {
        if (!(obj is TreeView))
            return;

        if (!behaviors.ContainsKey(obj))
            behaviors.Add(obj, new TreeViewSelectedItemBehavior(obj as TreeView));

        TreeViewSelectedItemBehavior view = behaviors[obj];
        view.ChangeSelectedItem(e.NewValue);
    }

    private class TreeViewSelectedItemBehavior
    {
        TreeView view;
        public TreeViewSelectedItemBehavior(TreeView view)
        {
            this.view = view;
            view.SelectedItemChanged += (sender, e) => SetSelectedItem(view, e.NewValue);
        }

        internal void ChangeSelectedItem(object p)
        {
            TreeViewItem item = (TreeViewItem)view.ItemContainerGenerator.ContainerFromItem(p);
            item.IsSelected = true;
        }
    }
}

将包含该类的名称空间声明添加到XAML并按如下方式绑定（本地是我命名名称空间声明的方式）：

<TreeView ItemsSource="{Binding Path=Root.Children}" local:TreeViewHelper.SelectedItem="{Binding Path=SelectedItem, Mode=TwoWay}">

    </TreeView>

现在，您可以绑定所选项目，并在视图模型中将其设置为以编程方式更改它，如果该要求出现的话 . 当然，这是假设您在该特定属性上实现INotifyPropertyChanged .

回复于 2024-04-27T16:00:17+08:00

它的回答比OP预期的要多一点......但我希望它至少可以帮助一些人 .

如果要在 SelectedItem 更改时执行 ICommand ，则可以在事件上绑定命令，并且不再需要在 ViewModel 中使用属性 SelectedItem .

为此：

1-添加对 System.Windows.Interactivity 的引用

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

2-将命令绑定到事件 SelectedItemChanged

<TreeView x:Name="myTreeView" Margin="1"
            ItemsSource="{Binding Directories}">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="SelectedItemChanged">
            <i:InvokeCommandAction Command="{Binding SomeCommand}"
                                   CommandParameter="
                                            {Binding ElementName=myTreeView
                                             ,Path=SelectedItem}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
    <TreeView.ItemTemplate>
           <!-- ... -->
    </TreeView.ItemTemplate>
</TreeView>

回复于 2024-04-27T16:00:17+08:00

这可以通过仅使用绑定和GalaSoft MVVM Light库的EventToCommand以更好的方式完成 . 在您的VM中添加一个命令，该命令将在更改所选项目时调用，并初始化该命令以执行必要的操作 . 在这个例子中，我使用了一个RelayCommand，只是设置了SelectedCluster属性 .

public class ViewModel
{
    public ViewModel()
    {
        SelectedClusterChanged = new RelayCommand<Cluster>( c => SelectedCluster = c );
    }

    public RelayCommand<Cluster> SelectedClusterChanged { get; private set; } 

    public Cluster SelectedCluster { get; private set; }
}

然后在xaml中添加EventToCommand行为 . 使用混合物非常容易 .

<TreeView
      x:Name="lstClusters"
      ItemsSource="{Binding Path=Model.Clusters}" 
      ItemTemplate="{StaticResource HoofdCLusterTemplate}">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="SelectedItemChanged">
            <GalaSoft_MvvmLight_Command:EventToCommand Command="{Binding SelectedClusterChanged}" CommandParameter="{Binding ElementName=lstClusters,Path=SelectedValue}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</TreeView>

回复于 2024-04-27T16:00:17+08:00

19
我遇到了这个寻找与原作者相同答案的页面，并且证明总是有不止一种方法可以做到这一点，对我来说解决方案比到目前为止提供的答案更容易，所以我想我不妨添加到了一堆 .

绑定的动机是保持它和MVVM . ViewModel的可能用法是使用具有诸如“CurrentThingy”之类的名称的属性，并且在其他地方，将某些其他东西上的DataContext绑定到“CurrentThingy” .

而不是通过所需的其他步骤（例如：自定义行为，第三方控件）来支持从TreeView到我的模型的良好绑定，然后从其他东西到我的模型，我的解决方案是使用简单的元素绑定另一个东西到TreeView.SelectedItem，而不是将其他东西绑定到我的ViewModel，从而跳过所需的额外工作 .

XAML：
```
<TreeView x:Name="myTreeView" ItemsSource="{Binding MyThingyCollection}">
.... stuff
</TreeView>



<local:MyThingyDetailsView 
       DataContext="{Binding ElementName=myTreeView, Path=SelectedItem}" />
```
当然，这非常适合阅读当前所选项目，但不能设置它，这就是我所需要的 .
回复于 2024-04-27T16:00:17+08:00
0

您也可以使用TreeViewItem.IsSelected属性

回复于 2024-04-27T16:00:17+08:00

还有一种方法可以在不使用Interaction.Behaviors的情况下创建XAML可绑定SelectedItem属性 .

public static class BindableSelectedItemHelper
{
    #region Properties

    public static readonly DependencyProperty SelectedItemProperty = DependencyProperty.RegisterAttached("SelectedItem", typeof(object), typeof(BindableSelectedItemHelper),
        new FrameworkPropertyMetadata(null, OnSelectedItemPropertyChanged));

    public static readonly DependencyProperty AttachProperty = DependencyProperty.RegisterAttached("Attach", typeof(bool), typeof(BindableSelectedItemHelper), new PropertyMetadata(false, Attach));

    private static readonly DependencyProperty IsUpdatingProperty = DependencyProperty.RegisterAttached("IsUpdating", typeof(bool), typeof(BindableSelectedItemHelper));

    #endregion

    #region Implementation

    public static void SetAttach(DependencyObject dp, bool value)
    {
        dp.SetValue(AttachProperty, value);
    }

    public static bool GetAttach(DependencyObject dp)
    {
        return (bool)dp.GetValue(AttachProperty);
    }

    public static string GetSelectedItem(DependencyObject dp)
    {
        return (string)dp.GetValue(SelectedItemProperty);
    }

    public static void SetSelectedItem(DependencyObject dp, object value)
    {
        dp.SetValue(SelectedItemProperty, value);
    }

    private static bool GetIsUpdating(DependencyObject dp)
    {
        return (bool)dp.GetValue(IsUpdatingProperty);
    }

    private static void SetIsUpdating(DependencyObject dp, bool value)
    {
        dp.SetValue(IsUpdatingProperty, value);
    }

    private static void Attach(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        TreeListView treeListView = sender as TreeListView;
        if (treeListView != null)
        {
            if ((bool)e.OldValue)
                treeListView.SelectedItemChanged -= SelectedItemChanged;

            if ((bool)e.NewValue)
                treeListView.SelectedItemChanged += SelectedItemChanged;
        }
    }

    private static void OnSelectedItemPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        TreeListView treeListView = sender as TreeListView;
        if (treeListView != null)
        {
            treeListView.SelectedItemChanged -= SelectedItemChanged;

            if (!(bool)GetIsUpdating(treeListView))
            {
                foreach (TreeViewItem item in treeListView.Items)
                {
                    if (item == e.NewValue)
                    {
                        item.IsSelected = true;
                        break;
                    }
                    else
                       item.IsSelected = false;                        
                }
            }

            treeListView.SelectedItemChanged += SelectedItemChanged;
        }
    }

    private static void SelectedItemChanged(object sender, RoutedEventArgs e)
    {
        TreeListView treeListView = sender as TreeListView;
        if (treeListView != null)
        {
            SetIsUpdating(treeListView, true);
            SetSelectedItem(treeListView, treeListView.SelectedItem);
            SetIsUpdating(treeListView, false);
        }
    }
    #endregion
}

然后，您可以在XAML中使用它：

<TreeView  helper:BindableSelectedItemHelper.Attach="True" 
           helper:BindableSelectedItemHelper.SelectedItem="{Binding SelectedItem, Mode=TwoWay}">

回复于 2024-04-27T16:00:17+08:00

我试过这个问题的所有解决方案 . 没有人完全解决我的问题 . 所以我认为最好将这样的继承类与重新定义的属性SelectedItem一起使用 . 如果从GUI中选择树元素并在代码中设置此属性值，它将完美地工作

public class TreeViewEx : TreeView
{
    public TreeViewEx()
    {
        this.SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(TreeViewEx_SelectedItemChanged);
    }

    void TreeViewEx_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        this.SelectedItem = e.NewValue;
    }

    #region SelectedItem

    /// <summary>
    /// Gets or Sets the SelectedItem possible Value of the TreeViewItem object.
    /// </summary>
    public new object SelectedItem
    {
        get { return this.GetValue(TreeViewEx.SelectedItemProperty); }
        set { this.SetValue(TreeViewEx.SelectedItemProperty, value); }
    }

    // Using a DependencyProperty as the backing store for MyProperty.  This enables animation, styling, binding, etc...
    public new static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register("SelectedItem", typeof(object), typeof(TreeViewEx),
        new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, SelectedItemProperty_Changed));

    static void SelectedItemProperty_Changed(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        TreeViewEx targetObject = dependencyObject as TreeViewEx;
        if (targetObject != null)
        {
            TreeViewItem tvi = targetObject.FindItemNode(targetObject.SelectedItem) as TreeViewItem;
            if (tvi != null)
                tvi.IsSelected = true;
        }
    }                                               
    #endregion SelectedItem   

    public TreeViewItem FindItemNode(object item)
    {
        TreeViewItem node = null;
        foreach (object data in this.Items)
        {
            node = this.ItemContainerGenerator.ContainerFromItem(data) as TreeViewItem;
            if (node != null)
            {
                if (data == item)
                    break;
                node = FindItemNodeInChildren(node, item);
                if (node != null)
                    break;
            }
        }
        return node;
    }

    protected TreeViewItem FindItemNodeInChildren(TreeViewItem parent, object item)
    {
        TreeViewItem node = null;
        bool isExpanded = parent.IsExpanded;
        if (!isExpanded) //Can't find child container unless the parent node is Expanded once
        {
            parent.IsExpanded = true;
            parent.UpdateLayout();
        }
        foreach (object data in parent.Items)
        {
            node = parent.ItemContainerGenerator.ContainerFromItem(data) as TreeViewItem;
            if (data == item && node != null)
                break;
            node = FindItemNodeInChildren(node, item);
            if (node != null)
                break;
        }
        if (node == null && parent.IsExpanded != isExpanded)
            parent.IsExpanded = isExpanded;
        if (node != null)
            parent.IsExpanded = true;
        return node;
    }
}

回复于 2024-04-27T16:00:17+08:00

我建议增加Steve Greatrex提供的行为 . 他的行为并不反映来自源的更改，因为它可能不是TreeViewItems的集合 . 所以这是在树中找到TreeViewItem的问题，datacontext是来自源的selectedValue . TreeView有一个名为“ItemsHost”的受保护属性，它保存TreeViewItem集合 . 我们可以通过反射得到它并走树搜索所选项目 .

private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var behavior = sender as BindableSelectedItemBehaviour;

        if (behavior == null) return;

        var tree = behavior.AssociatedObject;

        if (tree == null) return;

        if (e.NewValue == null) 
            foreach (var item in tree.Items.OfType<TreeViewItem>())
                item.SetValue(TreeViewItem.IsSelectedProperty, false);

        var treeViewItem = e.NewValue as TreeViewItem; 
        if (treeViewItem != null)
        {
            treeViewItem.SetValue(TreeViewItem.IsSelectedProperty, true);
        }
        else
        {
            var itemsHostProperty = tree.GetType().GetProperty("ItemsHost", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);

            if (itemsHostProperty == null) return;

            var itemsHost = itemsHostProperty.GetValue(tree, null) as Panel;

            if (itemsHost == null) return;

            foreach (var item in itemsHost.Children.OfType<TreeViewItem>())
                if (WalkTreeViewItem(item, e.NewValue)) break;
        }
    }

    public static bool WalkTreeViewItem(TreeViewItem treeViewItem, object selectedValue) {
        if (treeViewItem.DataContext == selectedValue)
        {
            treeViewItem.SetValue(TreeViewItem.IsSelectedProperty, true);
            treeViewItem.Focus();
            return true;
        }

        foreach (var item in treeViewItem.Items.OfType<TreeViewItem>())
            if (WalkTreeViewItem(item, selectedValue)) return true;

        return false;
    }

这种行为适用于双向绑定 . 或者，可以将ItemsHost采集移动到Behavior的OnAttached方法，从而节省每次绑定时使用反射的开销更新 .

回复于 2024-04-27T16:00:17+08:00

WPF MVVM TreeView SelectedItem

...是一个更好的答案，但没有提到在ViewModel中获取/设置SelectedItem的方法 .

将IsSelected布尔属性添加到ItemViewModel，并在TreeViewItem的样式设置器中绑定它 .
将SelectedItem属性添加到用作TreeView的DataContext的ViewModel . 这是上述解决方案中缺失的部分 .

' ItemVM...
    Public Property IsSelected As Boolean
        Get
            Return _func.SelectedNode Is Me
        End Get
        Set(value As Boolean)
            If IsSelected  value Then
                _func.SelectedNode = If(value, Me, Nothing)
            End If
            RaisePropertyChange()
        End Set
    End Property
    ' TreeVM...
    Public Property SelectedItem As ItemVM
        Get
            Return _selectedItem
        End Get
        Set(value As ItemVM)
            If _selectedItem Is value Then
                Return
            End If
            Dim prev = _selectedItem
            _selectedItem = value
            If prev IsNot Nothing Then
                prev.IsSelected = False
            End If
            If _selectedItem IsNot Nothing Then
                _selectedItem.IsSelected = True
            End If
        End Set
    End Property

<TreeView ItemsSource="{Binding Path=TreeVM}" 
          BorderBrush="Transparent">
    <TreeView.ItemContainerStyle>
        <Style TargetType="TreeViewItem">
            <Setter Property="IsExpanded" Value="{Binding IsExpanded}"/>
            <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}"/>
        </Style>
    </TreeView.ItemContainerStyle>
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}">
            <TextBlock Text="{Binding Name}"/>
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>

回复于 2024-04-27T16:00:17+08:00

我的要求是基于PRISM-MVVM的解决方案，其中需要TreeView，绑定对象的类型为Collection <>，因此需要HierarchicalDataTemplate . 默认的BindableSelectedItemBehavior将无法识别子TreeViewItem . 使其在此方案中起作用 .

public class BindableSelectedItemBehavior : Behavior<TreeView>
{
    #region SelectedItem Property

    public object SelectedItem
    {
        get { return (object)GetValue(SelectedItemProperty); }
        set { SetValue(SelectedItemProperty, value); }
    }

    public static readonly DependencyProperty SelectedItemProperty =
        DependencyProperty.Register("SelectedItem", typeof(object), typeof(BindableSelectedItemBehavior), new UIPropertyMetadata(null, OnSelectedItemChanged));

    private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var behavior = sender as BindableSelectedItemBehavior;
        if (behavior == null) return;
        var tree = behavior.AssociatedObject;
        if (tree == null) return;
        if (e.NewValue == null)
            foreach (var item in tree.Items.OfType<TreeViewItem>())
                item.SetValue(TreeViewItem.IsSelectedProperty, false);
        var treeViewItem = e.NewValue as TreeViewItem;
        if (treeViewItem != null)
            treeViewItem.SetValue(TreeViewItem.IsSelectedProperty, true);
        else
        {
            var itemsHostProperty = tree.GetType().GetProperty("ItemsHost", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
            if (itemsHostProperty == null) return;
            var itemsHost = itemsHostProperty.GetValue(tree, null) as Panel;
            if (itemsHost == null) return;
            foreach (var item in itemsHost.Children.OfType<TreeViewItem>())
            {
                if (WalkTreeViewItem(item, e.NewValue)) 
                    break;
            }
        }
    }

    public static bool WalkTreeViewItem(TreeViewItem treeViewItem, object selectedValue)
    {
        if (treeViewItem.DataContext == selectedValue)
        {
            treeViewItem.SetValue(TreeViewItem.IsSelectedProperty, true);
            treeViewItem.Focus();
            return true;
        }
        var itemsHostProperty = treeViewItem.GetType().GetProperty("ItemsHost", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
        if (itemsHostProperty == null) return false;
        var itemsHost = itemsHostProperty.GetValue(treeViewItem, null) as Panel;
        if (itemsHost == null) return false;
        foreach (var item in itemsHost.Children.OfType<TreeViewItem>())
        {
            if (WalkTreeViewItem(item, selectedValue))
                break;
        }
        return false;
    }
    #endregion

    protected override void OnAttached()
    {
        base.OnAttached();
        this.AssociatedObject.SelectedItemChanged += OnTreeViewSelectedItemChanged;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        if (this.AssociatedObject != null)
        {
            this.AssociatedObject.SelectedItemChanged -= OnTreeViewSelectedItemChanged;
        }
    }

    private void OnTreeViewSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        this.SelectedItem = e.NewValue;
    }
}

这使得能够迭代所有元素而不管级别 .

回复于 2024-04-27T16:00:17+08:00

209

在研究了互联网一天后，我在 normal WPF / C＃环境中创建 normal 树视图后找到了自己选择项目的解决方案

private void BuildSortTree(int sel)
        {
            MergeSort.Items.Clear();
            TreeViewItem itTemp = new TreeViewItem();
            itTemp.Header = SortList[0];
            MergeSort.Items.Add(itTemp);
            TreeViewItem prev;
            itTemp.IsExpanded = true;
            if (0 == sel) itTemp.IsSelected= true;
            prev = itTemp;
            for(int i = 1; i<SortList.Count; i++)
            {

                TreeViewItem itTempNEW = new TreeViewItem();
                itTempNEW.Header = SortList[i];
                prev.Items.Add(itTempNEW);
                itTempNEW.IsExpanded = true;
                if (i == sel) itTempNEW.IsSelected = true;
                prev = itTempNEW ;
            }
        }

回复于 2024-04-27T16:00:17+08:00

它也可以使用TreeView项的IsSelected属性来完成 . 这是我管理它的方式，

public delegate void TreeviewItemSelectedHandler(TreeViewItem item);
public class TreeViewItem
{      
  public static event TreeviewItemSelectedHandler OnItemSelected = delegate { };
  public bool IsSelected 
  {
    get { return isSelected; }
    set 
    { 
      isSelected = value;
      if (value)
        OnItemSelected(this);
    }
  }
}

然后在包含TreeView绑定的数据的ViewModel中，只需订阅TreeViewItem类中的事件 .

TreeViewItem.OnItemSelected += TreeViewItemSelected;

最后，在同一个ViewModel中实现这个处理程序，

private void TreeViewItemSelected(TreeViewItem item)
{
  //Do something
}

而绑定当然，

<Setter Property="IsSelected" Value="{Binding IsSelected}" />

回复于 2024-04-27T16:00:17+08:00

我为您带来了我的解决方案，它提供以下功能：

支持2种方式绑定
自动更新TreeViewItem.IsSelected属性（根据SelectedItem）
没有TreeView子类化
绑定到ViewModel的项可以是任何类型（甚至为null）

1 /在CS中粘贴以下代码：

public class BindableSelectedItem
{
    public static readonly DependencyProperty SelectedItemProperty = DependencyProperty.RegisterAttached(
        "SelectedItem", typeof(object), typeof(BindableSelectedItem), new PropertyMetadata(default(object), OnSelectedItemPropertyChangedCallback));

    private static void OnSelectedItemPropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var treeView = d as TreeView;
        if (treeView != null)
        {
            BrowseTreeViewItems(treeView, tvi =>
            {
                tvi.IsSelected = tvi.DataContext == e.NewValue;
            });
        }
        else
        {
            throw new Exception("Attached property supports only TreeView");
        }
    }

    public static void SetSelectedItem(DependencyObject element, object value)
    {
        element.SetValue(SelectedItemProperty, value);
    }

    public static object GetSelectedItem(DependencyObject element)
    {
        return element.GetValue(SelectedItemProperty);
    }

    public static void BrowseTreeViewItems(TreeView treeView, Action<TreeViewItem> onBrowsedTreeViewItem)
    {
        var collectionsToVisit = new System.Collections.Generic.List<Tuple<ItemContainerGenerator, ItemCollection>> { new Tuple<ItemContainerGenerator, ItemCollection>(treeView.ItemContainerGenerator, treeView.Items) };
        var collectionIndex = 0;
        while (collectionIndex < collectionsToVisit.Count)
        {
            var itemContainerGenerator = collectionsToVisit[collectionIndex].Item1;
            var itemCollection = collectionsToVisit[collectionIndex].Item2;
            for (var i = 0; i < itemCollection.Count; i++)
            {
                var tvi = itemContainerGenerator.ContainerFromIndex(i) as TreeViewItem;
                if (tvi == null)
                {
                    continue;
                }

                if (tvi.ItemContainerGenerator.Status == System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated)
                {
                    collectionsToVisit.Add(new Tuple<ItemContainerGenerator, ItemCollection>(tvi.ItemContainerGenerator, tvi.Items));
                }

                onBrowsedTreeViewItem(tvi);
            }

            collectionIndex++;
        }
    }

}

2 /在XAML文件中使用的示例

<TreeView myNS:BindableSelectedItem.SelectedItem="{Binding Path=SelectedItem, Mode=TwoWay}" />

回复于 2024-04-27T16:00:17+08:00

（让我们都同意TreeView在这个问题上明显被破坏 . 绑定到SelectedItem会很明显 . 叹气）

我需要解决方案与TreeViewItem的IsSelected属性正确交互，所以这是我如何做到的：

// the Type CustomThing needs to implement IsSelected with notification
// for this to work.
public class CustomTreeView : TreeView
{
    public CustomThing SelectedCustomThing
    {
        get
        {
            return (CustomThing)GetValue(SelectedNode_Property);
        }
        set
        {
            SetValue(SelectedNode_Property, value);
            if(value != null) value.IsSelected = true;
        }
    }

    public static DependencyProperty SelectedNode_Property =
        DependencyProperty.Register(
            "SelectedCustomThing",
            typeof(CustomThing),
            typeof(CustomTreeView),
            new FrameworkPropertyMetadata(
                null,
                FrameworkPropertyMetadataOptions.None,
                SelectedNodeChanged));

    public CustomTreeView(): base()
    {
        this.SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(SelectedItemChanged_CustomHandler);
    }

    void SelectedItemChanged_CustomHandler(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        SetValue(SelectedNode_Property, SelectedItem);
    }

    private static void SelectedNodeChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var treeView = d as CustomTreeView;
        var newNode = e.NewValue as CustomThing;

        treeView.SelectedCustomThing = (CustomThing)e.NewValue;
    }
}

有了这个XAML：

<local:CustonTreeView ItemsSource="{Binding TreeRoot}" 
    SelectedCustomThing="{Binding SelectedNode,Mode=TwoWay}">
    <TreeView.ItemContainerStyle>
        <Style TargetType="TreeViewItem">
            <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
        </Style>
    </TreeView.ItemContainerStyle>
</local:CustonTreeView>

回复于 2024-04-27T16:00:17+08:00

43
如果XAML有
```
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
```
在列表中找到该项目有什么问题？我也用
```
<Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
```
为了确保我在VM中设置IsSelected = true时父项被扩展 .
回复于 2024-04-27T16:00:17+08:00

数据绑定到WPF Treeview中的SelectedItem

19 回答

相关问题