数据绑定到 WPF 树视图中的 SelectedItem
https://stackoverflow.com/questions/1000040
-
05-07-2019 - |
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如何检索在 WPF 树视图中选择的项目？我想在 XAML 中执行此操作，因为我想绑定它。
你可能认为它是 SelectedItem 但显然 不存在 是只读的，因此不可用。
这就是我想做的：
<TreeView ItemsSource="{Binding Path=Model.Clusters}"
ItemTemplate="{StaticResource ClusterTemplate}"
SelectedItem="{Binding Path=Model.SelectedCluster}" />
我想绑定 SelectedItem 到我的模型上的属性。
但这给了我错误：
“SelectedItem”属性是只读的，无法从标记中设置。
编辑：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 的代码隐藏文件中：
private void TreeView_OnSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
Model.SelectedCluster = (Cluster)e.NewValue;
}
解决方案
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中将其用作：
<TreeView>
<e:Interaction.Behaviors>
<behaviours:BindableSelectedItemBehavior SelectedItem="{Binding SelectedItem, Mode=TwoWay}" />
</e:Interaction.Behaviors>
</TreeView>
希望它会帮助别人！
其他提示
此属性存在： TreeView.SelectedItem
但它只是readonly，所以你不能通过绑定分配它，只能检索它
好吧，我找到了解决方案。它移动了混乱，以便MVVM工作。
首先添加此类：
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>
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且具有getter和setter的附加属性：
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。
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ICommand更改时执行SelectedItem，可以在事件上绑定命令，并且不再需要在ViewModel中使用属性System.Windows.Interactivity。
这样做：
1-添加对SelectedItemChanged
xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
2-将命令绑定到事件<=>
<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>
E DPS ENFIA O CODIG ONO CU NE
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所需的任何操作。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>
一切都很复杂......请使用Caliburn Micro（http://caliburnmicro.codeplex.com/）
查看：
<TreeView Micro:Message.Attach="[Event SelectedItemChanged] = [Action SetSelectedItem($this.SelectedItem)]" />
视图模型：
public void SetSelectedItem(YourNodeViewModel item) {};
我看到这个页面寻找与原作者相同的答案，并证明总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，所以我想我可能以及添加到桩。
绑定的动机是保持良好<！>放大器; MVVM。 ViewModel的可能用法是拥有一个带有名称的属性，例如<！> quot; CurrentThingy <！>，并且在其他地方，某些其他东西上的DataContext被绑定到<！> quot; CurrentThingy <！ > QUOT;
我的解决方案是使用简单的元素绑定，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。 TreeView.SelectedItem的另一件事，而不是将其他东西绑定到我的ViewModel，从而省去了额外的工作。
XAML：
<TreeView x:Name="myTreeView" ItemsSource="{Binding MyThingyCollection}">
.... stuff
</TreeView>
<!-- then.. somewhere else where I want to see the currently selected TreeView item: -->
<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。
您也可以使用TreeViewItem.IsSelected属性
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中将其用作：
<TreeView helper:BindableSelectedItemHelper.Attach="True"
helper:BindableSelectedItemHelper.SelectedItem="{Binding SelectedItem, Mode=TwoWay}">
我尝试了这些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种继承的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;
}
}
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 <！> lt; <！> gt;因此需要HierarchicalDataTemplate。默认的BindableSelectedItemBehavior将无法识别子TreeViewItem。使它在这种情况下起作用。
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;
}
}
无论级别如何，都可以遍历所有元素。
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。 因此，需要在树中查找TreeaconItem，其中datacontext是来自源的selectedValue。 TreeView有一个名为<！> quot; 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，从而节省每次绑定更新时使用反射的开销。
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。
- 将一个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>
在对互联网进行了一天的研究之后，我在正常 WPF / C＃环境中创建正常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 ;
}
}
也可以使用TreeView项的IsSelected属性来完成。这就是我管理它的方式，
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
}
当然还有绑定，
<Setter Property="IsSelected" Value="{Binding IsSelected}" />
我为您带来我的解决方案，它具有以下功能：
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/ 将以下代码粘贴到您的 CS 中：
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/ XAML 文件中的使用示例
<TreeView myNS:BindableSelectedItem.SelectedItem="{Binding Path=SelectedItem, Mode=TwoWay}" />
我知道这个帖子已经有 10 年历史了，但问题仍然存在......
最初的问题是“检索”所选项目。我还需要在我的视图模型中“获取”所选项目（而不是设置它）。在该线程的所有答案中，“Wes”的答案是唯一以不同方式处理该问题的答案：如果您可以使用“所选项目”作为数据绑定的目标，请将其用作数据绑定的源。Wes 对另一个视图属性执行了此操作，我将对视图模型属性执行此操作：
我们需要两件事：
- 在视图模型中创建一个依赖属性（在我的例子中，类型为“MyObject”，因为我的树视图绑定到“MyObject”类型的对象）
- 从 Treeview.SelectedItem 绑定到视图构造函数中的此属性（是的，这是代码隐藏，但是，您可能也会在那里初始化数据上下文）
视图模型：
public static readonly DependencyProperty SelectedTreeViewItemProperty = DependencyProperty.Register("SelectedTreeViewItem", typeof(MyObject), typeof(MyViewModel), new PropertyMetadata(OnSelectedTreeViewItemChanged));
private static void OnSelectedTreeViewItemChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
(d as MyViewModel).OnSelectedTreeViewItemChanged(e);
}
private void OnSelectedTreeViewItemChanged(DependencyPropertyChangedEventArgs e)
{
//do your stuff here
}
public MyObject SelectedWorkOrderTreeViewItem
{
get { return (MyObject)GetValue(SelectedTreeViewItemProperty); }
set { SetValue(SelectedTreeViewItemProperty, value); }
}
查看构造函数：
Binding binding = new Binding("SelectedItem")
{
Source = treeView, //name of tree view in xaml
Mode = BindingMode.OneWay
};
BindingOperations.SetBinding(DataContext, MyViewModel.SelectedTreeViewItemProperty, binding);
（我们都同意TreeView在这个问题上显然已被破坏了。绑定到SelectedItem会很明显。叹息）
我需要解决方案与TreeViewItem的IsSelected属性正确交互，所以我的方法就是这样：
// 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;
}
}
使用此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>
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