如何以编程方式选择 WPF TreeView 中的项目?
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03-07-2019 - |
题
如何以编程方式选择 WPF 中的项目 TreeView
?这 ItemsControl
模型似乎可以阻止它。
解决方案
由于一些奇怪的原因,这是一个真正的痛苦,您必须使用ContainerFromItem来获取容器,然后调用select方法。
// selectedItemObject is not a TreeViewItem, but an item from the collection that
// populated the TreeView.
var tvi = treeView.ItemContainerGenerator.ContainerFromItem(selectedItemObject)
as TreeViewItem;
if (tvi != null)
{
tvi.IsSelected = true;
}
曾经有一篇关于如何做的博客文章这里,但链接已经死了。
其他提示
对于仍在寻找正确解决此问题的人,请参见下文。我在代码项目文章的评论中找到了这一篇<!>#8220; WPF TreeView Selection <!>#8221; http://www.codeproject.com/KB/WPF/TreeView_SelectionWPF.aspx 由DaWanderer。 它由Kenrae于2008年11月25日发布。这对我来说非常有用。谢谢Kenrae!
这是他的帖子:
让自己的数据对象拥有IsSelected属性(我也建议使用IsExpanded属性),而不是遍历树。使用TreeView上的ItemContainerStyle属性为TreeViewItems定义样式,该属性将TreeViewItem中的这些属性绑定到数据对象。像这样:
<Style x:Key="LibraryTreeViewItemStyle"
TargetType="{x:Type TreeViewItem}">
<Setter Property="IsExpanded"
Value="{Binding IsExpanded, Mode=TwoWay}" />
<Setter Property="IsSelected"
Value="{Binding IsSelected, Mode=TwoWay}" />
<Setter Property="FontWeight"
Value="Normal" />
<Style.Triggers>
<Trigger Property="IsSelected"
Value="True">
<Setter Property="FontWeight"
Value="Bold" />
</Trigger>
</Style.Triggers>
</Style>
<TreeView ItemsSource="{Binding Path=YourCollection}"
ItemContainerStyle="{StaticResource LibraryTreeViewItemStyle}"
ItemTemplate={StaticResource YourHierarchicalDataTemplate}/>
您需要获取TreeViewItem
然后将IsSelected
设置为true
。
我已成功使用此代码:
public static TreeViewItem FindTviFromObjectRecursive(ItemsControl ic, object o) {
//Search for the object model in first level children (recursively)
TreeViewItem tvi = ic.ItemContainerGenerator.ContainerFromItem(o) as TreeViewItem;
if (tvi != null) return tvi;
//Loop through user object models
foreach (object i in ic.Items) {
//Get the TreeViewItem associated with the iterated object model
TreeViewItem tvi2 = ic.ItemContainerGenerator.ContainerFromItem(i) as TreeViewItem;
tvi = FindTviFromObjectRecursive(tvi2, o);
if (tvi != null) return tvi;
}
return null;
}
用法:
var tvi = FindTviFromObjectRecursive(TheTreeView, TheModel);
if (tvi != null) tvi.IsSelected = true;
这并不像看起来那么简单,Steven提供的链接在2008年发布了一个解决方案,该解决方案可能仍然有效,但不会处理Virtualized TreeViews。此外,该条的评论中还提到了许多其他问题。没有违法行为,但我也遇到了同样的问题,无法找到完美的解决方案。以下是一些帮助我很多的文章/帖子的链接 -
如何在TreeView中展开项目? <!> 8211#;第三部分: http://bea.stollnitz.com/blog/?p=59
以编程方式选择TreeView中的项目: http:// blog。 quantumbitdesigns.com/2008/07/22/programmatically-selecting-an-item-in-a-treeview/#respond
TreeView,TreeViewItem和IsSelected: http:// social。 msdn.microsoft.com/Forums/en-US/wpf/thread/7e368b93-f509-4cd6-88e7-561e8d3246ae/
我写了一个扩展方法:
using System.Windows.Controls;
namespace Extensions
{
public static class TreeViewEx
{
/// <summary>
/// Select specified item in a TreeView
/// </summary>
public static void SelectItem(this TreeView treeView, object item)
{
var tvItem = treeView.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem;
if (tvItem != null)
{
tvItem.IsSelected = true;
}
}
}
}
我可以这样使用:
if (_items.Count > 0)
_treeView.SelectItem(_items[0]);
如果你想选择位于孩子的孩子中的项目,你可以使用递归来做到这一点。
public bool Select(TreeViewItem item, object select) // recursive function to set item selection in treeview
{
if (item == null)
return false;
TreeViewItem child = item.ItemContainerGenerator.ContainerFromItem(select) as TreeViewItem;
if (child != null)
{
child.IsSelected = true;
return true;
}
foreach (object c in item.Items)
{
bool result = Select(item.ItemContainerGenerator.ContainerFromItem(c) as TreeViewItem, select);
if (result == true)
return true;
}
return false;
}
试试这个
/// <summary>
/// Selects the tree view item.
/// </summary>
/// <param name="Collection">The collection.</param>
/// <param name="Value">The value.</param>
/// <returns></returns>
private TreeViewItem SelectTreeViewItem(ItemCollection Collection, String Value)
{
if (Collection == null) return null;
foreach(TreeViewItem Item in Collection)
{
/// Find in current
if (Item.Header.Equals(Value))
{
Item.IsSelected = true;
return Item;
}
/// Find in Childs
if (Item.Items != null)
{
TreeViewItem childItem = this.SelectTreeViewItem(Item.Items, Value);
if (childItem != null)
{
Item.IsExpanded = true;
return childItem;
}
}
}
return null;
}
参考: http://amastaneh.blogspot.com/ 2011/06 / WPF-的SelectedValue换treeview.html
我只想到我会使用我所使用的解决方案,以防这可以帮助任何人。请注意,执行此操作的最佳方法是根据kuninl的答案使用“IsSelected”等绑定属性,但在我的情况下,它是一个不遵循MVVM的遗留应用程序,因此我最终得到了以下内容。
private void ChangeSessionSelection()
{
foreach (SessionContainer item in this.treeActiveSessions.Items)
{
var treeviewItem = this.treeActiveSessions.ItemContainerGenerator.ContainerFromItem(item) as TreeViewItem;
if (item.Session == this.selectedSession.Session)
{
treeviewItem.IsSelected = true;
treeviewItem.IsExpanded = true;
}
else
{
treeviewItem.IsSelected = false;
treeviewItem.IsExpanded = false;
}
}
}
这样做是选择并展开UI中的树视图项,该项代表后面代码中的选定数据项。这样做的目的是在同一窗口中的项目控件中更改用户选择时,在树视图中进行选择更改。
我创建了一个方法VisualTreeExt.GetDescendants<T>
,它返回一个与指定类型匹配的可枚举元素集合:
public static class VisualTreeExt
{
public static IEnumerable<T> GetDescendants<T>(DependencyObject parent) where T : DependencyObject
{
var count = VisualTreeHelper.GetChildrenCount(parent);
for (var i = 0; i < count; ++i)
{
// Obtain the child
var child = VisualTreeHelper.GetChild(parent, i);
if (child is T)
yield return (T)child;
// Return all the descendant children
foreach (var subItem in GetDescendants<T>(child))
yield return subItem;
}
}
}
当您要求VisualTreeHelperExt.GetDescendants<TreeViewItem>(MyAmazingTreeView)
时,您将获得所有TreeViewItem
孩子。您可以使用以下代码选择特定值:
var treeViewItem = VisualTreeExt.GetDescendants<TreeViewItem>(MyTreeView).FirstOrDefault(tvi => tvi.DataContext == newValue);
if (treeViewItem != null)
treeViewItem.IsSelected = true;
这是一个肮脏的解决方案(并且可能不是最有效的)并且如果您使用虚拟化TreeView将无法工作,因为它取决于实际视觉元素的存在。但它适用于我的情况......
是的..我知道自从这个问题被提出以来已经过去很多年了,但是..仍然没有快速解决这个问题..所以:
以下将按照OP的要求进行操作。
我基本上所做的就是阅读本页中的所有答案并按照所有相关链接创建一个 一劳永逸 解决这个恼人的问题。
好处:
- 它还支持虚拟化 TreeView。
- 它使用行为技术,因此 XAML 非常简单。
- 添加依赖属性以允许绑定到选定的 TreeView 项。
这部分是您需要复制的唯一代码,其他部分只是为了帮助完成示例。
public static class TreeViewSelectedItemExBehavior
{
private static List<TreeView> isRegisteredToSelectionChanged = new List<TreeView>();
public static readonly DependencyProperty SelectedItemExProperty =
DependencyProperty.RegisterAttached("SelectedItemEx",
typeof(object),
typeof(TreeViewSelectedItemExBehavior),
new FrameworkPropertyMetadata(new object(), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnSelectedItemExChanged, null));
#region SelectedItemEx
public static object GetSelectedItemEx(TreeView target)
{
return target.GetValue(SelectedItemExProperty);
}
public static void SetSelectedItemEx(TreeView target, object value)
{
target.SetValue(SelectedItemExProperty, value);
var treeViewItemToSelect = GetTreeViewItem(target, value);
if (treeViewItemToSelect == null)
{
if (target.SelectedItem == null)
return;
var treeViewItemToUnSelect = GetTreeViewItem(target, target.SelectedItem);
treeViewItemToUnSelect.IsSelected = false;
}
else
treeViewItemToSelect.IsSelected = true;
}
public static void OnSelectedItemExChanged(DependencyObject depObj, DependencyPropertyChangedEventArgs e)
{
var treeView = depObj as TreeView;
if (treeView == null)
return;
if (!isRegisteredToSelectionChanged.Contains(treeView))
{
treeView.SelectedItemChanged += TreeView_SelectedItemChanged;
isRegisteredToSelectionChanged.Add(treeView);
}
}
#endregion
private static void TreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
var treeView = (TreeView)sender;
SetSelectedItemEx(treeView, e.NewValue);
}
#region Helper Structures & Methods
public class MyVirtualizingStackPanel : VirtualizingStackPanel
{
/// <summary>
/// Publically expose BringIndexIntoView.
/// </summary>
public void BringIntoView(int index)
{
BringIndexIntoView(index);
}
}
/// <summary>Recursively search for an item in this subtree.</summary>
/// <param name="container">The parent ItemsControl. This can be a TreeView or a TreeViewItem.</param>
/// <param name="item">The item to search for.</param>
/// <returns>The TreeViewItem that contains the specified item.</returns>
private static TreeViewItem GetTreeViewItem(ItemsControl container, object item)
{
if (container != null)
{
if (container.DataContext == item)
{
return container as TreeViewItem;
}
// Expand the current container
if (container is TreeViewItem && !((TreeViewItem)container).IsExpanded)
{
container.SetValue(TreeViewItem.IsExpandedProperty, true);
}
// Try to generate the ItemsPresenter and the ItemsPanel.
// by calling ApplyTemplate. Note that in the
// virtualizing case even if the item is marked
// expanded we still need to do this step in order to
// regenerate the visuals because they may have been virtualized away.
container.ApplyTemplate();
ItemsPresenter itemsPresenter =
(ItemsPresenter)container.Template.FindName("ItemsHost", container);
if (itemsPresenter != null)
{
itemsPresenter.ApplyTemplate();
}
else
{
// The Tree template has not named the ItemsPresenter,
// so walk the descendents and find the child.
itemsPresenter = FindVisualChild<ItemsPresenter>(container);
if (itemsPresenter == null)
{
container.UpdateLayout();
itemsPresenter = FindVisualChild<ItemsPresenter>(container);
}
}
Panel itemsHostPanel = (Panel)VisualTreeHelper.GetChild(itemsPresenter, 0);
// Ensure that the generator for this panel has been created.
UIElementCollection children = itemsHostPanel.Children;
MyVirtualizingStackPanel virtualizingPanel =
itemsHostPanel as MyVirtualizingStackPanel;
for (int i = 0, count = container.Items.Count; i < count; i++)
{
TreeViewItem subContainer;
if (virtualizingPanel != null)
{
// Bring the item into view so
// that the container will be generated.
virtualizingPanel.BringIntoView(i);
subContainer =
(TreeViewItem)container.ItemContainerGenerator.
ContainerFromIndex(i);
}
else
{
subContainer =
(TreeViewItem)container.ItemContainerGenerator.
ContainerFromIndex(i);
// Bring the item into view to maintain the
// same behavior as with a virtualizing panel.
subContainer.BringIntoView();
}
if (subContainer != null)
{
// Search the next level for the object.
TreeViewItem resultContainer = GetTreeViewItem(subContainer, item);
if (resultContainer != null)
{
return resultContainer;
}
else
{
// The object is not under this TreeViewItem
// so collapse it.
subContainer.IsExpanded = false;
}
}
}
}
return null;
}
/// <summary>Search for an element of a certain type in the visual tree.</summary>
/// <typeparam name="T">The type of element to find.</typeparam>
/// <param name="visual">The parent element.</param>
/// <returns></returns>
private static T FindVisualChild<T>(Visual visual) where T : Visual
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(visual); i++)
{
Visual child = (Visual)VisualTreeHelper.GetChild(visual, i);
if (child != null)
{
T correctlyTyped = child as T;
if (correctlyTyped != null)
{
return correctlyTyped;
}
T descendent = FindVisualChild<T>(child);
if (descendent != null)
{
return descendent;
}
}
}
return null;
}
#endregion
}
这是 TreeView 行在 XAML 中的样子的示例:
<TreeView x:Name="trvwSs"
Grid.Column="2" Grid.Row="1" Margin="4" ItemsSource="{Binding ItemsTreeViewSs}"
behaviors:TreeViewSelectedItemExBehavior.SelectedItemEx="{Binding SelectedItemTreeViewSs}" />
唯一需要担心的是确保要绑定到 SelectedItemEx 的视图模型属性不为 null。但这不是特殊情况..只是提到这一点以防人们感到困惑。
public class VmMainContainer : INotifyPropertyChanged
{
private object selectedItemTreeViewSs = new object();
private ObservableCollection<object> selectedItemsTreeViewSs = new ObservableCollection<object>();
private ObservableCollection<VmItem> itemsTreeViewSs = new ObservableCollection<VmItem>();
public object SelectedItemTreeViewSs
{
get
{
return selectedItemTreeViewSs;
}
set
{
selectedItemTreeViewSs = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(SelectedItemTreeViewSs)));
}
}
public ObservableCollection<object> SelectedItemsTreeViewSs
{
get
{
return selectedItemsTreeViewSs;
}
set
{
selectedItemsTreeViewSs = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(SelectedItemsTreeViewSs)));
}
}
public ObservableCollection<VmItem> ItemsTreeViewSs
{
get { return itemsTreeViewSs; }
set
{
itemsTreeViewSs = value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(ItemsTreeViewSs)));
}
}
}
最后一件事..以编程方式选择的示例:我在 MainWindow.xaml 上及其处理程序中创建了一个按钮。
private void Button_Click(object sender, RoutedEventArgs e)
{
TreeViewSelectedItemExBehavior.SetSelectedItemEx(trvwSs, trvwSs.Items[3]);
//TreeViewSelectedItemExBehavior.SetSelectedItemEx(trvwSs, null);
}
希望这对某人有帮助:)
你可以通过代码
来实现if (TreeView1.Items.Count > 0)
(TreeView1.Items[0] as TreeViewItem).IsSelected = true;
我认为这是最简单的解决方案:
private void MouseDownEventProcessing(TreeNodeMouseClickEventArgs e)
{
tvEmployeeDirectory.SelectedNode = e.Node;
}
建议的答案不起作用。 @ fandisusanto的答案可能确实有效,但它可以变得更简单。这是我能提出的最简单的答案:
private static void DeselectTreeViewItem(IEnumerable<TreeViewItem> treeViewItems)
{
foreach (var treeViewItem in treeViewItems)
{
if (treeViewItem.IsSelected)
{
treeViewItem.IsSelected = false;
return;
}
DeselectTreeViewItem(treeViewItem.Items.Cast<TreeViewItem>());
}
}
用法:
private void ClearSelectedItem()
{
if (AssetTreeView.SelectedItem != null)
{
DeselectTreeViewItem(AssetTreeView.Items.Cast<TreeViewItem>());
}
}