用户选择子项后,TreeView自动选择父级

Question

在我的窗口中,我有一个TreeView和TextBox.假设TextBox用于编写自定义脚本,TreeView是一种选择要插入的函数的方法; 想想Crystal Report脚本编辑器.

我的目标是让用户单击TreeView的一个子项,并将该子项插入TextBox.子项是函数签名,位于父节点下.然后,用户可以导航到TextBox,选择一个功能参数并将其替换为另一个功能签名.为此,我处理TreeView的SelectedItemChanged事件,设置TextBox的SelectedText,然后尝试在文本更改后突出显示该文本.

正确地交换TextBox的SelectedText.但是,文本未突出显示,滚动条未滚动到所选文本.

这是我编写的测试项目中的XAML,用于重现行为:

  <Window x:Class="SelectedTextWeirdness.MainWindow"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:System="clr-namespace:System;assembly=mscorlib"
          xmlns:SelectedTextWeirdness="clr-namespace:SelectedTextWeirdness" Title="MainWindow" Width="600" Height="600"
          x:Name="Me">
     <Grid>
        <Grid.RowDefinitions>
           <RowDefinition Height="Auto" />
           <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <TreeView Grid.Row="0" x:Name="treeView" ItemsSource="{Binding ElementName=Me, Path=TreeViewItems, Mode=TwoWay}" 
                  SelectedItemChanged="treeView_SelectedItemChanged" Margin="10">
           <TreeView.Resources>
              <HierarchicalDataTemplate DataType="{x:Type SelectedTextWeirdness:Parent}" ItemsSource="{Binding Children}">
                 <TextBlock Text="{Binding Name}" />
              </HierarchicalDataTemplate>
              <DataTemplate DataType="{x:Type SelectedTextWeirdness:Child}">
                 <TextBlock Text="{Binding Name}" />
              </DataTemplate>
           </TreeView.Resources>
        </TreeView>
        <TextBox Grid.Row="1" x:Name="scriptTextBox" Margin="10" Height="200" Width="Auto" FontFamily="Consolas, Courier New" 
                 HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Auto"
                 MaxLines="9999" AcceptsReturn="True" AcceptsTab="True" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" 
                 Text="{Binding Path=Script, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                 />
     </Grid>
  </Window>

这是代码隐藏:

  using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Windows;
  using System.Windows.Controls;
  using System.Windows.Data;
  using System.Windows.Documents;
  using System.Windows.Input;
  using System.Windows.Media;
  using System.Windows.Media.Imaging;
  using System.Windows.Navigation;
  using System.Windows.Shapes;

  namespace SelectedTextWeirdness
  {
     public class Child
     {
        public string Name
        {
           get;
           set;
        }
     }

     public class Parent
     {
        public string Name
        {
           get;
           set;
        }

        public List<Child> Children
        {
           get;
           set;
        }   
     }

     /// <summary>
     /// Interaction logic for MainWindow.xaml
     /// </summary>
     public partial class MainWindow : Window
     {
        public List<Parent> TreeViewItems
        {
           get;
           set;
        }

        public MainWindow()
        {
           BuildTreeViewItems();

           InitializeComponent();
        }

        private void BuildTreeViewItems()
        {
           TreeViewItems = new List<Parent>()
                              {
                                 new Parent()
                                    {
                                       Name = "Parent1",
                                       Children =
                                          new List<Child>()
                                             {
                                                new Child() {Name = "ReallyLongFunctionNameNumber1(ReallyLongLeft1, ReallyLongRight1)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber2(ReallyLongLeft2, ReallyLongRight2)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber3(ReallyLongLeft3, ReallyLongRight3)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber4(ReallyLongLeft4, ReallyLongRight4)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber5(ReallyLongLeft5, ReallyLongRight5)"}
                                             }
                                    },
                                 new Parent()
                                    {
                                       Name = "Parent2",
                                       Children =
                                          new List<Child>()
                                             {
                                                new Child() {Name = "ReallyLongFunctionNameNumber1(ReallyLongLeft1, ReallyLongRight1)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber2(ReallyLongLeft2, ReallyLongRight2)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber3(ReallyLongLeft3, ReallyLongRight3)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber4(ReallyLongLeft4, ReallyLongRight4)"},
                                                new Child() {Name = "ReallyLongFunctionNameNumber5(ReallyLongLeft5, ReallyLongRight5)"}
                                             }
                                    }
                              };
        }

        private void treeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
        {
           var tree = (TreeView)sender;
           var selectedItem = tree.SelectedItem as Child;
           if (selectedItem != null)
           {
              int selectionStart = scriptTextBox.SelectionStart;
              string selectedText = selectedItem.Name;
              scriptTextBox.SelectedText = selectedText;
              scriptTextBox.Focus();            
              scriptTextBox.Select(selectionStart, selectedText.Length);
           }
        }
     }
  }

我尝试过设置SelectedItemChanged e.Handled = true.那没用.我已经尝试处理TextBox的LostFocus并设置e.Handled = true并且没有用.这似乎只在我使用HierarchicalDateTemplate时发生.如果我将数据更改为仅一级,则此设置可正常工作.

有任何想法吗？

Answer 1

核心问题是Focus()在事件处理程序中进行更改.通过在一个内部调用它来推迟焦点BeginInvoke.

就像是:

delegate void voidDelegate();

private void treeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
    var tree = (TreeView)sender;
    var selectedItem = tree.SelectedItem as Child;
    if (selectedItem != null)
    {
        int selectionStart = scriptTextBox.SelectionStart;
        string selectedText = selectedItem.Name;
        voidDelegate giveFocusDelegate = new  voidDelegate(giveFocus);  
        Dispatcher.BeginInvoke(giveFocusDelegate, new object[] { });
        scriptTextBox.SelectedText = selectedText;         
    }
}

private void giveFocus()
{
    scriptTextBox.Focus();
}    

应该让你离目标更近.

编辑:我们怎么知道这会起作用？

正如文档Dispatcher.BeginInvoke所说:

该操作将添加到指定DispatcherPriority的Dispatcher的事件队列中.

因此,无论您调用beginInvoke的任务的优先级如何,调用可能发生的最近时间是在当前操作的执行结束之后:beginInvoked操作在调度程序队列的某处"推送",该操作在单个上运行线.