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是选择要插入的函数的一种方式；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，然后该子项插入到TextBox中。子节点是一个函数签名，位于Parent节点下。然后，用户可以导航到TextBox，选择其中一个函数参数，并将其替换为另一个函数签名。为了实现这一点，我处理TreeView的SelectedItemChanged事件，设置TextBox的SelectedText，然后在更改后尝试高亮显示文本。
正在正确交换TextBox的SelectedText。但是，文本没有被突出显示，滚动条也没有滚动到选定的文本。
这是我为重现行为而编写的测试项目的XAML：
<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>
下面是代码：
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);
}
}
}
}
我已尝试设置SelectedItemChanged e.Handled=true。那没用。我尝试过处理TextBox的LostFocus并设置e.Handled=true，但没有成功。这似乎只有在我使用层次结构日期模板时才会发生。如果我将数据更改为仅一个级别，则此设置工作正常。
有什么想法吗？
核心问题是在事件处理程序中更改Focus()。通过在BeginInvoke中调用Focus来推迟Focus。
类似于：
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();
}
应该会让你离目标更近。
编辑：我们怎么知道这会起作用？
正如Dispatcher.BeginInvoke的文档所说：
操作将添加到位于的Dispatcher的事件队列中指定的DispatcherPriority。
因此，无论调用beginInvoke的任务的优先级如何，调用发生的最近时间都是在当前操作的执行结束之后：beginInvoked操作被"推送"到调度程序队列中的某个位置，该调度程序在单个线程上工作。