问题描述
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，而 TreeView 是一种选择要插入的函数的方法；想想 Crystal Report 脚本编辑器.
In my window I have a TreeView and TextBox. Pretend the TextBox is used for writing a custom script and the TreeView is a way to select a function to insert; think Crystal Report script editor.
我的目标是让用户单击 TreeView 的其中一个子项，然后该子项插入到 TextBox 中.子节点是一个函数签名，位于父节点下.然后用户可以导航到文本框，选择一个函数参数并将其替换为另一个函数签名.为此，我处理了 TreeView 的 SelectedItemChanged 事件，设置了 TextBox 的 SelectedText，然后尝试在更改后突出显示文本.
My goal is for a user to click one of the children of the TreeView and that child inserts into the TextBox. The child is a function signature and resides under a Parent node. The user can then navigate to the TextBox, select one of the function parameters and replace it with another function signature. To accomplish this, I handle the TreeView's SelectedItemChanged event, set the TextBox's SelectedText, and then try to highlight the text after it's changed.
TextBox 的 SelectedText 已正确交换.但是，文本没有突出显示，滚动条也没有滚动到选定的文本.
The SelectedText of the TextBox is properly being swapped. However, the text is not being highlighted and the scrollbar isn't scrolling to the selected text.
这是我为重现该行为而编写的测试项目中的 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);
}
}
}
}
我已尝试设置 SelectedItemChanged e.Handled = true.那没有用.我已经尝试处理 TextBox 的 LostFocus 并设置 e.Handled = true 并且没有奏效.这似乎只在我使用 HierarchicalDateTemplate 时发生.如果我将数据更改为仅一级，则此设置可以正常工作.
I have tried setting the SelectedItemChanged e.Handled = true. That didn't work. I've tried handling the LostFocus of the TextBox and setting e.Handled = true and that hasn't worked. This only seems to happen when I use the HierarchicalDateTemplate. If I change the data to be one level only, this setup works fine.
有什么想法吗?
推荐答案
核心问题是在事件处理程序中进行 Focus() 更改.通过在 BeginInvoke 中调用来推迟焦点.
The core issue is to have a Focus() change within an event handler. Postpone the Focus by calling it within a BeginInvoke.
类似:
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.
我们怎么知道这会起作用?
Edit : How do we know this will work ?
作为 Dispatcher.BeginInvoke 的文档说:
As the documentation for Dispatcher.BeginInvoke says :
操作被添加到 Dispatcher 的事件队列中指定 DispatcherPriority.
The operation is added to the event queue of the Dispatcher at the specified DispatcherPriority.
因此，无论您调用 beginInvoke 的任务的优先级如何，调用发生的最近时间是在当前操作的执行结束之后:beginInvoked 操作被推送"到调度程序队列的某个位置，这是有效的在一个线程上.
So whatever the priority of the task where you call beginInvoke, the nearest time when the call can happen is right after the execution of current operation ended : the beginInvoked operation is 'pushed' somewhere on the queue of the dispatcher, which works on a single thread.
这篇关于用户选择子项后 TreeView 自动选择父项的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！