在 ListView 'SelectionChanged' 事件之后关注文本框

Question

我希望在从 ListView 控件中选择一个项目后将焦点设置在 TextBox 上，但我似乎无法从我的“SelectionChanged”事件方法 FocusOnTextBox() 中获得焦点。

出于某种原因，ListView 在做出选择后始终具有焦点。

我创建了一个 Visual Studio 应用程序来演示这个问题：

http://maq.co/focusapp.zip

如何让焦点从我的“SelectionChanged”事件方法中返回到TextBox？

MainWindow.xaml：

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition />
            <ColumnDefinition />
        </Grid.ColumnDefinitions>

        <ListView Name="list_view1" Grid.Column="0" SelectionChanged="FocusOnTextBox">
            <ListViewItem Content="1" />
            <ListViewItem Content="2" />
            <ListViewItem Content="3" />
        </ListView>
        <TextBox Name="text_box1" Grid.Column="1" Text="When a selection is chosen from the left hand side ListView, I want THIS word to be selected and for the focus to change to this text box - this will show the selection to the user.&#x0a;&#x0a;However, right now it doesn't seem to work, the focus remains on the ListView regardless of it being set to Focus() in the FocusOnTextBox() method, which is fired on the 'SelectionChanged' event." TextWrapping="Wrap" />
    </Grid>
</Window>

MainWindow.xaml.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
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 WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            // Test that the selection of the word THIS and the Focus() works
            text_box1.SelectionStart = 68;
            text_box1.SelectionLength = 4;

            text_box1.Focus();
        }

        private void FocusOnTextBox(object sender, SelectionChangedEventArgs e)
        {
            MessageBox.Show("FocusOnTextBox fired on selection with list view");

            text_box1.SelectionStart = 68;
            text_box1.SelectionLength = 4;

            text_box1.Focus();
        }
    }
}

Answer 1

我相信发生这种情况是因为 ListView 没有完成更改选择，因此您从 SelectionChanged 事件处理程序中切换焦点不会粘住，因为在您更改焦点后，ListView 会更改它返回以完成其选择更改流程。

如果你在FocusOnTextBox 函数中放置一个断点并查看调用堆栈，你会发现你已经深入堆栈了，ListView 在你的@ 之后会做很多事情987654326@ 函数执行。我想它会做的其中一件事是将焦点设置到ListView 中的选定项目。

如果您更改它以便在 ListView 完成更改当前选择后转移焦点，它应该可以工作。例如，更改它以便在MouseLeftButtonUp 中切换焦点似乎有效：

<ListView Name="list_view1" Grid.Column="0" MouseLeftButtonUp="FocusOnTextBox">
    <ListViewItem Content="1" />
    <ListViewItem Content="2" />
    <ListViewItem Content="3" />
</ListView>

然后您需要将FocusOnTextBox 事件处理程序定义更改为使用MouseEventArgs 而不是SelectionChangedEventArgs。