注重文本框的ListView「的SelectionChanged」事件後

Question

我想將焦點設置TextBox一個項目從ListView控制選定之後，但我似乎無法得到它的注意力從我的「的SelectionChanged」事件方法FocusOnTextBox()內。

由於某些原因，ListView在選擇後始終關注。

我創建了一個Visual Studio應用程序來演示這個問題：

http://maq.co/focusapp.zip

我怎樣才能獲得焦點返回到TextBox從我「的SelectionChanged」事件方法內？

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

我相信這是因爲該ListView沒有完成改變選擇，所以你切換來自SelectionChanged事件處理程序的焦點不會因爲在焦點發生變化之後而停止，ListView會將其重新更改回爲了完成其選擇變更流程。

如果你把一個斷點在FocusOnTextBox功能，並期待在調用堆棧，你會看到，你是相當深入堆棧，並且有很多，你FocusOnTextBox函數執行後的ListView會做。我想它會做的一件事是將焦點設置在ListView中的選定項目。

如果在ListView完成更改當前選擇後更改它以便轉移焦點，它應該可以工作。例如，改變它，就切換焦點在MouseLeftButtonUp似乎工作：

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

然後你就需要改變FocusOnTextBox事件處理函數定義中使用MouseEventArgs，而不是SelectionChangedEventArgs爲好。