CODEWITHSUNDEEP
c#wpflistviewfocus
Luke
Luke

Reputation: 23680

Focus on TextBox after ListView 'SelectionChanged' Event

I wish to set focus on a TextBox after an item is selected from a ListView control, but I can't seem to get it to focus from within my 'SelectionChanged' event method FocusOnTextBox().

For some reason the ListView always has focus after a selection is made.

I have created a Visual Studio application to demonstrate this problem:

http://maq.co/focusapp.zip

How can I get the focus to return to the TextBox from within my 'SelectionChanged' event method?

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();
        }
    }
}

Upvotes: 2

Views: 2553

Answers (1)

Brian S
Brian S

Reputation: 5785

I believe this happens because the ListView is not finished changing the selection, and so you switching focus from within the SelectionChanged event handler doesn't stick because after you've changed focus, the ListView changes it back in order to complete its selection change flow.

If you put a breakpoint in the FocusOnTextBox function and look at the Call Stack, you'll see that you're pretty deep into the stack, and there is a lot that the ListView will do after your FocusOnTextBox function executes. I imagine one of the things it will do is set focus to the selected item in the ListView.

If you change it so that you're shifting focus after the ListView has completed changing the current selection, it should work. For example, changing it so you switch focus in the MouseLeftButtonUp seems to work:

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

And then you'll need to change the FocusOnTextBox event handler definition to use MouseEventArgs rather than SelectionChangedEventArgs as well.

Upvotes: 2

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