Inline editing TextBlock in a ListBox with Data Template (WPF)

Question

Using WPF, I have a ListBox control with a DataTemplate inside it. The relevant XAML code is shown below:

<ListBox Name="_todoList" Grid.Row="1" BorderThickness="2"
     Drop="todoList_Drop" AllowDrop="True"
     HorizontalContentAlignment="Stretch"
     ScrollViewer.HorizontalScrollBarVisibility="Disabled"                 
     AlternationCount="2">
     <ListBox.ItemTemplate>
         <DataTemplate>
             <Grid Margin="4">
                 <Grid.ColumnDefinitions>
                     <ColumnDefinition Width="Auto" />
                     <ColumnDefinition Width="*" />
                 </Grid.ColumnDefinitions>
                 <CheckBox Grid.Column="0" Checked="CheckBox_Check" />
                 <TextBlock Name="descriptionBlock"
                            Grid.Column="1"
                            Text="{Binding Description}"
                            Cursor="Hand" FontSize="14"
                            ToolTip="{Binding Description}"
                            MouseDown="TextBlock_MouseDown" />                      
             </Grid>
         </DataTemplate>
     </ListBox.ItemTemplate>
</ListBox>

What I am trying to do is make the TextBlock respond to a (double)click which turns it into a TextBox. The user can then edit the description, and press return or change focus to make the change.

I have tried adding a TextBox element in the same position as the TextBlock and making its visiblity Collapsed, but I don't know how to navigate to the right TextBox when the user has clicked on a TextBlock. That is, I know the user has clicked on a certain TextBlock, now which TextBox do I show?

Any help would be appreciated greatly,

-Ko9

Homorganic

As a tip, rather than using pre tags and explicitly escaping angle brackets, you can just paste XAML directly into the editor and use the 101010 button to format it as code. – Ileana

Thx also for showing in a basic and very comprehensive way how a DataTemplate in a ListBox works! – Occlusive

Answer 1

What I've done in these situations is used the XAML hierarchy to determine which element to show/hide. Something along the lines of:

<Grid>
  <TextBlock MouseDown="txtblk_MouseDown" />
  <TextBox LostFocus="txtbox_LostFocus" Visibility="Collapsed" />
</Grid>

with the code:

protected void txtblk_MouseDown(object sender, MouseButtonEventArgs e)
{
    TextBox txt = (TextBox)((Grid)((TextBlock)sender).Parent).Children[1];
    txt.Visibility = Visibility.Visible;
    ((TextBlock)sender).Visibility = Visibility.Collapsed;
}

protected void txtbox_LostFocus(object sender, RoutedEventArgs e)
{
    TextBlock tb = (TextBlock)((Grid)((TextBox)sender).Parent).Children[0];
    tb.Text = ((TextBox)sender).Text;
    tb.Visibility = Visibility.Visible;
    ((TextBox)sender).Visibility = Visibility.Collapsed;
}

I always turn stuff like this that I'm going to reuse into a UserControl, which I can add additional error handling to, and guarantee that the Grid will only contain two items, and the order of them will never change.

EDIT: Additionally, turning this into a UserControl allows you to create a Text property for each instantiation, so you can name each one and reference the text directly without fishing for the current value through the ((TextBox)myGrid.Children[1]).Text casting. This will make your code much more efficient and clean. If you make it into a UserControl, you can also name the TextBlock and TextBox elements, so no casting is needed at all.

Hawserlaid

this may sound odd, could you edit your answer... I clicked up prematurely, then removed my vote, because I wasnt sure if this was what I was after. I then tried to post an up vote again because it was what I needed and Stack Overflow says I cannot vote on this post unless it was edited. hence the request. Cheers, very useful post as it turned out. – Ancient

Answer 2

Refer to the Nathan Wheeler's code snippet, the following codes are complete UserControl source that I coded yesterday. Especially, Binding issues are addressed. Nathan's code is easy to follow, but needs some aid in order to work with databound text.

ClickToEditTextboxControl.xaml.cs

public partial class ClickToEditTextboxControl : UserControl
{
    public ClickToEditTextboxControl()
    {
        InitializeComponent();
    }

    public string Text
    {
        get { return (string)GetValue(TextProperty); }
        set { SetValue(TextProperty, value); }
    }

    // Using a DependencyProperty as the backing store for Text.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty TextProperty =
        DependencyProperty.Register("Text", typeof(string), typeof(ClickToEditTextboxControl), new UIPropertyMetadata());

    private void textBoxName_LostFocus(object sender, RoutedEventArgs e)
    {
        var txtBlock = (TextBlock)((Grid)((TextBox)sender).Parent).Children[0];

        txtBlock.Visibility = Visibility.Visible;
        ((TextBox)sender).Visibility = Visibility.Collapsed;
    }

    private void textBlockName_MouseDown(object sender, MouseButtonEventArgs e)
    {
        var grid = ((Grid) ((TextBlock) sender).Parent);
        var tbx = (TextBox)grid.Children[1];
        ((TextBlock)sender).Visibility = Visibility.Collapsed;
        tbx.Visibility = Visibility.Visible;

        this.Dispatcher.BeginInvoke((Action)(() => Keyboard.Focus(tbx)), DispatcherPriority.Render);
    }

    private void TextBoxKeyDown(object sender, KeyEventArgs e)
    {
        if (e == null)
            return;

        if (e.Key == Key.Return)
        {
            textBoxName_LostFocus(sender, null);
        }
    }
}

ClickToEditTextboxControl.xaml

<UserControl x:Class="Template.ClickToEditTextboxControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d" 
         Name="root"
         d:DesignHeight="30" d:DesignWidth="100">
<Grid>
    <TextBlock Name="textBlockName" Text="{Binding ElementName=root, Path=Text}" VerticalAlignment="Center" MouseDown="textBlockName_MouseDown" />
    <TextBox Name="textBoxName" Text="{Binding ElementName=root, Path=Text, UpdateSourceTrigger=PropertyChanged}" Visibility="Collapsed" LostFocus="textBoxName_LostFocus" KeyDown ="TextBoxKeyDown"/>
</Grid>
</UserControl>

And, finally, you can use this control in the XAML as below:

<Template1:ClickToEditTextboxControl Text="{Binding Path=Name, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" MinWidth="40" Height="23" />

Note that Mode=TwoWay, UpdateSourceTrigger=PropertyChanged is set. It enables to change the binded value in every type.

Technetium

Thanks for this solution, I use it via DataTemplate for my ListBox, but the new value does not get updated in the source. The ItemsSource is of type ObservableCollection<string>. Any ideas? – Subaxillary

Answer 3

The ideal way to do this would be to create a ClickEditableTextBlock control, which by default renders as a TextBlock but shows a TextBox when the user clicks it. Because any given ClickEditableTextBlock has only one TextBlock and one TextBox, you don't have the matching issue. Then you use a ClickEditableTextBlock instead of separate TextBlocks and TextBoxes in your DataTemplate.

This has the side benefit of encapsulating the functionality in a control so you don't pollute your main window code-behind with the edit behaviour, plus you can easily reuse it in other templates.

---

If this sounds like too much effort, you can use Tag or an attached property to associate each TextBlock with a TextBox:

<DataTemplate>
  <StackPanel>
    <TextBlock Text="whatever"
               MouseDown="TextBlock_MouseDown"
               Tag="{Binding ElementName=tb}" />
    <TextBox Name="tb" />
  </StackPanel>
</DataTemplate>

Note the use of {Binding ElementName=tb} on the Tag to refer to the TextBox named tb.

And in your code-behind:

private void TextBlock_MouseDown(object sender, MouseButtonEventArgs e)
{
  FrameworkElement textBlock = (FrameworkElement)sender;
  TextBox editBox = (TextBox)(textBlock.Tag);
  editBox.Text = "Wow!";  // or set visible or whatever
}

(To avoid the use of the nasty Tag property, you could define a custom attached property to carry the TextBox binding, but for brevity I'm not showing that.)

Ileana

Answer 4

If I may supplement, in order to cover the (double) part of the original question, in Youngjae's reply you make the following replacement in the xaml file:

<TextBlock Name="textBlockName" Text="{Binding ElementName=root, Path=Text}" VerticalAlignment="Center" MouseDown="textBlockName_MouseDown" />

is replaced with

<TextBlock Name="textBlockName" Text="{Binding ElementName=root, Path=Text}" VerticalAlignment="Center" >
    <TextBlock.InputBindings>
        <MouseBinding Gesture="LeftDoubleCLick" Command="{StaticResource cmdEditTextblock}"/>
    </TextBlock.InputBindings>
</TextBlock>

adding also the proper RoutedCommand in UserControl.Resources

<UserControl.Resources>
    <RoutedCommand x:Key="cmdEditTextblock"/>
</UserControl.Resources>

and a CommandBinding in UserControl.CommandBindings

<UserControl.CommandBindings>
    <CommandBinding Command="{StaticResource cmdEditTextblock}"
                    Executed="CmdEditTextblock_Executed"/>
</UserControl.CommandBindings>

Also in the code behind file:

private void textBlockName_MouseDown(object sender, MouseButtonEventArgs e)
{
    var grid = ((Grid)((TextBlock) sender).Parent);
    var tbx = (TextBox)grid.Children[1];
    ((TextBlock)sender).Visibility = Visibility.Collapsed;
    tbx.Visibility = Visibility.Visible;
    this.Dispatcher.BeginInvoke((Action)(() => Keyboard.Focus(tbx)), DispatcherPriority.Render);
}

is replaced by

private void CmdEditTextblock_Executed(object sender, ExecutedRoutedEventArgs e)
{
    var grid = ((Grid)((TextBlock)e.OriginalSource).Parent);
    var tbx = (TextBox)grid.Children[1];
    ((TextBlock)e.OriginalSource).Visibility = Visibility.Collapsed;
    tbx.Visibility = Visibility.Visible;
    this.Dispatcher.BeginInvoke((Action)(() => Keyboard.Focus(tbx)), DispatcherPriority.Render);
}

In case some people want to have left doubleclick as input gesture, like I did.

Espinal