WPF: TextTrimming in CheckBox with no fixed width

Question

I have a checkbox located in a grid with a column span of 3, where 2 of the columns are resizable, and can be resized during runtime.

I want the checkbox to show ellipsis when its text doesn't fit, but can't get this to work.

Here is my XAML code.

<Grid>
     <Grid.ColumnDefinitions>
          <ColumnDefinition Width="Auto" />
          <ColumnDefinition Width="*" />
          <ColumnDefinition Width="*" />
          <ColumnDefinition Width="Auto" />
     </Grid.ColumnDefinitions>
...
    <CheckBox IsEnabled="False"  Grid.Row="2" Padding="5" Margin="11,12,0,0" Name="chkSelectedCat" VerticalAlignment="Top" HorizontalAlignment="Stretch" Grid.ColumnSpan="3">
         <AccessText Text="Search in selected category only." TextTrimming="CharacterEllipsis"/>
    </CheckBox>

Thanks in advance for your help.

EDIT

The CheckBox in question is located within a Grid, which is in turn contained within a GroupBox, which is in a column adjacent to a column which is resized using a GridSplitter.

Answer 1

The problem was that the GroupBox allots infinite width to its child controls, as discussed at this MSDN forum thread.

In fact, when setting a MaxWidth to the CheckBox, text trimming worked and the ellipsis were displayed.

However the CheckBox maximum width needed to be changed during runtime.

I tried using a MultiValueConverter to bind the MaxWidth of the CheckBox to the total ActualWidth of the three columns, but the Convert method was only being called during initialisation (again I think this is something to do with how the GroupBox assigns sizes to its child controls).

Anyway I managed to achieve what I wanted by removing the ChechkBox's AccessText and using a TextBlock in a StackPanel in its stead, and then surrounding everything with a Border.

<Border Grid.Row="2" Grid.ColumnSpan="3" Name="chkBorder" SizeChanged="chkBorder_SizeChanged">
     <StackPanel Orientation="Horizontal" VerticalAlignment="Stretch">
               <CheckBox IsEnabled="False" Padding="0" Margin="11,7,0,5" Name="chkSelectedCat"  VerticalAlignment="Center"/>
               <TextBlock Foreground="Black" Name="txtChkSelectedCat" Text="Search in selected category only." TextTrimming="CharacterEllipsis" TextWrapping="NoWrap" VerticalAlignment="Center" Margin="0,5,5,5"/>
      </StackPanel>
</Border>

When the size of the Border is changed, I update the Width of the StackPanel in the event handler, and the text in the TextBox trims accordingly.

private void chkBorder_SizeChanged(object sender, SizeChangedEventArgs e)
{
     this.txtChkSelectedCat.Width = this.chkBorder.ActualWidth - this.chkSelectedCat.ActualWidth - 11 - 5 - 5; // margins
}

Hope this helps someone in the future (even though it is sort of a hack).

UPDATE

If you can eliminate the StackPanel and use a Grid instead, TextTrimming works automatically, without having to do any event handling, as shown below.

<Grid Grid.Row="2" Grid.ColumnSpan="3">
     <Grid.ColumnDefinitions>
          <ColumnDefinition Width="Auto" />
          <ColumnDefinition Width="*" />
     </Grid.ColumnDefinitions>
     <CheckBox Grid.Column="0" IsEnabled="False" Padding="0" Margin="11,7,0,5" Name="chkSelectedCat" VerticalAlignment="Center" ToolTipService.ShowOnDisabled="True"/>
     <TextBlock Grid.Column="1" Foreground="Black"  Name="txtChkSelectedCat" Text="Search in selected category only." TextTrimming="CharacterEllipsis" TextWrapping="NoWrap" VerticalAlignment="Center" Margin="0,5,5,5" MouseLeftButtonDown="txtChkSelectedCat_MouseLeftButtonDown" ToolTip="{Binding ElementName=chkSelectedCat, Path=ToolTip}" />
</Grid>

Make sure to set the Width of the column containing the textbox to "*", because "Auto" basically tells the TextBox that it can have as much space as it wants, so TextTrimming would not work.