Question

in my ListBox ItemTemplate i want set TextBlock UnderLine.
as fllow:

    <StackPanel x:Name="TaskContent_SP"  Orientation="Horizontal" Background="#16191B" Height="80"  Width="455" >
                                    <Grid x:Name="DonePreDragCoreItem_GD" >
                                        <TextBlock x:Name="TaskNameItem_TB"  Canvas.ZIndex="0"   Text="{Binding TaskName}" Margin="10,10,10,10"   HorizontalAlignment="Left" Foreground="#414444" FontWeight="ExtraLight"  FontSize="30"></TextBlock>
                                        <Line x:Name="DoneForgroundLine_LE" Stroke="#414444" StrokeThickness="4" 
                                              X1="0" X2="{Binding ElementName=TaskNameItem_TB,Path=ActualWidth}"                                              
                                              Canvas.ZIndex="1" Margin="10,33,10,10"></Line>
                                    </Grid>
                                </StackPanel>

if i don’t use Databinding set Textblock text value. ActualWidth have normal value。 otherwise it will still 0.

how to get ActualWidth value when datebinding ?

Answer 1

You cannot get ActualWidth in binding because it is not a DependencyProperty. You can get a line on the bottom by using a Border

<Border BorderThickness="0,0,0,1" BorderBrush="Black">
    <TextBlock x:Name="TaskNameItem_TB" Text="{Binding TaskName}" Margin="10,10,10,10"   HorizontalAlignment="Left" Foreground="#414444" FontWeight="ExtraLight" FontSize="30"/>
</Border>