Listbox, DataTemplate and HorizontalContentAlignment

Question

Hi all,

using silverlight2 beta1, it seems that in a datatemplate of a listbox the ListBox.HorizontalContentAlignment is not supported.

 

Is there a bug?

Answer 1

deltakosh,

Could you please post a sample demonstrating the issue you're seeing? Below is a very simplified attempt at what I think you're getting at that demonstrates how HorizontalContentAlignment may not work quite the way one expects. In particular, this XAML shows a *centered* red rectangle on both WPF and Silverlight:

<ItemsControl HorizontalContentAlignment="Right">
    <ItemsControl.Template>
        <ControlTemplate>
            <Border BorderBrush="Black" BorderThickness="1">
                <ItemsPresenter/>
            </Border>
        </ControlTemplate>
    </ItemsControl.Template>
    <Rectangle Width="20" Height="20" Fill="Red"/>
</ItemsControl>

Answer 2

Hi David, I use a DataTemplate in my template.

Here is the sample:

        <ListBox x:Name="lstSamples" Grid.Row="1" ItemsSource="{Binding ''}" HorizontalContentAlignment="Stretch">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Image Source="{Binding Preview}">
                        <Image.RenderTransform>
                            <ScaleTransform ScaleX="1" ScaleY="1" />
                        </Image.RenderTransform>
                    </Image>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

Each item are left aligned and don't stretch at all.

 

Am I wrong?

Answer 3

Thanks for reporting this issue. It's a known bug which our developers are working on it.

Answer 4

deltakosh,

If this is the issue I have in mind, then the problem is caused by the Line element near the bottom of the ListBoxItem's default style in generic.xaml having Stretch=Fill.

This is not an ideal solution, but you can provide your own Template for ListBoxItem (easily via ListBox.ItemContainerStyle and copy+paste) that does not have this Line and therefore does not have the alignment problem (at least in the scenario I looked earlier today).

Hope this helps!

Answer 5

I've tried to copy default template from http://msdn2.microsoft.com/en-us/library/cc278062(vs.95).aspx , but I got lot of errors:

Error 1 'Library.App' does not contain a definition for 'FindName' and no extension method 'FindName' accepting a first argument of type 'Library.App' could be found (are you missing a using directive or an assembly reference?) 

Error 2 The property 'Name' was not found in type 'GradientStop'. ( x 6 times)

First error opens up "hidden" app.g.cs ....

Same things happens when I copy this to App.Resources and use it via key, or copy in ListBox.ItemContainerStyle

What I am doing wrong?

Answer 6

I found how to use default style for ItemContainerStyle. Style has to be in <ListBox.ItemContainerStyle>, and it works. Error with app.g.cs was showing because debuger had that file open during first scenario (to include Style in App.Resources). However I would like to find soultion how to resource this stule to use it accross controls.

David Anson: Line is fine, removing Line won't solve Streching problem, but removing "hardcoded" HorizontalAlignment="Left" from ContentPresenter in ControlTemplate solved my problems and content is streching w/o problem.