Problem with ListBoxItem - produce "System.Windows.Data Error: 4"

Question

Hi.

I have craeted the fallowing ListBox:

<ListBox x:Name="RecentItemsListBox" Grid.Row="1" BorderThickness="0" Margin="2,0,0,0" SelectionChanged="RecentItemsListBox_SelectionChanged">
  <ListBox.Resources>
      <Style TargetType="{x:Type ListBoxItem}"
             BasedOn="{StaticResource {x:Type ListBoxItem}}">
          <Style.Triggers>
              <!--This trigger is needed, because RelativeSource binding can only succeeds if the current ListBoxItem is already connected to its visual parent-->
              <Trigger Property="IsVisible"
                       Value="True">
                  <Setter Property="HorizontalContentAlignment"
                          Value="{Binding Path=HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}" />
                  <Setter Property="VerticalContentAlignment"
                          Value="{Binding Path=VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}" />
              </Trigger>
          </Style.Triggers>
      </Style>
  </ListBox.Resources>
  <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal" Margin="0,2,0,0">
                    <TextBlock Text="{Binding Number}" />
                                <StackPanel Orientation="Vertical" Margin="7,0,0,0">
                                    <TextBlock Text="{Binding File}" />
                                    <TextBlock Text="{Binding Dir}" Foreground="DarkGray" />
                                </StackPanel>
                            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

This will produce at runtime the fallowing Line in the OutputWindow of VisualStudio:

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'ListBoxItem' (Name='');

Can someone give me a tip, how I can solve this?

Thank you very much.

Best Regards, Thomas

Answer 1

Do you need that style at all? why can't you set the alignments on the stackpanel/textblock in the datatemplate?

Answer 2

Hi. I have added the Properties to the style to try to eleminate the warning/error.