I have created 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?
Update:
I have added the Properties to the style to try to eliminate the warning/error.
The easiest way to solve this is to ensure that your Listbox has a ItemContainerStyle. See the following example:
<ListBox x:Name="RecentItemsListBox" Grid.Row="1" BorderThickness="0" Margin="2,0,0,0" SelectionChanged="RecentItemsListBox_SelectionChanged">
<ListBox.ItemContainerStyle>
<Style TargetType="{x:Type ListBoxItem}">
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
</Style>
</ListBox.ItemContainerStyle>
...
</ListBox>
What happens is that your Items are being created, and by default they look for parent's property which isn't defined. Explicitly defining it will solve this problem.
I had the same issue using a TreeView and changing the bound source for these templates would cause those warnings.