HierarchicalDataTemplate binding - wpf

Question

I have an hierarchical Treeview which each item contains a complexed entity which consists of:
Border
-- Check box
-- TextBlock
i want to change the opacity of the border whenever the checkbox IsEnabled property is set to "False"
this is what i have:
<HierarchicalDataTemplate DataType="{x:Type sd:LegendTreeViewItem}" ItemsSource="{Binding Path=SubSensors}">
<Border x:Name="treeViewItemBorder" Height="24" Margin="3 3 3 3" Width="350" Background="{Binding Path=Color}" CornerRadius="8 8 8 8">
<StackPanel Orientation="Horizontal">
<CheckBox x:Name="treeViewItemCheckbox" Margin="5 5 5 5" Click="CheckBox_Click" IsChecked="{Binding IsChecked}" VerticalAlignment="Center" IsEnabled="{Binding Enabled}" Style="{StaticResource OpacityOnDisabled}"/>
<TextBlock Height="Auto" FontFamily="Tahoma" FontWeight="Bold" Foreground="Black" HorizontalAlignment="Left" Text="{Binding Path=Name}"
VerticalAlignment="Center" ToolTip="{Binding Path=Name}"/>
</StackPanel> </Border>
</HierarchicalDataTemplate>
<TreeView x:Name="legendTypeTree" Grid.Row="1" Foreground="White" ItemsSource="{Binding ElementName=uc, Path=TypeItemsSource}">
<TreeView.Resources>
<Style x:Key="OpacityOnDisabled" TargetType="{Binding RelativeSource={RelativeSource AncestorType=Border}}">
<Style.Triggers>
<DataTrigger Binding="{Binding IsEnabled}" Value="False">
<Setter Property="Border.Opacity" Value="0.3"/>
<Setter Property="Border.Background" Value="White"/>
</DataTrigger>
</Style.Triggers>
</Style>
</TreeView.Resources>
</TreeView>

Answer 1

Move both HierarchicalDataTemplate and Style for the Border in the TreeView resources. (Style first in order for the StaticResource OpacityOnDisabled to resolve properly).
You want to change the style of the border, so there is no sense to apply style on the checkbox. Move Style="{StaticResource OpacityOnDisabled}" from the CheckBox to the Border element. Set the correct type of the style and for the DataTrigger change the bindinig to Binding="{Binding ElementName=treeViewItemCheckbox, Path=IsChecked}"
In the end you should have something like, which should do what you want:
Result:
<TreeView
x:Name="legendTypeTree"
Grid.Row="1"
Foreground="White"
ItemsSource="{Binding ElementName=uc, Path=TypeItemsSource}">
<TreeView.Resources>
<Style x:Key="OpacityOnDisabled" TargetType="{x:Type Border}">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=treeViewItemCheckbox, Path=IsChecked}" Value="False">
<Setter Property="Border.Opacity" Value="0.3"/>
<Setter Property="Border.Background" Value="White"/>
</DataTrigger>
</Style.Triggers>
</Style>
<HierarchicalDataTemplate DataType="{x:Type sd:LegendTreeViewItem}" ItemsSource="{Binding Path=SubSensors}">
<Border
x:Name="treeViewItemBorder"
Height="24"
Margin="3 3 3 3"
Width="350"
Background="{Binding Path=Color}"
CornerRadius="8 8 8 8"
Style="{StaticResource OpacityOnDisabled}">
<StackPanel Orientation="Horizontal">
<CheckBox
x:Name="treeViewItemCheckbox"
Margin="5 5 5 5"
Click="CheckBox_Click"
IsChecked="{Binding IsChecked}"
VerticalAlignment="Center"
IsEnabled="{Binding Enabled}" />
<TextBlock
Height="Auto"
FontFamily="Tahoma"
FontWeight="Bold"
Foreground="Black"
HorizontalAlignment="Left"
Text="{Binding Path=Name}"
VerticalAlignment="Center"
ToolTip="{Binding Path=Name}"/>
</StackPanel>
</Border>
</HierarchicalDataTemplate>
</TreeView.Resources>
</TreeView>