WPF - How to apply style to AdornedElementPlacehol

Question

I'm trying to apply a style to an adorned element, but I don't know the correct syntax. Here is what I've tried:

    <!-- ValidationRule Based Validitaion Control Template -->
    <ControlTemplate x:Key="validationTemplate">
        <DockPanel>
            <TextBlock Foreground="Red" FontSize="20">!</TextBlock>
            <AdornedElementPlaceholder Style="textStyleTextBox"/>
        </DockPanel>
    </ControlTemplate>

The only problem is that the following line doesn't work:

            <AdornedElementPlaceholder Style="textStyleTextBox"/>

Any help would be greatly appreciated.

Thanks,

-Charles

Answer 1

Need to put where the resource is coming from.

<TextBox Style="{StaticResource textStyleTextBox}"/>

Then define the style in a resource such as the user control resources:

<UserControl.Resources>
  <Style TargetType="TextBox" x:Key="textStyleTextBox">
    <Setter Property="Background" Value="Blue"/>
  </Style>
</UserControl.Resources>

However I dont believe you want to set the style of the adornedelement within the placeholder. It's just a placeholder for any control with that template. You should set the style of the adornedelement in the element itself like the example I provided above. If you want to style the control based upon it's validation then something like this:

<Window.Resources>
   <ControlTemplate x:Key="validationTemplate">
       <DockPanel>
           <TextBlock Foreground="Yellow" Width="55" FontSize="18">!</TextBlock>
           <AdornedElementPlaceholder/>
       </DockPanel>
   </ControlTemplate>
   <Style x:Key="textBoxInError" TargetType="{x:Type TextBox}">
       <Style.Triggers>
           <Trigger Property="Validation.HasError" Value="true">
               <Setter Property="Background" Value="Red"/>
               <Setter Property="Foreground" Value="White"/>
           </Trigger>
       </Style.Triggers>
   </Style>
</Window.Resources>
<StackPanel x:Name="mainPanel">
    <TextBlock>Age:</TextBlock>
    <TextBox x:Name="txtAge"
             Validation.ErrorTemplate="{DynamicResource validationTemplate}"
             Style="{StaticResource textBoxInError}">
         <Binding Path="Age" UpdateSourceTrigger="PropertyChanged" >
             <Binding.ValidationRules>
                 <ExceptionValidationRule/>
             </Binding.ValidationRules>
         </Binding>
    </TextBox> 
</StackPanel>