WPF - How to apply style to AdornedElementPlaceholder's AdornedElement?

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>