WPF: Apply TextBlock Style for ContentPresenter

Question

I would like to create a ControlTemplate. Text in the ContentPresenter must be styled, but dont. How to style textblock in contentpresenter? This is my code:

    <Style x:Key="PrimaryPanel" TargetType="GroupBox">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="GroupBox">
                    <Border  BorderThickness="1" BorderBrush="#337AB7">
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="*"/>
                            </Grid.RowDefinitions>
                            <StackPanel Background="#337AB7">
                                <ContentPresenter ContentSource="Header">
                                    <ContentPresenter.Resources>
                                        <Style TargetType="{x:Type TextBlock}">
                                            <Setter Property="Foreground" Value="#fff"></Setter>
                                            <Setter Property="Margin" Value="0 -1 0 0"></Setter>
                                            <Setter Property="Padding" Value="5"></Setter>
                                            <Setter Property="VerticalAlignment" Value="Center"></Setter>
                                        </Style>
                                    </ContentPresenter.Resources>
                                </ContentPresenter>
                            </StackPanel>
                            <Border Grid.Row="1" Padding="10 5" Margin="5 0 5 10" >
                                <StackPanel>
                                    <ContentPresenter />
                                </StackPanel>
                            </Border>
                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

Using:

<GroupBox Style="{StaticResource PrimaryPanel}">
    <GroupBox.Header>
        <TextBlock Text="Title"/> this text must by styled
    </GroupBox.Header>
  </GroupBox>

Thanks for advice.

Answer 1

I've created a simple behavior for you that resolves your issue pretty well:

 public class Behaviour
{
    public static object GetStyleToLoad(DependencyObject obj)
    {
        return (object)obj.GetValue(StyleToLoadProperty);
    }

    public static void SetStyleToLoad(DependencyObject obj, object value)
    {
        obj.SetValue(StyleToLoadProperty, value);
    }

    // Using a DependencyProperty as the backing store for StyleToLoad.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty StyleToLoadProperty =
        DependencyProperty.RegisterAttached("StyleToLoad", typeof(object), typeof(Behaviour), new PropertyMetadata(null,
            (o, e) =>
            {
                if (e.NewValue != null)
                {
                    Style s = e.NewValue as Style;
                    if (s != null)
                    {
                        FrameworkElement fe = o as FrameworkElement;

                        if (fe != null)
                        {
                            fe.Resources.Add(s.TargetType, s);
                        }
                    }
                }
            }));


}

Usage:

In my View I put a TextBlock Style with HotPink Foreground:

 <UserControl.Resources>
   <Style TargetType="{x:Type TextBlock}">

        <Setter Property="Foreground"
                Value="HotPink" />

    </Style>

Applying of the Behaviour for your ContentPresenter:

<ContentPresenter local:Behaviour.StyleToLoad="{StaticResource {x:Type TextBlock}}"
                      Content="My Text" />

There the result after compilation:

As you can see the Style has been applied.