Wpf – GroupBox header template

foregroundheaderstylestemplateswpf

My Groupbox template is defined as so

<Style x:Key="{x:Type GroupBox}" TargetType="{x:Type GroupBox}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type GroupBox}">
                <Border BorderThickness="1" BorderBrush="SomeColour" 
                        Background="SomeColour"
                        CornerRadius="4">
                    <Grid SnapsToDevicePixels="true">
                        <Grid.RowDefinitions>
                            <RowDefinition Height="auto" />
                            <RowDefinition Height="auto" />
                        </Grid.RowDefinitions>
                        <ContentPresenter Grid.Row="0" ContentSource="Header" 
                                          Margin="2"/>
                        <ContentPresenter Grid.Row="1"
                                          Margin="{TemplateBinding Padding}"/>
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

How do I make it so that if the Header is set to a simple simple string, e.g

<GroupBox Header="The header!" />

The text is bold and with some default colour?

I tried the following, but it only works for the weight, not the colour.

<ContentPresenter ContentSource="Header" TextBlock.Foreground="Red" 
                  TextBlock.FontWeight="Bold"/>

Edit : here is the textblock style

<Style TargetType="{x:Type TextBlock}">
        <Setter Property="Foreground" Value="{StaticResource LabelForegroundBrush}" />
        <Setter Property="Background" Value="Transparent" />
        <Setter Property="VerticalAlignment" Value="Center" />
        <Setter Property="HorizontalAlignment" Value="Stretch" />
        <Setter Property="Margin" Value="1" />

        <Style.Triggers>
            <Trigger Property="IsEnabled" Value="False">
                <Setter Property="Foreground" Value="{StaticResource DisabledLabelForegroundBrush}" />
            </Trigger>
        </Style.Triggers>
    </Style>

Edit 2 : If I place the following in <Window.Resources> it seems to work, yet if I place them in <Application.Resources>, .. it fails???

<XXX.Resources>
        <Style TargetType="{x:Type TextBlock}">
            <Setter Property="Foreground" Value="Green" />
        </Style>

        <Style x:Key="{x:Type GroupBox}" TargetType="{x:Type GroupBox}">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type GroupBox}">
                        <Grid SnapsToDevicePixels="true">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="auto" />
                                <RowDefinition Height="auto" />
                            </Grid.RowDefinitions>
                            <ContentPresenter Grid.Row="0" ContentSource="Header" TextElement.Foreground="Red" />
                            <ContentPresenter Grid.Row="1" />
                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </XXX.Resources>

Usage :

<GroupBox Header="Header">
        <Button Content="Content" />
    </GroupBox>

Best Answer

Try this

 <Style x:Key="{x:Type GroupBox}" TargetType="{x:Type GroupBox}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type GroupBox}">
                    <Border BorderThickness="1" BorderBrush="SomeColour" 
                    Background="SomeColour"
                    CornerRadius="4">
                        <Grid SnapsToDevicePixels="true">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="auto" />
                                <RowDefinition Height="auto" />
                            </Grid.RowDefinitions>
                            <TextBlock Grid.Row="0" Foreground="Red" FontWeight="Bold" Margin="2"> 
                            <ContentPresenter ContentSource="Header"/>
                            </TextBlock>
                            <ContentPresenter Grid.Row="1" Margin="{TemplateBinding Padding}"/>
                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

Related Solutions

.net – the best approach for applying styles to massive amounts of items

You can put a "global" style into the Resources section of the grid, thus confining its impact. To re-use "global" styles in different locations, put them into a non-default resource dictionary and include it as MergedDictionary:

in Styles.xaml:

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style x:Key="{x:Type ...}"> ... </Style>
</ResourceDictionary>

in the form:

<Grid>
   <Grid.ColumnDefinitions.../>
   <Grid.RowDefinitions.../>

    <Grid.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="Styles.xaml" />
            </ResourceDictionary.MergedDictionaries>

            <!-- other resources here -->

        </ResourceDictionary>
    </Grid.Resources>

    ...
</Grid>

C++ – Why can templates only be implemented in the header file

Caveat: It is not necessary to put the implementation in the header file, see the alternative solution at the end of this answer.

Anyway, the reason your code is failing is that, when instantiating a template, the compiler creates a new class with the given template argument. For example:

template<typename T>
struct Foo
{
    T bar;
    void doSomething(T param) {/* do stuff using T */}
};

// somewhere in a .cpp
Foo<int> f;

When reading this line, the compiler will create a new class (let's call it FooInt), which is equivalent to the following:

struct FooInt
{
    int bar;
    void doSomething(int param) {/* do stuff using int */}
}

Consequently, the compiler needs to have access to the implementation of the methods, to instantiate them with the template argument (in this case int). If these implementations were not in the header, they wouldn't be accessible, and therefore the compiler wouldn't be able to instantiate the template.

A common solution to this is to write the template declaration in a header file, then implement the class in an implementation file (for example .tpp), and include this implementation file at the end of the header.

Foo.h

template <typename T>
struct Foo
{
    void doSomething(T param);
};

#include "Foo.tpp"

Foo.tpp

template <typename T>
void Foo<T>::doSomething(T param)
{
    //implementation
}

This way, implementation is still separated from declaration, but is accessible to the compiler.

Alternative solution

Another solution is to keep the implementation separated, and explicitly instantiate all the template instances you'll need:

Foo.h

// no implementation
template <typename T> struct Foo { ... };

Foo.cpp

// implementation of Foo's methods

// explicit instantiations
template class Foo<int>;
template class Foo<float>;
// You will only be able to use Foo with int or float

If my explanation isn't clear enough, you can have a look at the C++ Super-FAQ on this subject.

Best Answer

Related Solutions

.net – the best approach for applying styles to massive amounts of items

C++ – Why can templates only be implemented in the header file

Alternative solution

Related Topic