WPF Formatting text in a TextBlock bound to a string

Question

I have a custom control which has a string Description dependancy property as shown below:

<CustomControl>
    <CustomControl.Description>
        Hello World
    </CustomControl.Description>
</CustomControl>

This description is bound in several places in TextBlock's as shown below:

<Button>
    <Button.ToolTip>
        <TextBlock Text="{Binding Path=Description}"/>
    </Button.ToolTip>
    <TextBlock Text="{Binding Path=Description}"/>
</Button>

How can I add new lines and bold formatting to the text blocks? I have tried:

1. Adding \r\n to the description but this is not picked up.
2. Adding 
 or 
 to the description but this is not picked up.
3. Adding <![CDATA[<LineBreak/>]]> to the description but this is not picked up.
4. Changing the type of the Description to a Label and using ContentPresenter controls to bind to the label but I found that only one ContentPresenter can bind to the Label at a time and the other keeps dissapearing.
5. Changing the type of Description to a FlowDocument but I found that I could not add multiple viewer controls to view the same document.

Answer 1

You might change your Description type from a simple string to a object thus allowing the container to set it to whatever it wants, rich text, images, etc.

The same framework element cannot be the logical child of two elements, therefore you can't use it as the content of the button and the tooltip at the same time.

Example:

<CustomControl>
    <CustomControl.Description>
        <WrapPanel>
            <TextBlock Text="Hello " Foreground="Red"/>
            <TextBlock Text="World!" Foreground="Blue"/>
        </WrapPanel>
    </CustomControl.Description>
</CustomControl>

Template:

<Button>
    <Button.ToolTip>
        <ContentPresenter Content="{TemplateBinding SomeOtherProperty}"/>
    </Button.ToolTip>
    <ContentPresenter Content="{TemplateBinding Description}"/>
</Button>

Answer 2

The type of Description should be DataTemplate:

    <DataTemplate>
        <TextBlock>
                <Run>Hello</Run>
                <LineBreak/>
                <Run>World</Run>
        </TextBlock>
    </DataTemplate>

You can then use labels and assign the template to each label.

<Label FontSize="24" ContentTemplate="{Binding Inlines}"/>
<Label FontSize="10" ContentTemplate="{Binding Inlines}"/>