.net - What is the WPF XAML Data Binding equivalent of String.Format?

Question

Or, to be more clear, how can I format a block of text (in my case, to be included within a tooltip) such that some portions of the text come from bound values.

In plain C# I would use:

_toolTip.Text = string.Format("{1:#0}% up, {2:#0}% down",
    Environment.NewLine, percentageOne, percentage2);

However the WPF XAML markup for a Text property seems able to contain only a single binding. The curly braces gave me high hopes, but this isn't possible:

<Element>
  <Element.Tooltip>
    <!-- This won't compile -->
    <TextBlock Text="{Binding Path=PercentageOne}% up, {Binding Path=PercentageTwo}% down"/>
  </Element.Tooltip>
</Element>

I read that the Run.Text property is not a dependency property and can therefore not be bound.

Is there a way I can perform this formatting in XAML?

Answer 1

You can use MultiBinding + StringFormat (requires WPF 3.5 SP1):

<TextBox.Text>
    <MultiBinding StringFormat="{}{1:#0}% up, {2:#0}% down">
      <Binding Path="PercentageOne" />
      <Binding Path="PercentageTwo"/>
    </MultiBinding>
</TextBox.Text>

Regarding Run.Text - you can't bind to it but there are some workarounds:

• http://fortes.com/2007/03/20/bindablerun/
• http://paulstovell.net/blog/index.php/attached-bindablerun/