How to center text around point using xaml - silverlight

Question

I would like to be able to place the word "hello" centered on a specific point. I need to do this completely in XAML without extra code. Best I can tell, all the text alignment properties/styles in XAML act on text within some bounding canvas or other element.
Since I don't know the length of the text I want to center, I can't center it using my own code.
The reason I need to solve the problem entirely in XAML is that I'm not using WPF to create the XAML, I'm writing it directly to an XML DOM. It will then be loaded into a Silverlight or WPF control for display.
In most graphic languages, including SVG, which is where my code originated, text can be aligned against a "stationary point" without a bounding box.
Any suggestions appreciated

Answer 1

(Yes, I know this question is old.)
The effectiveness of this solution may vary with the version of Silverlight or the .NET Framework you are using, and I haven't tried it with Silverlight for Windows Phone 7. I wrote a version for stand-alone WPF applications, and I wrote another version that also works in Silverlight.
First, the version that works in Silverlight and WPF. Please note that you will need to refactor the code a little bit if you aren't using a Canvas to provide an absolute position for the center of your TextBlock. For example, you may be using a TranslateTransform to position your text.
<Canvas>
<Canvas.Resources>
<ScaleTransform x:Key="transform" ScaleX="-1" ScaleY="-1" />
</Canvas.Resources>
<Grid RenderTransform="{StaticResource transform}" RenderTransformOrigin="-.25 -.25">
<TextBlock RenderTransform="{StaticResource transform}">
Hello!
</TextBlock>
</Grid>
</Canvas>
Second, the version that works only in WPF. It doesn't work in Silverlight because it depends on the presence of the Canvas.Right and Canvas.Bottom attached properties. UniformGrid isn't in Silverlight either, but that code could have been replaced by a regular Grid with 2 star-length rows and columns.
<Canvas>
<UniformGrid Rows="2" Columns="2"
DataContext="{Binding ElementName=textBox1}"
Width="{Binding Path=ActualWidth}"
Height="{Binding Path=ActualHeight}">
<Canvas>
<TextBlock Name="textBox1" Canvas.Right="0" Canvas.Bottom="0">
Hello!
</TextBlock>
</Canvas>
</UniformGrid>
</Canvas>
By the way, there may be more efficient ways to solve this problem available. I am making no guarantees!