In the process of developing my Silverlight game, Diver, I came across what can only be a bug or limitation of the current Silverlight Beta 1 release.

If you create a PathGeometry in Blend using the pen tool, you can not automatically access the path data from code.

For example, the following snippet is the XAML created by Blend for a simple triangle. (I removed some of the attributes to to keep the code snippet short.)

<Path x:Name="Triangle" Data="M195,81 L267,173 L158,177 z" Fill="#FFFFFFFF" .../> 

(Note that Blend uses the short-hand path mini-language to describe the geometry of the triangle.)

Now, in Visual Studio, if you try to get access to the PathFigureCollection of the triangle's PathGeometry like so:

PathGeometry pg = (PathGeometry)Triangle.Data;
PathFigureCollection pf = pg.Figures;

no errors are thrown, but the pg.Figures returns null.

Furthermore, there is no property, that I could find, to get at the PathGeometry's mini language text.

It turns out this is only true of PathGeometry objects that use the mini language in their XAML mark-up.  If a PathGeometry is fully described (ie no mini language) then you can programmatically get at the PathFigureCollection.

The problem is Blend ONLY creates PathGeometry objects using the short-hand mini-language. There is no option in Blend to force full XAML mark-up for all PathGeometry objects.

This has been an issue since Silverlight 1.1 and I was hoping it would be fixed for the Silverlight 2.0 Beta, but no such luck it seems.

I have, however, found a bit of a hack to get around this for now.  This hack will force Blend to generate the full PathGeometry XAML rather than the mini language. 

Within Blend, go into XAML view and in the UserControl.Resources section add a bogus Storyboard like so. (I apologize for the poor formatting, my blog editor was not cooperating)

<UserControl.Resources>
<Storyboard x:Name="PathGeomHack">                    
<PointAnimationUsingKeyFrames Storyboard.TargetName="MyPath">                    
</PointAnimationUsingKeyFrames>             
</Storyboard>      
</UserControl.Resources>

Where "Triangle" is the PathGeometry for which I want Blend to render the full XAML.

Now go back to the design view and make an edit to the PathGeometry. I usually just slide a vertex point around a little. This is just to trigger Blend to regenerate the XAML.

What you should see is that with the bogus Storyboard pointing at your PathGemoetry, Blend will generate the full XAML tree rather than just the mini language.  This means you can then get programmatic access to the PathFigureCollection object from your code-behind.

I haven't done much else with this to discover any further simplifications or limitations, but this does give me what I need for now. Hopefully the next beta will have this issue resolved.

Hope this helps someone.