An MSDN blog gives us an idea of the complexity that comes with font positioning.  The author tries to clean things up for the reader by having a lot of variables to keep the code readable:

Lecture for tonights class, which I would like to share with you dear reader, the first part is about how to position fonts on the screen using the least number lines of code.  Unfortunately, it requires a lot of variables, but there you go, complexity comes in many forms.  Variables are easy to understand, but the code is more messy than I like.  But to make neat code requires that the code readers understand what I am trying to do, and that can be difficult.

Here is the end result:

Go take a look at the code and download the package to see how the positioning works.  It'll take a bit of time to study.

Source: http://blogs.msdn.com/b/devschool/archive/2011/10/31/positioning-fonts-on-the-windows-phone-7-screen.aspx