试图在C＃WPF程序中确定FPS

I'm writing an application for a touch table using WPF and C#. (And, I'm not terribly familiar with WPF. At all.) We suspect we're not getting the framerate we're "requesting" from the API so I'm trying to write my own FPS calculator. I'm aware of the math to calculate it based on the internal clock, I just don't know how to access a timer within the Windows/WPF API. us