title: given a MatrixTransform how do I determine its current angle?
body: <p>I'm using WPF's MatrixTransform for managing my translation, scaling, and rotation on a Canvas (all 2D). It works well. However, I would like to be able to calculate the current angle of rotation. How is this done? Do I need to invert the matrix and then use that to rotate something? I can provide a "rotation-at" point if necessary.</p>