Implementing Two-finger scroll with Windows 7 Surface Toolkit - need some thoughts!

I'm working with the Surface Toolkit and am willing to code a basic two-finger scroll algorithm for Scatterviews which contain FlowDocumentScrollViewer , but I'm not exactly sure how to do this.

How is the math done if you take into consideration that even rotated ScatterViews should be scrollable? What else do I need to take into consideration?

One thing that bothers me is that TouchMove is fired one 开发者_开发问答finger at a time so you can't really check if both fingers are down.

Its not my aim to make a perfect implementation (yet) but it should be at least useable.

I did this by surrounding the FlowDocumentScrollviewer with a SurfaceScrollViewer. This isn't ideal since the default-behavior means you can scroll in the middle and do everything else on the outside.

Josh Santangelo modified the behaviour so it can do both (look here) but it only works with Surface SDK SP1 now (the one for the Surface Device) but not Surface SDK for Windows Touch Beta (the Windows 7 one).