How do I retrieve screen geometry?

Just getting into Garmin Apps.
I'd like to design a watch face. I happen to have an Instinct 2 which has the peculiar geometry of a circular view embedded in a larger circle.

How would I programatically get watch screen geometry to adjust a layout? Or is that not the way to think about it?

Or where can I read different screen specifications, resolutions, geometry, etc if I want to do pixel-perfect layouts?

Thanks.