I've now defined parent classes for camera and stage, and depend only on those. This allows
proper typing while enabling the actual hardware
classes to be swapped.
The interfaces definitely aren't final - this is a first
draft, largely to enable me to test out the concept
of a configuration server.
This allows the server to run on a laptop, to some extent. I've not tested if this will make the whole
web app work properly.
As StreamingPiCamera2 is hardcoded in various places, this certainly doesn't make cameras totally
interchangeable - but it is a step towards that.
