I wanted to have keyboard control of the 3D printer carriage, moving the webcam view by pressing arrow keys. I knew enough about the application framework to know I needed to implement handlers for the
KeyUp events, but in my first implementation those handlers are never called.
If at first I don’t succeed, it’s time to go to the manual.
The first stop is the overview for UWP Events and Routed Events, the umbrella of event processing architecture including keyboard events. It was an useful review and I was glad I hadn’t forgotten anything fundamental or have missed anything significantly new.
Next stop was the UI design document for keyboard interactions. Again this was technically a review, but I’ve forgotten much of this information. Keyboard handling is complicated! It’s not just an array of buttons, there are a lot of interactions between keys and conventions build up over decades as to what computer literate users have come to expect.
When I think of key interactions, my first reaction is to think about the shift key and control key. These modifier keys change the meaning of another button: the difference between lowercase ‘c’, uppercase ‘C’ and Control+C which might be anything from “interrupt command line program” to “Copy to clipboard.”
But that’s not important to my current project. My desire to move the camera carriage using arrow keys opened up an entirely different can of worms: keyboard navigation.