G'day folks,
If you've got a trackpad on your Mac, you can enabled and disable the zoom/rotation/etc. gestures in System Settings. I think you can also do this if you have a Magic Mouse. My question is: is there any API for determining if the user has done this? If I add an NSMagnificationGestureRecognizer, is there a way to know if it's even possible for it to be triggered?
I know, I know – the standard answer – don't give the user one way of doing a thing if that one way is a gesture. Add zoom in and out buttons like Maps does. But I'm talking about a game, and the default set of controls should be different for different input mechanisms. Think about a sim game: if you're using a standard mouse, then scroll wheel should be zoom, that's what the player expects - but if you're using a trackpad, zoom should be zoom and two-finger pan should move you around the map. With a mouse, the player probably expects that to be bound to right-click-and-drag, or middle-click-and-drag – gestures that are difficult or impossible to perform on a trackpad.
I feel like the ability to interrogate this is pretty central to the whole "do something sensible by default" at the heart of the Mac HIG.