I need to do self deep tissue massage on my back each night. I roll around on the floor on top of a tennis ball for a half hour. During this time I watch stuff on my MacBook Pro, which is running El Capitan. I control it with my Magic Trackpad.
I'm sufficiently far away that reading Finder items is a little difficult, so I'd love to be able to zoom the screen with the trackpad. But the Trackpad System Preference is useless for this; it seems it only works with e.g. iPhotos. Accessibility System Preference insists that a key be held down while doing the zoom gesture in order to zoom the screen, so it's useless too.
So, does anyone know of an application or extension for El Capitan which will do whole-screen zooms from JUST a trackpad gesture? Googling turns up nothing useful :(