Apple has done research on, and has patents for, a display-based keyboard for the rumored all-screen foldable Macbook, in which the areas where "keys" are displayed either raise up when you invoke the keyboard, forming rows of bumps that deform downward when you press on them, to simulate the movement of mechanical keytops, along with a haptic engine click, to provide tactile feedback/home row positioning, and another design in which the "keys" stay flat, but they deform downward when you press on them.