This builds on the basic idea behind pie menus, which is to exploit Fitt's Law, by lowering the target distance by centering the menu around the point of contact, and increasing the target area by basing the selection on the direction of movement instead of hitting a small absolutely positioned target. https://en.wikipedia.org/wiki/Fitts_law

An Empirical Comparison of Pie vs. Linear Menus,
Jack Callahan, Don Hopkins, Mark Weiser and Ben Shneiderman.
Computer Science Department University of Maryland College Park, Maryland 20742.
Presented at ACM CHI'88 Conference, Washington DC, 1988.
http://www.donhopkins.com/drupal/node/100

I've applied pie menus to various applications including tools like window managers and text editors, and games like SimCity and The Sims, which uses pie menus for controlling the lives of the simulated people.
https://en.wikipedia.org/wiki/Pie_menu

Since the direction of motion, which selects the pie menu item, is independent from the distance of motion, you can use the distance as a parameter. Here's a demo and an article showing various kinds of pie menus I've developed:

Pie menus from "All The Widgets" CHI'90 Special Isssue #57 ACM SIGGRAPH Video Review. Including Doug Engelbart's NLS demo and the credits. Tape produced by and narrated by Brad Meyers. Research performed under the direction of Mark Weiser and Ben Shneiderman. Pie menus developed and demonstrated by Don Hopkins. http://www.donhopkins.com/home/movies/AllTheWidgets.mov

The Design and Implementation of Pie Menus -- Dr. Dobb's Journal, Dec. 1991.
There're Fast, Easy, and Self-Revealing.
Copyright (C) 1991 by Don Hopkins.
Originally published in Dr. Dobb's Journal, Dec. 1991, lead cover story, user interface issue. http://www.donhopkins.com/drupal/node/98

Here's a more modern implementation in Unity3D: http://www.youtube.com/watch?v=sMN1LQ7qx9g

The multi finger interface is obviously a very nice touch that this interface brings to the tablet (if you'll pardon the pun ;). I like to call touch screen pie menus "finger pies", in a nod to the Liverpool slang term from the Beatles' "Penny Lane": "a four of fish and finger pie". ;) http://www.songfacts.com/detail.php?id=115

"ConnectedTV" is a finger controlled Palm app that David Levitt and I developed more than a decade ago for the Palm (without multitouch of course): a handheld personalized TV guide integrated with a universal remote control, which you could reliably operate with your fingers instead of the stylus that most Palm apps required at the time. Here is a review than mentions the single handed finger touching and stroking interface:

ConnectedTV: TV Guide + Remote Control, Geoff Walker, 2/2/02.
http://www.pencomputing.com/palm/Pen44/connectedTV.html

"On the Palm, the application user interface is simple. The application checks the clock on the Palm and displays the names of all the TV programs for the current 15-minute window. The program buttons are large enough to easily hit with your finger. For easy identification of programs that are about to start, one corner of the button is clipped. To tune the TV to a selected program, you just tap the button. To display more information about a program (i.e., the blurb from the guide), you do a downstroke on the button. The downstroke is a result of the program menu buttons being implemented via "pie menus" (see www.piemenu.com), which makes it very easy to use the application with one hand."

"For instant access to frequently used functions, the application remaps the Palm’s hardware buttons to Power, Mute, Volume Up/Down, Next and Back. At initial release, the program will include support for TiVo and some brands & models of VCR, as well as the ability to program it for other brands. Management of "Favorites" (e.g., flagging favorite programs with their first run/rerun status) is planned but may not make the first release."

Most Palm apps required a stylus to operate, because their interfaces required a lot of precision and visual feedback. But it was quite easy to accidentally lose your stylus in the couch cushions in the dark living room, so pie menus made it possible to control the Palm in a dark room with your fingers, which was unusual at the time (long before the iPhone).

ConnectedTV used big multi-purpose buttons that you could reliably operate with your finger, supporting up to five complementary functions for taps and strokes up, down left and right, with immediate audio and visual feedback during tracking.

The directional strokes worked very nicely with complementary sets of commands that remote controls tend to use like changing volume up and down, changing channels next and previous, liking and ignoring programs, paging up and down, moving forwards and backwards in time, etc.

David Levitt wrote up a summary of how it worked:

iPhone Lovefest - How Don and I Invented Stroking vs Poking
https://www.facebook.com/note.php?note_id=106220169912

On a recent Sunday, journalist Steven Levy hosted an iPhone Lovefest at Sylvia Paull's Berkeley Salon, and more than a hundred of us showed up. I realized some of us had quietly helped invent something historic, and I spoke briefly about it that day, but first I did a little demo.

More than a dozen developers brought iPhone applications to show off; a camera and projector showed the crowd each little screen. I went up last, commenting that with its sensor, the iPhone had the same motion sensitivity as the Wii's legendary game controller, and tapped mine on the table. As it tumbled from my hand there was a nasty cracking noise and the audience saw this: Gasps and shrieks were soon followed by laughter, a woman shouting "I have version 1.0 of that!", and relieved applause. I explained that the iPhone application draft I was showing was called iBustedIt, the cracking sound and image were triggered by motion, and Levity Novelty aimed to make it available by April Fool's Day. Only it turns out Apple considers this kind of trick an impersonation of its fine software and doesn't allow it in the App Store - so my apologies to those of you who planned to trick and shock your friends with iBustedIt. (Eventually I learned Ms "I have 1.0!" is Ann Greenberg, whose iPhone glass is actually cracked that way and still works fine.)

As the laughs died down, I noted how easily we can miss major technology transitions, not realizing what's actually new. When I developed software for the Palm in 2002, every handheld application required a stylus: to operate the tiny on-screen buttons you had to use both hands and poke them with a little stick. Remember?

Back when my old company ConnectedMedia created ConnectedTV - a Palm app showing personal TV listings that let you change the TV channel by touching the screen - I considered the poking interface unacceptable. Requiring a stylus would mean a nerds-only experience no consumer could love. Unless you could operate it with a thumb - and with one hand - it could never compete with a remote control.

So the on-screen buttons had to be much larger, with each screen elegant and simple. Only, most screen space was needed for TV listings and show descriptions. My ingenious friend and partner Don Hopkins realized that we could repurpose the Palm OS screen 'stroke' detection capability - previously used only as a way of entering characters - into a kind of short cut: if you stroked the button, its label would change with a click, and then if you lifted your finger it would perform the function shown. Since you could easily stroke up|down|left|right, we could stash up to 4 helpful shortcuts under each finger-sized screen button.

To prevent accidental channel changes, we also required you to stroke down on the TV show name or description to watch it. It worked perfectly. Of course, this is a predecessor of the swipe today's iPhone needs so it can't be unlocked accidentally as you carry it.

Users adored ConnectedTV, calling it "addictive". Handheld Computing called it "one of the most impressive Palm OS applications we've ever seen." It was more responsive, more personalized (stroke to set a Favorite show), and less obtrusive for browsing than the TV's on-screen guide.

Sony paid us to make custom 'skins' for their sweet CLIÉ line of Palms for cable TV trade shows, and then offered to bundle ConnectedTV with the CLIÉs, pre-installed. However, soon Sony Japan dropped Palm OS and discontinued the whole CLIÉ line. Still, our stylus-free interface had provided a peek at the strokable handheld future.

Stroke replaces Poke
Just a few years later, no popular handheld device uses a stylus. The iPhone has expanded the idea further to support animated scrolling and multi-touch pinching.

Is there really such a big difference between poking with a stick - occupying both hands - versus being able to stroke, rub, caress with a finger, and even pinch? Um, ask your mate. Such quiet GUI software innovations help us fully enjoy, literally embrace and yes, love our technology.