Rather like what I had in mind: A DataHand-like implementation for touch screens. I wonder if the patent on MessagEase would preclude that?

What I thought up would be based on Colemak (or the layout of your choice), giving you a button for each home position key on one hand that can then be "leaned" to the side for its bottom/upper/top row counterparts. I was thinking 6 buttons in a row - 2 columns for the index and pinky fingers more or less like there are on a standard keyboard. There would have to be an easy-to-use mirroring switch to use this with only one hand as you hold the device with your off hand.

But maybe two-thumbs typing is the way to go instead? Check out on the MessagEase page how Cheng Wei Chang breaks a world texting record(!) using MessagEase. But here's the thing: It's not optimized for dual-thumb typing!? I would go with two columns (4 rows?) at the screen edges and in the middle a column for rarely-used keys.

Contenders: I found a keyboard called Little Big Keyboard (by Thomas Lundquist) that seems to be a bit like what I've described, and one called Chorded Keyboard - GKOS. Going to try them out as they're both free downloads on Android.

[edit: Other options - Slide Keyboard (v2 seems customiseable?); Flit Keyboard (also "skinnable"?); ETAOI keyboard (nice name!)]

I personally find Swype quite good for English. And if reliability is an issue – since you can't stop after each word to double-check it's guessed it correctly – why not using the old-fashioned t9? I've found it soo useful back when I had a normal 9-key keyboard. I also think it's very good on a touchscreen. If the screen is too big (or big enough?) why not use QW-ER-TY (two letters on a key), with similar to t9 recognition technology, so you press each key only once? To be honest these two seem to me more efficient than the keyboard described by ghen in the first post. But I haven't tested it, so...

I'm using a phone with 3.7" screen and a physical keyboard. For portrait in one hand I use swype-style full keyboard, and for two hands I type on the physical keyboard. When I got it I trested my speed (on Qwerty) and I hit 66 wpm, without much training.

PS: I take back what I said about the first layout. I checked the website and the video, and it does seem promising.

With most touch input methods there are two distinct aspects: the input method itself, and the layout used ontop (which could be localized).

For T9, I think the input method itself isn't that bad, using double/triple tap instead of swiping like MessagEase.  It has a bit less potential since you're limited to 9*4=36 characters even with quadruple-taps (which are quite annoying already), you need to pause between letters on the same key (although the letter layout could be optimized for this), and it is not really "touch specific"; it works on physical buttons too, and does not make use of touch gestures like swipes.  But is is simple and on the other hand universal between classic and touch screen phones.

But the standard alphabetic layout is horrible!  My wife's name is Sofie, typing that means tapping "prqs", "mno", "def", "ghi", "de", or 15 presses for 5 letters, 4 of which are among the most common ones!  Surely this layout could be optimized, and it should have been even on a classic phone.  I have searched the web for this, but apart from the idea, I found no actual layouts let alone implementations.

I think if someone could come up with a sane T9 layout, it could become the Colemak of touch screen keyboards. ;-)  You could even produce variants optimized for one vs. two thumb typing.

Yes, the LBK is interesting (and since the author is a Swede he's probably a nice guy too? - hehe) although for me it'd still take a little tweaking. It too needs relearning which is a hinder to acceptance. It seems nice to write on! Responsive and accurate as far as I could test it. I think it's based on the Big Keyboard app which is Asian.

I agree that the chorded boards seem efficient but also a bit ... scary. That would also take a fair bit of learning.

So, let's think up the "perfect" touch board that lets you use what you already know (even if it's stupid QWERTY)! The Dvorak people may actually have an edge on this topic since hand/thumb alternation is better than rolling in this context.

Question: The MessagEase in full mode has a 7×4 key matrix. That seems acceptable to me for 2-thumb use! The LBK has only 5×3 (and another called Flit uses 4×2) which seems a waste of space; but then again I have a Galaxy Note with a largish screen. However, the little keyboards people are used to have 10×5 or more keys across - no wonder we keep missing those keys! What is the sweet spot then?

I think that with 8 keys we could fit the main home position (ARST and NEIO in our case) comfortably. But is that acceptable or too crowded? If it passes as acceptable, I'd go for an 8×4 button layout with a 2×1 spacebar and a few special keys (like the MessagEase has). Sound good?

I should look into MessagEase's patent, what it covers exactly, as LBK (and others) look very similar: a matrix of big buttons with central tap + 8 directions sweep.

Apart from the basic tap+sweep idea, we'd need to cover:
- dimensions (like DreymaR said), either a one size fits all, or variants for small/large phones and tablets?
- rules to design a letter layout, independent of alphabet and language at hand
- a place for control characters (ME has select/copy/paste etc, others even Ctrl, Alt, Esc, ...)
- a flexible implementation, that can be configured for any of the above :-)

I don't think you understood what I meatn by T9 (maybe I'm calling it wrong?). I'm talking about the method, for which you type each key only once, and it predicts which letter from  the ones assigned to the key you need. So for Sophia, you'd need 6 taps, not 15. Add one, if it guesses it wrong, but it's left me with good memories.

In my understanding, "T9" is the traditional letters-on-the-number-keypad kind of 9(actually 12)-key hardware keyboard found on any cell phone.  "XT9" is enriching that same physical keypad with predictive text in software, mostly to eliminate the multi-presses.

But it seems Wikipedia proves me wrong.  So what is the traditional alphabetic 9-key layout called then?  This is something that can potentially be improved by rearranging the letters in a smart way.

Back on topic...  Just looked at the reviews for 8pen on GooglePlay,  doesn't quite give you the impression that you can get up to amazing speeds.

I'd have thought though that your main speed gains would be in predictive text mechanisms, whether using Swype, 8pen or whatever.

I'm pretty sure you could get quite fast with Dasher.  And that's with one pointer - one finger.  Could you make that any better?

When I looked at 8pen, what stood out to me was the idea that you might be able to do it blindly.  I doubt you could with MessagEase from your description.

Of course Dasher requires visual feedback.  Having said that, perhaps you could  incorporate a a tactile display for haptic feedback.

As soon as winter kicks in the phone is totally out for messaging for me.  An authoring tool that does not require much dexterity / accuracy could be a real winner.

(Then again speech recognition may get to the point where it's cheap enough to not bother.)

I'm more and more getting the hang of MessagEase now.  I really prefer its big 3x3 grid over LBK's 2x4 or others.  It makes the most sense on a phone in portrait position.  And I think its focus on centric swipes –potentially– reduces finger travel a lot.  Also a 3x3, with visual feedback as with ME, can be usable while only cursory glancing at the keyboard, once you're familiar with the letter positions.  Any more rows or columns will make that harder.

But I'm still not convinced by its letter placement, and it's not easy to remember, either.  I should go study digram frequencies again to see whether it really minimizes finger travel.

@ghen: For the portrait position, maybe something like this? Keep in mind that the MessagEase is really 4×4 when you count in the extra keys:

| A |spc| D |
| R | S | T |
| N | E | I |
| H |←↓•| O |

| A | H | N |
| R |spc| E |
| S |←↓•| I |
| T | D | O |

I do like the idea of a low profile though, as it's so space conserving.

@pinkyache: Of course, chorded typing using glove buttons could be awesome on the move. But that's another topic entirely - for instance the Chordmak one. ;)

And dual-thumb typing with taps&slides seems to be the most efficient way on a touch screen, flat out (cf the MessagEase speed record). Yes, you can one-hand type T9 on your bike. Yes, some peeps are perfectly happy to type QWERTY with one index finger and word recognition. But it isn't a very flexible AND efficient solution for most.

I just sent an e-mail to the MessagEase author with a bunch of questions, both philosophical and practical, and almost instantly got a very detailed response.

First of all, there is a white paper, a very interesting read!  Next, I was wondering about the central position of "O", I would have put "E" there instead?  But the author reasoned E should be close to <space>, which is the most frequent character (and E+<space> the most frequent digram?).  Furthermore, like Shai, he also realized the least-frequent letters have the least influence on the efficiency of the layout, so he manually arranged those in a "logical" way rather than a micro-optimal one.

He also indicated that future versions will allow some customisation of the layout (even using arbitrary Unicode characters), but not the base letter layout.  I was thinking about swapping D and H for my native language (Dutch/Flemish), but I could use the Spanish layout which already does that, and then replace the accented letters I don't need.

In the meanwhile I also learned some clever tips 'n tricks from the app's "How to" documentation, and I must say I'm impressed by the maturity of the implementation...

So I think I'm going to stick with ME now.  After just three days, I'm already at ~20 wpm. :-)

Thank you Saied! And congrats on one of the best Touchscreen keyboards I've seen.

Almost fully configurable is nice, granted. But why you choose to modify the main 9 yourself (between English and other versions) and not leave that open to modification strikes me as odd. Also, to make me happy I'd have to be able to modify a 4-wide or preferably 6-wide pad not just 3 (plus a static special column). I feel you're wasting space on smartphones at least, using only 4 columns but 4 rows which takes up vertical space! 5×3 (4+1 columns OR 3 rows of 5 with special keys at the bottom row) or 6×3 would've been much more sensible I feel.

A quick fix for the smartphone implementations would be an option to move the space bar row to a new column for a workable 5×3 form factor.

Right now I'm leaning towards 5×3 with the upper rows ARSTD and HNEIO (or AOEUI and DHTNS if you're coming from Dvorak) and special keys on the bottom row (which may be 2/3 as tall as the upper ones). Note that the E can still be right above the space this way! ;) Then you have a way of learning the SAME layout for your touch device and computer keyboard, both very good IMO. Existing Dvorak/Colemak users could jump right in and immediately feel at home.

The possibility of easy one-handed use together with the possibility of fast two-handed use is a strength. I've explored both and MessagEase performs well (apart from the waste of horizontal space). The dual layout with numbers and letters is NOT good for two-handed use though!