Multi-Touch

[Florent THIERY]

>With that being said I have been thinking about
> multi-touch lately and after some things on the wiki page
> http://wiki.openmoko.org/wiki/UI_Improvements I noticed
> that is mentioned the zoom feature of the iphone.

as an example. The aim of the question is to discover how a monotouch
screen behaves when you try to use it as multi touch: is it
determinist, or erratical?

If somebody could try reproducing various "strange" usages of the
screen and report any deterministic/detectable behaviour, we might
find ourselves additional input methods based on "guess hacks".

For instance, i think we can use cursor jumps as inputs; example:

P**************+
*                     2 *
*                        *
*  1                    *
- **************N
Zoom +

P **************+
*  1                     *
*                         *
*                    2   *
- **************N
Next page/item

It would be some timing-based detection, like non-linear handgesture
recognition, done with 1 or 2 fingers.

We have to:
1- experiment the touchscreen with all imaginable gestures (ex: 2
finger sliding, ...)
2- select the interesting behaviours
3- evaluate their determinism, eventually low level hacks on the kernel module
4- integrate them into openmoko finger-based controls

> So my question now is do we have access to the bounding box?  If we can get
> at the coordinates of the bounding box can we not figure out if the bounding
> box is shrinking or growing?

Yes, that is an open question :)

> Also if we have
> access to the bounding box we could with some practice figure out when users
> are trying to rotate an image.

Indeed: if the "bounding box" is accurate, what if:
- you narrow the 2 fingers? <----- zoom
- rotate the box? <---- rotation / linear map rotation....
- 2 parallel fingers (horizontal) sliding down = flat bounding box
(almost a line) = scrolling down

... But, i'm not sure i understood what a bouncing box is: if all of
this was true, then the touchscreen would report 2 points / an area...

It would be great if people having access to hardware could try doing
some detailed testing / reporting. But, it can wait until the next
shipping phase is over :)

> the
> high resolution of the neo this should help a great deal.

Well, even with high resolution, our eyes don't have better zooming :)
Especially on mobility situation...

>.  You press the zoom button then click an area to enlarge.  Just
> curious how difficult would this be?

Well, it's quite easily doable if the webbrowser / image displayer
implements zooming !

> looking at the iphone and it doesn't seem to be very multi touch but as it
> has not come out I could be wrong.  It seems to only be able to accept 2
> simultaneous inputs.

Hey, that's just what's needed :) How many free space do you have on
such a screen?

Ciao

Florent