MPX and multitouch

Jordi Polo mumismo at
Sun May 11 08:10:41 PDT 2008

On Sun, May 11, 2008 at 11:17 PM, Peter Hutterer <peter at>

> On Sat, May 10, 2008 at 09:20:11AM +0900, Jordi Polo wrote:
> >    I am interested in bringing multitouch to normal applications,
> obvious
> >    examples are multitouch gestures for copy, paste, the famous zoom,
> etc.
> >    As I am mostly a KDE guy,  I planned to create new Qt Events from
> >    multitouch. They will add to the current QKeyEvent QMouseMoveEvent,
> >    etc.
> >    AFAIK, MPX multi-mouse, multi-keyboard can not be used for multitouch
> >    gestures (a gesture is what you do in iphone touch  or mac air for
> >    zooming, etc.). At least the youtube demos I've seen so far do not
> use
> >    it like that. Gestures basically links the cursors together, so the
> >    user has no different cursors but one cursor doing multiple things at
> >    the same time. I wonder if gestures can be create above MPX mouse
> >    events and forwarded to apps (X should be the best place for this
> >    also).
> I thought about how how to get multitouch support into the X server last
> year
> when I was experimenting with it.
> Basically, gestures do not belong into the X server. They are
> contextually-dependent interpretation of hardware events. i.e the server
> doesn't know when two cursors are to be interpreted as a two-finger
> scrolling
> gesture and when it is just two people doing something in close vincinity.
> IMHO, the only way to get the gestures you want is to put them into a
> client-side library. Only there can you get the contextual information to
> interpret the gestures correctly.

I agree that gestures should belown to a client library
Someone in the kde-core list pointed to your presentation in Linux-conf last
year. I wrote the first email before knowing that you already did some
development with blob events. At that time I thought a multitouch panel will
appear as several cursors in MPX.
Having a multitouch specific development simplifies things, that is what I
To further clarify it, I will not create gestures from multiple cursor
devices but from single multitouch devices.
The basic idea is take the events from X, convert them to QEvents, give them
to a library to create gestures and send gestures and events that wasn't
recognized as gestures to KDE apps.

> >    Basically I was planning using a multitouch library (touchlib) that
> >    already gives events using the TUIO protocol and create QEvents based
> >    on those.
> >    If it can be done with MPX in a more standard way, we may try that
> >    instead.
> MPX will get multitouch-screen support, but not in this upcoming version.
> Mind
> you, this is not the same as multi-touch gesture support.

Then, I need next to next version :D
The current plan is, then, mergue multi-devices in 1.5 and multitouch in
What devices if any are already working with MPX multitouch?

If so, I may create a TUIO to MPX blob events bridge library and build
everything on MPX blob events, knowing that future 1.6 multitouch will be
similar to that.

Jordi Polo Carres
NLP laboratory - NAIST
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