MPX and multitouch

Peter Hutterer peter at
Sun May 11 07:17:07 PDT 2008

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.

>    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.


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