From our Windows 7 application experience, I would like to echo the need for 
sophisticated applications needing their own gesture recognition capability and 
access to raw touch data.

For example SpaceClaim Engineer (a multi-touch CAD app on Windows) has dozens, 
perhaps going on hundreds, of unique gestures it recognizes.  They also use 
combinations of pen & touch in innovative ways which motivates them to want raw 
HID data from both touch and pen

There won’t be a lot of these applications, but the ones that do will really 
show the advantages of multi-touch (and pen) and should be supported IMHO.

James Carrington
N-trig




From: multi-touch-dev-bounces+james.carrington=n-trig....@lists.launchpad.net 
[mailto:multi-touch-dev-bounces+james.carrington=n-trig....@lists.launchpad.net]
 On Behalf Of Mark Shuttleworth
Sent: Wednesday, October 06, 2010 7:51 AM
To: Peter Hutterer
Cc: multi-touch-dev
Subject: Re: [Multi-touch-dev] Peter Hutterer's thoughts on MT in X

On 06/10/10 02:45, Peter Hutterer wrote:


This smacks of the old X inability to make a decision and commit to a

direction.



[citation needed]

From http://www.faqs.org/docs/Linux-HOWTO/XWindow-Overview-HOWTO.html

"One of X's fundamental tenets is "we provide mechanism, but not policy". So, 
while the X server provides a way (mechanism) for window manipulation, it 
doesn't actually say how this manipulation behaves (policy)."
;-)



But I predict that sooner or later, we'll see a second and third

engine emerge, maybe for an app that needs really specialised gestures.

I agree, and I can think of use cases that support that, for example CAD 
applications.

Where I disagree with your speculation is the idea that it would be a good 
thing to support multiple gesture engines for different tookits. By definition, 
a toolkit is general-purpose, and maps to a whole portfolio of apps. XUL, Qt, 
Gtk are examples. Having different engines there means that whole sets of apps 
will behave differently, depending on their toolkit. And it means that 
improvements, such as latency and signal processing work, are diluted across 
all the toolkits - bad for the user.

That's quite different to the idea that a CAD app might invest in some highly 
specialised and unique gesture processing. As soon as it's "competing toolkit 
engines" you're in a world of user pain.

We've seen this before, and since this is a new area we can avoid it. We ship 
too many spelling checkers already :)




We can be very clear about this: Ubuntu won't support

multiple simultaneous competing gesture engines.



How does this work out if an application decides to interpret raw touch data

into gestures by itself? That would be a competing gesture engine then.

If the use is defensible, encourage it, if it's not, patch it out or deprecate 
the app.

Mark
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