Bradley T. Hughes at
Mon Mar 1 05:56:57 PST 2010

On 03/01/2010 01:55 PM, ext Daniel Stone wrote:
> I don't really see the conceptual difference between multiple devices
> and multiple axes on a single device beyond the ability to potentially
> deliver events to multiple windows.  If you need the flexibility that
> multiple devices offer you, then just use multiple devices and make your
> internal representation look like a single device with multiple axes.

This is where the context confusion comes in. How do we know what the 
user(s) is/are trying to do solely based on a set of x/y/z/w/h coordinates? 
In some cases, a single device with multiple axes is enough, but in other 
cases it is not.

On a side note, I have a feeling this is why things like the iPhone/iPad are 
full-screen only, and Windows 7 is single-window multi-touch only.

> Given that no-one's been able to articulate in much detail what any
> other proposed solution should look like or how it will actually work
> in the real world, I'm fairly terrified of it.
> Can you guys (Bradley, Peter, Matthew) think of any specific problems
> with the multi-layered model? Usecases as above would be great, bonus
> points for diagrams. :)

I'm concerned about the event routing and implicit grabbing behaviour, 
specifically. I don't know enough about the internals to really put my 
concerns into words or link to code in the server.

Use-cases? Collaboration is the main use-case. Class rooms, meeting rooms, 
conferences are ones that I often think about. Think about the GIMP having 
multi-user and multi-touch support so that art students could work together 
on a multi-touch table top. I think the MS Surface marketing videos are a 
good indication of what could be done as well.

One thing that we definitely want is for normal button and motion events for 
one of the active touch-points over a client window. As Peter pointed out, 
we shouldn't have to rewrite the desktop to support multi-touch. In addition 
to specialized applications like I described above, we definitely want 
"normal" applications to remain usable in such an environment (I can 
definitely see someone bringing up a terminal and/or code editor just for 
themselves to try out an idea that they get while in a meeting).

(Sorry for the lack of diagrams, my ascii-art kung-fu is non-existent. How 
about a video?

Bradley T. Hughes (Nokia-D-Qt/Oslo), at
Sandakervn. 116, P.O. Box 4332 Nydalen, 0402 Oslo, Norway

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