[Bf-committers] New event system / MPX

Ettore Pasquini ettore_pasquini at 3dconnexion.com
Tue Jun 26 20:13:32 CEST 2007

On 6/26/07 10:34 AM, "Jean-Luc Peurière" <jlp at nerim.net> wrote:

>> A distinction is also to be made: there are multi-touch events that
>> "collaborate" in creating a complex action (like the iPhone 2-
>> finger zoom),
>> and there are other (simpler) events that are really just normal
>> events
>> coming from multiple sources (like the MPX demo of moving and
>> resizing a
>> window). The former case could be seen as one higher level event
>> composed by
>> many lower lever events.
>> The main problem is sending these kind of events, as apparently no
>> GUIs
>> framework can currently do that (is this true?)... Well beside MPX.
> On the mac, you can identify which device sent the event and so
> associate it to the
>   good pointer. There is however only one system pointer.
> In any case, multiple input devices (6Dof, knobs, specialized
> keyboards) are indeed
> very desirable. We just need good use metaphors for use. Ton pointed
> me to an
> interesting article which was such case

Now you got me curious... Can I see the article as well? :-)

> However, I'm much more sceptic on having more than one pointer. Such
> things can
> easily lead to user confusion.
> Just look how gestures are badly understood by most, where some could
> not work
> without.

I agree it can be confusing if badly implemented. My point is that if we
choose the right abstractions, future extensions will be easy to add instead
of being in the situation we are in now where we have to redesign the whole
thing. That's why things like MPX and gestures are very interesting: not
because they work at the moment, but because they give hints on possible
future UI models and trends. What I'm saying is that the new system should
be ready to allow a good level of extension.

As you said it's a matter of choosing the right abstractions. For instance,
we could abstract out the notion of a single pointer, which _could_ become
obsolete in the near future. Multi-touch gestures are conceptually very
similar to having multiple pointers on the screen: each finger is a pointer.
So, when a multi-touch computer will be shipped, we'll be ready. And so on.


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