Re: [PATCH 7/7] elantech: average the two coordinates when 2 fingers

["Éric Piel" <E.A.B.Piel@tudelft.nl>]

Op 02-08-10 15:03, Henrik Rydberg schreef:
> On 08/02/2010 02:46 PM, Éric Piel wrote:
> 
> [...]
> 
>>>
>>> We can do better in the sense that since the device cannot comply with MT-A, we
>>> can do as close as possible to MT-B with less cpu usage. But frankly, the best
>>> solution at this stage seems to be to drop MT handling altogether, since there
>>> does not seem to be any plan to use it.
>> Ah, this alternative solution is a bit boring ;-) In addition it's not
>> compatible with my own master plan to eventually have the "pinch to
>> zoom" and "rotate to rotate" gestures work on my laptop, like in Windows ;-)
> 
> 
> Since rotational symmetry is what prevents us from implementing proper MT
> support, it is not likely going to work anyways.
Well, yes, in Windows to do the rotation gesture, they "suggest" you to
keep one finger on the bottom left, and rotate only the other finger.
It's kind of fake, but it works perfectly in practice. You just have to
know about it.

>> So, let's agree on just the two patches I'm going to send to support
>> "better than nothing" MT-protocol for now. When, later, someone has
>> better ideas, he can send patches to improve MT-protocol
>> support/compliance. Fine?
> 
> 
> No. I think it is fair to say we tried to make it work properly, but the (known)
> information about the device is simply not enough. As long as MT does not work
> properly, there is no point in adding it at all - in particular not an elaborate
> solution. I can see that zoom would work even with a poor MT implementation, but
> that is not what the MT protocol is about. Maybe one day someone will find the
> missing information somewhere in the packets.
> 
> For your usecase, perhaps one should add ABS_ZOOM etcetera instead, and patch up
> synaptics to use those values.
Detecting the pinch gesture in-kernel? In addition to me not knowing how
to do gesture recognition, I doubt Dmitry would ever accept such a
patch, and Peter Hutterer would probably not enjoy a lot either the
patch for synaptics.

That's why I like the idea of reporting MT events as well as we can (the
user will know that on his device some gestures are limited), and  the
rest of the stack can stay completely standard.

Eric
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