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

[Henrik Rydberg <rydberg@euromail.se>]

On 08/02/2010 10:17 AM, Éric Piel wrote:

> Op 01-08-10 15:57, Henrik Rydberg schreef:
>> On 08/01/2010 01:28 PM, Éric Piel wrote:
> :
>>> I still think that for the very specific use case of scrolling when
>>> pressing one finger and moving up and dow the other one, reporting the
>>> average works better than the first finger. However, I guess this can be
>>> considered just as a drawback of the ST protocol, and fixed in userspace
>>> by using the MT protocol.
>>>
>>> What do you think? Does it look fine to you? Below is the code.
>>
>>
>> I might have lost track of what problem needs to be solved. The current patch
>> seems to implement tracking, but still does not solve the individual MT finger
>> problem. And, it uses the same definition of ABS_X/Y as before. I was also under
>> the impression that synaptics needs fixing, anyways. All of this taken together
>> sadly suggests that this patch could just as well be reverted to the original
>> one. Or? Alternatively, one could switch to the type B protocol, since no
>> further tracking improvement is possible in userspace. The implementation is
>> tidy and simple enough, I think.
> Yes, you're right, the patch I've sent was still with the "average of
> the 2 fingers", but I'm now willing to drop it. With the tracking, at
> least we can keep sending info about a real finger and avoid jumps at
> the transition 1->2, so reporting the first finger might have advantages
> over reporting the average :-) The improvement for the test case can
> just go to userspace.
> 
> The tracking is still not so clever, so it's definitly not adapted to a
> type B MT protocol (think transition 2->1).


You need to add the tracking id and a couple of lines, but i do not see why the
2->1 transition would be treated any differently. The one-finger coordinate
would be close to either position[0] or position[1], which would determine the
tracking id to keep. Every time you add a finger you add a new tracking id. What
is your planned support for three fingers?

Henrik

> Dmitry, if that's ok with you, you can drop this patch 7/7, and I'll
> send you two new patches to add MT support and finger tracking?
> 
> Eric


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