Re: [Mactel-linux-users] appletouch zig-zags

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Andy Botting wrote:
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  <pre wrap="">Hi Ivan,

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      <pre wrap="">&nbsp; &nbsp;I have been using the appletouch driver for more than a year now,
currently on linux 2.6.30. I noticed some time ago when trying to draw
something on gimp, that when you move your finger the cursor response is
not linear, but instead kind of "saw-tooth wave" shaped, across both X
and Y. Of course it is more noticeable if your 'sensitivity' setting on
X is high, but it is always there. Just to be clear, when you try to
draw a diagonal line, for example a 45 deg line, &nbsp;you end up with a
zig-zag shape, no matter how straight you slide your finger.
&nbsp; &nbsp;I did not know anything about how the trackpad works until now, and I
am not completely sure, but the number of 'jumps' of the response
pattern seems to match the number of sensor elements for both X and Y,
10x20 in my case (05ac:021b Apple, Inc Internal Keyboard/Trackpad).
&nbsp; &nbsp;I tried on O$X it seems to work fine. I believe that there is
something in the algorithm, perhaps in the atp_calculate_abs function,
that is not totally correct, at least for this trackpad type.
&nbsp; &nbsp;Any suggestions or comments are welcome.
Regards
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    <pre wrap="">Hi, no comments on this? I poked the source code without positive results.
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  <pre wrap=""><!---->
I've noticed the zig-zag on my MacBook Pro also, and it's really
starting to irritate me.

Have you had any luck identifying or fixing the problem?

If not, I've found the authors of the appletouch driver, and it might
be worth dropping them a line to see if they've noticed the same
problem.
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I agree. 
 
Hi, I've poking the source code and more or less figured how it works,
but I'm not sure on how to implement a fix. If you have any news let me
know. I'm copying to the list, I hope you don't mind. 
cheers 
 
<pre class="moz-signature" cols="72">-- 
Iv&aacute;n Stepaniuk</pre>
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