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  1. Qt
  2. QTBUG-48151

Jittery tablet input in Linux does not respond to RawSampleRate

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    • e4532224145a0a72cde9b40cb7fd39011624d1c1 (qt/qtbase/5.12)

      We've noticed tablet input has become more jittery in Krita 3.0 versus 2.9. It seems that the problem is our events are no longer passing through the linux wacom driver's location smoother. The driver provides a parameter RawSample which is used to determine the number of points used for averaging jittery input. http://doswa.com/2010/01/01/wacom-jitter-fix-for-linux.html

      The key evidence is that in Krita 2.9 (built on Qt 4), changing the RawSample parameter will make drawing more jittery or smoother. In Krita 3.0, the RawSample parameter seems to have no effect. https://phabricator.kde.org/T530

      I've attached a file that magnifies the effect, created by zooming out the canvas and drawing a tiny circle.

        1. hooray.png
          hooray.png
          26 kB
        2. noise-regularity.png
          noise-regularity.png
          11 kB
        3. tablet-test.png
          tablet-test.png
          16 kB
        4. terrible.png
          terrible.png
          31 kB
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            srutledg Shawn Rutledge
            abrahams Michael Abrahams
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