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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)

    Description

      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.

      Attachments

        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

        Issue Links

          duplicates

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-45375 Jittery lines with Wacom tablet and QTabletEvent

          • P4: Low - Would be nice to fix, but it's not very important.
          • Closed
          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-36937 Windows: QTabletEvent hiResGlobalX() hiResGlobalY() returns int precision values (nothing after decimal point)

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          resulted in

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-77826 Wacom tablet: Cursor input offset from cursor position

          • P1: Critical - Urgent and Important, will STOP the release if matched with set FixVersion field. This includes regressions from the last version that are not edge cases; Data loss; Build issues; All but the most unlikely crashes/lockups/hanging; Serious usability issues and embarrassing bugs & Bugs critical to a deliverable. This is the highest possible priority for requirements.
          • Closed
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              srutledg Shawn Rutledge
              abrahams Michael Abrahams
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              Dates

                Created:
                Updated:
                Resolved:

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