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Tablet Tester: Fix extreme lag with S Pen on Android

Joshua Goins requested to merge work/redstrate/fix-tablet-tester-lag into master

So this is weird, I noticed that on my S9 tablet the tester is very laggy. I found a solution, but it's not... clear why this happens?

Unless the tablet tester itself (the widget inside of the tablet tester you draw on) is focused, it will appear to lag greatly and the reason isn't exactly clear why. Here's the broken vs. fixed tablet tester to show what I mean:


But I really don't like these kinds of "???" fixes, although it does seem to work. Note that you can do this in the currently released Krita by selecting the log window with your pen, and it has the same effect. This patch just makes it work out of the box.

Test Plan

  • Try the tablet tester on Android and see if it lags before and after this patch.
    • I have no other Android tablets on hand with pen support, only this S9 :/

Formalities Checklist

  • I confirmed this builds.
  • I confirmed Krita ran and the relevant functions work.
  • I tested the relevant unit tests and can confirm they are not broken. (If not possible, don't hesitate to ask for help!)
  • I made sure my commits build individually and have good descriptions as per KDE guidelines.
  • I made sure my code conforms to the standards set in the HACKING file.
  • I can confirm the code is licensed and attributed appropriately, and that unattributed code is mine, as per KDE Licensing Policy.
  • Does the patch add a user-visible feature? If yes, is there a documentation MR ready for it at Krita Documentation Repository?

Reminder: the reviewer is responsible for merging the patch, this is to ensure at the least two people can build the patch. In case a patch breaks the build, both the author and the reviewer should be contacted to fix the build. If this is not possible, the commits shall be reverted, and a notification with the reasoning and any relevant logs shall be sent to the mailing list,

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