Bug 458361

Summary:	Sharpness brushes are functionally inaccurate when "Align the brush preview outline to the pixel grid" is disabled
Product:	[Applications] krita	Reporter:	tomtomtomreportingin
Component:	Brush engines	Assignee:	Dmitry Kazakov <dimula73>
Status:	RESOLVED FIXED
Severity:	normal	CC:	halla
Priority:	NOR	Keywords:	regression
Version:	5.1.0
Target Milestone:	---
Platform:	Appimage
OS:	Linux
Latest Commit:	https://invent.kde.org/graphics/krita/commit/dd48fb72fb289519917be6c79247f78a8ff38a46	Version Fixed In:
Sentry Crash Report:

Description tomtomtomreportingin 2022-08-27 00:35:58 UTC

SUMMARY
When "Align the brush preview outline to the pixel grid" is disabled (as it is by default), the brush doesn't perform the way it did pre-5.1. This difference in behavior can be observed in the brush settings preview when toggling the option.

Please note that this bug did NOT occur in the demo I recorded in https://invent.kde.org/graphics/krita/-/merge_requests/1405 (as you can tell from the brush settings preview not changing), so it seems the behavior regressed in some way sometime after my initial merge request. Perhaps the additional commits might have introduced new problems.

STEPS TO REPRODUCE
1. Select Pixel Art Fill brush.
2. Select Sharpness option.
3. Enable "Align the brush preview outline to the pixel grid"

OBSERVED RESULT
The functional behavior of the brush changes. Disabling the setting makes it so that brush doesn't make strokes the same way it did pre-5.1.

EXPECTED RESULT
The setting should only affect the brush preview outline. 

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Debian sid
KDE Plasma Version: 5.25.4
KDE Frameworks Version: 5.96.0
Qt Version: 5.12.12 (appimage)

Comment 1 tomtomtomreportingin 2022-08-27 00:43:29 UTC

Since this issue changes how sharpness brushes create strokes between 5.0 and 5.1, without any user intervention, marking this as a regression.

Comment 2 tomtomtomreportingin 2022-09-01 18:53:03 UTC

In the wild:
https://old.reddit.com/r/krita/comments/x2excx/pixel_brush_is_not_accurate_after_510_pixel_art/
https://old.reddit.com/r/krita/comments/wyobfn/just_updated_versions_and_the_brush_tip_size_2_is/
Setting to confirmed.

Comment 3 Bug Janitor Service 2022-09-09 06:27:12 UTC

A possibly relevant merge request was started @ https://invent.kde.org/graphics/krita/-/merge_requests/1582

Comment 4 Dmitry Kazakov 2022-09-15 08:25:22 UTC

Git commit cca625b7a09e5e4226ec1283d27cdf725dc29e9b by Dmitry Kazakov, on behalf of Tom Tom Tom.
Committed on 15/09/2022 at 08:24.
Pushed by dkazakov into branch 'master'.

Fix dab inaccuracy of Sharpness brushes when outline preview snapping is disabled

M  +1    -1    plugins/paintops/libpaintop/kis_current_outline_fetcher.cpp
M  +6    -5    plugins/paintops/libpaintop/kis_pressure_sharpness_option.cpp

https://invent.kde.org/graphics/krita/commit/cca625b7a09e5e4226ec1283d27cdf725dc29e9b

Comment 5 Dmitry Kazakov 2022-09-15 08:25:54 UTC

Git commit dd48fb72fb289519917be6c79247f78a8ff38a46 by Dmitry Kazakov, on behalf of Tom Tom Tom.
Committed on 15/09/2022 at 08:25.
Pushed by dkazakov into branch 'krita/5.1'.

Fix dab inaccuracy of Sharpness brushes when outline preview snapping is disabled


(cherry picked from commit cca625b7a09e5e4226ec1283d27cdf725dc29e9b)

M  +1    -1    plugins/paintops/libpaintop/kis_current_outline_fetcher.cpp
M  +6    -5    plugins/paintops/libpaintop/kis_pressure_sharpness_option.cpp

https://invent.kde.org/graphics/krita/commit/dd48fb72fb289519917be6c79247f78a8ff38a46