Bug 289915

Summary:	Krita's Canvas produces subtle artifacts on incremental updates
Product:	[Applications] krita	Reporter:	Dmitry Kazakov <dimula73>
Component:	General	Assignee:	Krita Bugs <krita-bugs-null>
Status:	RESOLVED UNMAINTAINED
Severity:	normal	CC:	halla
Priority:	NOR
Version:	unspecified
Target Milestone:	---
Platform:	Unlisted Binaries
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	Before transparent painting After painting After painting (with marks, pointing to the artifacts)

Description Dmitry Kazakov 2011-12-27 11:22:08 UTC

Way to reproduce:
1) Open quite contrast image, e.g. lena.png
2) Set the Opacity of the brush to 0%
3) Paint with such a brush on a canvas (it just triggers updates of it)
4) You'll see the small changes of pixels on the border of your brush

It happens on all zoom-levels. It we disable QImage pre-scaling, the effect is much less, but still present.

Comment 1 Dmitry Kazakov 2011-12-27 11:25:26 UTC

No such thing happens in Gimp

Comment 2 Halla Rempt 2011-12-27 11:27:59 UTC

Can you attach a screenshot?

Comment 3 Dmitry Kazakov 2011-12-27 16:31:59 UTC

Git commit ace38fcf7c62bbd3a0db6d21118cb7695ff20c99 by Dmitry Kazakov.
Committed on 27/12/2011 at 18:22.
Pushed by dkazakov into branch 'master'.

KisPrescaleProjection::updateCache should not depend on ant UI data

So now it doesn't fill in the KisUpadteInfo fully, it just saves the
dirty image rect in it and fetches the data. All the UI related actions
are performed in KisPrescaleProjection::recalculateCache.

Added some unittests for KisPrescaleProjection, including the testcase
for bug 289915.
Related: bug 289790
Related: bug 289915

M  +28   -0    krita/sdk/tests/testutil.h
M  +2    -2    krita/ui/canvas/kis_image_pyramid.cpp
M  +1    -1    krita/ui/canvas/kis_image_pyramid.h
M  +30   -23   krita/ui/canvas/kis_prescaled_projection.cpp
M  +23   -4    krita/ui/canvas/kis_prescaled_projection.h
M  +1    -1    krita/ui/canvas/kis_projection_backend.h
A  +-    --    krita/ui/tests/data/prescaled_projection_test/testScrollingZoom50/testScrollingZoom50_initial.png
A  +-    --    krita/ui/tests/data/prescaled_projection_test/testScrollingZoom50/testScrollingZoom50_zoom50.png
A  +-    --    krita/ui/tests/data/prescaled_projection_test/testScrollingZoom50/testScrollingZoom50_zoom50_moved50.png
A  +-    --    krita/ui/tests/data/prescaled_projection_test/testUpdates/testUpdates_cleared.png
A  +-    --    krita/ui/tests/data/prescaled_projection_test/testUpdates/testUpdates_zoom50.png
M  +128  -30   krita/ui/tests/kis_prescaled_projection_test.cpp
M  +3    -1    krita/ui/tests/kis_prescaled_projection_test.h

http://commits.kde.org/calligra/ace38fcf7c62bbd3a0db6d21118cb7695ff20c99

Comment 4 Halla Rempt 2012-01-03 12:06:36 UTC

Isn't this now fixed?

Comment 5 Dmitry Kazakov 2012-01-03 17:26:41 UTC

Created attachment 67402 [details]
Before transparent painting

Comment 6 Dmitry Kazakov 2012-01-03 17:27:00 UTC

Created attachment 67403 [details]
After painting

Comment 7 Dmitry Kazakov 2012-01-03 17:28:19 UTC

Created attachment 67404 [details]
After painting (with marks, pointing to the artifacts)

Please see the screenshots in detailed zoom to see the difference

Comment 8 Dmitry Kazakov 2012-01-03 17:30:17 UTC

The patch above adds a testcase for this bug. See KisPrescaledProjectionTest::testUpdates(). Currently, it is marked as QEXPECT_FAIL, but it can be used for reproducing the bug.

Comment 9 Halla Rempt 2012-06-28 13:10:23 UTC

This looks related to 302664 	on Windows.

Comment 10 Halla Rempt 2013-06-22 13:19:38 UTC


*** This bug has been marked as a duplicate of bug 313502 ***

Comment 11 Dmitry Kazakov 2013-11-04 14:12:16 UTC

This bug is still present in master

Comment 12 Dmitry Kazakov 2015-06-15 11:57:13 UTC

We now use openGL canvas as the mainstream engine. There are no plans to make QPainter Canvas fast and hi-quality. It is mostly a fallback solution. So let's close this bug as UNMAINTAINED :(