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.
No such thing happens in Gimp
Can you attach a screenshot?
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
Isn't this now fixed?
Created attachment 67402 [details] Before transparent painting
Created attachment 67403 [details] After painting
Created attachment 67404 [details] After painting (with marks, pointing to the artifacts) Please see the screenshots in detailed zoom to see the difference
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.
This looks related to 302664 on Windows.
*** This bug has been marked as a duplicate of bug 313502 ***
This bug is still present in master
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 :(