GNOME Bugzilla – Bug 701415
Rotated Canvas - small artefacts
Last modified: 2017-12-07 15:01:39 UTC
Created attachment 245819 [details]
artefacts screenshot 
When stroking brush strokes close to themselves some small jaggy artefacts appear  (in attached image).
To get reed of them you have to rotate canvas or zoom in/out and back, then it refreshes and line look like it should .
still unconfirmed? :) it slipped somehow?
My first confirmed bug report :P yey~ :D
It this related to transparency like bug 759287 ?
Does this still happen in current versions?
I believe it still happens as of today, "commit 465eba3260", and was happening with the one I had previously, whatever that was (of a couple of months ago, I guess). It does not happen with the Debian's 2.8.18 version, but that's probably well known.
However, to me it certainly happens irrespective of rotation, you can reproduce it easily by just drawing somewhat smooth wiggly lines with a hard brush or the ink tool, a few dents will show up along the lines.
The visual jagged/misaligned "tiles" are fixed when rotating visually or zooming in or out (and back again, or not), or even with further brushstrokes near the artifacts, even though it will also create new visual artifacts where there was none.
It also manifests in such a way that it seems that you're painting with a little bit of a strong, but small, "smudge" effect, most noticeable when painting over hard lines (in any layer), but that's not noticeable in a static screen capture.
It happens with and without OpenCL activated.
I've upgraded today to the latest 2.9 git version, and the problem still persists; however, I've determined it's specific to the Intel driver, not happening with kernel mode-setting.
"Hardinfo" says it's a "Intel Corporation 4 Series Chipset Integrated Graphics Controller (rev 03)" if that's of any use (not the same one I was using before, on a different motherboard, but visually the artifact was identical), but I guess that's probably a driver issue then.
Well with 2 people experiencing it, it's confirmed and anyway I just tried. It's quite easy to reproduce:
- open a white canvas;
- with a round brush (makes it easier to see with a simple shape), click on the canvas;
- then with shift, create a linear stroke;
- with shift again, create a second linear stroke close to the first one.
Result: various artefacts will appear. Actually it's quite funny since you can see the artefacts appearing and disappearing as you move your last line before you click to draw it. I.e. don't even do the last step, and simply hit shift again, and move your mouse around. Don't actually draw the second line. While doing so, one will see artefacts appearing on the existing line.
Created attachment 363786 [details]
Screenshot of artefacts
Also showing a screenshot. In my case, they didn't look as bad as in the original poster's screenshot, but they are quite obvious when they appear while you draw.
Also using straight (shift-click) line with a round brush make them more obvious since we don't expect any bumps on the line.
Adding a dependency on bug 759287 which is also about corrupted canvas preview when painting. Not sure if that is really the same issue, but since there are WIP patches on this other bug, let's see after these are fixed. Maybe when this happens, this issue will not happen either.
(In reply to Jehan from comment #8)
> Well with 2 people experiencing it, it's confirmed and anyway I just tried.
> It's quite easy to reproduce:
> - open a white canvas;
> - with a round brush (makes it easier to see with a simple shape), click on
> the canvas;
> - then with shift, create a linear stroke;
> - with shift again, create a second linear stroke close to the first one.
> Result: various artefacts will appear. Actually it's quite funny since you
> can see the artefacts appearing and disappearing as you move your last line
> before you click to draw it. I.e. don't even do the last step, and simply
> hit shift again, and move your mouse around. Don't actually draw the second
> line. While doing so, one will see artefacts appearing on the existing line.
I tested this with/without the patch attached to
and it seems it is the same problem: GIMP renders rotated rectangles
and the edges are covering partly the destinations so where the clip
is missing they're painted multiple times resulting in a different final
In my tests I used a 'Random color' paint dynamic so the effect is not
limited to the border of the stroke.
Ok thanks Massimo. Let's mark them as duplicate then.
*** This bug has been marked as a duplicate of bug 759287 ***