Bug 393995 - [GridDelegate] Previews are blurry
Summary: [GridDelegate] Previews are blurry
Alias: None
Product: frameworks-kdeclarative
Classification: Frameworks and Libraries
Component: general (show other bugs)
Version: unspecified
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: Marco Martin
Depends on:
Reported: 2018-05-08 11:55 UTC by Harald Sitter
Modified: 2019-05-30 20:07 UTC (History)
7 users (show)

See Also:
Latest Commit:
Version Fixed In: 5.57

smooth=false screenshot (159.78 KB, image/png)
2018-05-14 09:04 UTC, Harald Sitter
smooth=true screenshot (159.06 KB, image/png)
2018-05-14 09:04 UTC, Harald Sitter
Plasma 5.16 beta (313.52 KB, image/png)
2019-05-17 16:47 UTC, Patrick Silva

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Description Harald Sitter 2018-05-08 11:55:44 UTC
This recently improved a bit but icons continue to be very blurry.

Icon smoothing seems to severely blur the icon previews. I am attaching two screenshots. One with smoothing the other without, this should highlight the blur caused by the smoothing. It looks really bad.

Do we usually smooth icons? If so, are we requesting too large preview sizes to cause the smoothing?
I'd think that if we request 32x32 (e.g.) and get 32x32 smoothing wouldn't even kick in since we don't scale, so something must definitely be wrong there.

CCing kbroulik as he worked on this
Comment 1 Nate Graham 2018-05-08 17:14:20 UTC
Needz moar attachments
Comment 2 Harald Sitter 2018-05-14 09:04:34 UTC
Created attachment 112635 [details]
smooth=false screenshot
Comment 3 Harald Sitter 2018-05-14 09:04:48 UTC
Created attachment 112636 [details]
smooth=true screenshot
Comment 4 Harald Sitter 2018-05-14 09:05:03 UTC
I think I fell asleep while reporting this bug lol
Comment 5 Harald Sitter 2018-05-14 09:08:44 UTC
(screenshots are the other way around from what they are labeled as)
Comment 6 Patrick Silva 2018-10-16 17:16:39 UTC
Previews are still blury.

Operating System: Arch Linux 
KDE Plasma Version: 5.14.1
Qt Version: 5.11.2
KDE Frameworks Version: 5.51.0
Comment 7 Filip Fila 2019-03-04 21:36:38 UTC
Based on the research in https://phabricator.kde.org/D19467 it seems that all previews are blurry and that is a general issue with GridViewKCM.
Comment 8 Filip Fila 2019-03-04 21:47:04 UTC
FWIW and concerning the Icons KCM, the previews become sharp with view.implicitCellWidth = Kirigami.Units.gridUnit * 16

Proof: https://i.ibb.co/CzSs5xp/Screenshot-20190304-224455.png
Comment 9 David Edmundson 2019-03-04 22:10:53 UTC
Try this: https://phabricator.kde.org/D19530
Comment 10 Patrick Silva 2019-05-17 16:47:08 UTC
Created attachment 120140 [details]
Plasma 5.16 beta

Previews look blurry when I set 1.2 as scale factor on Plasma 5.16 beta.

Operating System: Arch Linux 
KDE Plasma Version: 5.15.90
KDE Frameworks Version: 5.58.0
Qt Version: 5.13.0 beta3
Comment 11 Nate Graham 2019-05-17 16:51:15 UTC
Since these are pixmaps, there is no way for them to not be blurry with fractional scaling, I'm afraid. It's just a fact of life with fractional scaling: you lose out on the ability for things to be "pixel-perfect".
Comment 12 Christoph Feck 2019-05-17 20:56:38 UTC
Nate, an application can create pixmaps with the same scale factor as the screen, and thus can of course be pixel-perfect. It has to be adapted, though.
Comment 13 Nate Graham 2019-05-17 21:02:23 UTC
But the pixmap's contents may not be able to scale cleanly without being blurry. My point was that something that's pixel-perfect at 1x or 2x may not be able to be pixel-perfect at 1.2x.
Comment 14 Christoph Feck 2019-05-30 19:51:45 UTC
The pixmaps are not pre-rendered images, but created on the fly from SVG graphics, so the contents can be made pixel-perfect according to the scaling ratio of the screen the pixmap is displayed on.

Anyway, does this need to be reopened, or is it actually already fixed?
Comment 15 Nate Graham 2019-05-30 20:07:38 UTC
This bug was tracking integer scaling blurriness which is now fixed, so it should remain closed. I can reproduce factional scale factor blurriness though. Since it seems that this should theoretically be fixable, please file a new bug for it. Thanks!