Bug 497576

Summary:	Preview pixelation and scale problems in Dolphin after upgrade from Dolphin 24.08.3 -> 24.12.0
Product:	[Applications] dolphin	Reporter:	OIRNOIR <hi>
Component:	panels: information	Assignee:	Dolphin Bug Assignee <dolphin-bugs-null>
Status:	RESOLVED FIXED
Severity:	normal	CC:	dolphin-bugs-null, erasmocaponio, hi, meven29, nate, nbelavic
Priority:	NOR	Keywords:	regression
Version First Reported In:	24.12.0
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:	https://invent.kde.org/system/dolphin/-/commit/c7e2cb3a5a4a72b1b560153cea8454280f8155a8	Version Fixed In:	24.12.2
Sentry Crash Report:
Attachments:	Screenshot of Dolphin, information panel shows broken preview of folder containing image Screenshot of Dolphin, information panel shows broken preview of image itself Dolphin image preview with 100% scaling Dolphin image preview with 125% scaling

Description OIRNOIR 2024-12-16 21:18:21 UTC

SUMMARY
Upon updating to dolphin 24.12.0, the information panel (F11) in Dolphin now displays previews wrongly for images. Instead of fitting the image, it fills it, cutting off the longer side. In addition, it seems unusually pixelated, even for high resolution images. I was able to reproduce this on a clean install in a VM.

STEPS TO REPRODUCE
- Install Fedora 41 KDE spin
- Obtain any non-square (so, either horizontal or vertical) image in either png or jpg format
- In Dolphin, navigate to the directory containing your image
- Enable the information portal via hamburger menu → Show Panels → Information
- Hover over the image

OBSERVED RESULT
Part of the image is now cut off, and it may look slightly pixelated.

EXPECTED RESULT
The entire image is shown within the borders of the preview, and it doesn’t look pixelated

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: Linux 6.12.4
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.1

ADDITIONAL INFORMATION

Comment 1 OIRNOIR 2024-12-16 21:35:56 UTC

In addition to the fresh Fedora KDE install, I was also able to reproduce it on a fresh EndeavourOS install.

Comment 2 OIRNOIR 2024-12-16 21:37:12 UTC

Created attachment 176697 [details]
Screenshot of Dolphin, information panel shows broken preview of folder containing image

Comment 3 OIRNOIR 2024-12-16 21:37:45 UTC

Created attachment 176698 [details]
Screenshot of Dolphin, information panel shows broken preview of image itself

Comment 4 OIRNOIR 2024-12-16 21:52:52 UTC

Update: This bug seems to be most apparent on display scalings above 100%.

Comment 5 OIRNOIR 2024-12-17 21:11:15 UTC

This is still a problem on KDE Frameworks 6.9.0

Comment 6 nicols 2024-12-23 10:53:10 UTC

Same problem is present on KDE Neon:
- Plasma 6.2.4
- KDE Frameworks: 6.9.0
- Qt Version 6.8.1
- Kernel 6.8.0-51-generic (64 bit)
- Dolphin 24.12.0.1

Scaling is set to 125%, problem with Dolphin preview is both on Wayland and X11

Comment 7 nicols 2024-12-29 16:03:57 UTC

Created attachment 176952 [details]
Dolphin image preview with 100% scaling

Comment 8 nicols 2024-12-29 16:04:24 UTC

Created attachment 176953 [details]
Dolphin image preview with 125% scaling

Comment 9 Bug Janitor Service 2025-01-06 17:27:43 UTC

A possibly relevant merge request was started @ https://invent.kde.org/system/dolphin/-/merge_requests/884

Comment 10 Erasmo Caponio 2025-01-07 21:29:31 UTC

(In reply to OIRNOIR from comment #4)
> Update: This bug seems to be most apparent on display scalings above 100%.

I can confirm this bug on Manjaro. I also confirm that when the diplayed is not scaled the bug is not present

Comment 11 Méven 2025-01-09 12:22:02 UTC

Git commit 863c1be871d7dbd16800cf7400284783d52352d5 by Méven Car.
Committed on 09/01/2025 at 09:44.
Pushed by meven into branch 'master'.

information panel: scale according dpr

Also use dpr for icons.

Amends cebcf8db

M  +2    -2    src/kitemviews/kfileitemmodelrolesupdater.cpp
M  +1    -1    src/kitemviews/kstandarditemlistwidget.cpp
M  +7    -5    src/panels/information/informationpanelcontent.cpp

https://invent.kde.org/system/dolphin/-/commit/863c1be871d7dbd16800cf7400284783d52352d5

Comment 12 Méven 2025-01-09 12:29:45 UTC

Git commit c7e2cb3a5a4a72b1b560153cea8454280f8155a8 by Méven Car.
Committed on 09/01/2025 at 12:22.
Pushed by meven into branch 'release/24.12'.

information panel: scale according dpr

Also use dpr for icons.

Amends cebcf8db

(cherry picked from commit 863c1be871d7dbd16800cf7400284783d52352d5)

M  +2    -2    src/kitemviews/kfileitemmodelrolesupdater.cpp
M  +1    -1    src/kitemviews/kstandarditemlistwidget.cpp
M  +7    -5    src/panels/information/informationpanelcontent.cpp

https://invent.kde.org/system/dolphin/-/commit/c7e2cb3a5a4a72b1b560153cea8454280f8155a8