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:	REPORTED ---
Severity:	normal	CC:	hi, kfm-devel, nbelavic
Priority:	NOR
Version:	24.12.0
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed In:
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