https://bugs.kde.org/show_bug.cgi?id=517357
Bug ID: 517357
Summary: Incompatible thumbnail cache between Gwenview and
Dolphin
Classification: Applications
Product: gwenview
Version First 25.12.3
Reported In:
Platform: unspecified
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
The Gwenview thumbnailer cacher does not properly encode file URI leading to
incorrect hash code and interop with other XDG thumbnail consumers/producers.
This can be verified with any path containing spaces for example.
0. Setup dolphin and gwenview to use 256px thumbnails.
1. Delete all thumbnails (`rm -rf ~/.cache/thumbnails/*`)
2. Open a folder with large enough image files (`gwenview "some/folder with
spaces/files"`)
3. Wait for thumbnail generation
4. Open dolphin on the same folder
5. Dolphin regenerates thumbnails - expected it to use the same thumbnails
6. `~/.cache/thumbnails/large` contains about 2x the number of thumbs it should
I believe the problem is the URI encoding. Dolphin uses the "full" encoding and
gwenview uses the "pretty" encoding:
>From kio-extras we have full encoding, which escapes spaces:
https://github.com/KDE/kio-extras/blob/5d20ceb39e5725e2a575583b071acb165335237d/thumbnail/thumbnail.cpp#L796
And in gwenview we have pretty encoding:
https://github.com/KDE/gwenview/blob/f8e7bb9d9ecb851e023a8c71389d269084ce78d5/lib/thumbnailprovider/thumbnailprovider.cpp#L74
The XDG spec says
https://specifications.freedesktop.org/thumbnail/latest/thumbsave.html
"use of the canonical, minimally encoded form of the URI is required to avoid
mismatches between thumbnail generator and thumbnail reader."
So I can see it going either way. But I guess KDE frameworks wins?
Gwenview: 25.12.3
Dolphin: 25.12.2
Linux/KDE Plasma: User-2026-03-05
KDE Plasma Version: 6.6.1
KDE Frameworks Version: 6.23.0
Qt Version: 6.10.2
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