Bug 447571

Summary:	Flexible or larger thumbnail size AND per folder view settings
Product:	[Applications] dolphin	Reporter:	Julius R. <c3i8zv295>
Component:	view-engine: general	Assignee:	Dolphin Bug Assignee <dolphin-bugs-null>
Status:	CONFIRMED ---
Severity:	wishlist	CC:	andy, chameleonscales, kdedev, kfm-devel, meven
Priority:	NOR	Keywords:	accessibility
Version First Reported In:	21.12.0
Target Milestone:	---
Platform:	unspecified
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Julius R. 2021-12-27 12:28:03 UTC

Since the early dawn of Dolphin, technology has advanced rapidly: Displays have higher resolutions and 4K became a standard. Especially for media designers a quick overview of images in adequate resolution is necessary. Unfortunately, 256x256 as a maximum preview size (as given in Dolphin as to date) for thumbnails seldomly satisfies.

Yes, there are image viewers (gwenview etc) that can be used to see larger thumbnails, but imagine the use case of grandma trying to sort its private picture library. She has to switch back and forth between Dolphin and Gwenview, which is highly disrupting the workflow and not quite intuitive.

So, my feature request would be
A) Add an option to select the maximum thumbnail zoom size OR at least scale up to 512x512 for good measure
and
B) Add an option to save views per folder. Meaning: Have on default view (grid layout and thumbnail size), but when browsing pictures, make Dolphin remember the higher thumbnail preview size.

Comment 1 caetano 2022-11-05 02:58:42 UTC

nemo and caja have a dconf setting for the thumbnail size that you can customize to any size you want.

IMO this is a great solution because while I sometimes want very big thumbnails, I also understand that this is probably not a desirable option to provide in the preferences, as it may lead to performance or memory issues for some users, so having it as a dconf setting makes it clear that this is not an intended use and you're making changes at your own risk.

Perhaps Dolphin could use some equivalent of that?

Comment 2 caetano 2022-11-05 03:31:16 UTC

regardless I agree that 512 is reasonable these days.

Dolphin went to great lengths to be the best for managing pictures by e.g. showing thumbnails of a folder's contents directly onto the folder's icon (something no other manager can do to my knowledge), so I think allowing for very large previews would go in that continuity.

Comment 3 andy 2025-08-25 01:29:21 UTC

Also been wanting this feature for years.

And if the Qt thumbnail spec is limited to 256x256 or whatnot, then just do some scaling/interpolation.

I use desktop zoom all the time to make up for this.

Comment 4 TraceyC 2025-09-08 13:20:09 UTC

Even with Breeze icons, on 6.4.4, icon size still has a maximum of 256px
I agree that larger icons would be an accessibility benefit

Comment 5 Méven 2025-09-10 12:40:54 UTC

Btw Dolphin can do 512 pixels resolution images when using an higher dpi than 1 to compensate.

This is a bit of a pickle.

I did this:
http://gitlab.freedesktop.org/xdg/xdg-specs/-/merge_requests/40 and https://invent.kde.org/frameworks/kio/-/merge_requests/266
To achieve the aforementioned better support for Hidpi.

This starts to add a lot of disk usage if we were to keep using thumbnails.
Then a workaround would be to not cache the thumbnail when using 512x512 resolution but read it each time from files, which would remove the advantage of caching thumbnails for snappy file browsing.
At the same time minimizing say a photo to 512 or 1024 is not harder on the CPU than to compute for 256, only in memory usage.
This could be acceptable, but users would feel it, a bit like when you browse a folder whose thumbnails haven't been computed yet, except all the time depending on the zoom level.

Do you think that would be reasonable ?
I would consider have an opt-in option to allow to generate 512x512 preview (in logical pixel that is 1024x1024 for dpi>1).

Comment 6 Julius R. 2025-09-10 12:45:59 UTC

Hi Méven,

thank you very much for your suggestion. I think, that would be a good compromise. One thought though, is it really that slow to create larger thumbnails? I mean yes, HDD will get reasonably slower, when trying to create the caches, but on the other hand, modern PCs are running with PCIE SSDs.

Best regards, Julius