Information panel does not show PNG, AVIF or WebP images, just generic icon

jamesfrederik · October 13, 2024, 11:16am

Fresh install of Fedora Workstation and updated to latest 6.2

When I press F11 in Dolphin, the “Information Panel” opens and displays a large icon rather than rendering the image for PNG, AVIF, WebP and possibly more image formats. Oddly, it renders the contents of folders that contain these image formats, so I’m guessing it’s a setting I’ve made somewhere.

I seem to have all the relevant codecs installed.

But maybe it’s something to do with Fedora being weird about licences, it’s quite confusing with all the freeworld stuff.

meven · October 13, 2024, 11:20am

Check your preview settings in dolphin settings > Interface > Preview.

jamesfrederik · October 13, 2024, 11:36am

Thanks.

I looked, and all boxes are checked.

Unchecking the boxes, however, makes it work.

meven · October 13, 2024, 12:02pm

The reason is bit complicated.

Previews are provided by /usr/share/thumbnailers/ and kio-extras thumbnail plugins.
The plugins are used by default, but the “image” one does not explicitly declare supporting heif/webp because their support might not be present on the system (i.e qt image plugins), despite it might well work.

Here it seems your /usr/share/thumbnailers/ are not working and deactivating them made their preview be rendered by the default image plugin Images (GIf PNG, BMP... in the file type list.

tldr; Check your thumbnailers in /usr/share/thumbnailers/ work and their dependencies executables are installed, or removes the concerned files.

If you tried to launch dolphin from the command line you might have got some output hinting this way.

audiothumbnail and imagethumbnail: Mention supported mimetypes explicitly (b61847f4) · Commits · Network / KIO Extras · GitLab will fix the png issue in 24.12, kio does not detect image plugin supports png.

jamesfrederik · October 13, 2024, 12:30pm

Indeed, dolphin reports :

kf.coreaddons: "Could not find plugin gdk-pixbuf-thumbnailer"

Thank you for the explanation.

I do have the following :

/usr/share/thumbnailers/avif.thumbnailer
/usr/share/thumbnailers/gdk-pixbuf-thumbnailer.thumbnailer
/usr/share/thumbnailers/jxl.thumbnailer
/usr/share/thumbnailers/librsvg.thumbnailer
/usr/share/thumbnailers/webp-pixbuf.thumbnailer

and it looks like all the relevant libs are installed.

So I’ll have to have a poke about in Fedora.

Good to know what’s going wrong.

jamesfrederik · October 15, 2024, 2:37pm

Fresh install of openSUSE Tumbleweed and the same problem exists.

meven · October 15, 2024, 3:46pm

I made a mistake in my answer.

This concerns the Information Panel, which has a different behavior that the context I had in mind, regular thumbnails in the view.

The information does not cache file rendering, so we don’t use standard thumbnailer, since using our own plugins would save some disk IO.

So here your issue is the opposite it seems, you’d need GitHub - jakar/qt-heif-image-plugin: Qt plugin for HEIF images or GitHub - novomesk/qt-avif-image-plugin: Qt plug-in to allow Qt and KDE based applications to read/write AVIF images. to add support for those formats to qt and KDE apps.
Those might not be available in your distro packages, not sure.

So I can consider this a bug, we probably want to use the standard thumbnailer to read those files, just not store it to cache and remove their file after use.

webp (at least with Qt 6.7+) and PNG are a different issue. The one mentioning audiothumbnail and imagethumbnail: Mention supported mimetypes explicitly (!367) · Merge requests · Network / KIO Extras · GitLab we should probably backport it.

meven · October 15, 2024, 4:19pm

I made a fix for the PNG/webp issue for 24.08 audiothumbnail and imagethumbnail: Mention supported mimetypes explicitly (!376) · Merge requests · Network / KIO Extras · GitLab

jamesfrederik · October 17, 2024, 8:23am

Hey thanks. Good to hear there are solutions in the pipeline.

I should report this stuff to bugs.kde in the future though right?

Well I kind of lost the thread on what does what. Turning the image types off in Dolphin fixes the problem for me.

I notice I need the Images(GIF,PNG,BMP…) option turned on.

I think a good solution, for me, will be to convert the webp and avif and heic stuff to max res jpg and be done with it. Make things easier to sort too.

meven · October 17, 2024, 10:02am

That’s best to report to bugs.kde.org

You were just lucky, a dolphin maintainer was around, but discussions on discuss can fade or buried in noice, whereas bugs.kde.org keeps everything and categorize things.

The bug report could be reported for kio:
The information panel missing heif/avif images.

or more precisely:
Previewjob does not use standard thumbnailer when caching is not on.

At the cost of disk space and some amount of quality loss (as those formats are not lossless). If you are patient, it should be fixed in a month or two.

Thanks for reporting the issue

meven · October 19, 2024, 11:44am

Made the MR to fix the information panel preview missing for heif/avif PreviewJob: use standard thumbnailer when no cache (!1744) · Merge requests · Frameworks / KIO · GitLab

medin · October 26, 2024, 2:25pm

In plasma 6.2.2, the problem is at two places: information panel in Dolphin and also the preview panel in open/save dialogs, they fail to show preview of some formats like heif, png

While previews of png, heif… are correctly generated in the regular view inside Dolphin.

Running Dolphin from terminal shows the following errors:
kf.coreaddons: "Could not find plugin gdk-pixbuf-thumbnailer"
kf.coreaddons: "Could not find plugin heif"

meven · October 27, 2024, 10:14am

In plasma 6.2.2, the problem is at two places: information panel in Dolphin and also the preview panel in open/save dialogs, they fail to show preview of some formats like heif, png

This is fixed in next KDE Frameworks version 6.8.

PreviewJob: use standard thumbnailer caching is disabled (!1744) · Merge requests · Frameworks / KIO · GitLab mentionned above is the fix.