Created attachment 117196 [details] Existing XDG thumbnails are being ignored by Dolphin SUMMARY Thumbnails in XDG thumbnailer spec compliant places are ignored by Dolphin STEPS TO REPRODUCE 1. Put thumbnails into XDG thumbnailer spec compliant places, https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-0.8.0.html 2. See if the thumbnails are displayed 3. There is no step three OBSERVED RESULT XDG thumbnailer spec compliant thumbnails are ignored by Dolphin EXPECTED RESULT XDG thumbnailer spec compliant thumbnails are displayed by Dolphin SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.14.80 KDE Plasma Version: What is the difference to the above? KDE Frameworks Version: 5.14.0 Qt Version: 5.11.2 Dolphin Version: 19.03.70 ADDITIONAL INFORMATION The thumbnails (in this case) are generated by appimaged. Other desktops (such as Xfce) show them just fine https://github.com/AppImage/appimaged
What happens if you copy those AppImages to somewhere in ~? Do they get thumbnails?
No, they don't. It looks like Dolphin does not follow the XDG thumbnailer spec at all, or am I wrong?
It is supposed to, so this is a bug somewhere.
Probono, can you give a concrete example of a thumbnail file and where you put it? Did you expect the file manager to pick up the new thumbnail automatically? What have been your file manager display settings ("Preview enabled")?
Thanks azubieta for the following test case: wget -c "http://icons.iconarchive.com/icons/custom-icon-design/mono-general-3/256/home-icon.png" -O ~/.cache/thumbnails/normal/646c2e0867c1bdd38aa5876337af2284.png touch /tmp/file xdg-open /tmp/ A file manager that follows the XDG thumbnail spec will show a "home" icon thumbnail for /tmp/file. Thanks kossebau for the following analysis: It seems like Dolphin only shows thumbnails that it knows the thumbnailer which generated them: https://cgit.kde.org/kio-extras.git/tree/thumbnail/thumbnail.cpp#n697 ff. https://cgit.kde.org/kio-extras.git/tree/thumbnail/thumbnail.cpp#n90 "enabledPlugins - a list of enabled thumbnailer plugins. PreviewJob does not call this thumbnail slave when a given plugin isn't enabled." This may be the root cause of this issue.
For comparison, in Xfce wget -c "http://icons.iconarchive.com/icons/custom-icon-design/mono-general-3/256/home-icon.png" -O ~/.cache/thumbnails/normal/646c2e0867c1bdd38aa5876337af2284.png touch /tmp/file xdg-open /tmp/ I do see a "home" icon thumbnail for /tmp/file.
By Thumbnail Managing Standard: https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-0.8.0.html -> 5.2. Thumbnail Attributes: https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-0.8.0.html#ADDINFOS "The following keys and their appropriate values must be provided by every program which supports this standard... Table 1. Required attributes. Thumb::URI The absolute canonical uri for the original file. Thumb::MTime The modification time of the original file! If you just add an image to the cache it won't have those.
... you could add the attributes with the exiftool.
Can you confirm that adding the required attributes (see comment #7 with references to the XDG Thumbnail Managing Standard) resolved the issue?
Dear Bug Submitter, This bug has been in NEEDSINFO status with no change for at least 15 days. Please provide the requested information as soon as possible and set the bug status as REPORTED. Due to regular bug tracker maintenance, if the bug is still in NEEDSINFO status with no change in 30 days the bug will be closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging If you have already provided the requested information, please mark the bug as REPORTED so that the KDE team knows that the bug is ready to be confirmed. Thank you for helping us make KDE software even better for everyone!
This bug has been in NEEDSINFO status with no change for at least 30 days. The bug is now closed as RESOLVED > WORKSFORME due to lack of needed information. For more information about our bug triaging procedures please read the wiki located here: https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging Thank you for helping us make KDE software even better for everyone!
Been talking to @kbroulik and the main reason KIO ignores thumbnails is not the lack of these extended attributes, but KIO not showing thumbnails for files it doesn't have (enabled) thumbnailers for. The logic seems to be "no thumbnailer in the list -> thumbnailer must be disabled", the use case "thumbnailer doesn't exist" isn't covered. Now, you might think "okay, then let's change that and add a 'fallback' thumbnailer that looks for existing thumbnails and can make use of them when there's no thumbnailer at all", but that wouldn't really solve the issue either, since we have a _proper_ AppImage thumbnailer and don't have to rely on the thumbs AppImages create. Therefore: not worth the effort. On the AppImage side, adding these attributes to thumbnails is a non-trivial task that will bloat our runtime and will add dependencies. Therefore: also not worth the effort.