I have installed the flatpak version of evince, and because it is the former elementary document viewer it looks like the flatpak version takes the responsability of creating thumbnails, but while I browse files with the pantheon files application, the processor overheats if there are a lot of files into the folder, and
dmesg command always returns a lot of lines like this:
audit: type=1400 audit(1577484935.935:59): apparmor="DENIED" operation="open" profile="/usr/bin/evince-thumbnailer" name="/var/lib/flatpak/exports/share/mime/mime.cache" pid=25977 comm="evince-thumbnai" requested_mask="r" denied_mask="r" fsuid=1001 ouid=0
Maybe I am wrong, but it looks like apparmor denies evince to accept the mimecache file and as a result all thumbnails are recreated every time I open the folder - if there are a lot of images in it I can see them with the default jpg icon for a while following the thumbnail previews. Uninnstalling the flatpak version of the app do not remove the problem - I can see new similar lines when I type dmesg into terminal, always incliding the flatpak mime.cache path while I am browsing with the pantheon files application. It looks like there are two options - 1. To change the system thumbnailer program to be the default Document viewer or 2. to configure apparmor to grant access to the flatpak version to the mime.cache file but I do not know how to achieve neighter one of both. Anybody can help?