Core: Thumbnails for file browsers not created on Linux

Is there an existing issue for this?

• I have searched the existing issues

Problem description

When using a file browser (e.g. Nautilus on GNOME-based OSs), .FCStd files used to be shown as the thumbnail of the contents of the file. It currently does not seem to work, and the file is shown as a generic blank icon.

This is the script that generates the thumbnails:

https://github.com/FreeCAD/FreeCAD/blob/main/src/Tools/freecad-thumbnailer.in

It says in a comment:

Register this thumbnailer Adding a file /usr/share/thumbnailers/FreeCAD.thumbnailer with the following content:

[Thumbnailer Entry] TryExec=freecad-thumbnailer Exec=freecad-thumbnailer -s %s %i %o MimeType=application/x-extension-fcstd;

However, taking the freecad-daily PPA's Debian package as an example, I noticed:

1. The file to register a thumbnailer is shipped at /usr/share/freecad-daily/share/thumbnailers/FreeCAD.thumbnailer instead of /usr/share/thumbnailers/FreeCAD.thumbnailer
2. Listing the contents of /usr/share/freecad-daily/share/thumbnailers/FreeCAD.thumbnailer points to a bin/freecad-thumbnailer executable that is not installed by the Debian package

   [Thumbnailer Entry]
   TryExec=bin/freecad-thumbnailer
   Exec=bin/freecad-thumbnailer -s %s %i %o
   MimeType=application/x-extension-fcstd;
   

It also says:

• The application/x-extension-fcstd MIME type should be registered Check that a corresponding /usr/share/mime/packages/freecad.xml file exists

3. I could not find any freecad.xml file on my system, but there are:

   /usr/local/share/mime/packages/org.freecad.FreeCAD.xml
   /usr/share/freecad-daily/share/mime/packages/org.freecad.FreeCAD.xml
   

I'm not sure if point 1 makes a difference (can thumbnailers that are not in the /usr/share/thumbnailers location be registered?), but point 2 seems to be wrong. Point 3 is probably not an issue, other than needing to update the comment on the thumbnailer with the right location.

Full version info

OS: Ubuntu 22.04.5 LTS (ubuntu:GNOME/ubuntu/xcb)
Architecture: x86_64
Version: 1.1.0dev.40971 (Git)
Build date: 2025/03/24 18:02:34
Build type: Release
Branch: main
Hash: b33c2363226a5fc1e8222a02659118c95e1a5119
Python 3.10.12, Qt 5.15.3, Coin 4.0.0, Vtk 9.1.0, IfcOpenShell 0.8.1.post1, OCC 7.8.1
Stylesheet/Theme/QtStyle: FreeCAD Light.qss/FreeCAD Light/Fusion
Logical DPI/Physical DPI/Pixel Ratio: 96/159.34/1
Installed mods: 
  * OpenTheme 2024.9.1
  * fasteners 0.5.37

Subproject(s) affected?

Core

Anything else?

https://github.com/FreeCAD/FreeCAD/blob/main/src/XDGData/FreeCAD.thumbnailer.in

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