Re: [Gimp-developer] GIMP 2.9 XCF files and digiKam, gnome file browsers, etc

[Elle Stone <ellestone ninedegreesbelow com>]

On 03/15/2016 10:51 AM, Kevin Payne wrote:
> A very quick bit of rummaging round in source code leads me to libgimpthumb\gimpthumb-utils.c
>
> Where it shows a fall-back if the thumbnails directory cannot be created - it uses the tmp dir instead.
>
> Kevin
Hmm, 
https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html#DIRECTORY 
says the "normal" place for the thumbnail directory is 
$XDG_CACHE_HOME/thumbnails/ and the "normal" location for 
$XDG_CACHE_HOME is /$HOME/.cache.
For whatever reason on my computer $XDG_CACHE_HOME is set to 
/tmp/elle/.cache. So that's probably why GIMP is writing thumbnails to 
the tmp folder.
If I start GIMP by adding the line:

export XDG_CACHE_HOME=/home/elle/.cache

then GIMP saves thumbnails to /home/elle/.cache/thumbnails.

The thumbnail contains information that points to the corresponding XCF 
file, for example:
Description : Thumbnail of 
file:///home/elle/edit/digiKam/working/080810-2252-1855-house-rainbow.xcf
Software : GIMP 2.9.3
Thumb URI : 
file:///home/elle/edit/digiKam/working/080810-2252-1855-house-rainbow.xcf
digiKam doesn't offer the option of adding a hidden folder to the database.

Copying the thumbnail folder to a folder that digiKam monitors and 
trying to open the correspoinding XCF file by opening the the thumbnail 
just opens the thumbnail itself, not the XCF file.
Are there any image/file browsers that can use the uri location 
information in the thumbnail to open the corresponding XCF file rather 
than the actual thumbnail png?
I mean besides Nautilus. I don't want to install Nautilus on my computer 
as it would mean making considerable changes to my Gentoo installation.
As an aside, 
https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html 
says $XDG_CACHE_HOME is for "user-specific non-essential (cached) data".
It seems to me that the thumbnails that make it possible to browse one's 
XCF files don't count as "non-essential". As it is, for the thumbnails 
to be useful I'd have to use GIMP to recreate thumbnails for the 500 or 
so XCF files currently indexed by digiKam, and that would take an 
enormouse amount of time to accomplish.
Thumbnail browsing is at best a temporary and fragile workaround for 
using an image DAM software like digiKam, that can make its own 
thumbnails (except for GIMP 2.9 XCF files), or at least can read a 
thumbnail already embedded in the image file.
Are GIMP 2.9 XCF files saved to disk with embedded thumbnails?

Best,
Elle