As Eike indicated in https://bugs.documentfoundation.org/show_bug.cgi?id=146404#c4
COLOR format codes are preserved in ods/fods format.
The pb was the missing map back.
Indeed, we had the mapping for [COLOR<something>] => Color value (eg: "ffaa16")
but not the reverse mapping Color value => [COLOR<something>]
Eike had provided the right code pointer in xmlnumfi.cxx.
First, I thought using PaletteManager but this one is in svx and svx shouldn't be used in xmloff
(dependency pb).
Then I used ChatGpt (GPT-5.6 Luna) and it pointed the right process.
It just consisted to use a similar callback system (DECL_LINK, IMPL_LINK, LINK) of GetUserDefinedColor.
In addition, by testing all this, I noticed that maList in XColorList::GetIndexOfColor was empty.
So I added the Load call in case mbListDirty is true.
Change-Id: I0ef6b5901f2e4c757e88994412dbf79a13100ffd
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/210518
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>
Tested-by: Jenkins
Julien Nabet
e808025d6f