[QGIS-Developer] Backward compatibility for style in project files between QGIS versions

[FERRATON Alain (Adjoint au chef de groupe) - SG/DNUM/MSP/DS/GSG]

Hi 

A polygon layer saved in a project file with QGIS 3.28 is systematically
opened in blue in QGIS 3.16 (the style is lost). 

There has been a change in the storage of style in project files
introduced in QGIS 3.22. 

QGIS 3.22 save the style in both formats (<Option.../> 

and <prop k=.../> 

(see the attachment) 

This is no longer the case in QGIS 3.28 

We have a heterogeneous QGIS version park. The non backward
compatibility of style is an important brake to migrate progressively
our services to QGIS 3.28 

We could consider developing or having developed a plugin to ensure this
backward compatibility.
Is this possible? What would be the best way to proceed? Can we find
documentation on the storage of styles in QGIS project files and on its
evolution?
(I didn't find anything relevant by searching on the internet). 

Sincerely,

-- 
Alain FERRATON

Adjoint au chef de groupe
MSP/DS/GSG
Direction du numérique | Secrétariat général 

MAN 7, rue René Viviani 44200 NANTES
Bureau : MAN étage 1 plateau B
Tel : +33 240128408 - Mobile : +33 671794593
www.ecologie.gouv.fr [1]

 		Secrétariat général

 MINISTÈRES
TRANSITION ÉCOLOGIQUE
COHÉSION DES TERRITOIRES
TRANSITION ÉNERGÉTIQUE
MER 

 

Links:
------
[1] https://www.ecologie.gouv.fr
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