Writing Exif data to RAW files

[Johannes Zarl-Zierl]

Hi Tobias,

Am Samstag, 10. September 2022, 19:20:48 CEST schrieb Tobias Leupold:
> Question is: Why is this disabled by default libkexiv2-side? And how should
> we deal with this? Add another option "Enable writing to RAW files"? And
> only add "cr2" with the MIME type "image/x-canon-cr2", as we now know it
> works for those?
> 
> I'm a bit unsure at this point ... all comments are welcome!

The feature seems to have been considered experimental when it was added:
https://commits.kde.org/libkexiv2/a6deed7521d709bc303b0def98ae24dcec398461

I don't know, though, if that is still the case or if the libkexiv2 authors 
simply didn't come around to changing the defaults.

The safest way to handle any files that you can read but not reliably write 
would be to always write to sidecar files for those.

If I read the info on https://exiv2.org/whatsnew.html correctly, though, it 
seems that writing to raw files was considered experimental (on the exiv2 side) 
only for the pre-release of 0.18. The 0.18 release does not mention the 
feature to be experimental.

Looking at the TIFF-related code in https://invent.kde.org/graphics/
libkexiv2/-/blob/master/src/kexiv2_p.cpp#L209 I do understand the reasoning 
behind marking it experimental on the libkexiv2 side of things. 

So defaulting to sidecar files for raw files (and maybe adding a warning when 
writing into raw files directly) seems to be the prudent way forward.

Cheers,
  Johannes