Is it possible to detect support for brotli compressed JXL metadata?

[heirecka]

At build time, I could check for EXV_HAVE_BROTLI but I couldn't find anything I could use for a runtime check.

[clanmills]

I'm not sure that I've understood the question. Why are you interested in this. Do you have a test image which isn't been correctly handled?

By default, brotli support is built into exiv2. You can check to built status of exiv2 with the command $ exiv2 --verbose --version

1168 rmills@rmillsm1:~/gnu/github/exiv2/main/build $ bin/exiv2 -vV | grep brotli
library=/opt/homebrew/Cellar/brotli/1.1.0/lib/libbrotlicommon.1.1.0.dylib
library=/opt/homebrew/Cellar/brotli/1.1.0/lib/libbrotlidec.1.1.0.dylib
have_brotli=1
1169 rmills@rmillsm1:~/gnu/github/exiv2/main/build $ 

Is brotli being used to decompress the metadata in a JXL? I don't know. I retired from Exiv2 two years ago, just as JXL surfaced. I maintained Exiv2 0.14-v0.27. JXL support was added to main and I wasn't involved.