APNG support?

[hmaarrfk]

https://sourceforge.net/projects/libpng-apng/

See https://en.wikipedia.org/wiki/APNG#History

[ocefpaf]

I don't see reasons why not. @msarahan should we create a variant or do you think it is OK to add that to the main libpng?

[RSully]

I would think this should be a separate package