Tag representations are not decoder- or encoder-specific, so should live
in their own module accessible to both for reuse. The decoder::ifd
module remains since this module is mainly dedicated to decoding the
IFD.
Resolve several TODOs where tag values were cast from u32 without checks
by providing generic methods that error when the value fails casting to
the desired type. In addition to being more correct, this simplifies and
shortens decoding logic.
Remove `find_tag_u32` and `find_tag_u32_vec` as they are now redundant
and a GitHub code search found no usages outside copies of
`image-tiff`.
This makes it cheaper to introduce new features that might require
amending the list of variants by allowing us to introduce previously
uncovered causes or more specialized representations.
Avoids leaking the dependency on `miniz_oxide` into the public interface
by making a constructor taking a status argument crate internal. It
would otherwise not be possible to replace the deflate decoder without
breaking that interface.
Andrew Champion