- Switch to streaming decompression via `flate2`. Aside from performance improvements and lower RAM consumption, this fixes a bug where `max_uncompressed_length` was precalculated for a single tile but then used as a hard limit on the whole data, failing to decompress any tiled images.
- Deprecate `InflateError` - this was used for wrapping `miniz_oxide` raw status, but `flate2` already reports them as `io::Error` instead. This makes errors from both Lzw and Deflate modes more consistent - they're all now just `io::Error`.
- Add support for new `Deflate` tag in addition to `OldDeflate` - format-wise it's same Zlib, and on practice decodes successfully with the same underlying code.
- Slightly simplify partial reads from the `Reader` by using the `std::io::copy` helper instead of doing it manually.
Fixes#131.
When the required amount of data was just a tiny bit larger than full a
page size (one buffer increment), the decoder would stop since all
compressed data had been read. However, the lzw decoder contains a small
internal bit buffer for code decoding. That is, some remaining bytes had
been retained and were still left to be decoded.
Since it is known that libtiff produces other sample format variants we
do not support, represent these as variants. This also allows returning
the sample formats in errors so that composition of formats and known
and unknown formats are clearly reported.
Convert most unchecked size/index `as` casts to checked casts with
`TryFrom`, included another top-level error variant.
This has several motivations:
- Making the library as robust as possible, including to platform
differences.
- Unchecked casts are susceptible to breakage during refactorings.
- Preparing for BigTIFF support, which will require the introduction of
generics and associated types for some parts of the de/encoders.
Unchecked primitive casts cannot be bound, while TryFrom can, and
overflowing conversions become more likely.
- Remaining u16 casts may be prone in failure in existing practice and
not just in theory during future changes.
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.
Ingvar Stepanyan