The two Adler32 checksums are u16 and these two getters were mistakenly
left as u32 when PNGChunk::add_as_big_endian() was templated leading
to corrupted IDAT fields in our PNGs.
Before this change PNGWriter::add_chunk used to make a copy of
PNGChunk's ByteBuffer to prepend the size of the data.
With this change, 4-byte space is saved from the beginning and written
at the end of the operation. Avoiding this copy yields significant
speed up.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
With this patch it is possible to create PNG files. Only minimal options
are supported. The PNG is created with one big IDAT chunk containing
only non-compressible DEFLATE blocks.
