typst/vendor/fdeflate/README.md
2024-10-16 14:18:46 +03:00

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fdeflate

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A fast deflate implementation.

This crate contains an optimized implementation of the deflate algorithm tuned to compress PNG images. It is compatible with standard zlib, but make a bunch of simplifying assumptions that drastically improve encoding performance:

  • Exactly one block per deflate stream.
  • No distance codes except for run length encoding of zeros.
  • A single fixed huffman tree trained on a large corpus of PNG images.
  • All huffman codes are <= 12 bits.

It also contains a fast decompressor that supports arbitrary zlib streams but does especially well on streams that meet the above assumptions.

Inspiration

The algorithms in this crate take inspiration from multiple sources: