HarfBuzz Files

• The major feature of this release is that the Variable Composites / Components (VARC table) addition to the ISO OpenFontFormat has graduated from experimental, and is now enabled by default. It can be disabled at compile time by defining the HB_NO_VAR_COMPOSITES macro.

VARC table is a new way to store glyph outlines, that allows for better shape reuse, and can reduce font file size for Chinese, Japanese, Korean, and some other scripts drastically. Some font design tools provide a similar feature to designers, known as "smart components". This technology brings the same idea to the compiled font file. For the format specification, see: https://github.com/harfbuzz/boring-expansion-spec/blob/main/VARC.md

Test fonts can be found at: https://github.com/notofonts/noto-cjk-varco/releases/tag/v0.003

The Fontra font editor already supports this technology.

Note that this new format involves just the HarfBuzz draw API and does not affect shaping.

• Correctly handle markFilteringSet lookup field during subsetting.
• Deduplicate features during subsetting.
• Disable “more” buffer messages that give more verbose output when using buffer messages callbacks, as it has a performance overhead. Users / tools that need the more verbose messages should define HB_BUFFER_MESSAGE_MORE to 1 when building HarfBuzz.
• Shaping and instancing optimizations.
• Fix subsetting issues when building with GCC 12.