oxideav-ttf

Pure-Rust TrueType font parser for the oxideav framework. Implements the sfnt container, the core OpenType tables, and just enough of GSUB / GPOS to do Latin/Cyrillic/Greek/CJK shaping with ligatures and kerning.

Round-1 scope (this release)

sfnt + table directory walker.
head, hhea, maxp, cmap (formats 0, 4, 6, 12), name, OS/2, hmtx, loca, glyf (simple + composite), post.
Legacy kern table (format 0).
GSUB LookupType 4 (ligature substitution).
GPOS LookupType 2 (pair-adjustment / kerning).
GDEF (glyph class definitions, used to skip mark glyphs).

The companion oxideav-scribe crate consumes the outlines + shaping output to rasterise text to RGBA bitmaps for subtitles and the scene compositor.

Public API

use oxideav_ttf::Font;

let bytes = std::fs::read("DejaVuSansMono.ttf")?;
let font  = Font::from_bytes(&bytes)?;

// Metadata.
let _ = font.family_name();         // Some("DejaVu Sans Mono")
let _ = font.units_per_em();        // 2048
let _ = font.glyph_count();
let _ = font.ascent();
let _ = font.descent();
let _ = font.line_gap();

// Glyph lookup.
let gid_a = font.glyph_index('A').unwrap();
let _ = font.glyph_advance(gid_a);  // i16 advance width in font units
let _ = font.glyph_lsb(gid_a);
let _ = font.glyph_bounding_box(gid_a);
let _ = font.glyph_outline(gid_a)?; // contours of i16 points

// Shaping helpers.
let gid_f = font.glyph_index('f').unwrap();
let gid_i = font.glyph_index('i').unwrap();
if let Some((replacement_gid, consumed)) = font.lookup_ligature(&[gid_f, gid_i]) {
    // `fi` ligature substitutes 2 input glyphs with `replacement_gid`.
    let _ = (replacement_gid, consumed);
}

let gid_v = font.glyph_index('V').unwrap();
let _ = font.lookup_kerning(gid_a, gid_v); // negative i16 in font units

Out of scope (round 2+)

CFF / Type 2 charstrings — moves to a sibling oxideav-otf crate.
Bidi, Arabic shaping, Indic conjuncts, complex contextual GSUB/GPOS.
Variable fonts (fvar / gvar / MVAR).
TrueType bytecode hinting (modern AA at ≥ 16 px does not need it).
cmap formats 2, 8, 10, 13, 14.
GSUB lookup types 1/2/3/5/6/7/8 and GPOS lookup types 1/3..9.

Test fixture

tests/fixtures/DejaVuSansMono.ttf is the upstream DejaVu Sans Mono 2.37 under the Bitstream Vera license (see tests/fixtures/DEJAVU-LICENSE).

License