Change Log

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

Unreleased

Fixed

Reject GSUB/GPOS lookups with an out-of-range lookupType instead of truncating it to u8. A malformed font could have e.g. type 3586 dispatched as MultipleSubst, expanding a single character into thousands of glyphs and costing up to a second per shape call. HarfBuzz rejects such tables.
When a variation selector is replaced by the not-found variation selector glyph, reset that selector's Unicode properties instead of the first glyph's, matching HarfBuzz.
Document that glyph IDs are not limited to u16: glyphs supplied by the caller, such as the not-found variation selector glyph, are passed through unchanged. Shaping tests now cover values above u16::MAX.

0.14.0 - 2026-10-03

This release matches HarfBuzz v14.5.1, and has an MSRV (minimum supported Rust version) of 1.85.

Breaking changes

Replace UnicodeBuffer and GlyphBuffer with one Buffer that holds input Unicode code points before shaping and glyphs afterward. ContentType reports which state the buffer is in. The old buffer types and their conversion methods have been removed.
Replace the FontRef entry point with Font from read-fonts, re-exported as harfrust::Font. Create a ShaperFont from a Font (or one of its instances) before shaping.
Replace the old Shaper, ShaperBuilder, ShaperInstance, and ShaperData API with ShaperFont.
Configure scale and custom FontFuncs on ShaperFont instead of ShapeOptions.
Shape in place with harfrust::shape(&shaper_font, &mut buffer, options). It returns Result<(), ShapeError> for invalid shaping state or properties, rather than returning a separate glyph buffer. Check Buffer::allocation_successful() separately for allocation or shaping-limit failure.

Migration

Replace UnicodeBuffer construction and the returned GlyphBuffer with a single mutable Buffer. For example, with font_data containing font bytes:

use harfrust::{shape, Buffer, Font, ShapeOptions, ShaperFont};

let font = Font::new(font_data, 0).expect("invalid font");
let shaper_font = ShaperFont::new(&font);
let mut buffer = Buffer::new();
buffer.push_str("Hello");
buffer.guess_segment_properties();
shape(&shaper_font, &mut buffer, ShapeOptions::new()).expect("shaping failed");
let glyphs = buffer.glyph_infos();
let positions = buffer.glyph_positions();

Use buffer.clear() to reuse its allocation for another run, then push new text. Call guess_segment_properties() or set the direction and other segment properties explicitly before shaping.

Use ShaperFont::set_scale or set_scale_separate for scaling, and ShaperFont::set_font_funcs for custom font callbacks. ShaperFont borrows the Font and any supplied callbacks, so it is intended as a short-lived shaping view; keep the Font and callbacks alive and construct a ShaperFont as needed. ShapeOptions holds per-call features, an optional plan, and point size.

Other changes

Update read-fonts to 0.45.0 and use its current font model API.
Update the built-in Unicode data to 18.0. Add Jurchen, Proto-Cuneiform, and Seal script constants to the Rust and C APIs and route them through USE.
Treat U+180F as default ignorable during shaping.
Support hexadecimal OpenType language and script overrides in x-hbot- and x-hbsc- private-use subtags, such as x-hbot-4d4f4e54 for MONT.
Expose Unicode composition, one-step canonical decomposition, and canonical combining classes through the public harfrust::unicode module. Decomposition returns a Decomposed enum.
Add the harfrust_capi crate, a C API mirroring the shaping half of HarfBuzz's API with an hr_ prefix in place of hb_.
Speed up repeated hr-shape runs and contextual lookup matching.
Reduce OpenType subtable cache memory by boxing the two large contextual cache variants.
Leave a GPOS mark unattached when it is more than 32767 glyphs from its base, as HarfBuzz does, instead of storing a truncated attach_chain that mispositioned the mark.
Fix would_apply for format 3 (coverage-based) contextual lookups, which never matched, so the Indic shaper missed features built from them. Noto Sans Bengali's ra-phala (e.g. গ্র) came out as consonant, visible hasant and ra.

0.13.3 - 2026-08-25

This release matches HarfBuzz v14.3.1, and has an MSRV (minimum supported Rust version) of 1.85.

Add support for shaping legacy AAT mort tables, including language-specific morph features (#451, #453).
Handle tuple kerning in AAT kerx tables (#452).
Fix a debug assertion for legacy kern state tables that declare more than 256 classes (#455).
Synthesize Arabic fallback GSUB lookups, including legacy Windows-1256 glyph layouts and no_std builds (#454, #456).
Update read-fonts to 0.43.3.

0.13.2 - 2026-08-23

This release matches HarfBuzz v14.3.1, and has an MSRV (minimum supported Rust version) of 1.85.

Speed up contextual and chained-context lookup matching by probing raw rule offsets and reusing parsed coverage tables (#437).
Skip the redundant per-subtable digest test for single-subtable lookups (#438).
Set up glyph-set acceleration before applying legacy kern tables (#439).
Precompute and pack AAT state-machine safe-to-break probes in the face cache (#445).
Cache reusable shaping table metadata and avoid moving shaper and buffer temporaries on every shape (#446, #447).

0.13.1 - 2026-08-21

This release matches HarfBuzz v14.3.1, and has an MSRV (minimum supported Rust version) of 1.85.

Saturate shaping and positioning math across GPOS, kerx, trak, fallback, shaping, metrics, and font scaling paths to avoid overflow and better match HarfBuzz behavior (#420).
Cache GDEF mark filtering sets in bitmaps (#421).
Lock icu_properties to 2.2.0 (#422).
Optimize hot loops in contextual and layout matching by probing rules before parsing, hoisting invariants, moving recursion state instead of cloning, and replacing per-element copies with block copies (#423, #424, #425).
Optimize buffer internals by copying small counts inline and charging move_to operations against max_ops (#426, #429).
Improve AAT shaping performance by walking morx subtables through packed descriptors, resolving subtable kinds from cached parts, and adding a state-machine fast path (#428, #430, #431).
Skip the post-morx digest update when GPOS is not present (#433).
Add a batched nominal-glyph callback to FontFuncs (#434).
Update read-fonts to 0.43.2 (#432, #435).