Expand description

Font parser, shaping engine, and subsetter

Allsorts is a font parser, shaping engine, and subsetter for OpenType, WOFF, and WOFF2 written entirely in Rust. It was extracted from Prince, a tool that typesets and lays out HTML and CSS documents into PDF.

The Allsorts shaping engine was developed in conjunction with a specification for OpenType shaping, which aims to specify OpenType font shaping behaviour.


  • Parse TrueType (ttf), OpenType (otf), WOFF, and WOFF2 files.
  • Shape Arabic, Cyrillic, Greek, Hebrew, Indic scripts (Bengali, Devanagari, Gujarati, Gurmukhi, Kannada, Malayalam, Oriya, Sinhala, Tamil, Telugu), Khmer, Lao, Latin, Syriac, Thai, and other scripts.
  • Subset from TrueType, OpenType, WOFF, and WOFF2 files into OpenType.

What is font shaping?

Font shaping is the process of taking text in the form of Unicode codepoints and a font, and laying out glyphs from the font according to the text. This involves honouring kerning, ligatures, and substitutions specified by the font. For some languages this is relatively straightforward. For others, such as Indic scripts it is quite complex. After shaping, another library such as Pathfinder or FreeType is responsible for rendering the glyphs. To learn more about text rendering, Andrea Cognolato has a good overview of modern font rending on Linux. The concepts remain similar on other platforms.


Refer to the Allsorts Tools repository for a set of tools that exercise Allsorts font parsing, shaping, and subsetting.

Unimplemented Features / Known Issues

We don’t currently support:

  • Shaping Mongolian, and Tibetan.
  • Apple’s morx table.
  • Unicode normalisation.

Known limitations:

  • The crate is not extensively documented yet (#5).
  • Allsorts does not do font lookup/matching. For this something like font-kit is recommended.

Development Status

Allsorts is still under active development but reached its first release milestone with its inclusion in Prince 13. In Prince it is responsible for all font loading, and font shaping.

Currently, the font parsing code is handwritten. It is planned for this to eventually be replaced by machine generated code via our declarative data definition language project.

Platform Support

Allsorts CI runs tests on Linux, macOS, and Windows. Via Prince it is also built for FreeBSD.

Building and Testing

Minimum Supported Rust Version: 1.51.0

To build the crate ensure you have Rust 1.51.0 or newer installed.

Build with cargo build and run the tests with cargo test.

Cargo Features

FeatureDescriptionDefault EnabledExtra Dependencies
outlineEnable code for accessing glyph outlinespathfinder_geometry
flate2_zlibUse the zlib backend to flate2zlib
flate2_rustUse the Rust backend to flate2miniz_oxide
princeEnable Prince specific tests and code

Note: In our testing the zlib flate2 backend was faster but you may prefer the Rust backend for a pure Rust solution when compiling to WASM or similar.


Contributions are welcome, please refer to the contributing document for more details.

Code of Conduct

We aim to uphold the Rust community standards:

We are committed to providing a friendly, safe and welcoming environment for all, regardless of gender, sexual orientation, disability, ethnicity, religion, or similar personal characteristic.

We follow the Rust code of conduct.



Allsorts is distributed under the terms of the Apache License (Version 2.0).

See LICENSE for details.


pub use font::Font;
pub use tinyvec;


Big5 encoding.

Reading and writing of binary data.

Bitmap font handling.

CFF font handling.

Checksum calculation routines.

Utilities for performing contextual lookup in gpos and gsub.

Error types

Central font handling support.

Top-level font file representation.

gdef font table utilities.

Utilities for obtaining a name from a fonts name table.

Utilities for accessing glyph information such as advance.

Calculate glyph positions.

Glyph positioning (gpos) implementation.

Glyph substitution (gsub) implementation.

GDEF font table parsing and glyph lookup and layout properties.

Utilities for handling the Mac OS Roman character set.

Access glyphs outlines. Requires the outline cargo feature (enabled by default).

post table parsing and writing.

Definitions of the sizes of binary types.

Font subsetting.

OpenType font table parsing and writing.

Utilities and constants for OpenType tags.

Unicode utilities and character properties.

Reading of the WOFF font format.

Reading of the WOFF2 font format.


Generate a 4-byte OpenType tag from byte string