Module discovery 

typg-core: the engine behind fast font search.

Point it at a folder of fonts. Tell it what you need — Arabic script support, a weight axis, ligatures, a specific glyph. It reads every font file in parallel, extracts the OpenType metadata that matters, and hands back the matches. Thousands of fonts in under a second on a modern machine.

How a search works, end to end

1. Discovery (discovery) walks your directories, collecting every .ttf, .otf, .ttc, and .otc file it finds. Broken symlinks and permission errors get a warning, not a crash.

2. Search (search) opens each file with the read-fonts and skrifa crates (Google’s Rust font-parsing libraries), pulls out metadata — names, axes, features, scripts, tables, codepoints, weight/width classification — and checks it against your query. This step runs on all available CPU cores via rayon.

3. Query (query) is the filter specification. Every criterion is optional; an empty query matches everything. Criteria combine with AND logic: a font must satisfy all of them to appear in results.

4. Output (output) serializes results to JSON or NDJSON for downstream tools and pipelines.

5. Tags (tags) handles parsing and formatting of OpenType tags — the four-character codes (wght, liga, latn, GSUB) that identify axes, features, scripts, and tables inside a font.

6. Index ([index], behind the hpindex feature flag) stores extracted metadata in an LMDB database with Roaring Bitmap inverted indices. Queries that would take seconds over thousands of files on disk take milliseconds against the index.

Quick example

Find all variable fonts with Arabic script support and a weight axis:

use std::path::PathBuf;
use typg_core::query::Query;
use typg_core::search::{search, SearchOptions};
use typg_core::tags::tag4;

let query = Query::new()
    .with_scripts(vec![tag4("arab").unwrap()])
    .with_axes(vec![tag4("wght").unwrap()])
    .require_variable(true);

let dirs = vec![PathBuf::from("/Library/Fonts")];
let results = search(&dirs, &query, &SearchOptions::default())?;

for font in &results {
    println!("{}", font.source.path_with_index());
}

Font vocabulary cheat sheet

Term	What it means
OpenType	The modern font format standard. A .ttf or .otf file is an OpenType font.
Variable font	A single font file that contains a continuous range of weights, widths, or other design variations. Controlled by axes.
Axis	A dimension of variation in a variable font. wght = weight (thin→black), wdth = width (condensed→expanded), opsz = optical size.
Feature	An OpenType layout feature like liga (ligatures), smcp (small caps), or kern (kerning). Controls how glyphs are substituted or positioned.
Script	A writing system tag like latn (Latin), arab (Arabic), cyrl (Cyrillic). Tells the shaping engine which rules to apply.
Table	A named data block inside the font file. GSUB holds glyph substitution rules, GPOS holds positioning rules, OS/2 holds classification metadata.
TTC/OTC	TrueType/OpenType Collection — a single file bundling multiple font faces. Each face has a numeric index.
cmap	The character map table. Maps Unicode codepoints to glyph IDs — it’s how the font says “I can draw this character.”
OS/2	A metadata table carrying weight class, width class, font family classification, and other attributes originally designed for IBM’s OS/2 operating system (the name stuck).

Made by FontLab https://www.fontlab.com/

Structs

PathDiscovery

Discovers fonts by walking filesystem paths.

TypgFontSourceRef

A font file found on disk during discovery.

Traits

FontDiscovery

Trait for font discovery backends.