wasm

img2bez (WebAssembly)

Trace bitmap glyph images into font-ready bezier outlines, entirely in the browser. WebAssembly bindings for img2bez.

Give it the bytes of a PNG/JPEG/BMP glyph image; get back the outline as a structured JSON object, an SVG path, or UFO GLIF XML.

Usage

import init, { traceToJson, traceToSvg, traceToGlif } from "img2bez-wasm";

await init(); // load the .wasm

const bytes = new Uint8Array(await file.arrayBuffer());
const config = JSON.stringify({ glyph: "a", unicode: "0061" });

// Structured outline — the easiest to consume in an editor:
const glyph = JSON.parse(traceToJson(bytes, config));
// {
//   name: "a",
//   unicodes: ["0061"],
//   advance: { width: 640 },
//   unitsPerEm: 1024,
//   outline: {
//     contours: [
//       { points: [ { x, y, type: "curve"|"line"|"qcurve", smooth? }, … ] },
//       …
//     ]
//   }
// }

// Or an SVG path string (y-up; flip for a y-down viewport):
const d = traceToSvg(bytes, "{}");

// Or UFO GLIF XML:
const glif = traceToGlif(bytes, config);

Coordinates

Outlines are y-up (font convention), placed into a font using the metrics in config (targetHeight / yOffset). contours is the canonical img2bez point model: off-curve control points precede the on-curve point they lead into, off-curve points omit type, and the first point of each contour carries the closing segment's type — i.e. the UFO .glif point order, so it maps losslessly to UFO/GLIF.

Config

All fields optional; defaults mirror the img2bez CLI's wild profile.

Field	Default	Meaning
glyph	"a"	Glyph name
unicode	—	Hex codepoint, e.g. "0061"
profile	"wild"	"wild" (unknown raster) or "clean" (font render)
accuracy	profile	Curve-fit accuracy in font units (smaller = more points)
grid	2	Coordinate snap grid (0 = off)
chamfer	0	Automatic line-corner chamfer size in font units
chamferMinEdge	40	Minimum edge length eligible for chamfering
refine	true	Enable raster-loss refinement
targetHeight	1088	Em the tracer normalizes to (ascender − descender)
yOffset	-256	Descender (baseline placement)
width	auto	Advance width (auto from bounds + sidebearings)
invert	false	Swap foreground/background
threshold	Otsu	Fixed brightness threshold 0–255

Build & publish

wasm-pack build wasm --target web --release   # → wasm/pkg
npm publish wasm/pkg                           # or: npm publish --access public wasm/pkg

TypeScript types (.d.ts) are generated automatically by wasm-bindgen.

License

Apache-2.0 OR MIT