@fekit/harfbuzz

ESM wrapper for HarfBuzz font shaping engine with bidirectional text support for browsers.

Features

• ✅ Pure ESM - Modern ES Module support
• ✅ Browser-only - Optimized for browser environments
• ✅ Bidirectional Text - Built-in bidi support using bidi-js
• ✅ WebAssembly - Fast font shaping using HarfBuzz WASM
• ✅ TypeScript - Full TypeScript type definitions
• ✅ Zero Configuration - Works out of the box in Vite/Webpack
• ✅ Zero Runtime Requests - WASM inlined at build time

Installation

npm install @fekit/harfbuzz

Usage

Basic Example

import harfbuzz from '@fekit/harfbuzz';

// Initialize HarfBuzz (zero configuration!)
await harfbuzz.init();

// Load a font file
const fontData = await fetch('/path/to/font.ttf').then(r => r.arrayBuffer());

// Create a font instance
const font = harfbuzz.createFont('my-font', fontData);

// Shape text (automatic bidirectional support)
const result = font.shape('Hello مرحبا');

console.log(result.glyphs);  // Array of glyph information
console.log(result.bounds);  // Text bounds

How It Works

The library automatically handles WASM loading with zero configuration:

• In Vite/Webpack: WASM is automatically inlined at build time using import('./hb.wasm?init')
• Zero runtime requests - No need to fetch .wasm files
• Fallback support - Works in all environments with automatic detection

Bidirectional Text

The library automatically handles bidirectional text (Arabic, Hebrew, mixed):

// Arabic text
const arabicResult = font.shape('مرحبا بك');

// Hebrew text
const hebrewResult = font.shape('שלום עולם');

// Mixed LTR/RTL
const mixedResult = font.shape('Hello مرحبا World');

Advanced Usage

// Get glyph information
const glyphName = font.glyphName(42);
const glyphPath = font.glyphPath(42);  // SVG path string
const glyphGeometry = font.glyphGeometry(42);  // Path segments

// Variable fonts
const axisInfos = font.getAxisInfos();
font.setVariations({ 'wght': 700, 'wdth': 100 });

// Set font scale
font.setScale(1000, 1000);

// Get supported Unicode codepoints
const unicodes = font.collectUnicodes();

// Access OpenType tables
const gsubTable = font.referenceTable('GSUB');

// Clean up when done
font.destroy();
harfbuzz.freeFont('my-font');

Managing Multiple Fonts

await harfbuzz.init();

// Create multiple fonts
const font1 = harfbuzz.createFont('font1', data1);
const font2 = harfbuzz.createFont('font2', data2);

// Get font by ID
const myFont = harfbuzz.getFont('font1');

// List all loaded fonts
console.log(harfbuzz.fontIds);  // ['font1', 'font2']

// Free individual font
harfbuzz.freeFont('font1');

Using Bidi Separately

If you need direct access to the bidirectional text algorithm:

import bidiFactory from 'bidi-js';

const bidi = bidiFactory();
const result = bidi.getEmbeddingLevels('مرحبا Hello');
console.log(result.levels);

API Reference

HarfBuzzSingleton (default export)

init(options?): Promise<void>

Initialize HarfBuzz. Must be called before using any other methods.

Options (all optional):

• wasmURL (string): Custom WASM file URL
• locateFile (function): Custom file locator function
• wasmBinary (Uint8Array): Pre-loaded WASM binary

Examples:

// Zero configuration (recommended)
await harfbuzz.init();

// (Optional) With custom WASM URL if needed
import wasmURL from '@fekit/harfbuzz/src/hb.wasm?url';
await harfbuzz.init({ wasmURL });

createFont(id, data, index?): Font

Create a new font instance.

• id: Unique identifier for the font
• data: Font binary data (ArrayBuffer or Uint8Array)
• index: Font index for TTC/OTC files (default: 0)

getFont(id): Font | undefined

Get an existing font by ID.

freeFont(id): void

Free font resources by ID.

fontIds: string[]

Array of all loaded font IDs.

version(): VersionInfo

Get HarfBuzz version information.

versionString(): string

Get HarfBuzz version as string.

Font

shape(text): ShapeResult

Shape text with automatic bidirectional support.

Returns:

{
  glyphs: Array<{ id: number, base: { x: number, y: number } }>,
  bounds: { width: number, height: number }
}

glyphName(id): string

Get glyph name by glyph ID.

glyphPath(id): string

Get glyph outline as SVG path string.

glyphGeometry(id): PathSegment[]

Get glyph outline as path segments.

setScale(xScale, yScale): void

Set font scale factors.

setVariations(variations): void

Set variable font variations.

font.setVariations({ 'wght': 700, 'wdth': 100 });

getAxisInfos(): Record<string, AxisInfo>

Get variation axis information.

collectUnicodes(): Uint32Array

Get all supported Unicode codepoints.

referenceTable(table): Uint8Array | undefined

Get OpenType table data.

destroy(): void

Free font resources.

upem: number

Units per em (read-only).

Browser Compatibility

This library requires:

• ES Modules support
• WebAssembly support
• Modern browsers (Chrome 61+, Firefox 60+, Safari 11+, Edge 79+)

License

MIT

Credits

• HarfBuzz - Text shaping engine
• harfbuzzjs - Original WASM wrapper
• bidi-js - Unicode bidirectional algorithm
• harfbuzz-modern-wrapper - Simplified wrapper