awaforge

fontWoff2

AGPL-3.0-onlyRelease 2L4

WOFF2 container — RFC 8311 §4, Brotli + glyf/loca transform.

Module fontWoff2 | Source packages/front/office/fonts/src/sfnt/woff2.js | Deps fontErrors, fontsShared, fontReader, fontTag, brotli | Worker-safe yes

Reads the WOFF2 envelope (wOF2 signature, UIntBase128 directory, Brotli body). The glyf/loca transform is not inverted: decodeWoff2 returns { header, body, tables, inverseGlyfTransform }, where tables is keyed by table tag ({ tag, origLength, transformLength, transformed, bytes }) and inverseGlyfTransform is true only when there is no glyf table or it was not transformed — most real-world WOFF2 fonts carry a transformed glyf, so this flag is typically false for them. Untransformed tables can be reassembled directly.

Exports

Symbol Type Description
WOFF2_MAGIC const 0x774F4632 ('wOF2').
WOFF2_KNOWN_TABLES const List of indexed tags (flags < 0x3F).
parseWoff2Header function (bytes) => { signature, flavor, length, numTables, … }.
decodeWoff2 function (bytes, deps?) => { header, body, tables, inverseGlyfTransform }. deps.brotli overrides the DI-injected brotli module.
parseHeader / decode function One-argument aliases of parseWoff2Header and of decodeWoff2 bound to the DI-injected brotli.
fontWoff2 factory Factory { name, dependencies, factory }.

Usage

import fw from '@awacloud/fw';
import { fw_require, modules } from '@awacloud/fonts';

for (const m of [...fw_require, ...modules]) fw.runtime.register(m);
const { decode } = fw.runtime.resolve('fontWoff2');
const { header, body, tables, inverseGlyfTransform } = decode(woff2Bytes);   // brotli is DI-injected

Notes

  • A full SFNT is not reconstructed from a transformed glyf table: the transform is not reversed.
  • UIntBase128: 1..5 bytes, 7 bits payload + continuation bit.

See also