awaforge

extraWoff2Write

AGPL-3.0-onlyRelease 2L4

WOFF2 encoder — packs an SFNT into a Brotli envelope (no glyf/loca transform).

Module extraWoff2Write | Source packages/front/office/fonts/src/extra/woff2-write.js | Deps fontErrors, fontWriter, fontSfnt, brotli | Worker-safe yes

Symmetric counterpart to the fontWoff2 reader: emits the WOFF2 header, the UIntBase128 directory, and the Brotli-compressed concatenation of the untransformed tables. The glyf/loca transform stays out of scope.

Exports

Symbol Type Description
WOFF2_MAGIC const 0x774F4632.
encodeWoff2 function (sfntBytes, brotli: { brotliCompressSync }) => Uint8Array (WOFF2 bytes).
encode function (sfntBytes) => Uint8Array — convenience overload bound to the DI-injected brotli module; equivalent to encodeWoff2(sfntBytes, brotliMod). Not documented on the previous revision of this page (woff2-write.js line 123).
extraWoff2Write factory Factory.

Usage

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

for (const m of [...fw_require, ...modules, ...extras]) fw.runtime.register(m);
const { encode } = fw.runtime.resolve('extraWoff2Write');
const woff2 = encode(sfntBytes);   // brotli is DI-injected

Transform versions

Each table-directory entry starts with a flags byte: bits 0-5 hold the known-tag index and bits 6-7 the preprocessing transformation version (W3C WOFF2 § 4.1). The encoder always uses index 63 (the explicit 4-byte tag follows, slightly larger than the known-tag form) and writes every table body untransformed, so it marks each entry with its null transform: version 3 for glyf and loca (flags 0xFF), where version 0 would mean the WOFF2 glyf/loca transform, and version 0 for every other table (flags 0x3F). Because no table is transformed, no entry carries a transformLength. A full TrueType font (glyf + loca) therefore round-trips through decodeWoff2 with every table byte-identical to the source SFNT (inverseGlyfTransform: true); the output is larger than a transformed WOFF2, since the glyf/loca transform itself is not implemented.

Notes

  • The factory's DI dependency list also includes brotli (@awacloud/fw/io/compress/brotli.js) beyond fontErrors/fontWriter/fontSfnt — it powers the encode convenience overload. A hand-built brotli passed to encodeWoff2 needs its full dependency set (lz77 included) to compress a real font.
  • Not included in fonts-large; requires the fonts-full bundle.

See also