renderText: shape text in every script, bidirectional text, UAX #14 wrapping

A port of HarfBuzz 14.6's OpenType shaping (Old MIT, credited in the
file headers and THIRD_PARTY_NOTICES.md):
- buffer.ts: the in/out buffer with HarfBuzz's cluster merging
- layout.ts: GDEF, script/language/feature selection with feature
  variations at the default instance, the feature map with stages and
  masks, every GSUB (1-8) and GPOS (1-9) lookup type with HarfBuzz's
  matching (ZWJ/ZWNJ, per-syllable, ligature components, mark
  attachment to ligature components, cursive chains)
- shape.ts: unicode properties, dotted circles, native direction,
  mirroring, normalization (decompose/reorder/recompose by what the
  font has), fractions, space fallback, kern table, fallback mark
  positioning, default ignorables
- shapers: Arabic (with presentation-form fallback and stch), Hebrew,
  Thai/Lao, Hangul, Indic, Khmer, Myanmar and the Universal Shaping
  Engine, their syllable grammars as longest-match NFA scanners
- scripts/unicode.js also generates the Indic/USE categories (after
  HarfBuzz's generators, with Microsoft's USE data in scripts/ms-use),
  canonical decompositions, Arabic presentation forms, vowel
  constraints; property values are translated to short names

Identical to HarfBuzz (glyphs, clusters, positions) on the UDHR in 29
scripts, ~300,000 random sequences over 30 Noto fonts, 15,000 emoji
sequences in the color test fonts and 12,000 with the Latin test fonts.

renderText now analyzes each paragraph (UAX #9 levels, UAX #29
graphemes for font fallback, script itemization with paired brackets,
UAX #14 break opportunities), shapes runs of one level, script and font
with surrounding context, wraps at break opportunities (graphemes for
char wrapping and overlong words), and shapes and reorders every line
by itself (L1/L2). Hinted glyphs keep their hinted advances with the
positioning's adjustments rounded cumulatively. The old GSUB and GPOS
kerning code is removed.

Tests: tests/shaping.js compares 360 texts with HarfBuzz's output for
subsets of Noto fonts (scripts/shaping-reference.py), tests/unicode.js
adds GraphemeBreakTest, tests/font.js a bidirectional render test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YJgRK5qpwJEbHPuFv6kgAQ

Author: matmen

CHANGELOG.md

@@ -22,17 +22,33 @@
   palettes (e.g. Twemoji), CBDT/CBLC bitmaps (e.g. Noto Color Emoji, which now loads at all, it has no outlines) and
   sbix bitmaps (Apple's format).
   Invisible characters like joiners and variation selectors take no room, as in browsers.
-- `Image.renderText` applies the fonts' glyph substitutions (GSUB) that browsers apply by default (`ccmp`, `rlig`,
-  `liga`, `clig`, `calt`): emoji sequences (skin tones, flags, keycaps, families and other joined ones) become one
-  glyph, and text fonts use their ligatures (fi, ffi, ...) and contextual alternates. Emoji sequences come from one
-  font, the first that has all of their characters, and the emoji variation selector picks a color glyph (❤️ in an
-  emoji font rather than the text font's ❤).
+- `Image.renderText` shapes text in every script like browsers do (a port of HarfBuzz's OpenType shaping, glyph for
+  glyph and position for position the same as HarfBuzz 14.6 on the tested texts):
+  - right to left and bidirectional text (the Unicode Bidirectional Algorithm): Arabic, Hebrew and others, mixed with
+    left to right text and numbers, brackets mirrored
+  - joining scripts (Arabic, Syriac, N'Ko, Mongolian, Adlam, ...), with presentation forms for fonts without shaping
+    features
+  - Indic scripts (Devanagari, Bengali, Gurmukhi, Gujarati, Oriya, Tamil, Telugu, Kannada, Malayalam) with their
+    conjuncts, reph and matra reordering, Khmer, Myanmar, Thai and Lao, Hangul syllables, and the scripts of the
+    Universal Shaping Engine (Sinhala, Tibetan, Javanese, Balinese and many more)
+  - all GSUB and GPOS lookups: mark positioning (diacritics, vowel signs), cursive attachment, kerning, contextual
+    substitutions and positioning; the kern table for fonts without GPOS kerning, and marks placed by their combining
+    class for fonts without mark positioning
+  - emoji sequences (skin tones, flags, keycaps, families and other joined ones) become one glyph, from the first font
+    that has all of their characters; the emoji variation selector picks a color glyph (❤️ in an emoji font rather than
+    the text font's ❤)
+  - text wraps at the line break opportunities of the Unicode Line Breaking Algorithm (also in CJK text and before
+    or after punctuation, not only at spaces), words wider than a line between grapheme clusters; each line is
+    shaped and ordered by itself
+  The Unicode data (properties of version 18.0) with the bidirectional algorithm and line breaking add about 39 kB
+  (gzipped) to the package, the shaping about 39 kB.
 - `Image.renderText` renders COLR version 1 color glyphs (e.g. Noto-COLRv1): solid colors, linear, radial and sweep
   gradients (pad, repeat, reflect), glyph outlines as masks, transforms and all composite modes; variable paints with
   their default values. They are rendered at four times the size and scaled down, so layers sharing an edge don't let the
   ones below show through. Fonts with both prefer them over their other color glyphs, like browsers.
 - `Image.renderText` composes combining sequences (e + ◌́ to é, as in text from macOS) where the font has the composed
-  character, and decomposes characters the fonts lack where one has their parts, like HarfBuzz.
+  character, and decomposes characters the fonts lack where one has their parts, like HarfBuzz. Fallback fonts are
+  chosen per grapheme cluster (UAX #29).
 - Fallback fonts are only loaded when the text needs them, and glyphs (also decoded and scaled emoji bitmaps) are
   kept per font and size across calls.
 - `DecodeOptions.maxPixels` and `AnimationDecodeOptions.maxPixels` (default 268,402,689, that's 16383², like sharp):

README.md

@@ -34,8 +34,9 @@ deno add jsr:@matmen/imagescript     # Deno (npm:imagescript works too)
   frames, durations and disposal modes
 - [Rendering SVGs](https://imagescript.matmen.dev/classes/Image.html#rendersvg) (shapes, paths, gradients, strokes, clip paths,
   masks, CSS; no text, images or filters)
-- [Rendering vector fonts](https://imagescript.matmen.dev/classes/Image.html#rendertext) (TrueType and OpenType, with kerning,
-  ligatures, outlines, TrueType hinting, fallback fonts and color emoji)
+- [Rendering vector fonts](https://imagescript.matmen.dev/classes/Image.html#rendertext) (TrueType and OpenType, with
+  complex text shaping in every script, right to left and bidirectional text, outlines, TrueType hinting, fallback
+  fonts and color emoji)
 - [Resizing](https://imagescript.matmen.dev/classes/Image.html#resize) (bilinear, bicubic, area averaging and nearest neighbor)
 - Image manipulation functions ([crop](https://imagescript.matmen.dev/classes/Image.html#crop)
   , [rotate](https://imagescript.matmen.dev/classes/Image.html#rotate)
@@ -103,7 +104,9 @@ The JPEG codec is based in part on the work of the Independent JPEG Group (libjp
 [pdf.js](https://github.com/mozilla/pdf.js), the glyph rasterizer is translated from
 [font-rs](https://github.com/raphlinus/font-rs). The WebP codecs follow [RFC 9649](https://www.rfc-editor.org/rfc/rfc9649) and [RFC 6386](https://www.rfc-editor.org/rfc/rfc6386)
 and reproduce [libwebp](https://chromium.googlesource.com/webm/libwebp)'s color conversion, the TrueType hinting follows
-[FreeType](https://freetype.org)'s interpreter (portions of this software are copyright © 2026 The FreeType Project).
+[FreeType](https://freetype.org)'s interpreter (portions of this software are copyright © 2026 The FreeType Project),
+the text shaping is ported from [HarfBuzz](https://github.com/harfbuzz/harfbuzz) and uses data of the
+[Unicode Character Database](https://www.unicode.org/ucd/).
 See [THIRD_PARTY_NOTICES.md](THIRD_PARTY_NOTICES.md) for their licenses.
 
 ---

THIRD_PARTY_NOTICES.md

@@ -15,6 +15,8 @@ following projects, under their own licenses. Each derived file says so in its h
 | [libwebp](https://chromium.googlesource.com/webm/libwebp) | `src/codecs/vp8.ts` (YUV to RGB conversion, "fancy" chroma upsampling), `src/codecs/webp.ts` (animation frame blending) | BSD-3-Clause |
 | [FreeType](https://freetype.org) | `src/render/hinting.ts` (behavior and parts of the logic of the TrueType interpreter) | FreeType License |
 | [Pillow](https://github.com/python-pillow/Pillow) | `src/util/resample.ts` (filter coefficients, box, bilinear and bicubic filters) | MIT-CMU |
+| [HarfBuzz](https://github.com/harfbuzz/harfbuzz) | `src/render/buffer.ts`, `src/render/layout.ts`, `src/render/shape.ts`, `src/render/shapers/*` (OpenType shaping: buffer, GSUB/GPOS, normalization, fallback positioning, the script shapers and syllable grammars), `scripts/unicode.js` (shaping category tables) | Old MIT |
+| [Universal Shaping Engine data](https://github.com/harfbuzz/harfbuzz/tree/main/src/ms-use) by Microsoft | `scripts/ms-use` (category overrides, invalid vowel sequences), the tables generated from them in `src/render/unicode-data.ts` | MIT |
 | [Unicode Character Database](https://www.unicode.org/ucd/) | `src/render/unicode-data.ts` (character properties, generated by `scripts/unicode.js`) | Unicode License v3 |
 
 ## fflate, Fast CRC32 in JavaScript
@@ -206,3 +208,80 @@ Copyright © 1991-2026 Unicode, Inc.
 under the Unicode License v3, included as [licenses/Unicode-3.0.txt](licenses/Unicode-3.0.txt). The bidirectional
 algorithm (`src/render/bidi.ts`) and the line breaking (`src/render/linebreak.ts`) are written after UAX #9 and
 UAX #14.
+
+## HarfBuzz
+
+The shaping engine is ported from HarfBuzz 14.6.0; its license is included as
+[licenses/HarfBuzz.txt](licenses/HarfBuzz.txt). The copyright holders of the ported files are listed in the headers
+of the files derived from them.
+
+```
+HarfBuzz is licensed under the so-called "Old MIT" license.  Details follow.
+For parts of HarfBuzz that are licensed under different licenses see individual
+files names COPYING in subdirectories where applicable.
+
+Copyright © 2010-2022  Google, Inc.
+Copyright © 2015-2020  Ebrahim Byagowi
+Copyright © 2019,2020  Facebook, Inc.
+Copyright © 2012,2015  Mozilla Foundation
+Copyright © 2011  Codethink Limited
+Copyright © 2008,2010  Nokia Corporation and/or its subsidiary(-ies)
+Copyright © 2009  Keith Stribley
+Copyright © 2011  Martin Hosken and SIL International
+Copyright © 2007  Chris Wilson
+Copyright © 2005,2006,2020,2021,2022,2023  Behdad Esfahbod
+Copyright © 2004,2007,2008,2009,2010,2013,2021,2022,2023  Red Hat, Inc.
+Copyright © 1998-2005  David Turner and Werner Lemberg
+Copyright © 2016  Igalia S.L.
+Copyright © 2022  Matthias Clasen
+Copyright © 2018,2021  Khaled Hosny
+Copyright © 2018,2019,2020  Adobe, Inc
+Copyright © 2013-2015  Alexei Podtelezhnikov
+
+For full copyright notices consult the individual files in the package.
+
+
+Permission is hereby granted, without written agreement and without
+license or royalty fees, to use, copy, modify, and distribute this
+software and its documentation for any purpose, provided that the
+above copyright notice and the following two paragraphs appear in
+all copies of this software.
+
+IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
+
+THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+```
+
+## Universal Shaping Engine data
+
+```
+MIT License
+
+Copyright (c) Microsoft Corporation.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE
+```

licenses/HarfBuzz.txt

@@ -0,0 +1,42 @@
+HarfBuzz is licensed under the so-called "Old MIT" license.  Details follow.
+For parts of HarfBuzz that are licensed under different licenses see individual
+files names COPYING in subdirectories where applicable.
+
+Copyright © 2010-2022  Google, Inc.
+Copyright © 2015-2020  Ebrahim Byagowi
+Copyright © 2019,2020  Facebook, Inc.
+Copyright © 2012,2015  Mozilla Foundation
+Copyright © 2011  Codethink Limited
+Copyright © 2008,2010  Nokia Corporation and/or its subsidiary(-ies)
+Copyright © 2009  Keith Stribley
+Copyright © 2011  Martin Hosken and SIL International
+Copyright © 2007  Chris Wilson
+Copyright © 2005,2006,2020,2021,2022,2023  Behdad Esfahbod
+Copyright © 2004,2007,2008,2009,2010,2013,2021,2022,2023  Red Hat, Inc.
+Copyright © 1998-2005  David Turner and Werner Lemberg
+Copyright © 2016  Igalia S.L.
+Copyright © 2022  Matthias Clasen
+Copyright © 2018,2021  Khaled Hosny
+Copyright © 2018,2019,2020  Adobe, Inc
+Copyright © 2013-2015  Alexei Podtelezhnikov
+
+For full copyright notices consult the individual files in the package.
+
+
+Permission is hereby granted, without written agreement and without
+license or royalty fees, to use, copy, modify, and distribute this
+software and its documentation for any purpose, provided that the
+above copyright notice and the following two paragraphs appear in
+all copies of this software.
+
+IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.
+
+THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

scripts/ms-use/COPYING

@@ -0,0 +1,21 @@
+    MIT License
+
+    Copyright (c) Microsoft Corporation.
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in all
+    copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+    SOFTWARE