In short

One page of a fight in a Japanese comic, with tilted gaps between the panels so the action seems to lean, and the big Japanese sound of the hit left in place with a small translation beside it.

What you'll build

The page where the kendo final is decided, from the same manga as the right-to-left recipe, in two editions side by side: the Japanese original and its lettering in this page's language (English on the Japanese page). Four tiers: the gym, Hana's eyes through her helmet grille, the exchange, and the reactions. The third tier is cut by a gutter that leans, so the opponent's thrust and Hana's counter seem to rush at each other; the fourth leans the other way and slows the page down. Hana's strike has no frame at all, and its sound effect, ドン, is set in a heavy Japanese gothic that every edition keeps, with a small translation under it in the translated pages.

This recipe answers

How do I slant the gutters between panels?
How do I letter sound effects over the art?

The short answer

script.js · lines 44–62in full code

// The page is split in content.<lang>.md: `* [40~55 | *]` runs the gutter of the third
// tier from 40 % at the top to 55 % at the bottom, so both panels lean into the strike,
// and `24 [58~64 | *]` tilts the last tier the other way. The panel that lands the blow
// is drawn with `border=none`: no frame, so its speed lines run straight to the gutter.
// ドン keeps its Japanese face in every edition (`font=` on the line);
// the translations add a small subtitle under it, the way licensed manga gloss a drawn
// sound effect instead of redrawing it.
const comics = (lang) => ({
  artDirection: 'rtl', // drawn for right-to-left reading: slants and order mirror with it
  mirrorArt: false,
  gutter: { horizontal: mm(4), vertical: mm(2.5) }, // a slanted gutter keeps its width
  panel: { borderWidth: pt(1.1), borderColor: col('ink'), background: col('paper') },
  lettering: {
    fontFamily: EDITIONS[lang].faces[0], color: col('ink'),
    fontSize: pt(['ja', 'zh'].includes(lang) ? 8.5 : 7.5),
    writingMode: lang === 'zh' ? 'vertical' : 'auto',
  },
  balloonStyles: balloons(),
});

The slant is in the split; the impact is in the panel and the effect

Ingredients

Features: Panel splits Sound effects Reading direction and manga order Chinese, Japanese and Korean fonts Panel art and crops Panel borders and gutters Re-lettering in other languages Speakers and anchors Comic pages Comic lettering Balloon styles Vertical text Books bound on the right Semantic colour palette Pages on a canvas PDF export
Also uses: Chinese line breaking Paper colour Fonts embedded in the PDF Figures and tables as resources Superscripts and subscripts
Type: Zen Antique, Dela Gothic One, Comic Neue, Bangers, Noto Sans SC, ZCOOL KuaiLe, Playpen Sans Arabic, Lalezar (SIL OFL 1.1)
Assets: match-coach.jpg
match-eyes.jpg
match-final.jpg
match-lunge.jpg
match-stands.jpg
match-strike.jpg
The kendo final in a packed gym, two fighters between three referees (Generated With Diffusion Models, original)
Hana's eyes through her helmet grille (Generated With Diffusion Models, original)
The opponent lunging with speed lines (Generated With Diffusion Models, original)
Hana's leaping strike to the helmet (Generated With Diffusion Models, original)
Sora cheering in the stands (Generated With Diffusion Models, original)
Coach Mori nodding while the referees raise their flags (Generated With Diffusion Models, original)
API: buildDocumentclearMeasurementCachedecompressWoff2registerResourceImagerenderPageToCanvasrenderToPdf

Method

#1 · Slant the gutter in the split

The code is the short answer above. A size written 40~55 gives a cell's far edge two positions: 40 % of the tier at the top, 55 % at the bottom. The cells stay convex polygons, the gutter keeps its width measured across the slant, and with right-to-left reading the slant mirrors with the order, so the first cell is still the right-hand one. The page's split is 24 / 18 / * [40~55 | *] / 24 [58~64 | *]: two straight tiers to set up the moment, a slanted one for the hit, and a last one tilted the other way (page split).

#2 · Shout in bursts and let the effects break out

script.js · lines 66–74in full code

const balloons = () => [
  { id: 'speech', fill: col('paper'), stroke: col('ink'), strokeWidth: pt(0.6), roundness: 2 },
  { id: 'shout', fill: col('paper'), stroke: col('ink'), burstPoints: 18, burstDepth: 0.3 },
  { id: 'thought', fill: col('paper'), stroke: col('ink') },
  { id: 'inner', fill: col('tone'), stroke: col('tone'), strokeWidth: pt(0), italic: false },
  { id: 'caption', fill: col('paper'), stroke: col('ink'), strokeWidth: pt(0.5) },
  // white-edged on the art
  { id: 'sfx', color: col('ink'), haloColor: col('paper'), halo: pt(2.2) },
];

The kiai of both fighters are shouts: an 18-spike burst with deeper spikes than the default. The sound effects have no balloon at all; they are lettered on the art with a white edge, 2.2 pt, so they read over the speed lines. The strike's panel is written ::panel{art=strike border=none}, and its ドン carries break, so it may cross the slanted gutter into the panel beside it, the way a letterer lets a sound spill over the frame (sound effects).

#3 · Keep ドン in Japanese and subtitle it

script.js · lines 273–292in full code

const SFX = /^sfx(\{[^}\n]*\})?[ \t]*[:：](.*)$/gm; // sound effects: the second face sets them
async function loadEdition(lang) {
  const text = TEXT[lang];
  const [face, sfx] = EDITIONS[lang].faces;
  const faces = { [face]: FONTS[face], [sfx]: FONTS[sfx] };
  const effects = [...text.matchAll(SFX)];
  for (const [, attrs = '', words] of effects) { // ドン keeps its face in every language
    const family = /font="([^"]+)"/.exec(attrs)?.[1];
    if (!family) continue;
    faces[family] = FONTS[family];
    await loadCjkFonts({ [family]: FONTS[family] }, words, { vertical: true });
  }
  if (['ja', 'zh'].includes(lang)) { // CJK: only the files that hold these characters
    const own = effects.filter(([, attrs = '']) => !attrs.includes('font=')).map((m) => m[2]);
    await loadCjkFonts({ [face]: FONTS[face] }, text.replace(SFX, ''), { vertical: true });
    await loadCjkFonts({ [sfx]: FONTS[sfx] }, own.join(''), { vertical: true });
  }
  if (lang === 'ar') await loadArabicFonts(faces, text);
  await loadComicFonts(faces, text); // the bold and italic the faces do not ship
}

In manga the sound effects are part of the drawing, and licensed editions usually leave them in place and add a small translation beside them. The script does the same: every edition has the line sfx{… font="Dela Gothic One" break}: ドン; the editions lettered in rows add vertical to it, so ドン keeps the column it has in the original, and set a second, smaller effect under it, WHAM or ¡ZAS!. Because the face is named on the line, each edition loads Dela Gothic One with just the characters of ドン, whatever its own lettering face is.

#4 · Fit the safe areas to slanted cells

script.js · lines 185–269in full code

const ART = { // fractions of the picture: the same in every language
  final: {
    alt: t({ en: 'The kendo final in a packed gym: two fighters cross swords among three referees.',
      es: 'La final en un pabellón lleno: dos rivales cruzan las espadas entre tres árbitros.',
      ca: 'La final en un pavelló ple: dos rivals creuen les espases entre tres àrbitres.',
      pt: 'A final num ginásio lotado: dois lutadores cruzam as espadas entre três árbitros.',
      zh: '座无虚席的体育馆里的决赛：两名选手在三名裁判之间交剑。',
      ar: 'النهائي في صالة ممتلئة: متباريان يتقاطع سيفاهما بين ثلاثة حكّام.',
      ja: '満員の体育館での決勝。3人の審判の間で2人が剣先を交える。' }),
  safeArea: { x: 0.22, y: 0.44, width: 0.56, height: 0.46 },
  anchors: [{ id: 'hana', x: 0.31, y: 0.51, head: { x: 0.31, y: 0.49 },
    face: { x: 0.28, y: 0.45, width: 0.07, height: 0.1 } },
  { id: 'rival', x: 0.68, y: 0.51, head: { x: 0.68, y: 0.49 },
    face: { x: 0.65, y: 0.46, width: 0.06, height: 0.09 } },
  { id: 'shinpan', x: 0.575, y: 0.585, head: { x: 0.575, y: 0.56 },
    face: { x: 0.56, y: 0.54, width: 0.03, height: 0.06 } }] },
  eyes: {
    alt: t({ en: "Hana's eyes through the bars of her helmet grille.",
      es: 'Los ojos de Hana tras las barras de la rejilla del casco.',
      ca: 'Els ulls de la Hana darrere les barres de la reixa del casc.',
      pt: 'Os olhos de Hana atrás das barras da grade do capacete.',
      zh: '面罩铁栏后花的眼睛。',
      ar: 'عينا هانا خلف قضبان شبكة الخوذة.',
      ja: '面金の向こうの花の目。' }),
  safeArea: { x: 0.22, y: 0.26, width: 0.57, height: 0.38 },
  anchors: [{ id: 'hana', x: 0.5, y: 0.62, head: { x: 0.5, y: 0.4 },
    face: { x: 0.2, y: 0.3, width: 0.6, height: 0.3 } }] },
  lunge: {
    alt: t({ en: 'The opponent lunges at the viewer, speed lines all round.',
      es: 'El rival se lanza hacia el lector entre líneas cinéticas.',
      ca: 'El rival es llança cap al lector entre línies cinètiques.',
      pt: 'O adversário avança contra o leitor entre linhas de velocidade.',
      zh: '对手在速度线中朝读者猛刺过来。',
      ar: 'الخصم يندفع نحو القارئ وسط خطوط السرعة.',
      ja: '集中線の中、こちらへ突いてくる相手。' }),
  safeArea: { x: 0.03, y: 0.01, width: 0.8, height: 0.61 },
  avoid: [{ x: 0.02, y: 0.42, width: 0.23, height: 0.18 }],
  anchors: [{ id: 'rival', x: 0.7, y: 0.2, head: { x: 0.7, y: 0.14 },
    face: { x: 0.63, y: 0.02, width: 0.15, height: 0.24 } }] },
  strike: {
    alt: t({ en: "Hana leaps and strikes the top of the opponent's helmet; the sword bends.",
      es: 'Hana salta y golpea la parte alta del casco del rival; la espada se dobla.',
      ca: 'La Hana salta i colpeja la part alta del casc del rival; l’espasa es doblega.',
      pt: 'Hana salta e acerta o alto do capacete do adversário; a espada se curva.',
      zh: '花跃起击中对手面罩顶部，竹剑弯了起来。',
      ar: 'هانا تقفز وتضرب أعلى خوذة الخصم؛ ينثني السيف.',
      ja: '跳び込んで相手の面を打つ花。竹刀がしなる。' }),
  safeArea: { x: 0.36, y: 0.06, width: 0.42, height: 0.77 },
  avoid: [{ x: 0.52, y: 0.48, width: 0.13, height: 0.16 }],
  anchors: [{ id: 'hana', x: 0.43, y: 0.25, head: { x: 0.43, y: 0.18 },
    face: { x: 0.38, y: 0.07, width: 0.1, height: 0.25 } }, { id: 'sfx', x: 0.75, y: 0.25 }] },
  stands: {
    alt: t({ en: 'Sora jumps up in the stands, fists raised, shouting.',
      es: 'Sora salta en la grada con los puños en alto, gritando.',
      ca: 'En Sora salta a la graderia amb els punys enlaire, cridant.',
      pt: 'Sora pula na arquibancada de punhos erguidos, gritando.',
      zh: '空在看台上跳起来，举着拳头大喊。',
      ar: 'سورا يقفز في المدرّجات رافعًا قبضتيه وهو يصيح.',
      ja: '観客席で拳を突き上げて叫ぶ空。' }),
  safeArea: { x: 0.08, y: 0.07, width: 0.69, height: 0.44 },
  avoid: [{ x: 0.08, y: 0.06, width: 0.12, height: 0.1 },
    { x: 0.64, y: 0.35, width: 0.1, height: 0.12 }],
  anchors: [{ id: 'sora', x: 0.51, y: 0.44, head: { x: 0.5, y: 0.37 },
    face: { x: 0.4, y: 0.3, width: 0.22, height: 0.2 } }] },
  coach: {
    alt: t({ en: 'Mori, arms crossed and eyes closed; behind him the referees raise their flags.',
      es: 'Mori, de brazos cruzados y ojos cerrados; detrás, los árbitros alzan las banderas.',
      ca: 'En Mori, de braços plegats i ulls tancats; darrere, els àrbitres alcen les banderes.',
      pt: 'Mori, de braços cruzados e olhos fechados; atrás, os árbitros erguem as bandeiras.',
      zh: '森老师抱着双臂、闭着眼；身后的裁判举起了旗子。',
      ar: 'موري عاقد الذراعين مغمض العينين، وخلفه يرفع الحكّام راياتهم.',
      ja: '腕を組み目を閉じる森先生。後ろで審判が旗を上げる。' }),
  safeArea: { x: 0.16, y: 0.1, width: 0.76, height: 0.53 },
  avoid: [{ x: 0.55, y: 0.18, width: 0.4, height: 0.17 }],
  anchors: [{ id: 'mori', x: 0.29, y: 0.31, head: { x: 0.29, y: 0.2 },
    face: { x: 0.22, y: 0.1, width: 0.14, height: 0.24 } }] },
};
const panels = () => Promise.all([
  comicPanel('final', asset('match-final.jpg'), ART.final),
  comicPanel('eyes', asset('match-eyes.jpg'), ART.eyes),
  comicPanel('lunge', asset('match-lunge.jpg'), ART.lunge),
  comicPanel('strike', asset('match-strike.jpg'), ART.strike),
  comicPanel('coach', asset('match-coach.jpg'), ART.coach),
  comicPanel('stands', asset('match-stands.jpg'), ART.stands),
]);

A slanted cell is wider at one end than at the other, and the picture has to cover it whole. Each safe area is cut to what the panel needs, the eyes for the grille close-up and Sora's upper body for the cheer, so it fits inside the cell's widest crop and the engine never has to letterbox the picture.

#5 · Set the original beside each edition

script.js · lines 297–306in full code

const FACING = LANG === 'ja' ? 'en' : LANG; // Japanese readers see the English edition
const TEXT = { ja: original, [FACING]: LANG === 'ja' ? english : markdown };
await loadFonts(FONTS, Object.values(TEXT).join('\n'));
const resources = await panels();
const build = async (lang) => { // the same pictures and page; this language's lettering
  await loadEdition(lang);
  return buildWithFonts(() => buildDocument({ markdown: TEXT[lang], resources,
    continuation: { pageIndexOffset: lang === 'ja' ? 1 : 2 } }, edition(lang)), TEXT[lang]);
};
const docs = [await build('ja'), await build(FACING)];

Each language of the site letters the page in its own file, and the Japanese original faces it on the other side of the spread (the Japanese page faces the English edition). ドン stays in every edition, each one brings its own subtitle (WHAM, ZAS!, 咚, بوم!), and the slants never move.

The whole recipe

Sandbox

// ═══ Postext Cookbook · Nº 150 · An action page with slanted gutters ═════════════════
// https://postext.dev/en/cookbook/manga-action-slants
// Code: MIT · Story: written for the recipe (CC BY 4.0) · Pictures: generated with diffusion models
// Fonts: Zen Antique, Comic Neue and six more (SIL OFL 1.1) · Needs postext ≥ 1.21.0
// The last page of a kendo final: slanted panels, a borderless strike, ドン kept in every edition.
import {
  buildDocument, renderPageToCanvas, clearMeasurementCache, registerResourceImage,
  loadVerticalAlternates,
} from 'https://esm.sh/postext';
import { renderToPdf, decompressWoff2 } from 'https://esm.sh/postext-pdf';

const LANG = 'en'; // @lang: this edition's language; the Japanese original faces it
const RECIPE = 'manga-action-slants';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
// #region palette: black ink on a warm white, one screen-tone grey
const palette = {
  ink: '#151413', // panel borders, balloon outlines, the lettering
  paper: '#fdfcf9', // the page and the balloons
  tone: '#e8e6e1', // the inner-voice box, a light screen tone
  muted: '#6f6b64',
  accent: '#a8322b', // the cover red (the Folio case in recipe.json)
};
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
const colorPalette = [
  ...Object.entries(palette).map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } })),
  { id: 'main-color', name: 'ink (defaults)', value: { hex: palette.ink, model: 'hex' } },
];
// #endregion

// The engine's lettering and sound-effect faces per language (defaultComicFont and
// defaultComicSfxFont), written out so FONTS and the PDF know them.
const EDITIONS = {
  ja: { locale: 'ja', faces: ['Zen Antique', 'Dela Gothic One'] },
  en: { locale: 'en-us', faces: ['Comic Neue', 'Bangers'] },
  es: { locale: 'es', faces: ['Comic Neue', 'Bangers'] },
  ca: { locale: 'ca', faces: ['Comic Neue', 'Bangers'] },
  pt: { locale: 'pt-BR', faces: ['Comic Neue', 'Bangers'] },
  zh: { locale: 'zh-Hans', faces: ['Noto Sans SC', 'ZCOOL KuaiLe'] },
  ar: { locale: 'ar', faces: ['Playpen Sans Arabic', 'Lalezar'] },
};

// #region answer: the slant is in the split; the impact is in the panel and the effect
// The page is split in content.<lang>.md: `* [40~55 | *]` runs the gutter of the third
// tier from 40 % at the top to 55 % at the bottom, so both panels lean into the strike,
// and `24 [58~64 | *]` tilts the last tier the other way. The panel that lands the blow
// is drawn with `border=none`: no frame, so its speed lines run straight to the gutter.
// ドン keeps its Japanese face in every edition (`font=` on the line);
// the translations add a small subtitle under it, the way licensed manga gloss a drawn
// sound effect instead of redrawing it.
const comics = (lang) => ({
  artDirection: 'rtl', // drawn for right-to-left reading: slants and order mirror with it
  mirrorArt: false,
  gutter: { horizontal: mm(4), vertical: mm(2.5) }, // a slanted gutter keeps its width
  panel: { borderWidth: pt(1.1), borderColor: col('ink'), background: col('paper') },
  lettering: {
    fontFamily: EDITIONS[lang].faces[0], color: col('ink'),
    fontSize: pt(['ja', 'zh'].includes(lang) ? 8.5 : 7.5),
    writingMode: lang === 'zh' ? 'vertical' : 'auto',
  },
  balloonStyles: balloons(),
});
// #endregion

// #region balloons: oval speech, a spiky shout, a grey box for the inner voice
const balloons = () => [
  { id: 'speech', fill: col('paper'), stroke: col('ink'), strokeWidth: pt(0.6), roundness: 2 },
  { id: 'shout', fill: col('paper'), stroke: col('ink'), burstPoints: 18, burstDepth: 0.3 },
  { id: 'thought', fill: col('paper'), stroke: col('ink') },
  { id: 'inner', fill: col('tone'), stroke: col('tone'), strokeWidth: pt(0), italic: false },
  { id: 'caption', fill: col('paper'), stroke: col('ink'), strokeWidth: pt(0.5) },
  // white-edged on the art
  { id: 'sfx', color: col('ink'), haloColor: col('paper'), halo: pt(2.2) },
];
// #endregion

const config = () => ({ // a factory: the engine caches resolved configs per object
  // Each edition's language, written out (gotcha: ja-locale-tag); the original is built
  // with 'ja' in every edition (edition('ja') below).
  locale: t({ ja: 'ja', en: 'en-us', es: 'es', ca: 'ca', zh: 'zh-Hans', ar: 'ar', pt: 'pt-BR' }),
  colorPalette,
  page: {
    sizePreset: 'custom', width: mm(128), height: mm(182), dpi: 150, // B6, a tankōbon
    binding: 'right', backgroundColor: col('paper'), // manga open from the right, in any language
    margins: { top: mm(13), bottom: mm(15), left: mm(11), right: mm(11), mirror: true },
  },
  bodyText: {
    fontFamily: 'Zen Antique', fontSize: pt(9), lineHeight: pt(15), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
  },
  headings: { fontFamily: 'Zen Antique', color: col('ink'),
    levels: [{ level: 1, breakBefore: { enabled: true, parity: 'any' } }] }, // the H1 break
  header: { elements: [] }, // comic pages are all panels: no running heads, no folios
  footer: { elements: [] },
  comics: comics(LANG),
});
// Another edition changes the language and the faces; the page and its slants stay.
const edition = (lang) => ({ ...config(), locale: EDITIONS[lang].locale, comics: comics(lang) });

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Markdown sample · 23 lines · content.en.md
title: "The Final"
author: "Postext Cookbook"
---

:::page{split="24 / 18 / * [40~55 | *] / 24 [58~64 | *]"}
::panel{art=final}
caption: The final.
shinpan: Hajime!
::panel{art=eyes}
hana{inner}: …I can see it.
::panel{art=lunge}
sfx{rotate=-12}: STOMP
rival{shout}: MEEEN!
::panel{art=strike border=none}
sfx{at="74% 26%" rotate=-8 size=2.6 font="Dela Gothic One" vertical break}: ドン
sfx{at="64% 80%" rotate=-8 size=0.9}: WHAM
hana{shout}: MEN!!
::panel{art=coach}
shinpan{tail=top}: Men! Point!
mori{thought}: …Hmph. Not bad.
::panel{art=stands}
sora{shout}: She did it!!
:::
`; // content.<lang>.md: this edition's lettering
const original = String.raw`---
Markdown sample · 22 lines · content.ja.md
title: "決勝"
author: "Postext Cookbook"
---

:::page{split="24 / 18 / * [40~55 | *] / 24 [58~64 | *]"}
::panel{art=final}
caption: 決勝戦。
shinpan: 始め！
::panel{art=eyes}
hana{inner}: ……見える
::panel{art=lunge}
sfx{rotate=-12}: ダンッ
rival{shout}: メェェン！
::panel{art=strike border=none}
sfx{at="74% 26%" rotate=-8 size=2.6 font="Dela Gothic One" break}: ドン
hana{shout}: メン！！
::panel{art=coach}
shinpan{tail=top}: 面あり！
mori{thought}: ……ふん。悪くない
::panel{art=stands}
sora{shout break}: 決まったぁぁ！！
:::
`; // content.ja.md, the original, in every edition
const english = String.raw`---
Markdown sample · 23 lines · content.en.md
title: "The Final"
author: "Postext Cookbook"
---

:::page{split="24 / 18 / * [40~55 | *] / 24 [58~64 | *]"}
::panel{art=final}
caption: The final.
shinpan: Hajime!
::panel{art=eyes}
hana{inner}: …I can see it.
::panel{art=lunge}
sfx{rotate=-12}: STOMP
rival{shout}: MEEEN!
::panel{art=strike border=none}
sfx{at="74% 26%" rotate=-8 size=2.6 font="Dela Gothic One" vertical break}: ドン
sfx{at="64% 80%" rotate=-8 size=0.9}: WHAM
hana{shout}: MEN!!
::panel{art=coach}
shinpan{tail=top}: Men! Point!
mori{thought}: …Hmph. Not bad.
::panel{art=stands}
sora{shout}: She did it!!
:::
`; // the Japanese edition faces the original with it
// The same panels and speaker ids in every file; only the words change.

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = {
  'Zen Antique': ['400'], 'Dela Gothic One': ['400'], 'Comic Neue': ['400', '700', '400i', '700i'],
  Bangers: ['400'], 'Noto Sans SC': ['400', '700'], 'ZCOOL KuaiLe': ['400'],
  'Playpen Sans Arabic': ['400', '700'], Lalezar: ['400'],
};

// #region art: six panels drawn for the recipe, with each speaker's mouth, head and face marked
const ART = { // fractions of the picture: the same in every language
  final: {
    alt: t({ en: 'The kendo final in a packed gym: two fighters cross swords among three referees.',
      es: 'La final en un pabellón lleno: dos rivales cruzan las espadas entre tres árbitros.',
      ca: 'La final en un pavelló ple: dos rivals creuen les espases entre tres àrbitres.',
      pt: 'A final num ginásio lotado: dois lutadores cruzam as espadas entre três árbitros.',
      zh: '座无虚席的体育馆里的决赛：两名选手在三名裁判之间交剑。',
      ar: 'النهائي في صالة ممتلئة: متباريان يتقاطع سيفاهما بين ثلاثة حكّام.',
      ja: '満員の体育館での決勝。3人の審判の間で2人が剣先を交える。' }),
  safeArea: { x: 0.22, y: 0.44, width: 0.56, height: 0.46 },
  anchors: [{ id: 'hana', x: 0.31, y: 0.51, head: { x: 0.31, y: 0.49 },
    face: { x: 0.28, y: 0.45, width: 0.07, height: 0.1 } },
  { id: 'rival', x: 0.68, y: 0.51, head: { x: 0.68, y: 0.49 },
    face: { x: 0.65, y: 0.46, width: 0.06, height: 0.09 } },
  { id: 'shinpan', x: 0.575, y: 0.585, head: { x: 0.575, y: 0.56 },
    face: { x: 0.56, y: 0.54, width: 0.03, height: 0.06 } }] },
  eyes: {
    alt: t({ en: "Hana's eyes through the bars of her helmet grille.",
      es: 'Los ojos de Hana tras las barras de la rejilla del casco.',
      ca: 'Els ulls de la Hana darrere les barres de la reixa del casc.',
      pt: 'Os olhos de Hana atrás das barras da grade do capacete.',
      zh: '面罩铁栏后花的眼睛。',
      ar: 'عينا هانا خلف قضبان شبكة الخوذة.',
      ja: '面金の向こうの花の目。' }),
  safeArea: { x: 0.22, y: 0.26, width: 0.57, height: 0.38 },
  anchors: [{ id: 'hana', x: 0.5, y: 0.62, head: { x: 0.5, y: 0.4 },
    face: { x: 0.2, y: 0.3, width: 0.6, height: 0.3 } }] },
  lunge: {
    alt: t({ en: 'The opponent lunges at the viewer, speed lines all round.',
      es: 'El rival se lanza hacia el lector entre líneas cinéticas.',
      ca: 'El rival es llança cap al lector entre línies cinètiques.',
      pt: 'O adversário avança contra o leitor entre linhas de velocidade.',
      zh: '对手在速度线中朝读者猛刺过来。',
      ar: 'الخصم يندفع نحو القارئ وسط خطوط السرعة.',
      ja: '集中線の中、こちらへ突いてくる相手。' }),
  safeArea: { x: 0.03, y: 0.01, width: 0.8, height: 0.61 },
  avoid: [{ x: 0.02, y: 0.42, width: 0.23, height: 0.18 }],
  anchors: [{ id: 'rival', x: 0.7, y: 0.2, head: { x: 0.7, y: 0.14 },
    face: { x: 0.63, y: 0.02, width: 0.15, height: 0.24 } }] },
  strike: {
    alt: t({ en: "Hana leaps and strikes the top of the opponent's helmet; the sword bends.",
      es: 'Hana salta y golpea la parte alta del casco del rival; la espada se dobla.',
      ca: 'La Hana salta i colpeja la part alta del casc del rival; l’espasa es doblega.',
      pt: 'Hana salta e acerta o alto do capacete do adversário; a espada se curva.',
      zh: '花跃起击中对手面罩顶部，竹剑弯了起来。',
      ar: 'هانا تقفز وتضرب أعلى خوذة الخصم؛ ينثني السيف.',
      ja: '跳び込んで相手の面を打つ花。竹刀がしなる。' }),
  safeArea: { x: 0.36, y: 0.06, width: 0.42, height: 0.77 },
  avoid: [{ x: 0.52, y: 0.48, width: 0.13, height: 0.16 }],
  anchors: [{ id: 'hana', x: 0.43, y: 0.25, head: { x: 0.43, y: 0.18 },
    face: { x: 0.38, y: 0.07, width: 0.1, height: 0.25 } }, { id: 'sfx', x: 0.75, y: 0.25 }] },
  stands: {
    alt: t({ en: 'Sora jumps up in the stands, fists raised, shouting.',
      es: 'Sora salta en la grada con los puños en alto, gritando.',
      ca: 'En Sora salta a la graderia amb els punys enlaire, cridant.',
      pt: 'Sora pula na arquibancada de punhos erguidos, gritando.',
      zh: '空在看台上跳起来，举着拳头大喊。',
      ar: 'سورا يقفز في المدرّجات رافعًا قبضتيه وهو يصيح.',
      ja: '観客席で拳を突き上げて叫ぶ空。' }),
  safeArea: { x: 0.08, y: 0.07, width: 0.69, height: 0.44 },
  avoid: [{ x: 0.08, y: 0.06, width: 0.12, height: 0.1 },
    { x: 0.64, y: 0.35, width: 0.1, height: 0.12 }],
  anchors: [{ id: 'sora', x: 0.51, y: 0.44, head: { x: 0.5, y: 0.37 },
    face: { x: 0.4, y: 0.3, width: 0.22, height: 0.2 } }] },
  coach: {
    alt: t({ en: 'Mori, arms crossed and eyes closed; behind him the referees raise their flags.',
      es: 'Mori, de brazos cruzados y ojos cerrados; detrás, los árbitros alzan las banderas.',
      ca: 'En Mori, de braços plegats i ulls tancats; darrere, els àrbitres alcen les banderes.',
      pt: 'Mori, de braços cruzados e olhos fechados; atrás, os árbitros erguem as bandeiras.',
      zh: '森老师抱着双臂、闭着眼；身后的裁判举起了旗子。',
      ar: 'موري عاقد الذراعين مغمض العينين، وخلفه يرفع الحكّام راياتهم.',
      ja: '腕を組み目を閉じる森先生。後ろで審判が旗を上げる。' }),
  safeArea: { x: 0.16, y: 0.1, width: 0.76, height: 0.53 },
  avoid: [{ x: 0.55, y: 0.18, width: 0.4, height: 0.17 }],
  anchors: [{ id: 'mori', x: 0.29, y: 0.31, head: { x: 0.29, y: 0.2 },
    face: { x: 0.22, y: 0.1, width: 0.14, height: 0.24 } }] },
};
const panels = () => Promise.all([
  comicPanel('final', asset('match-final.jpg'), ART.final),
  comicPanel('eyes', asset('match-eyes.jpg'), ART.eyes),
  comicPanel('lunge', asset('match-lunge.jpg'), ART.lunge),
  comicPanel('strike', asset('match-strike.jpg'), ART.strike),
  comicPanel('coach', asset('match-coach.jpg'), ART.coach),
  comicPanel('stands', asset('match-stands.jpg'), ART.stands),
]);
// #endregion

// #region fonts: each edition loads its faces with the words they set
const SFX = /^sfx(\{[^}\n]*\})?[ \t]*[:：](.*)$/gm; // sound effects: the second face sets them
async function loadEdition(lang) {
  const text = TEXT[lang];
  const [face, sfx] = EDITIONS[lang].faces;
  const faces = { [face]: FONTS[face], [sfx]: FONTS[sfx] };
  const effects = [...text.matchAll(SFX)];
  for (const [, attrs = '', words] of effects) { // ドン keeps its face in every language
    const family = /font="([^"]+)"/.exec(attrs)?.[1];
    if (!family) continue;
    faces[family] = FONTS[family];
    await loadCjkFonts({ [family]: FONTS[family] }, words, { vertical: true });
  }
  if (['ja', 'zh'].includes(lang)) { // CJK: only the files that hold these characters
    const own = effects.filter(([, attrs = '']) => !attrs.includes('font=')).map((m) => m[2]);
    await loadCjkFonts({ [face]: FONTS[face] }, text.replace(SFX, ''), { vertical: true });
    await loadCjkFonts({ [sfx]: FONTS[sfx] }, own.join(''), { vertical: true });
  }
  if (lang === 'ar') await loadArabicFonts(faces, text);
  await loadComicFonts(faces, text); // the bold and italic the faces do not ship
}
// #endregion

// ─── 4 · Build & show ───────────────────────────────────────────────────────
// #region editions: the original on the right-hand page, this edition's lettering facing it
const FACING = LANG === 'ja' ? 'en' : LANG; // Japanese readers see the English edition
const TEXT = { ja: original, [FACING]: LANG === 'ja' ? english : markdown };
await loadFonts(FONTS, Object.values(TEXT).join('\n'));
const resources = await panels();
const build = async (lang) => { // the same pictures and page; this language's lettering
  await loadEdition(lang);
  return buildWithFonts(() => buildDocument({ markdown: TEXT[lang], resources,
    continuation: { pageIndexOffset: lang === 'ja' ? 1 : 2 } }, edition(lang)), TEXT[lang]);
};
const docs = [await build('ja'), await build(FACING)];
// #endregion
const TITLE = t({
  en: 'An action page with slanted gutters', es: 'Una página de acción con calles inclinadas',
  ca: 'Una pàgina d’acció amb carrers inclinats', zh: '斜向格间的动作页', ar: 'صفحة حركة بفواصل مائلة',
  pt: 'Uma página de ação com sarjetas inclinadas',
  ja: '斜めのコマ割りで組むアクションのページ' });
showBook(docs, { title: TITLE });
offerPdf(() => renderToPdf(docs, { fontProvider: comicPdfProvider, resourceBytes: imageBytes }),
  `${RECIPE}.pdf`);

Kit · core, fonts, viewer, pdf, images, cjk, arabic, comics: the same in every recipe · 722 lines
// ─── Kit ── helpers shared by every Cookbook recipe · postext.dev/cookbook ─────

// ─── Kit · core v1 ── the same in every recipe · postext.dev/cookbook
function mm(value) { return { value, unit: 'mm' }; }
function pt(value) { return { value, unit: 'pt' }; }
function em(value) { return { value, unit: 'em' }; }
/** The sample language's string: t({ en: 'Figure', es: 'Figura' }). */
function t(strings) { return strings[LANG] ?? Object.values(strings)[0]; }
/** A file in this recipe's assets folder, served from the Postext repo by jsDelivr. */
function asset(file) { return `https://cdn.jsdelivr.net/gh/drnachio/postext@main/cookbook/${RECIPE}/assets/${file}`; }

// ─── Kit · fonts v2 ── the same in every recipe · postext.dev/cookbook
// Postext measures with the loaded faces and caches the widths: load every face
// before the first build, from Fontsource, the files the PDF embeds too.

/** faces = { 'Family Name': ['400', '400i', '700'] }. `text` is the sample:
 *  č ł † α χ also load latin-ext and greek files (kitSubsetsFor). With
 *  `optional`, a face Fontsource does not ship is skipped instead of failing.
 *  Resolves to the number of faces added. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = {
    latin: 'U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,'
      + 'U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD',
    'latin-ext': 'U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,'
      + 'U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF',
    greek: 'U+0370-03FF',
  };
  const jobs = [];
  let added = 0;
  for (const [family, specs] of Object.entries(faces)) {
    const id = fontsourceId(family);
    const todo = [...new Set(specs)].map((spec) => [parseInt(spec, 10), spec.endsWith('i') ? 'italic' : 'normal'])
      .filter(([weight, style]) => !hasFace(family, weight, style)); // before any await
    const meta = optional || /[^\0-ÿ]/u.test(text) ? await fontsourceMeta(family) : null;
    const subsets = ['latin', ...kitSubsetsFor(text, meta)];
    for (const [weight, style] of todo) {
      if (optional && !(meta?.weights.includes(weight) && meta.styles.includes(style))) continue;
      for (const subset of subsets) {
        const url = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-${subset}-${weight}-${style}.woff2`;
        const face = new FontFace(family, `url(${url}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: ranges[subset] });
        jobs.push(face.load().then((ready) => { document.fonts.add(ready); added++; }, () => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return added;
}

/** Runs `build` and loads any face the pages use that FONTS missed (a regular
 *  one with a warning), then clears the measurement cache and builds again. */
async function buildWithFonts(build, text = '') {
  const tried = new Set();
  for (let round = 0; round < 3; round++) {
    kitStatus('Laying out…');
    await new Promise(requestAnimationFrame);          // let the status paint first
    const result = await Promise.resolve().then(build).catch((error) => { kitFail(error); throw error; });
    const wanted = { base: {}, variants: {} };
    for (const { font, base } of [result].flat().flatMap(fontStringsOf)) {
      const { family, weight, style } = parseFont(font);
      const key = `${family}|${weight}|${style}`;
      if (tried.has(key) || hasFace(family, weight, style)) continue;
      tried.add(key);
      (wanted[base ? 'base' : 'variants'][family] ??= []).push(`${weight}${style === 'italic' ? 'i' : ''}`);
    }
    if (Object.keys(wanted.base).length) {
      console.warn(`[cookbook] FONTS does not list ${JSON.stringify(wanted.base)}: loading them.`);
    }
    const added = await loadFonts(wanted.base, text) + await loadFonts(wanted.variants, text, { optional: true });
    if (added === 0) return result;
    clearMeasurementCache();
  }
  throw new Error('The fonts did not settle after three builds.');
}

/** Every font string of the layout; `base` marks a block's own face. */
function fontStringsOf(doc) {
  const found = new Map();
  const walk = (node) => {
    if (!node || typeof node !== 'object') return;
    if (Array.isArray(node)) { node.forEach(walk); return; }
    for (const [key, value] of Object.entries(node)) {
      if (typeof value === 'string' && /fontString$/i.test(key)) {
        found.set(value, found.get(value) || key === 'fontString');
      } else if (value && typeof value === 'object') walk(value);
    }
  };
  walk(doc.pages);
  walk(doc.blocks);
  return [...found].map(([font, base]) => ({ font, base }));
}

/** '700 37.5px Open Sans' / 'italic 400 13px "Source Serif 4"' → { family, weight, style }.
 *  A string with no weight ('95.8px Young Serif', from a design text) is 400. */
function parseFont(font) {
  const m = /^(?:(italic|oblique)\s+)?(?:small-caps\s+)?(?:(\d+|bold|normal)\s+)?[\d.]+px\s+(.+)$/.exec(font.trim());
  if (!m) throw new Error(`Unexpected font string: ${font}`);
  const weight = m[2] === 'bold' ? 700 : !m[2] || m[2] === 'normal' ? 400 : Number(m[2]);
  return { family: m[3].replace(/^["']|["']$/g, ''), weight, style: m[1] ? 'italic' : 'normal' };
}

/** A loaded FontFace covers this family, weight and style (fonts.check() would
 *  also say yes for families nobody declared). */
function hasFace(family, weight, style) {
  for (const face of document.fonts) {
    if (face.status !== 'loaded' || face.style !== style) continue;
    if (face.family.replace(/^["']|["']$/g, '') !== family) continue;
    const [low, high = low] = face.weight.split(' ').map(Number);
    if (weight >= low && weight <= high) return true;
  }
  return false;
}

/** The files beyond latin `text` needs that `meta`'s family ships. */
function kitSubsetsFor(text, meta) {
  return [[/[Ā-˿ᴀ-ᶿḀ-ỿ†ℓⱠ-Ɀ꜠-ꟿ]/u, 'latin-ext'], [/[Ͱ-Ͽ]/u, 'greek']]
    .filter(([re, x]) => re.test(text) && meta?.subsets?.includes(x)).map(([, x]) => x);
}

/** Fontsource's id for a family: 'Source Serif 4' → 'source-serif-4'. */
function fontsourceId(family) { return family.toLowerCase().replace(/\s+/g, '-'); }

/** The family's Fontsource metadata (weights, styles, subsets), or null. */
function fontsourceMeta(family) {
  fontsourceMeta.cache ??= new Map();
  const id = fontsourceId(family);
  if (!fontsourceMeta.cache.has(id)) {
    fontsourceMeta.cache.set(id, fetch(`https://api.fontsource.org/v1/fonts/${id}`)
      .then((res) => (res.ok ? res.json() : null), () => null));
  }
  return fontsourceMeta.cache.get(id);
}

// ─── Kit · viewer v1 ── the same in every recipe · postext.dev/cookbook
/** The pages as spreads on a dark desk, page 1 alone, then verso | recto,
 *  each painted when it scrolls near. */
function showPages(docs, { title, width = 460 } = {}) {
  const root = viewer(title);
  const pages = [docs].flat().flatMap((doc) =>
    doc.pages.map((page) => ({ doc, page, n: (doc.pageIndexOffset ?? 0) + page.index })));
  const spreads = [];
  let verso = null;
  for (const p of pages) {
    if (p.n % 2 === 1) { if (verso) spreads.push([verso, null]); verso = p; }
    else { spreads.push([verso, p]); verso = null; }
  }
  if (verso) spreads.push([verso, null]);
  const density = Math.min(window.devicePixelRatio || 1, 2);
  showPages.painter?.disconnect();
  const painter = new IntersectionObserver((entries) => {
    for (const { isIntersecting, target } of entries) {
      if (!isIntersecting) continue;
      painter.unobserve(target);
      const { doc, page } = target.postext;
      renderPageToCanvas(page, doc, target, { scale: (width * density) / page.width });
    }
  }, { rootMargin: '800px' });
  showPages.painter = painter;
  root.replaceChildren(...spreads.map((pair) => {
    const spread = document.createElement('div');
    spread.className = 'pt-spread';
    for (const p of pair) {
      const figure = document.createElement('figure');
      if (p) {
        const label = p.page.pageLabel || String(p.n + 1);
        const canvas = document.createElement('canvas');
        canvas.postext = p;
        canvas.style.aspectRatio = `${p.page.width} / ${p.page.height}`;
        canvas.setAttribute('role', 'img');
        canvas.setAttribute('aria-label', `Page ${label}`);
        const folio = document.createElement('figcaption');
        folio.textContent = label;
        figure.append(canvas, folio);
        painter.observe(canvas);
      } else figure.className = 'pt-blank';
      spread.append(figure);
    }
    return spread;
  }));
  kitStatus(`${pages.length} ${pages.length === 1 ? 'page' : 'pages'}`);
  document.documentElement.dataset.postext = 'ready';
  return pages.length;
}

/** The desk, the bar and the error reporting, created once. */
function viewer(title) {
  if (!document.getElementById('pt-kit')) {
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit">
      :root { color-scheme: dark; }
      body { margin: 0; background: #0e1014; color: #b9bcc4; font: 13px/1.45 system-ui, sans-serif; }
      #pt-bar { position: sticky; top: 0; z-index: 1; display: flex; flex-wrap: wrap; align-items: center;
        gap: 6px 16px; padding: 10px 16px; background: rgb(14 16 20 / .92); backdrop-filter: blur(6px);
        border-bottom: 1px solid #23262d; }
      #pt-bar strong { color: #f4f1ea; font-weight: 600; }
      #pt-actions { display: flex; gap: 12px; margin-left: auto; }
      #pt-actions a, #pt-actions button { color: #d8a21a; font: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
      #pages { display: grid; justify-items: center; gap: 48px; padding: 32px 16px 72px; }
      .pt-spread { display: flex; }
      .pt-spread figure { margin: 0; width: min(460px, 44vw); }
      .pt-spread canvas { display: block; width: 100%; background: #fff;
        box-shadow: 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figure:first-child canvas { box-shadow: inset -14px 0 14px -14px rgb(0 0 0 / .18), 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figcaption { margin-top: 10px; text-align: center; font: 600 10px/1 system-ui, sans-serif;
        letter-spacing: .18em; text-transform: uppercase; color: #6c7079; }
      .pt-blank { visibility: hidden; }
      @media (max-width: 760px) {
        .pt-spread { flex-direction: column; gap: 32px; }
        .pt-spread figure { width: min(460px, 92vw); }
        .pt-blank { display: none; }
      }
    </style>`);
    document.body.insertAdjacentHTML('afterbegin',
      '<header id="pt-bar"><strong id="pt-title"></strong><span id="pt-status" role="status"></span><span id="pt-actions"></span></header>');
    document.getElementById('pt-title').textContent = document.title || 'Postext';
    addEventListener('error', (event) => kitFail(event.error ?? event.message));
    addEventListener('unhandledrejection', (event) => kitFail(event.reason));
  }
  if (title) document.getElementById('pt-title').textContent = title;
  return document.getElementById('pages')
    ?? document.body.appendChild(Object.assign(document.createElement('main'), { id: 'pages' }));
}

function kitStatus(text) {
  viewer();
  document.getElementById('pt-status').textContent = text;
}

function kitFail(error) {
  document.documentElement.dataset.postext = 'error';
  kitStatus(`Error: ${error?.message ?? error}`);
}

// ─── Kit · pdf v2 ── the same in every recipe that exports a PDF
/** The Fontsource files the screen used, as TrueType: the nearest weight the
 *  family ships, upright if it has no italic; latin, then what the face's
 *  letters need (kitSubsetsFor). */
async function fontsourceProvider(family, weight, style, request) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  const weights = meta?.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && meta && !meta.styles.includes('italic') ? 'normal' : style;
  const text = String.fromCodePoint(...(request?.codePoints ?? []));
  const more = kitSubsetsFor(text, meta);
  const files = await Promise.all(['latin', ...more].map(async (subset) => {
    const res = await fetch(`https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-${subset}-${w}-${s}.woff2`);
    if (!res.ok) throw new Error(`Fontsource has no ${family} ${w} ${s} ${subset}`);
    return decompressWoff2(new Uint8Array(await res.arrayBuffer()));
  }));
  return files.length === 1 ? files[0] : files;
}

/** A "Build the PDF" button; then "Open the PDF" (a new tab: CodePen's frame
 *  shows no PDFs) and a download link. */
function offerPdf(makePdf, filename) {
  viewer();
  const button = Object.assign(document.createElement('button'), { type: 'button', textContent: 'Build the PDF' });
  button.dataset.postextPdf = filename;
  button.addEventListener('click', async () => {
    button.disabled = true;
    button.textContent = 'Building the PDF…';
    try {
      const bytes = await makePdf();
      const url = URL.createObjectURL(new Blob([bytes], { type: 'application/pdf' }));
      const size = `${Math.max(1, Math.round(bytes.length / 1024))} KB`;
      button.replaceWith(
        Object.assign(document.createElement('a'), { href: url, target: '_blank', rel: 'noopener', textContent: 'Open the PDF ↗' }),
        Object.assign(document.createElement('a'), { href: url, download: filename, textContent: `Download ${filename} · ${size}` }));
    } catch (error) {
      button.disabled = false;
      button.textContent = 'Build the PDF';
      kitFail(error);
    }
  });
  document.getElementById('pt-actions').append(button);
}

// ─── Kit · images v1 ── recipes with pictures · postext.dev/cookbook
/** Registers a photo or PNG for the canvas and keeps its bytes for the PDF.
 *  fetch → ImageBitmap never taints the canvas (a plain cross-origin <img> would). */
async function loadImage(fileId, url) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Image not found (${res.status}): ${url}`);
  const bytes = new Uint8Array(await res.arrayBuffer());
  registerResourceImage(fileId, await createImageBitmap(new Blob([bytes])));
  (loadImage.bytes ??= new Map()).set(fileId, bytes);
}

/** Registers SVG markup (drawn in code, or fetched) as a vector image. */
async function loadSvg(fileId, svg) {
  const img = new Image();
  img.src = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(svg)}`;
  await img.decode();
  registerResourceImage(fileId, img);
  (loadImage.bytes ??= new Map()).set(fileId, new TextEncoder().encode(svg));
}

/** renderToPdf({ resourceBytes: imageBytes }) */
function imageBytes(fileId) { return loadImage.bytes?.get(fileId); }

/** renderToHtml({ resourceImageUrl: imageUrl }) */
function imageUrl(fileId) {
  const bytes = imageBytes(fileId);
  if (!bytes) return undefined;
  imageUrl.urls ??= new Map();
  if (!imageUrl.urls.has(fileId)) {
    const type = /\.svg$/i.test(fileId) ? 'image/svg+xml' : /\.png$/i.test(fileId) ? 'image/png' : 'image/jpeg';
    imageUrl.urls.set(fileId, URL.createObjectURL(new Blob([bytes], { type })));
  }
  return imageUrl.urls.get(fileId);
}

// ─── Kit · cjk v1 ── Chinese, Japanese and Korean books · postext.dev/cookbook
// Fontsource ships a CJK family as about a hundred files per weight, each
// declared in its stylesheet with the unicode-range it covers. The screen
// loads the files the sample touches; the PDF gets the same files for the
// characters its pages set in each face, and embeds each as a subset.
// A book bound on the right (vertical text) is shown with its spreads
// mirrored: page 1 alone on the left of the spine, then [3 | 2].

/** The files of a Fontsource face, read from its stylesheet: { url, range,
 *  ranges }, the last declared first (the order the browser tries them in). */
function cjkSlices(family, weight, style) {
  cjkSlices.cache ??= new Map();
  const id = fontsourceId(family);
  const css = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/${weight}${style === 'italic' ? '-italic' : ''}.css`;
  if (!cjkSlices.cache.has(css)) {
    cjkSlices.cache.set(css, fetch(css)
      .then((res) => {
        if (!res.ok) throw new Error(`Fontsource has no ${family} ${weight} ${style} (${res.status})`);
        return res.text();
      })
      .then((text) => [...text.matchAll(/@font-face\s*{([^}]*)}/g)].map(([, rule]) => {
        const range = /unicode-range:\s*([^;]+);/.exec(rule)?.[1].trim() ?? 'U+0-10FFFF';
        const ranges = range.split(',').map((part) => {
          const [lo, hi = lo] = part.trim().slice(2).split('-');
          return [parseInt(lo, 16), parseInt(hi, 16)];
        });
        return { url: new URL(/url\(([^)]+?\.woff2)\)/.exec(rule)[1], css).href, range, ranges };
      }).reverse()));
  }
  return cjkSlices.cache.get(css);
}

/** The file of `slices` that holds code point `cp`, if any. */
function cjkSliceFor(slices, cp) {
  return slices.find((slice) => slice.ranges.some(([lo, hi]) => cp >= lo && cp <= hi));
}

/** Whether Fontsource serves `family` as a Chinese, Japanese or Korean
 *  family (its subsets name the script). Fails when the API does not
 *  answer: a CJK face taken for a Latin one would paint in a system face. */
async function isCjkFamily(family) {
  const meta = await fontsourceMeta(family);
  if (!meta) throw new Error(`api.fontsource.org did not describe ${family}: reload to try again`);
  return !!meta.subsets?.some((subset) => /^(chinese|japanese|korean)/.test(subset));
}

/** faces = { 'Noto Serif TC': ['400', '700'] }, as for loadFonts: the
 *  whole FONTS object may be passed, its other families are left to
 *  loadFonts. Adds one FontFace per file of each CJK face with its
 *  unicodeRange, then loads the files `text` touches. `text` is what the
 *  faces set: the sample for the text face; a book in several voices calls
 *  it once per voice (loadCjkFonts({ 'LXGW WenKai TC': ['400'] }, quotes)),
 *  so the heading and quotation faces fetch and check only their own
 *  characters. Fails when a character of `text` is in no file of a face.
 *  List every weight the pages use: a weight left to buildWithFonts gets
 *  the latin file only. With { vertical: true } it also loads each
 *  family's vertical forms (brackets, quotes, pause marks) for the canvas,
 *  which needs loadVerticalAlternates imported from postext. Resolves to
 *  the number of files loaded. */
async function loadCjkFonts(faces, text, { vertical = false } = {}) {
  kitStatus('Loading fonts…');
  let loaded = 0;
  try {
    if (vertical && typeof loadVerticalAlternates !== 'function') {
      throw new Error('loadCjkFonts(…, { vertical: true }) needs loadVerticalAlternates imported from postext');
    }
    for (const [family, specs] of Object.entries(faces)) {
      if (!(await isCjkFamily(family))) continue;
      const twin = [];
      for (const spec of new Set(specs)) {
        const weight = parseInt(spec, 10);
        const style = spec.endsWith('i') ? 'italic' : 'normal';
        const slices = await cjkSlices(family, weight, style);
        const missing = [...new Set(text)].filter((ch) => /\S/.test(ch) && !cjkSliceFor(slices, ch.codePointAt(0)));
        if (missing.length) {
          throw new Error(`${family} ${spec} has no file for ${missing.slice(0, 12).join(' ')}: `
            + `give each face the text it sets (loadCjkFonts({ '${family}': ['${spec}'] }, text))`);
        }
        for (const slice of slices) {
          document.fonts.add(new FontFace(family, `url(${slice.url}) format('woff2')`,
            { weight: String(weight), style, unicodeRange: slice.range }));
          twin.push({ source: slice.url, weight: String(weight), style, unicodeRange: slice.range });
        }
        const font = `${style === 'italic' ? 'italic ' : ''}${weight} 16px "${family}"`;
        loaded += (await document.fonts.load(font, text)).length;
        if (!document.fonts.check(font, text)) throw new Error(`${family} ${spec} did not load for the sample`);
      }
      // The same files under a twin name with the `vert` feature on: the
      // canvas paints the punctuation of vertical lines with it.
      if (vertical && twin.length) await loadVerticalAlternates(family, twin);
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return loaded;
}

/** The PDF font provider for recipes with CJK faces: a family whose
 *  Fontsource subsets are Chinese, Japanese or Korean gets the files that
 *  hold the characters its pages set (`request.codePoints`); any other
 *  family gets the latin file fontsourceProvider fetches (the "pdf" block)
 *  and, when the face sets letters only latin-ext has, that file too. */
async function cjkPdfProvider(family, weight, style, request) {
  if (!(await isCjkFamily(family))) return cjkLatinPdfFiles(family, weight, style, request);
  const meta = await fontsourceMeta(family);
  const weights = meta.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && !meta.styles.includes('italic') ? 'normal' : style;
  const slices = await cjkSlices(family, w, s);
  const picked = new Set();
  for (const cp of request?.codePoints ?? []) {
    const slice = cjkSliceFor(slices, cp);
    if (slice) picked.add(slice);
  }
  if (!picked.size) picked.add(slices[0]);
  return Promise.all(slices.filter((slice) => picked.has(slice)).map(async (slice) => {
    const res = await fetch(slice.url);
    if (!res.ok) throw new Error(`Fontsource file ${slice.url} (${res.status})`);
    return decompressWoff2(new Uint8Array(await res.arrayBuffer()));
  }));
}

/** A Latin family set next to the CJK faces: its latin file, then its
 *  latin-ext file when the face sets letters only latin-ext has (ō ū in
 *  Hepburn rōmaji, ǎ in pinyin), the file loadFonts adds on screen for
 *  them. Latin comes first: postext-pdf draws a character from the first
 *  file that has it, as the browser takes a character both files hold from
 *  latin. A face Fontsource ships without latin-ext, or whose file does
 *  not come, gets latin alone, and the PDF names the letters it lacks. */
async function cjkLatinPdfFiles(family, weight, style, request) {
  const meta = await fontsourceMeta(family);
  const beyond = [...(request?.codePoints ?? [])].some(cjkLatinExtOnly);
  if (!beyond || !meta?.subsets?.includes('latin-ext')) return fontsourceProvider(family, weight, style);
  const weights = meta.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && !meta.styles.includes('italic') ? 'normal' : style;
  const id = fontsourceId(family);
  const url = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-latin-ext-${w}-${s}.woff2`;
  const [latin, ext] = await Promise.all([fontsourceProvider(family, weight, style), fetch(url)
    .then(async (res) => (res.ok ? decompressWoff2(new Uint8Array(await res.arrayBuffer())) : null), () => null)]);
  return ext ? [latin, ext] : latin;
}

/** Whether code point `cp` is in Fontsource's latin-ext file and not in
 *  its latin file: Latin Extended-A and -B, IPA, the spacing modifiers and
 *  Latin Extended Additional (loadFonts's test for latin-ext), less the
 *  few latin holds too (ı Œ œ ʻ ʼ ˆ ˚ ˜). */
function cjkLatinExtOnly(cp) {
  if (!((cp >= 0x100 && cp <= 0x2ff) || (cp >= 0x1e00 && cp <= 0x1eff))) return false;
  return ![0x131, 0x152, 0x153, 0x2bb, 0x2bc, 0x2c6, 0x2da, 0x2dc].includes(cp);
}

/** showPages for a book bound on either edge. A right-bound book (the
 *  document says so: doc.binding is 'right' for page.binding 'right' and
 *  for vertical text) lies on the desk as it opens: page 1 alone on the
 *  left of the spine, then [3 | 2], the spine shade on each page's inner
 *  edge. `binding` ('left' | 'right') overrides the document's. */
function showBook(docs, { binding, ...options } = {}) {
  const count = showPages(docs, options);
  const right = (binding ?? [docs].flat()[0]?.binding) === 'right';
  if (!document.getElementById('pt-kit-cjk')) {
    // The pages keep direction ltr: a canvas draws text in the direction its
    // element inherits, and under rtl each run would end where the engine
    // starts it, its brackets mirrored.
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit-cjk">
      .pt-spread[dir="rtl"] canvas { direction: ltr; }
      .pt-spread[dir="rtl"] figure:first-child canvas { box-shadow: inset 14px 0 14px -14px rgb(0 0 0 / .18),
        0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
    </style>`);
  }
  // Each pair stays [verso, recto] in the page; right to left, the verso
  // sits on the right. Phones stack the pages in reading order either way.
  for (const spread of document.querySelectorAll('#pages > .pt-spread')) spread.dir = right ? 'rtl' : 'ltr';
  document.getElementById('pages').dataset.binding = right ? 'right' : 'left';
  return count;
}

// ─── Kit · arabic v1 ── Arabic-script faces · postext.dev/cookbook
// Fontsource ships an Arabic family as one file per subset and weight: the
// `arabic` file holds the letters, the harakat, the Arabic-Indic digits, the
// Arabic punctuation and the presentation forms; `latin` and `latin-ext`
// hold the rest. loadFonts loads the latin files; this block adds the arabic
// file of every Arabic family, for the canvas and for the PDF, which shapes
// the letters with HarfBuzz from the same bytes.

/** The code points of Fontsource's `arabic` subset, as its stylesheets
 *  declare them (the same unicode-range the browser picks the file by). A
 *  function, not a const: the kit is inlined after the recipe's top-level
 *  awaits, and a const read before its line throws, where a function
 *  declaration is hoisted. */
function arabicRange() {
  return 'U+0600-06FF,U+0750-077F,U+0870-088E,U+0890-0891,U+0897-08E1,U+08E3-08FF,'
    + 'U+200C-200E,U+2010-2011,U+204F,U+2E41,U+FB50-FDFF,U+FE70-FE74,U+FE76-FEFC,U+102E0-102FB,'
    + 'U+10E60-10E7E,U+10EC2-10EC4,U+10EFC-10EFF,U+1EE00-1EEFF';
}

/** Whether code point `cp` is in the arabic file. */
function inArabicRange(cp) {
  inArabicRange.ranges ??= arabicRange().split(',').map((part) => {
    const [lo, hi = lo] = part.slice(2).split('-');
    return [parseInt(lo, 16), parseInt(hi, 16)];
  });
  return inArabicRange.ranges.some(([lo, hi]) => cp >= lo && cp <= hi);
}

/** Whether Fontsource serves `family` with an `arabic` subset. Fails when
 *  the API does not answer: an Arabic face taken for a Latin one would set
 *  its letters in a system face. */
async function isArabicFamily(family) {
  const meta = await fontsourceMeta(family);
  if (!meta) throw new Error(`api.fontsource.org did not describe ${family}: reload to try again`);
  return !!meta.subsets?.includes('arabic');
}

/** The arabic file of a face. */
function arabicFileUrl(family, weight, style) {
  const id = fontsourceId(family);
  return `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-arabic-${weight}-${style}.woff2`;
}

/** faces = { Amiri: ['400', '700'] }, as for loadFonts, after it: the whole
 *  FONTS object may be passed, its families without an arabic subset are
 *  left alone. Adds the arabic file of every listed weight of each Arabic
 *  family (the latin files come from loadFonts) and loads it. `text` is
 *  the sample: fails when it holds an Arabic-script character the arabic
 *  file does not cover. List every weight the pages set in Arabic: a weight
 *  left to buildWithFonts gets the latin file only, and its Arabic letters
 *  fall back to a system face. Resolves to the number of files loaded. */
async function loadArabicFonts(faces, text = '') {
  kitStatus('Loading fonts…');
  let loaded = 0;
  try {
    const outside = [...new Set(text)].filter((ch) => /\p{Script=Arabic}/u.test(ch) && !inArabicRange(ch.codePointAt(0)));
    if (outside.length) throw new Error(`Fontsource's arabic files have no ${outside.slice(0, 12).join(' ')}`);
    for (const [family, specs] of Object.entries(faces)) {
      if (!(await isArabicFamily(family))) continue;
      for (const spec of new Set(specs)) {
        const weight = parseInt(spec, 10);
        const style = spec.endsWith('i') ? 'italic' : 'normal';
        const face = new FontFace(family, `url(${arabicFileUrl(family, weight, style)}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: arabicRange() });
        document.fonts.add(await face.load().catch(() => {
          throw new Error(`Fontsource has no arabic file for ${family} ${weight} ${style}`);
        }));
        loaded++;
      }
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return loaded;
}

/** The PDF font provider for recipes with Arabic faces: a family with an
 *  arabic subset gets its arabic file when its pages set Arabic letters
 *  (`request.codePoints`), then its latin file, and its latin-ext file for
 *  the letters beyond latin (transliteration: ā ḥ ʿ). The arabic file comes
 *  first: it also holds the space and the brackets, so a line of Arabic is
 *  shaped as one run and not cut at every space. Any other family goes to
 *  fontsourceProvider (the "pdf" block). */
async function arabicPdfProvider(family, weight, style, request) {
  if (!(await isArabicFamily(family))) return fontsourceProvider(family, weight, style, request);
  const meta = await fontsourceMeta(family);
  const weights = meta.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && !meta.styles.includes('italic') ? 'normal' : style;
  const wanted = [...(request?.codePoints ?? [])];
  const id = fontsourceId(family);
  const urls = [];
  if (!wanted.length || wanted.some(inArabicRange)) urls.push(arabicFileUrl(family, w, s));
  urls.push(`https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-latin-${w}-${s}.woff2`);
  if (meta.subsets.includes('latin-ext') && wanted.some((cp) => /[Ā-˿Ḁ-ỿ]/u.test(String.fromCodePoint(cp)))) {
    urls.push(`https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-latin-ext-${w}-${s}.woff2`);
  }
  return Promise.all(urls.map(async (url) => {
    const res = await fetch(url);
    if (!res.ok) throw new Error(`Fontsource file ${url} (${res.status})`);
    return decompressWoff2(new Uint8Array(await res.arrayBuffer()));
  }));
}

// ─── Kit · comics v1 ── comic pages · postext.dev/cookbook
// The engine letters a comic in a face per language (defaultComicFont:
// Comic Neue, Zen Antique for Japanese, Noto Sans SC, LXGW WenKai TC,
// Playpen Sans Arabic; defaultComicSfxFont: Bangers, Dela Gothic One,
// ZCOOL KuaiLe, Lalezar) and asks for the bold of a shout or a sound effect
// and the italic of an inner voice. Most of these faces ship one weight and
// no italic: this block declares the file Fontsource does ship for those
// variants, so the canvas measures and paints the letters the PDF embeds
// (the providers snap to the shipped file) and not a bold or a slant the
// browser makes up. It also turns the art manifest into panel resources.

/** faces = { 'Comic Neue': ['400', '700'], Bangers: ['400'] }, as for
 *  loadFonts, after it (and after loadCjkFonts or loadArabicFonts for the
 *  faces of those scripts); the whole FONTS object may be passed. List in
 *  FONTS only what Fontsource ships (Bangers: ['400']): loadFonts fails on
 *  the rest. For each family, the regular, bold, italic and bold italic it
 *  lacks are declared with its nearest file (the regular for the bold, the
 *  upright for the italic) and loaded for `text`. A CJK face needs the cjk
 *  block; an Arabic face setting Arabic, the arabic block. Resolves to the
 *  number of variants added. */
async function loadComicFonts(faces, text = '') {
  kitStatus('Loading fonts…');
  let added = 0;
  try {
    for (const family of Object.keys(faces)) {
      const meta = await fontsourceMeta(family);
      if (!meta) throw new Error(`api.fontsource.org did not describe ${family}: reload to try again`);
      const weights = meta.weights?.length ? meta.weights : [400, 700];
      const styles = meta.styles?.length ? meta.styles : ['normal'];
      for (const [weight, style] of [[400, 'normal'], [700, 'normal'], [400, 'italic'], [700, 'italic']]) {
        if ((weights.includes(weight) && styles.includes(style)) || hasFace(family, weight, style)) continue;
        const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
        const s = style === 'italic' && styles.includes('italic') ? 'italic' : 'normal';
        for (const { url, range } of await comicFaceFiles(family, w, s, meta, text)) {
          document.fonts.add(new FontFace(family, `url(${url}) format('woff2')`,
            { weight: String(weight), style, unicodeRange: range }));
        }
        await document.fonts.load(`${style === 'italic' ? 'italic ' : ''}${weight} 16px "${family}"`, text || 'A');
        added++;
      }
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return added;
}

/** The files of a shipped face ({ url, range }): a CJK face's slices (the
 *  cjk block reads them from its stylesheet), else latin, the latin-ext
 *  and greek files `text` needs, and the arabic file when `text` holds
 *  Arabic. */
async function comicFaceFiles(family, weight, style, meta, text) {
  if (meta.subsets?.some((subset) => /^(chinese|japanese|korean)/.test(subset))) {
    if (typeof cjkSlices !== 'function') throw new Error(`${family} is a CJK face: list the cjk kit block`);
    return (await cjkSlices(family, weight, style)).map(({ url, range }) => ({ url, range }));
  }
  const id = fontsourceId(family);
  const file = (subset) => `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${id}-${subset}-${weight}-${style}.woff2`;
  const files = ['latin', ...kitSubsetsFor(text, meta)].map((subset) => ({ url: file(subset), range: comicRange(subset) }));
  if (meta.subsets?.includes('arabic') && /\p{Script=Arabic}/u.test(text)) {
    if (typeof arabicRange !== 'function') throw new Error(`${family} sets Arabic: list the arabic kit block`);
    files.unshift({ url: file('arabic'), range: arabicRange() });
  }
  return files;
}

/** The unicode-range loadFonts gives a Fontsource file. A function, not a
 *  const: the kit is inlined after the recipe's top-level awaits. */
function comicRange(subset) {
  return {
    latin: 'U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,'
      + 'U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD',
    'latin-ext': 'U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,'
      + 'U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF',
    greek: 'U+0370-03FF',
  }[subset];
}

/** The PDF font provider of a comic in any script: a CJK face goes to
 *  cjkPdfProvider, an Arabic face to arabicPdfProvider, any other to
 *  fontsourceProvider (the "pdf" block). Each embeds the shipped weight
 *  and style nearest to the one asked for, the file loadComicFonts
 *  declared for the canvas. */
async function comicPdfProvider(family, weight, style, request) {
  const subsets = (await fontsourceMeta(family))?.subsets ?? [];
  if (subsets.some((subset) => /^(chinese|japanese|korean)/.test(subset))) {
    if (typeof cjkPdfProvider !== 'function') throw new Error(`${family} is a CJK face: list the cjk kit block`);
    return cjkPdfProvider(family, weight, style, request);
  }
  if (subsets.includes('arabic') && typeof arabicPdfProvider === 'function') {
    return arabicPdfProvider(family, weight, style, request);
  }
  return fontsourceProvider(family, weight, style, request);
}

/** A panel picture as a resource for art= (and pop=): loads `url`
 *  (write asset('lh-arrive.jpg') in the call, so the lint checks the file)
 *  and declares it with `meta`, its entry in the art manifest:
 *  { width, height, alt, safeArea, anchors, avoid }. The safe area is what
 *  every crop keeps, the anchors the speakers' mouths, heads and faces,
 *  the avoid zones what no balloon covers; all in fractions of the picture,
 *  the same in every language. Without width and height, the picture's own
 *  size. Needs the images block. Resolves to the resource. */
async function comicPanel(id, url, meta = {}) {
  const fileId = decodeURIComponent(url.split('/').pop());
  await loadImage(fileId, url);
  let { width, height } = meta;
  if (!width || !height) {
    const bitmap = await createImageBitmap(new Blob([imageBytes(fileId)]));
    ({ width, height } = bitmap);
    bitmap.close();
  }
  return {
    id, typeId: meta.typeId ?? 'figure', kind: 'bitmap', createdAt: 0, updatedAt: 0,
    bitmap: { fileId, format: /\.png$/i.test(fileId) ? 'png' : 'jpeg', width, height },
    ...(meta.alt && { altText: meta.alt }),
    ...(meta.safeArea && { safeArea: meta.safeArea }),
    ...(meta.anchors?.length && { anchors: meta.anchors }),
    ...(meta.avoid?.length && { avoid: meta.avoid }),
  };
}

// ─── /Kit ───────────────────────────────────────────────────────────────────────

The composed script.js runs as it is: paste it into any page’s module script, or open the recipe on CodePen. Recipe folder on GitHub ↗ (opens in a new tab)

Pitfalls

Pitfall

Tag a Japanese text 'ja', never zh-Hans or LANG

A recipe's editions are en and es, but a Japanese sample is Japanese in both: `locale: LANG` would tag it English or Spanish, and a Chinese tag would set it by the Chinese rules (Kaiming punctuation, small kana free to start a line, 图 for 図, Chinese glyph forms in the PDF). Write 'ja': it picks the Japan region (JLReq line breaking and punctuation, sesame emphasis marks, furigana spacing, 図 and 表 labels) and turns hyphenation off. The lint fails a text with kana under a zh or ko tag. Japanese line breaking (kinsoku) →

Pitfall

Chinese faces load by slices, through the cjk block

Fontsource serves a Chinese, Japanese or Korean family as about a hundred files per weight, each covering a range of characters. loadFonts fetches only the latin file, so on screen the Han characters come from a system face and measure wrong, and fontsourceProvider hands the PDF that latin file, which prints them as empty boxes. List the cjk kit block, call loadCjkFonts(FONTS, markdown) after loadFonts (once per voice, with the text it sets, when the book uses several CJK faces) and give renderToPdf fontProvider: cjkPdfProvider: both take the files that hold the text's characters. Chinese, Japanese and Korean fonts →

Pitfall

A config is cached by identity: build a fresh object

The engine caches resolved configs by object identity, so changing a config in place and building again reuses the old result. Build a fresh object for every build, which is why a recipe's config is a factory: config(). Pages on a canvas →

Pitfall

Load every face before layout

Layout measures text with the faces the browser has loaded and caches the widths, so a face that arrives after the first build leaves wrong line breaks and a PDF that no longer matches the screen. Load every weight and style first, and call clearMeasurementCache() before rebuilding when one arrives late. Fonts before layout →

A sound effect kept in Japanese in an edition lettered in rows is set in a row, like the rest of the edition, unless its line says vertical.
Sora's cheer is longer than his small panel in Japanese, Spanish and Catalan: left to the engine it crossed the border and the build warned comicBalloonOverflow. Those editions mark it break (sora{shout break}): it bursts up through the frame into the gutter and the panel above on purpose, and nothing is reported. A break balloon never runs into the page margin unless its panel bleeds; a pin (at=) puts it anywhere else.

Credits

Recipe: Ignacio Ferro
Text: 決勝 (The Final), a one-page kendo manga written for this recipe, with its English, Spanish, Catalan, Chinese and Arabic letterings · Postext Cookbook · CC BY 4.0
Images: The kendo final in a packed gym, two fighters between three referees · Generated With Diffusion Models · original
Hana's eyes through her helmet grille · Generated With Diffusion Models · original
The opponent lunging with speed lines · Generated With Diffusion Models · original
Hana's leaping strike to the helmet · Generated With Diffusion Models · original
Sora cheering in the stands · Generated With Diffusion Models · original
Coach Mori nodding while the referees raise their flags · Generated With Diffusion Models · original
Fonts: Zen Antique (SIL OFL 1.1) · Dela Gothic One (SIL OFL 1.1) · Comic Neue (SIL OFL 1.1) · Bangers (SIL OFL 1.1) · Noto Sans SC (SIL OFL 1.1) · ZCOOL KuaiLe (SIL OFL 1.1) · Playpen Sans Arabic (SIL OFL 1.1) · Lalezar (SIL OFL 1.1)
Code: MIT, like Postext

Edit this write-up ↗ (opens in a new tab)Recipe folder on GitHub ↗ (opens in a new tab)

In short

#What you'll build

#The short answer

#Ingredients

#Method

#1 · Slant the gutter in the split

#2 · Shout in bursts and let the effects break out

#3 · Keep ドン in Japanese and subtitle it

#4 · Fit the safe areas to slanted cells

#5 · Set the original beside each edition

#The whole recipe

#Pitfalls

#Credits

More from the Cookbook

A Japanese story in two tiers, its title across both

One set of panels, three page splits

One page lettered in six languages

What you'll build

The short answer

Ingredients

Method

The whole recipe

Pitfalls

Credits