Figurengedicht: Herberts Easter Wings, zeilenweise zentriert

// ═══ Postext Cookbook · Nº 062 · Shaped verse: Herbert's Easter Wings, centred line by line ═
// https://postext.dev/en/cookbook/shaped-verse
// Code: MIT · Text: G. Herbert, The Temple, 1633 (PD; EEBO-TCP, CC0) · Spanish version: CC BY 4.0
// Fonts: IM Fell English, Great Primer and English SC (SIL OFL 1.1) · Needs postext ≥ 1.25.0
import { buildDocumentWithFonts, renderPageToCanvas } from 'https://esm.sh/postext';

const LANG = 'en'; // @lang: the language of the sample document ('en' | 'es')
const RECIPE = 'shaped-verse';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
const palette = { // every colour in the config links to one of these
  ink: '#241d29', // the text: a violet-black
  violet: '#5c2a6f', // the one accent: the titles and the small-capital labels
  paper: '#fbf7ee', // the sheet: an uncoated cream
};
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' } })),
  // Italic and bold take their colour from 'main-color' unless set. With 'main-color' in ink,
  // the italic subtitle, epigraph and motto print in ink instead of the default blue.
  { id: 'main-color', name: 'ink (defaults)', value: { hex: palette.ink, model: 'hex' } },
];
const LEAD = 17; // pt: the leading of every line, verse and prose alike

// #region answer: centred text, one line of verse to a paragraph
// Postext joins the lines of a Markdown paragraph, so every line of the poem is a paragraph
// of its own, with a blank line after it. Centred, each line keeps its natural width on the
// axis of the measure, and the lengths Herbert gave his lines draw the figure:
//   Lord, who createdst man in wealth and store,
//
//   Though foolishly he lost the same,
//
//   Decaying more and more,
const verse = {
  fontFamily: 'IM Fell English', fontSize: pt(12.4), lineHeight: pt(LEAD), color: col('ink'),
  textAlign: 'center', // ragged on both sides; only justified text is hyphenated by default
  firstLineIndent: pt(0), // the default 1.5 em moves every line 3.3 mm off the titles' axis
};
// #endregion

// #region measure: an A5 leaf whose measure holds the longest line whole
// A line too long for the measure wraps, and both halves are centred, which adds a step to
// the outline.
// The widest line, 'Lord, who createdst man in wealth and store,', is 80.7 mm in 12.4 pt
// Fell, so the 110 mm measure takes every line of both poems whole.
const TRIM = { w: 148, h: 210 }; // mm: A5, one A4 sheet folded once
const MARGIN = { top: 22, bottom: 24, inner: 17, outer: 21 }; // mm: the measure is 110 mm
// #endregion

// #region titles: plain headings, centred, in the display face and the accent
// headings.textAlign centres every level. The Fell faces ship weight 400 only, so no level
// asks for bold.
const titles = {
  fontFamily: 'IM Fell Great Primer', fontWeight: 400, color: col('violet'), textAlign: 'center',
  levels: [
    // The keepsake's title opens page 1, where a break changes nothing; a second # title
    // would open on a recto.
    { level: 1, fontSize: pt(40), lineHeight: pt(LEAD * 3), textTransform: 'uppercase',
      marginBottom: pt(LEAD), breakBefore: { enabled: true, parity: 'odd' } },
    // A poem opens the next page, recto or verso: The Altar (page 2) faces Easter Wings.
    // A heading that opens a page drops its top margin, so the title is lowered by its
    // line box instead: three lines deep, it sets the title about 5 mm down. The default
    // half-em margin under it rounds up to a whole line, and each poem starts on line 5.
    { level: 2, fontSize: pt(24), lineHeight: pt(LEAD * 3), textTransform: 'uppercase',
      breakBefore: { enabled: true, parity: 'any' } },
    // The small-capital labels on pages 1 and 4: the sister face at the body size, with no
    // margins, since the :::space lines place them.
    { level: 3, fontFamily: 'IM Fell English SC', fontSize: pt(12.4), lineHeight: pt(LEAD),
      marginTop: pt(0), marginBottom: pt(0) },
  ],
};
// #endregion

// #region pages: four pages, spaced and broken from the Markdown
// A blank line adds no space, so every gap on these pages is a :::space{lines=N}, which adds
// N lines of the 17 pt grid (one without the attribute). ## opens a page for each poem, and
// :::pagebreak opens the last page.
const config = () => ({
  colorPalette,
  locale: t({ en: 'en-us', es: 'es' }), // the language of each edition, and of its bundle
  page: { // mirror: left is the inner margin; 150 dpi is for the screen
    sizePreset: 'custom', width: mm(TRIM.w), height: mm(TRIM.h), dpi: 150,
    backgroundColor: col('paper'),
    margins: { top: mm(MARGIN.top), bottom: mm(MARGIN.bottom), left: mm(MARGIN.inner),
      right: mm(MARGIN.outer), mirror: true },
  },
  layout: { layoutType: 'single' }, // the default is two columns
  bodyText: verse, // a :ref added to these pages takes main-color, the ink, like bold and italic
  headings: titles,
  header: { elements: [] }, // a folded keepsake of four pages: no running heads,
  footer: { elements: [] }, // and no folios
});
// #endregion

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Markdown-Beispiel · 129 Zeilen · content.en.md
title: "The Temple"
author: "George Herbert"
---

# The Temple

*Sacred Poems and Private Ejaculations*

:::space

By Mr. George Herbert

:::space{lines=5}

### Psal. 29.

*In his Temple doth every man speak of his honour.*

:::space{lines=10}

### Two shaped poems

in the text of the first edition

Cambridge, 1633

## The Altar

A broken ALTAR, Lord, thy servant reares,

Made of a heart, and cemented with teares:

Whose parts are as thy hand did frame;

No workmans tool hath touch’d the same.

A HEART alone

Is such a stone,

As nothing but

Thy pow’r doth cut.

Wherefore each part

Of my hard heart

Meets in this frame,

To praise thy name.

That if I chance to hold my peace,

These stones to praise thee may not cease.

O let thy blessed SACRIFICE be mine,

And sanctifie this ALTAR to be thine.

## Easter Wings

Lord, who createdst man in wealth and store,

Though foolishly he lost the same,

Decaying more and more,

Till he became

Most poore:

With thee

O let me rise

As larks, harmoniously,

And sing this day thy victories:

Then shall the fall further the flight in me.

:::space

My tender age in sorrow did beginne:

And still with sicknesses and shame

Thou didst so punish sinne,

That I became

Most thinne.

With thee

Let me combine,

And feel this day thy victorie:

For, if I imp my wing on thine,

Affliction shall advance the flight in me.

:::pagebreak

### Herbert’s motto

*Lesse then the least of Gods mercies.*

:::space

With it, his printers wrote, he used to conclude “all things that might seem to tend any way to his own honour”.

:::space{lines=7}

### A note on the text

The poems keep the spelling of the first edition, printed at Cambridge in 1633. There “The Altar” stands upright on page 18, and the two stanzas of “Easter Wings” lie sideways on pages 34 and 35. Here they stand upright; give the booklet a quarter turn and each opens into a pair of wings.

:::space{lines=5}

Set in IM Fell English, English SC and Great Primer,

Igino Marini’s revivals of the types

John Fell gathered at Oxford.

Text from EEBO-TCP.
`; // content.<lang>.md, inlined by the Cookbook

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
// Every face the design uses. Layout measures with the browser's fonts, so the
// kit loads them from Fontsource before the first build.
const FONTS = {
  'IM Fell English': ['400', '400i'],
  'IM Fell Great Primer': ['400'],
  'IM Fell English SC': ['400'],
};

// ─── 4 · Build & show ───────────────────────────────────────────────────────
const doc = await buildDocumentWithFonts({ markdown }, config(), kitFonts(FONTS));
showPages(doc, { title: t({ en: 'Easter Wings and The Altar', es: 'Alas de Pascua y El altar' }) });

Kit · core, fonts, viewer: in jedem Rezept gleich · 224 Zeilen
// ─── 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 v3 ── the same in every recipe · postext.dev/cookbook
// Postext loads the faces a config asks for before layout (prepareFonts,
// buildDocumentWithFonts) and asks the kit for the files: Fontsource's, the
// files the PDF embeds too.

/** The options of buildDocumentWithFonts / prepareFonts / withLoadedFonts:
 *  the Fontsource resolver, and the faces of FONTS loaded with the ones the
 *  config names. FONTS = { 'Family Name': ['400', '400i', '700'] }. */
function kitFonts(FONTS = {}) {
  const faces = Object.entries(FONTS).flatMap(([family, specs]) => specs.map((spec) =>
    ({ family, weight: parseInt(spec, 10), style: spec.endsWith('i') ? 'italic' : 'normal' })));
  return { resolve: fontsourceResolver, faces };
}

/** A face's Fontsource files, in a fixed order: latin, then latin-ext and greek
 *  when `text` needs them and the family ships them (kitSubsetsFor), each with
 *  its unicode-range. Null for a weight or slant Fontsource does not ship. */
async function fontsourceResolver(family, weight, style, { text = '' } = {}) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  if (meta && !(meta.weights.includes(weight) && meta.styles.includes(style))) return null;
  kitStatus('Loading fonts…');
  const at = await fontsourceAt(id);
  return ['latin', ...kitSubsetsFor(text, meta)].map((subset) => ({
    source: `${at}files/${id}-${subset}-${weight}-${style}.woff2`,
    unicodeRange: kitRanges()[subset],
  }));
}

/** The unicode-range of each Fontsource file the kit loads (a function: the
 *  kit is inlined after the pen's code, which runs before a const would be set). */
function kitRanges() {
  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',
  };
}

/** For the cjk, arabic and comics blocks, which add their own files: the
 *  faces of `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.
 *  The files are added once all have loaded, in the order asked (latin, then
 *  latin-ext, then greek), whatever order they arrive in: the last one added
 *  wins a character two files hold. Resolves to the number of faces added. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = kitRanges();
  const jobs = [];
  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 at = fontsourceAt(id);
    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 = `${await at}files/${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().catch(() => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  const ready = await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return ready.filter((face) => face && document.fonts.add(face)).length;
}

/** 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, '-'); }

/** A package's folder at the one version @5 names now (#766). */
function fontsourceAt(id, u = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@`) {
  return (fontsourceAt.c ??= {})[id] ??= fetch(u + '5/package.json').then((r) => r.json())
    .then((p) => p.version || 5, () => 5).then((v) => `${u}${v}/`);
}

/** 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 v2 ── 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. Other options go to renderPageToCanvas. */
function showPages(docs, { title, width = 460, ...render } = {}) {
  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, { ...render, 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 ───────────────────────────────────────────────────────────────────────