torqvoice/scripts/generate-font-widths.mjs

/**
 * Regenerates src/features/invoice-designer/Pdf/fontWidths.ts from the TTFs
 * the PDFs embed, so text can be wrapped identically on server and client
 * without loading font files at runtime. Run: node scripts/generate-font-widths.mjs
 */
import { createRequire } from 'node:module'
import { readFileSync, writeFileSync } from 'node:fs'
import path from 'node:path'

const require = createRequire(import.meta.url)
const fontkit = require('fontkit')

const FONTS = [
  ['Helvetica', 'Roboto-Regular.ttf', 'Roboto-Bold.ttf'],
  ['Times-Roman', 'NotoSerif-Regular.ttf', 'NotoSerif-Bold.ttf'],
  ['Courier', 'NotoSansMono-Regular.ttf', 'NotoSansMono-Bold.ttf'],
  ['Open Sans', 'OpenSans-Regular.ttf', 'OpenSans-Bold.ttf'],
  ['Lato', 'Lato-Regular.ttf', 'Lato-Bold.ttf'],
  ['Montserrat', 'Montserrat-Regular.ttf', 'Montserrat-Bold.ttf'],
  ['PT Sans', 'PTSans-Regular.ttf', 'PTSans-Bold.ttf'],
]

// ASCII plus the Latin-1/Latin Extended and Cyrillic ranges the app's locales use.
const CHARS = []
for (let c = 0x20; c <= 0x7e; c++) CHARS.push(c)
for (let c = 0xa0; c <= 0x17f; c++) CHARS.push(c)
for (const c of [0x2013, 0x2014, 0x2018, 0x2019, 0x201c, 0x201d, 0x2022, 0x20ac, 0xb7]) CHARS.push(c)
for (let c = 0x400; c <= 0x45f; c++) CHARS.push(c)

const dir = path.resolve('src/assets/fonts')
const table = {}
for (const [family, regular, bold] of FONTS) {
  for (const [weight, file] of [['regular', regular], ['bold', bold]]) {
    const font = fontkit.create(readFileSync(path.join(dir, file)))
    const upm = font.unitsPerEm
    const widths = {}
    for (const code of CHARS) {
      if (!font.hasGlyphForCodePoint(code)) continue
      const glyph = font.glyphForCodePoint(code)
      widths[code] = Math.round((glyph.advanceWidth / upm) * 1000)
    }
    // A representative width for anything outside the table.
    const fallback = widths[0x6e] ?? 500 // 'n'
    table[`${family}|${weight}`] = { fallback, widths }
  }
}

const out = `/**
 * Character advance widths, in thousandths of the font size, for the exact
 * font files the PDFs embed. Generated by scripts/generate-font-widths.mjs —
 * do not edit by hand. This is what lets the server wrap text the same way
 * the printed page will, without opening a font file at runtime.
 */
export interface WidthTable {
  fallback: number
  widths: Record<number, number>
}

export const FONT_WIDTHS: Record<string, WidthTable> = ${JSON.stringify(table)}
`
writeFileSync('src/features/invoice-designer/Pdf/fontWidths.ts', out)
console.log('written', Object.keys(table).join(', '))