Update font avg

packages/font/src/google/loader.ts

@@ -1,17 +1,19 @@
 import type { AdjustFontFallback, FontLoader } from 'next/font'
 // @ts-ignore
-import { calculateSizeAdjustValues } from 'next/dist/server/font-utils'
-// @ts-ignore
 import * as Log from 'next/dist/build/output/log'
 // @ts-ignore
 import chalk from 'next/dist/compiled/chalk'
+// @ts-ignore
+// eslint-disable-next-line import/no-extraneous-dependencies
+import fontFromBuffer from '@next/font/dist/fontkit'
 import {
   fetchCSSFromGoogleFonts,
   fetchFontFile,
   getFontAxes,
   getUrl,
   validateData,
 } from './utils'
+import { calculateFallbackFontValues } from '../utils'
 
 const cssCache = new Map<string, Promise<string>>()
 const fontCache = new Map<string, any>()
@@ -64,6 +66,7 @@ const downloadGoogleFonts: FontLoader = async ({
   const fontFiles: Array<{
     googleFontFileUrl: string
     preloadFontFile: boolean
+    isLatin: boolean
   }> = []
   let currentSubset = ''
   for (const line of fontFaceDeclarations.split('\n')) {
@@ -78,17 +81,24 @@ const downloadGoogleFonts: FontLoader = async ({
           googleFontFileUrl,
           preloadFontFile:
             !!preload && (callSubsets ?? subsets).includes(currentSubset),
+          isLatin: currentSubset === 'latin',
         })
       }
     }
   }
 
   // Download font files
+  let latinFont: any
   const downloadedFiles = await Promise.all(
-    fontFiles.map(async ({ googleFontFileUrl, preloadFontFile }) => {
+    fontFiles.map(async ({ googleFontFileUrl, preloadFontFile, isLatin }) => {
       let cachedFontRequest = fontCache.get(googleFontFileUrl)
       const fontFileBuffer =
         cachedFontRequest ?? (await fetchFontFile(googleFontFileUrl))
+      if (isLatin) {
+        try {
+          latinFont = fontFromBuffer(fontFileBuffer)
+        } catch {}
+      }
       if (!cachedFontRequest) {
         fontCache.set(googleFontFileUrl, fontFileBuffer)
       } else {
@@ -121,19 +131,13 @@ const downloadGoogleFonts: FontLoader = async ({
 
   // Add fallback font
   let adjustFontFallbackMetrics: AdjustFontFallback | undefined
-  if (adjustFontFallback) {
+  if (adjustFontFallback && latinFont) {
     try {
-      const { ascent, descent, lineGap, fallbackFont, sizeAdjust } =
-        calculateSizeAdjustValues(
-          require('next/dist/server/google-font-metrics.json')[fontFamily]
-        )
-      adjustFontFallbackMetrics = {
-        fallbackFont,
-        ascentOverride: `${ascent}%`,
-        descentOverride: `${descent}%`,
-        lineGapOverride: `${lineGap}%`,
-        sizeAdjust: `${sizeAdjust}%`,
-      }
+      adjustFontFallbackMetrics = calculateFallbackFontValues(
+        latinFont,
+        require('next/dist/server/google-font-metrics.json')[fontFamily]
+          .category
+      )
     } catch {
       Log.error(
         `Failed to find font override values for font \`${fontFamily}\``

packages/font/src/google/utils.ts

@@ -1,3 +1,4 @@
+import fs from 'fs'
 // @ts-ignore
 import fetch from 'next/dist/compiled/node-fetch'
 import fontData from './font-data.json'
@@ -161,6 +162,9 @@ export async function fetchCSSFromGoogleFonts(url: string, fontFamily: string) {
 
 export async function fetchFontFile(url: string) {
   if (process.env.NEXT_FONT_GOOGLE_MOCKED_RESPONSES) {
+    if (url.startsWith('/')) {
+      return fs.readFileSync(url)
+    }
     return Buffer.from(url)
   }
   const arrayBuffer = await fetch(url).then((r: any) => r.arrayBuffer())

packages/font/src/local/loader.ts

@@ -1,12 +1,11 @@
 // @ts-ignore
-import { calculateSizeAdjustValues } from 'next/dist/server/font-utils'
-// @ts-ignore
 // eslint-disable-next-line import/no-extraneous-dependencies
 import fontFromBuffer from '@next/font/dist/fontkit'
 import type { AdjustFontFallback, FontLoader } from 'next/font'
 
 import { promisify } from 'util'
-import { calcAzWidth, validateData } from './utils'
+import { validateData } from './utils'
+import { calculateFallbackFontValues } from '../utils'
 
 const fetchFonts: FontLoader = async ({
   functionName,
@@ -44,29 +43,10 @@ const fetchFonts: FontLoader = async ({
   // Add fallback font
   let adjustFontFallbackMetrics: AdjustFontFallback | undefined
   if (fontMetadata && adjustFontFallback !== false) {
-    const {
-      ascent,
-      descent,
-      lineGap,
-      fallbackFont,
-      sizeAdjust: fallbackSizeAdjust,
-    } = calculateSizeAdjustValues({
-      category:
-        adjustFontFallback === 'Times New Roman' ? 'serif' : 'sans-serif',
-      ascent: fontMetadata.ascent,
-      descent: fontMetadata.descent,
-      lineGap: fontMetadata.lineGap,
-      unitsPerEm: fontMetadata.unitsPerEm,
-      xAvgCharWidth: (fontMetadata as any)['OS/2']?.xAvgCharWidth,
-      azAvgWidth: calcAzWidth(fontMetadata),
-    })
-    adjustFontFallbackMetrics = {
-      fallbackFont,
-      ascentOverride: `${ascent}%`,
-      descentOverride: `${descent}%`,
-      lineGapOverride: `${lineGap}%`,
-      sizeAdjust: `${fallbackSizeAdjust}%`,
-    }
+    adjustFontFallbackMetrics = calculateFallbackFontValues(
+      fontMetadata,
+      adjustFontFallback === 'Times New Roman' ? 'serif' : 'sans-serif'
+    )
   }
 
   const fontFaceProperties = [

packages/font/src/local/utils.ts

@@ -1,5 +1,3 @@
-import type { Font } from 'fontkit'
-
 const allowedDisplayValues = ['auto', 'block', 'swap', 'fallback', 'optional']
 
 const formatValues = (values: string[]) =>
@@ -93,12 +91,3 @@ export function validateData(functionName: string, data: any): FontOptions {
     declarations,
   }
 }
-
-// Calculating the a-z average width
-export function calcAzWidth(font: Font) {
-  const widths = font
-    .glyphsForString('abcdefghijklmnopqrstuvwxyz')
-    .map((glyph) => glyph.advanceWidth)
-  const totalWidth = widths.reduce((sum, width) => sum + width, 0)
-  return totalWidth / widths.length
-}

packages/font/src/utils.ts

@@ -0,0 +1,57 @@
+import type { Font } from 'fontkit'
+import type { AdjustFontFallback } from 'next/font'
+
+const DEFAULT_SANS_SERIF_FONT = {
+  name: 'Arial',
+  azAvgWidth: 934.5116279069767,
+  unitsPerEm: 2048,
+}
+const DEFAULT_SERIF_FONT = {
+  name: 'Times New Roman',
+  azAvgWidth: 854.3953488372093,
+  unitsPerEm: 2048,
+}
+
+function calcAverageWidth(font: Font): number | undefined {
+  const avgCharacters = 'aaabcdeeeefghiijklmnnoopqrrssttuvwxyz      '
+  const hasAllChars = font
+    .glyphsForString(avgCharacters)
+    .flatMap((glyph) => glyph.codePoints)
+    .every((codePoint) => font.hasGlyphForCodePoint(codePoint))
+
+  if (!hasAllChars) return undefined
+
+  const widths = font
+    .glyphsForString(avgCharacters)
+    .map((glyph) => glyph.advanceWidth)
+  const totalWidth = widths.reduce((sum, width) => sum + width, 0)
+  return totalWidth / widths.length
+}
+
+function formatOverrideValue(val: number) {
+  return Math.abs(val * 100).toFixed(2) + '%'
+}
+
+export function calculateFallbackFontValues(
+  font: Font,
+  category = 'serif'
+): AdjustFontFallback {
+  const fallbackFont =
+    category === 'serif' ? DEFAULT_SERIF_FONT : DEFAULT_SANS_SERIF_FONT
+
+  const azAvgWidth = calcAverageWidth(font)
+  const { ascent, descent, lineGap, unitsPerEm } = font
+
+  const fallbackFontAvgWidth = fallbackFont.azAvgWidth / fallbackFont.unitsPerEm
+  let sizeAdjust = azAvgWidth
+    ? azAvgWidth / unitsPerEm / fallbackFontAvgWidth
+    : 1
+
+  return {
+    ascentOverride: formatOverrideValue(ascent / (unitsPerEm * sizeAdjust)),
+    descentOverride: formatOverrideValue(descent / (unitsPerEm * sizeAdjust)),
+    lineGapOverride: formatOverrideValue(lineGap / (unitsPerEm * sizeAdjust)),
+    fallbackFont: fallbackFont.name,
+    sizeAdjust: formatOverrideValue(sizeAdjust),
+  }
+}

test/e2e/next-font/google-font-mocked-responses.js

@@ -1,3 +1,5 @@
+const path = require('path')
+
 module.exports = {
   'https://fonts.googleapis.com/css2?family=Open+Sans:wght@300..800&display=optional': `
 /* cyrillic-ext */
@@ -499,7 +501,10 @@ module.exports = {
     font-style: normal;
     font-weight: 400;
     font-display: optional;
-    src: url(https://fonts.gstatic.com/s/fraunces/v24/6NUh8FyLNQOQZAnv9bYEvDiIdE9Ea92uemAk_WBq8U_9v0c2Wa0K7iN7hzFUPJH58nib1603gg7S2nfgRYIctxuTBv7Tp05GNyXkb24.woff2) format('woff2');
+    src: url(${path.join(
+      __dirname,
+      './fonts/6NUh8FyLNQOQZAnv9bYEvDiIdE9Ea92uemAk_WBq8U_9v0c2Wa0K7iN7hzFUPJH58nib1603gg7S2nfgRYIctxuTBv7Tp05GNyXkb24.woff2'
+    )}) format('woff2');
     unicode-range: U+0102-0103, U+0110-0111, U+0128-0129, U+0168-0169, U+01A0-01A1, U+01AF-01B0, U+1EA0-1EF9, U+20AB;
   }
   /* latin-ext */
@@ -508,7 +513,10 @@ module.exports = {
     font-style: normal;
     font-weight: 400;
     font-display: optional;
-    src: url(https://fonts.gstatic.com/s/fraunces/v24/6NUh8FyLNQOQZAnv9bYEvDiIdE9Ea92uemAk_WBq8U_9v0c2Wa0K7iN7hzFUPJH58nib1603gg7S2nfgRYIctxuTB_7Tp05GNyXkb24.woff2) format('woff2');
+    src: url(${path.join(
+      __dirname,
+      './fonts/6NUh8FyLNQOQZAnv9bYEvDiIdE9Ea92uemAk_WBq8U_9v0c2Wa0K7iN7hzFUPJH58nib1603gg7S2nfgRYIctxuTB_7Tp05GNyXkb24.woff2'
+    )}) format('woff2');
     unicode-range: U+0100-024F, U+0259, U+1E00-1EFF, U+2020, U+20A0-20AB, U+20AD-20CF, U+2113, U+2C60-2C7F, U+A720-A7FF;
   }
   /* latin */
@@ -517,7 +525,10 @@ module.exports = {
     font-style: normal;
     font-weight: 400;
     font-display: optional;
-    src: url(https://fonts.gstatic.com/s/fraunces/v24/6NUh8FyLNQOQZAnv9bYEvDiIdE9Ea92uemAk_WBq8U_9v0c2Wa0K7iN7hzFUPJH58nib1603gg7S2nfgRYIctxuTCf7Tp05GNyXk.woff2) format('woff2');
+    src: url(${path.join(
+      __dirname,
+      './fonts/6NUh8FyLNQOQZAnv9bYEvDiIdE9Ea92uemAk_WBq8U_9v0c2Wa0K7iN7hzFUPJH58nib1603gg7S2nfgRYIctxuTCf7Tp05GNyXk.woff2'
+    )}) format('woff2');
     unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
   }`,
   'https://fonts.googleapis.com/css2?family=Indie+Flower:wght@400&display=optional': `/* latin */
@@ -526,7 +537,10 @@ module.exports = {
     font-style: normal;
     font-weight: 400;
     font-display: optional;
-    src: url(https://fonts.gstatic.com/s/indieflower/v17/m8JVjfNVeKWVnh3QMuKkFcZVaUuH99GUDg.woff2) format('woff2');
+    src: url(${path.join(
+      __dirname,
+      './fonts/m8JVjfNVeKWVnh3QMuKkFcZVaUuH99GUDg.woff2'
+    )}) format('woff2');
     unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
   }`,
 }