Added emoji support to Satori when generating OG images

quartz/components/Head.tsx

@@ -4,6 +4,7 @@ import { CSSResourceToStyleElement, JSResourceToScriptElement } from "../util/re
 import { googleFontHref } from "../util/theme"
 import { QuartzComponent, QuartzComponentConstructor, QuartzComponentProps } from "./types"
 import satori, { SatoriOptions } from "satori"
+import { loadEmoji, getIconCode } from "../util/emoji"
 import fs from "fs"
 import sharp from "sharp"
 import { ImageOptions, SocialImageOptions, getSatoriFont, defaultImage } from "../util/og"
@@ -24,7 +25,18 @@ async function generateSocialImage(
   // JSX that will be used to generate satori svg
   const imageComponent = userOpts.imageStructure(cfg, userOpts, title, description, fonts, fileData)
 
-  const svg = await satori(imageComponent, { width, height, fonts })
+  const svg = await satori(imageComponent, { width, height, fonts,
+    // `code` will be the detected language code, `emoji` if it's an Emoji, or `unknown` if not able to tell.
+    // `segment` will be the content to render.
+    loadAdditionalAsset: async (code: string, segment: string) => {
+      if (code === "emoji") {
+        // if segment is an emoji, load the image.
+        return `data:image/svg+xml;base64,${btoa(await loadEmoji("twemoji", getIconCode(segment)))}`
+      }
+      // if segment is normal text
+      return code
+    },
+  })
 
   // Convert svg directly to webp (with additional compression)
   const compressed = await sharp(Buffer.from(svg)).webp({ quality: 40 }).toBuffer()

quartz/util/emoji.ts

@@ -0,0 +1,66 @@
+/**
+ * Modified version of https://unpkg.com/[email protected]/dist/twemoji.esm.js.
+ * Ported from https://github.com/vercel/satori/blob/48aea6f812365959c2888a25261c72ce17992c6d/playground/utils/twemoji.ts.
+ */
+
+/*! Copyright Twitter Inc. and other contributors. Licensed under MIT */
+
+const U200D = String.fromCharCode(8205)
+const UFE0Fg = /\uFE0F/g
+
+export function getIconCode(char: string) {
+  return toCodePoint(char.indexOf(U200D) < 0 ? char.replace(UFE0Fg, "") : char)
+}
+
+function toCodePoint(unicodeSurrogates: string) {
+  const r = []
+  let c = 0,
+    p = 0,
+    i = 0
+
+  while (i < unicodeSurrogates.length) {
+    c = unicodeSurrogates.charCodeAt(i++)
+    if (p) {
+      r.push((65536 + ((p - 55296) << 10) + (c - 56320)).toString(16))
+      p = 0
+    } else if (55296 <= c && c <= 56319) {
+      p = c
+    } else {
+      r.push(c.toString(16))
+    }
+  }
+  return r.join("-")
+}
+
+export const apis = {
+  twemoji: (code: string) =>
+    "https://cdnjs.cloudflare.com/ajax/libs/twemoji/15.1.0/svg/" + code.toLowerCase() + ".svg",
+  openmoji: "https://cdn.jsdelivr.net/npm/@svgmoji/[email protected]/svg/",
+  blobmoji: "https://cdn.jsdelivr.net/npm/@svgmoji/[email protected]/svg/",
+  noto: "https://cdn.jsdelivr.net/gh/svgmoji/svgmoji/packages/svgmoji__noto/svg/",
+  fluent: (code: string) =>
+    "https://cdn.jsdelivr.net/gh/shuding/fluentui-emoji-unicode/assets/" +
+    code.toLowerCase() +
+    "_color.svg",
+  fluentFlat: (code: string) =>
+    "https://cdn.jsdelivr.net/gh/shuding/fluentui-emoji-unicode/assets/" +
+    code.toLowerCase() +
+    "_flat.svg",
+}
+
+const emojiCache: Record<string, Promise<any>> = {}
+
+export function loadEmoji(type: keyof typeof apis, code: string) {
+  const key = type + ":" + code
+  if (key in emojiCache) return emojiCache[key]
+
+  if (!type || !apis[type]) {
+    type = "twemoji"
+  }
+
+  const api = apis[type]
+  if (typeof api === "function") {
+    return (emojiCache[key] = fetch(api(code)).then((r) => r.text()))
+  }
+  return (emojiCache[key] = fetch(`${api}${code.toUpperCase()}.svg`).then((r) => r.text()))
+}