Processing fallback fonts in the correct order

packages/excalidraw/components/FontPicker/FontPickerList.tsx

@@ -66,11 +66,11 @@ export const FontPickerList = React.memo(
           .filter(
             ([_, { metadata }]) => !metadata.serverSide && !metadata.fallback,
           )
-          .map(([familyId, { metadata, fonts }]) => {
+          .map(([familyId, { metadata, fontFaces }]) => {
             const fontDescriptor = {
               value: familyId,
               icon: metadata.icon ?? FontFamilyNormalIcon,
-              text: fonts[0].fontFace.family,
+              text: fontFaces[0]?.fontFace?.family ?? "Unknown",
             };
 
             if (metadata.deprecated) {

packages/excalidraw/constants.ts

@@ -114,6 +114,9 @@ export const CLASSES = {
   SHAPE_ACTIONS_MENU: "App-menu__left",
 };
 
+export const CHINESE_HANDWRITTEN_FALLBACK_FONT = "Xiaolai";
+export const WINDOWS_EMOJI_FALLBACK_FONT = "Segoe UI Emoji";
+
 /**
  * // TODO: shouldn't be really `const`, likely neither have integers as values, due to value for the custom fonts, which should likely be some hash.
  *
@@ -133,7 +136,17 @@ export const FONT_FAMILY = {
   "Comic Shanns": 8,
   "Liberation Sans": 9,
   // from here on fallback fonts only
-  Xiaolai: 1000,
+  [CHINESE_HANDWRITTEN_FALLBACK_FONT]: 1000,
+  [WINDOWS_EMOJI_FALLBACK_FONT]: 9999,
+};
+
+// TODO: perahaps could be specific per-family in the future
+export const FONT_FAMILY_FALLBACKS = {
+  string: `${CHINESE_HANDWRITTEN_FALLBACK_FONT}, ${WINDOWS_EMOJI_FALLBACK_FONT}`,
+  ordered: [
+    FONT_FAMILY[CHINESE_HANDWRITTEN_FALLBACK_FONT],
+    FONT_FAMILY[WINDOWS_EMOJI_FALLBACK_FONT],
+  ],
 };
 
 export const THEME = {
@@ -157,10 +170,6 @@ export const FRAME_STYLE = {
   nameLineHeight: 1.25,
 };
 
-// TODO: consider adding a built-in fallback font for emojis
-export const WINDOWS_EMOJI_FALLBACK_FONT = "Segoe UI Emoji";
-export const CHINESE_HANDWRITTEN_FALLBACK_FONT = "Xiaolai";
-
 export const MIN_FONT_SIZE = 1;
 export const DEFAULT_FONT_SIZE = 20;
 export const DEFAULT_FONT_FAMILY: FontFamilyValues = FONT_FAMILY.Excalifont;

packages/excalidraw/fonts/ExcalidrawFontFace.ts

@@ -3,31 +3,30 @@ import { LOCAL_FONT_PROTOCOL } from "./metadata";
 import loadWoff2 from "./wasm/woff2.loader";
 import loadHbSubset from "./wasm/hb-subset.loader";
 
-export interface Font {
+export interface IExcalidrawFontFace {
   urls: URL[];
   fontFace: FontFace;
-  getContent(codePoints: ReadonlySet<number>): Promise<string>;
+  toCSS(
+    characters: string,
+    codePoints: Set<number>,
+  ): Promise<string> | undefined;
 }
-export const UNPKG_FALLBACK_URL = `https://unpkg.com/${
-  import.meta.env.VITE_PKG_NAME
-    ? `${import.meta.env.VITE_PKG_NAME}@${import.meta.env.PKG_VERSION}` // should be provided by vite during package build
-    : "@excalidraw/excalidraw" // fallback to latest package version (i.e. for app)
-}/dist/prod/`;
 
-export interface ExcalidrawFontFace {
+export class ExcalidrawFontFace implements IExcalidrawFontFace {
-  uri: string;
-  descriptors?: FontFaceDescriptors;
-};
-
-export class ExcalidrawFont implements Font {
   public readonly urls: URL[];
   public readonly fontFace: FontFace;
 
+  private static readonly UNPKG_FALLBACK_URL = `https://unpkg.com/${
+    import.meta.env.VITE_PKG_NAME
+      ? `${import.meta.env.VITE_PKG_NAME}@${import.meta.env.PKG_VERSION}` // should be provided by vite during package build
+      : "@excalidraw/excalidraw" // fallback to latest package version (i.e. for app)
+  }/dist/prod/`;
+
   constructor(family: string, uri: string, descriptors?: FontFaceDescriptors) {
-    this.urls = ExcalidrawFont.createUrls(uri);
+    this.urls = ExcalidrawFontFace.createUrls(uri);
 
     const sources = this.urls
-      .map((url) => `url(${url}) ${ExcalidrawFont.getFormat(url)}`)
+      .map((url) => `url(${url}) ${ExcalidrawFontFace.getFormat(url)}`)
       .join(", ");
 
     this.fontFace = new FontFace(family, sources, {
@@ -38,6 +37,41 @@ export class ExcalidrawFont implements Font {
     });
   }
 
+  /**
+   * Generates CSS `@font-face` definition with the (subsetted) font source as a data url for the characters within the unicode range.
+   *
+   * Retrieves `undefined` otherwise.
+   */
+  public toCSS(
+    characters: string,
+    codePoints: Set<number>,
+  ): Promise<string> | undefined {
+    const unicodeRangeRegex = this.fontFace.unicodeRange
+      .split(", ")
+      .map((range) => {
+        const [start, end] = range.replace("U+", "").split("-");
+        if (end) {
+          return `\\u${start}-\\u${end}`;
+        }
+        return `\\u${start}`;
+      })
+      .join("");
+
+    if (!new RegExp(`[${unicodeRangeRegex}]`).exec(characters)) {
+      // quick exit, so that this does not count as a pending promsie
+      return;
+    }
+
+    return new Promise<string>((resolve) => {
+      this.getContent(codePoints).then((content) => {
+        resolve(`@font-face {
+          font-family: ${this.fontFace.family};
+          src: url(${content});
+        }`);
+      });
+    });
+  }
+
   /**
    * Tries to fetch woff2 content, based on the registered urls (from first to last, treated as fallbacks).
    *
@@ -45,29 +79,29 @@ export class ExcalidrawFont implements Font {
    *
    * @returns base64 with subsetted glyphs based on the passed codepoint, last defined url otherwise
    */
-  public async getContent(codePoints: ReadonlySet<number>): Promise<string> {
+  private async getContent(codePoints: ReadonlySet<number>): Promise<string> {
     let i = 0;
     const errorMessages = [];
 
     while (i < this.urls.length) {
       const url = this.urls[i];
 
-      // it's dataurl (server), the font is inlined as base64, no need to fetch
-      if (url.protocol === "data:") {
-        const arrayBuffer = Buffer.from(
-          url.toString().split(",")[1],
-          "base64",
-        ).buffer;
-
-        const base64 = await ExcalidrawFont.subsetGlyphsByCodePoints(
-          arrayBuffer,
-          codePoints,
-        );
-
-        return base64;
-      }
-
       try {
+        // it's dataurl (server), the font is inlined as base64, no need to fetch
+        if (url.protocol === "data:") {
+          const arrayBuffer = Buffer.from(
+            url.toString().split(",")[1],
+            "base64",
+          ).buffer;
+
+          const base64 = await ExcalidrawFontFace.subsetGlyphsByCodePoints(
+            arrayBuffer,
+            codePoints,
+          );
+
+          return base64;
+        }
+
         const response = await fetch(url, {
           headers: {
             Accept: "font/woff2",
@@ -76,7 +110,7 @@ export class ExcalidrawFont implements Font {
 
         if (response.ok) {
           const arrayBuffer = await response.arrayBuffer();
-          const base64 = await ExcalidrawFont.subsetGlyphsByCodePoints(
+          const base64 = await ExcalidrawFontFace.subsetGlyphsByCodePoints(
             arrayBuffer,
             codePoints,
           );
@@ -128,11 +162,11 @@ export class ExcalidrawFont implements Font {
       const subsetSnft = subset(decompressedBinary, codePoints);
       const compressedBinary = compress(subsetSnft.buffer);
 
-      return ExcalidrawFont.toBase64(compressedBinary.buffer);
+      return ExcalidrawFontFace.toBase64(compressedBinary.buffer);
     } catch (e) {
       console.error("Skipped glyph subsetting", e);
       // Fallback to encoding whole font in case of errors
-      return ExcalidrawFont.toBase64(arrayBuffer);
+      return ExcalidrawFontFace.toBase64(arrayBuffer);
     }
   }
 
@@ -178,7 +212,7 @@ export class ExcalidrawFont implements Font {
     }
 
     // fallback url for bundled fonts
-    urls.push(new URL(assetUrl, UNPKG_FALLBACK_URL));
+    urls.push(new URL(assetUrl, ExcalidrawFontFace.UNPKG_FALLBACK_URL));
 
     return urls;
   }

packages/excalidraw/fonts/index.ts

@@ -10,12 +10,11 @@ import { isTextElement } from "../element";
 import { getFontString } from "../utils";
 import { FONT_FAMILY } from "../constants";
 import { FONT_METADATA, type FontMetadata } from "./metadata";
-import {
-  ExcalidrawFont,
-  type ExcalidrawFontFace,
-  type Font,
-} from "./ExcalidrawFont";
 import { getContainerElement } from "../element/textElement";
+import {
+  ExcalidrawFontFace,
+  type IExcalidrawFontFace,
+} from "./ExcalidrawFontFace";
 import { CascadiaFontFaces } from "./woff2/Cascadia";
 import { ComicFontFaces } from "./woff2/Comic";
 import { ExcalifontFontFaces } from "./woff2/Excalifont";
@@ -25,6 +24,7 @@ import { LilitaFontFaces } from "./woff2/Lilita";
 import { NunitoFontFaces } from "./woff2/Nunito";
 import { VirgilFontFaces } from "./woff2/Virgil";
 import { XiaolaiFontFaces } from "./woff2/Xiaolai";
+import { EmojiFontFaces } from "./woff2/Emoji";
 
 export class Fonts {
   // it's ok to track fonts across multiple instances only once, so let's use
@@ -36,7 +36,7 @@ export class Fonts {
         number,
         {
           metadata: FontMetadata;
-          fonts: Font[];
+          fontFaces: IExcalidrawFontFace[];
         }
       >
     | undefined;
@@ -148,13 +148,13 @@ export class Fonts {
     fontFamilies: Array<ExcalidrawTextElement["fontFamily"]>,
   ) {
     // add all registered font faces into the `document.fonts` (if not added already)
-    for (const { fonts, metadata } of Fonts.registered.values()) {
+    for (const { fontFaces, metadata } of Fonts.registered.values()) {
       // skip registering font faces for local fonts (i.e. Helvetica)
       if (metadata.local) {
         continue;
       }
 
-      for (const { fontFace } of fonts) {
+      for (const { fontFace } of fontFaces) {
         if (!window.document.fonts.has(fontFace)) {
           window.document.fonts.add(fontFace);
         }
@@ -179,7 +179,7 @@ export class Fonts {
             console.error(
               `Failed to load font "${fontString}" from urls "${Fonts.registered
                 .get(fontFamily)
-                ?.fonts.map((x) => x.urls)}"`,
+                ?.fontFaces.map((x) => x.urls)}"`,
               e,
             );
           }
@@ -199,17 +199,17 @@ export class Fonts {
     const fonts = {
       registered: new Map<
         ValueOf<typeof FONT_FAMILY>,
-        { metadata: FontMetadata; fonts: Font[] }
+        { metadata: FontMetadata; fontFaces: IExcalidrawFontFace[] }
       >(),
     };
 
     const init = (
       family: keyof typeof FONT_FAMILY,
-      ...fontFaces: ExcalidrawFontFace[]
+      ...fontFacesDescriptors: ExcalidrawFontFaceDescriptor[]
     ) => {
       const metadata = FONT_METADATA[FONT_FAMILY[family]];
 
-      register.call(fonts, family, metadata, ...fontFaces);
+      register.call(fonts, family, metadata, ...fontFacesDescriptors);
     };
 
     init("Cascadia", ...CascadiaFontFaces);
@@ -222,7 +222,10 @@ export class Fonts {
     init("Lilita One", ...LilitaFontFaces);
     init("Nunito", ...NunitoFontFaces);
     init("Virgil", ...VirgilFontFaces);
+
+    // fallback font faces
     init("Xiaolai", ...XiaolaiFontFaces);
+    init("Segoe UI Emoji", ...EmojiFontFaces);
 
     Fonts._initialized = true;
 
@@ -248,7 +251,7 @@ export class Fonts {
  *
  * @param family font family
  * @param metadata font metadata
- * @param faces font faces
+ * @param fontFacesDecriptors font faces descriptors
  */
 function register(
   this:
@@ -256,12 +259,12 @@ function register(
     | {
         registered: Map<
           ValueOf<typeof FONT_FAMILY>,
-          { metadata: FontMetadata; fonts: Font[] }
+          { metadata: FontMetadata; fontFaces: IExcalidrawFontFace[] }
         >;
       },
   family: string,
   metadata: FontMetadata,
-  ...faces: ExcalidrawFontFace[]
+  ...fontFacesDecriptors: ExcalidrawFontFaceDescriptor[]
 ) {
   // TODO: likely we will need to abandon number "id" in order to support custom fonts
   const familyId = FONT_FAMILY[family as keyof typeof FONT_FAMILY];
@@ -270,8 +273,9 @@ function register(
   if (!registeredFamily) {
     this.registered.set(familyId, {
       metadata,
-      fonts: faces.map(
+      fontFaces: fontFacesDecriptors.map(
-        ({ uri, descriptors }) => new ExcalidrawFont(family, uri, descriptors),
+        ({ uri, descriptors }) =>
+          new ExcalidrawFontFace(family, uri, descriptors),
       ),
     });
   }
@@ -309,3 +313,8 @@ export const getLineHeight = (fontFamily: FontFamilyValues) => {
 
   return lineHeight as ExcalidrawTextElement["lineHeight"];
 };
+
+export interface ExcalidrawFontFaceDescriptor {
+  uri: string;
+  descriptors?: FontFaceDescriptors;
+}

packages/excalidraw/fonts/metadata.ts

@@ -119,6 +119,17 @@ export const FONT_METADATA: Record<number, FontMetadata> = {
     },
     fallback: true,
   },
+  [FONT_FAMILY["Segoe UI Emoji"]]: {
+    metrics: {
+      // reusing Excalifont metrics
+      unitsPerEm: 1000,
+      ascender: 886,
+      descender: -374,
+      lineHeight: 1.25,
+    },
+    local: true,
+    fallback: true,
+  },
 };
 
 /** Unicode ranges defined by google fonts */

packages/excalidraw/fonts/woff2/Cascadia/index.ts

@@ -1,7 +1,7 @@
 import CascadiaCodeRegular from "./CascadiaCode-Regular.woff2";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const CascadiaFontFaces: ExcalidrawFontFace[] = [
+export const CascadiaFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: CascadiaCodeRegular,
   },

packages/excalidraw/fonts/woff2/Comic/index.ts

@@ -1,7 +1,7 @@
 import ComicShannsRegular from "./ComicShanns-Regular.woff2";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const ComicFontFaces: ExcalidrawFontFace[] = [
+export const ComicFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: ComicShannsRegular,
   },

packages/excalidraw/fonts/woff2/Emoji/index.ts

@@ -0,0 +1,8 @@
+import { LOCAL_FONT_PROTOCOL } from "../../metadata";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
+
+export const EmojiFontFaces: ExcalidrawFontFaceDescriptor[] = [
+  {
+    uri: LOCAL_FONT_PROTOCOL,
+  },
+];

packages/excalidraw/fonts/woff2/Excalifont/index.ts

@@ -1,7 +1,7 @@
 import Excalifont from "./Excalifont-Regular.woff2";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const ExcalifontFontFaces: ExcalidrawFontFace[] = [
+export const ExcalifontFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: Excalifont,
   },

packages/excalidraw/fonts/woff2/Helvetica/index.ts

@@ -1,7 +1,7 @@
 import { LOCAL_FONT_PROTOCOL } from "../../metadata";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const HelveticaFontFaces: ExcalidrawFontFace[] = [
+export const HelveticaFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: LOCAL_FONT_PROTOCOL,
   },

packages/excalidraw/fonts/woff2/Liberation/index.ts

@@ -1,7 +1,7 @@
 import LiberationSansRegular from "./LiberationSans-Regular.woff2";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const LiberationFontFaces: ExcalidrawFontFace[] = [
+export const LiberationFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: LiberationSansRegular,
   },

packages/excalidraw/fonts/woff2/Lilita/index.ts

@@ -2,9 +2,9 @@ import LilitaLatin from "https://fonts.gstatic.com/s/lilitaone/v15/i7dPIFZ9Zz-WB
 import LilitaLatinExt from "https://fonts.gstatic.com/s/lilitaone/v15/i7dPIFZ9Zz-WBtRtedDbYE98RXi4EwSsbg.woff2";
 
 import { GOOGLE_FONTS_RANGES } from "../../metadata";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const LilitaFontFaces: ExcalidrawFontFace[] = [
+export const LilitaFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: LilitaLatinExt,
     descriptors: { unicodeRange: GOOGLE_FONTS_RANGES.LATIN_EXT },

packages/excalidraw/fonts/woff2/Nunito/index.ts

@@ -5,9 +5,9 @@ import CyrilicExt from "https://fonts.gstatic.com/s/nunito/v26/XRXI3I6Li01BKofiO
 import Vietnamese from "https://fonts.gstatic.com/s/nunito/v26/XRXI3I6Li01BKofiOc5wtlZ2di8HDIkhdTs3j6zbXWjgevT5.woff2";
 
 import { GOOGLE_FONTS_RANGES } from "../../metadata";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const NunitoFontFaces: ExcalidrawFontFace[] = [
+export const NunitoFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: CyrilicExt,
     descriptors: {

packages/excalidraw/fonts/woff2/Virgil/index.ts

@@ -1,7 +1,7 @@
 import Virgil from "./Virgil-Regular.woff2";
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
-export const VirgilFontFaces: ExcalidrawFontFace[] = [
+export const VirgilFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: Virgil,
   },

packages/excalidraw/fonts/woff2/Xiaolai/index.ts

@@ -218,7 +218,7 @@ import _213 from "./31dc7ab58ea136b7dca23037305e023b.woff2";
 import _214 from "./d53f5bd45db0e96874d1174341701b59.woff2";
 import _215 from "./6fe856ceea3ef870142b02ddecc1b006.woff2";
 
-import type { ExcalidrawFontFace } from "../../ExcalidrawFont";
+import { type ExcalidrawFontFaceDescriptor } from "../..";
 
 /* Generated By cn-font-split@5.2.1 https://www.npmjs.com/package/cn-font-split
 CreateTime: Thu, 22 Aug 2024 10:58:35 GMT;
@@ -240,7 +240,7 @@ licenseURL: http://scripts.sil.org/OFL
 */
 
 // TODO_CHINESE: consider having import for each (to automate build step)
-export const XiaolaiFontFaces: ExcalidrawFontFace[] = [
+export const XiaolaiFontFaces: ExcalidrawFontFaceDescriptor[] = [
   {
     uri: _0,
     descriptors: {

packages/excalidraw/package.json

@@ -67,6 +67,7 @@
     "canvas-roundrect-polyfill": "0.0.1",
     "clsx": "1.1.1",
     "cross-env": "7.0.3",
+    "es6-promise-pool": "2.5.0",
     "fractional-indexing": "3.2.0",
     "fuzzy": "0.1.3",
     "image-blob-reduce": "3.0.1",

packages/excalidraw/scene/export.ts

@@ -9,7 +9,13 @@ import type {
 import type { Bounds } from "../element/bounds";
 import { getCommonBounds, getElementAbsoluteCoords } from "../element/bounds";
 import { renderSceneToSvg } from "../renderer/staticSvgScene";
-import { arrayToMap, distance, getFontString, toBrandedType } from "../utils";
+import {
+  arrayToMap,
+  distance,
+  getFontString,
+  PromisePool,
+  toBrandedType,
+} from "../utils";
 import type { AppState, BinaryFiles } from "../types";
 import {
   DEFAULT_EXPORT_PADDING,
@@ -18,6 +24,7 @@ import {
   SVG_NS,
   THEME,
   THEME_FILTER,
+  FONT_FAMILY_FALLBACKS,
 } from "../constants";
 import { getDefaultAppState } from "../appState";
 import { serializeAsJSON } from "../data/json";
@@ -39,7 +46,6 @@ import type { RenderableElementsMap } from "./types";
 import { syncInvalidIndices } from "../fractionalIndex";
 import { renderStaticScene } from "../renderer/staticScene";
 import { Fonts } from "../fonts";
-import type { Font } from "../fonts/ExcalidrawFont";
 
 const SVG_EXPORT_TAG = `<!-- svg-source:excalidraw -->`;
 
@@ -439,6 +445,7 @@ const getFontFaces = async (
   elements: readonly ExcalidrawElement[],
 ): Promise<string[]> => {
   const fontFamilies = new Set<number>();
+  const characters = new Set<string>();
   const codePoints = new Set<number>();
 
   for (const element of elements) {
@@ -449,52 +456,85 @@ const getFontFaces = async (
     fontFamilies.add(element.fontFamily);
 
     // gather unique codepoints only when inlining fonts
-    for (const codePoint of Array.from(element.originalText, (u) =>
+    for (const char of element.originalText) {
-      u.codePointAt(0),
+      if (!characters.has(char)) {
-    )) {
+        characters.add(char);
-      if (codePoint) {
+        codePoints.add(char.codePointAt(0)!);
-        codePoints.add(codePoint);
       }
     }
   }
 
-  const getSource = (font: Font) => {
+  const uniqueChars = Array.from(characters).join("");
-    try {
-      // retrieve font source as dataurl based on the used codepoints
-      return font.getContent(codePoints);
-    } catch {
-      // fallback to font source as a url
-      return font.urls[0].toString();
-    }
-  };
 
-  const fontFaces = await Promise.all(
+  // quick check for Han (might match a bit more, but that's fine)
-    Array.from(fontFamilies).map(async (x) => {
+  if (uniqueChars.match(/\p{Script=Han}/u)) {
-      const { fonts, metadata } = Fonts.registered.get(x) ?? {};
+    fontFamilies.add(FONT_FAMILY.Xiaolai);
+  }
 
-      if (!Array.isArray(fonts)) {
+  const iterator = fontFacesIterator(fontFamilies, uniqueChars, codePoints);
-        console.error(
-          `Couldn't find registered fonts for font-family "${x}"`,
-          Fonts.registered,
-        );
-        return [];
-      }
 
-      if (metadata?.local) {
+  // don't trigger hundreds/thousands of concurrent requests, instead go 3 requests at a time, in a controlled manner
-        // don't inline local fonts
+  // in other words, does not block the main thread and avoids related issues, including potential rate limits
-        return [];
+  const concurrency = 3;
-      }
+  const fontFaces = await new PromisePool(iterator, concurrency).all();
 
-      return Promise.all(
+  // dedup just in case (i.e. could be the same font faces with 0 glyphs)
-        fonts.map(
+  return Array.from(new Set(fontFaces));
-          async (font) => `@font-face {
-        font-family: ${font.fontFace.family};
-        src: url(${await getSource(font)});
-          }`,
-        ),
-      );
-    }),
-  );
-
-  return fontFaces.flat();
 };
+
+function* fontFacesIterator(
+  families: Set<number>,
+  characters: string,
+  codePoints: Set<number>,
+): Generator<Promise<[number, string]>> {
+  // the order between the families is important, as fallbacks need to be defined first and in the reversed order
+  // so that they get overriden with the later defined font faces, i.e. in case they share some codepoints
+  const reversedFallbacks = Array.from(FONT_FAMILY_FALLBACKS.ordered).reverse();
+
+  for (const [familyIndex, family] of Array.from(families).entries()) {
+    const fallbackIndex = reversedFallbacks.findIndex(
+      (fallback) => fallback === family,
+    );
+
+    let order: number;
+
+    if (fallbackIndex !== -1) {
+      // making sure the fallback fonts are defined first
+      order = fallbackIndex;
+    } else {
+      // making sure the built-in font faces are always defined after fallback fonts
+      order = FONT_FAMILY_FALLBACKS.ordered.length + familyIndex;
+    }
+
+    // making a safe buffer in between the families, assuming there won't be more than 10k font faces per family
+    order *= 10_000;
+
+    const { fontFaces, metadata } = Fonts.registered.get(family) ?? {};
+
+    if (!Array.isArray(fontFaces)) {
+      console.error(
+        `Couldn't find registered fonts for font-family "${family}"`,
+        Fonts.registered,
+      );
+      continue;
+    }
+
+    if (metadata?.local) {
+      // don't inline local fonts
+      continue;
+    }
+
+    for (const [fontFaceIndex, fontFace] of fontFaces.entries()) {
+      const pendingFontFace = fontFace.toCSS(characters, codePoints);
+
+      // so that we don't add undefined to the pool
+      if (pendingFontFace) {
+        yield new Promise(async (resolve) => {
+          const promiseIndex = order + fontFaceIndex;
+          const fontFaceCSS = await pendingFontFace;
+          resolve([promiseIndex, fontFaceCSS]);
+        });
+      }
+    }
+  }
+}

packages/excalidraw/utils.ts

@@ -1,9 +1,10 @@
+import Pool from "es6-promise-pool";
 import { COLOR_PALETTE } from "./colors";
 import type { EVENT } from "./constants";
 import {
-  CHINESE_HANDWRITTEN_FALLBACK_FONT,
   DEFAULT_VERSION,
   FONT_FAMILY,
+  FONT_FAMILY_FALLBACKS,
   isDarwin,
   WINDOWS_EMOJI_FALLBACK_FONT,
 } from "./constants";
@@ -89,8 +90,8 @@ export const getFontFamilyString = ({
 }) => {
   for (const [fontFamilyString, id] of Object.entries(FONT_FAMILY)) {
     if (id === fontFamily) {
-      // TODO: we should fallback first to generic family names first, rather than directly to the emoji font
+      // TODO: we should fallback first to generic family names first
-      return `${fontFamilyString}, ${CHINESE_HANDWRITTEN_FALLBACK_FONT}, ${WINDOWS_EMOJI_FALLBACK_FONT}`;
+      return `${fontFamilyString}, ${FONT_FAMILY_FALLBACKS.string}`;
     }
   }
   return WINDOWS_EMOJI_FALLBACK_FONT;
@@ -1167,3 +1168,43 @@ export const promiseTry = async <TValue, TArgs extends unknown[]>(
 
 export const isAnyTrue = (...args: boolean[]): boolean =>
   Math.max(...args.map((arg) => (arg ? 1 : 0))) > 0;
+
+// extending the missing types
+// relying on the [Index, T] to keep a correct order
+type TPromisePool<T, Index = number> = Pool<[Index, T][]> & {
+  addEventListener: (
+    type: "fulfilled",
+    listener: (event: { data: { result: [Index, T] } }) => void,
+  ) => (event: { data: { result: [Index, T] } }) => void;
+  removeEventListener: (
+    type: "fulfilled",
+    listener: (event: { data: { result: [Index, T] } }) => void,
+  ) => void;
+};
+
+export class PromisePool<T> {
+  private readonly pool: TPromisePool<T>;
+  private readonly entries: Record<number, T> = {};
+
+  constructor(
+    source: IterableIterator<Promise<[number, T]>>,
+    concurrency: number,
+  ) {
+    this.pool = new Pool(
+      source as unknown as () => void | PromiseLike<[number, T][]>,
+      concurrency,
+    ) as TPromisePool<T>;
+  }
+
+  public all() {
+    const listener = this.pool.addEventListener("fulfilled", (event) => {
+      const [index, value] = event.data.result;
+      this.entries[index] = value;
+    });
+
+    return this.pool.start().then(() => {
+      setTimeout(() => this.pool.removeEventListener("fulfilled", listener));
+      return Object.values(this.entries);
+    });
+  }
+}

yarn.lock

@@ -5521,6 +5521,11 @@ es-to-primitive@^1.2.1:
     is-date-object "^1.0.1"
     is-symbol "^1.0.2"
 
+es6-promise-pool@2.5.0:
+  version "2.5.0"
+  resolved "https://registry.yarnpkg.com/es6-promise-pool/-/es6-promise-pool-2.5.0.tgz#147c612b36b47f105027f9d2bf54a598a99d9ccb"
+  integrity sha512-VHErXfzR/6r/+yyzPKeBvO0lgjfC5cbDCQWjWwMZWSb6YU39TGIl51OUmCfWCq4ylMdJSB8zkz2vIuIeIxXApA==
+
 esbuild-plugin-external-global@1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/esbuild-plugin-external-global/-/esbuild-plugin-external-global-1.0.1.tgz#e3bba0e3a561f61b395bec0984a90ed0de06c4ce"