Move the compileFontInfo call into the Font.prototype.exportData method (PR 20197 follow-up)

After the changes in PR 20197 the code in the `TranslatedFont.prototype.send` method is not all that readable[1] given how it handles e.g. the `charProcOperatorList` data used with Type3 fonts.
Since this is the only spot where `Font.prototype.exportData` is used, it seems much simpler to move the `compileFontInfo` call there and *directly* return the intended data rather than messing with it after the fact.

Finally, while it doesn't really matter, the patch flips the order of the `charProcOperatorList` and `extra` properties throughout the code-base since the former is used with Type3 fonts while the latter (effectively) requires that debugging is enabled.

---

[1] I had to re-read it twice, also looking at all the involved methods, in order to convince myself that it's actually correct.

src/core/evaluator.js

@@ -32,7 +32,6 @@ import {
 import { CMapFactory, IdentityCMap } from "./cmap.js";
 import { Cmd, Dict, EOF, isName, Name, Ref, RefSet } from "./primitives.js";
 import {
-  compileFontInfo,
   compileFontPathInfo,
   compilePatternInfo,
 } from "./obj_bin_transform_core.js";
@@ -4804,16 +4803,11 @@ class TranslatedFont {
       return;
     }
     this.#sent = true;
-    const fontData = this.font.exportData();
-    const transfer = [];
-    if (fontData.data) {
-      if (fontData.data.charProcOperatorList) {
-        fontData.charProcOperatorList = fontData.data.charProcOperatorList;
-      }
-      fontData.data = compileFontInfo(fontData.data);
-      transfer.push(fontData.data);
-    }
-    handler.send("commonobj", [this.loadedName, "Font", fontData], transfer);
+
+    const fontData = this.font.exportData(),
+      transfers = fontData.buffer ? [fontData.buffer] : null;
+
+    handler.send("commonobj", [this.loadedName, "Font", fontData], transfers);
     // future path: switch to a SharedArrayBuffer
     // const sab = new SharedArrayBuffer(data.byteLength);
     // const view = new Uint8Array(sab);

src/core/fonts.js

@@ -57,6 +57,7 @@ import {
 } from "./standard_fonts.js";
 import { IdentityToUnicodeMap, ToUnicodeMap } from "./to_unicode_map.js";
 import { CFFFont } from "./cff_font.js";
+import { compileFontInfo } from "./obj_bin_transform_core.js";
 import { FontRendererFactory } from "./font_renderer.js";
 import { getFontBasicMetrics } from "./metrics.js";
 import { GlyfTable } from "./glyf.js";
@@ -80,7 +81,7 @@ const EXPORT_DATA_PROPERTIES = [
   "bbox",
   "black",
   "bold",
-  "charProcOperatorList",
+  // "charProcOperatorList" is handled separately, since it's not compiled.
   "cssFontInfo",
   "data",
   "defaultVMetrics",
@@ -973,6 +974,8 @@ class Font {
 
   #glyphCache = new Map();
 
+  charProcOperatorList;
+
   constructor(name, file, properties, evaluatorOptions) {
     this.name = name;
     this.psName = null;
@@ -1147,28 +1150,26 @@ class Font {
     return shadow(this, "renderer", renderer);
   }
 
-  exportData() {
+  #getExportData(props) {
     const data = Object.create(null);
-    for (const prop of EXPORT_DATA_PROPERTIES) {
+    for (const prop of props) {
       const value = this[prop];
       // Ignore properties that haven't been explicitly set.
       if (value !== undefined) {
         data[prop] = value;
       }
     }
+    return data;
+  }
 
-    if (!this.fontExtraProperties) {
-      return { data };
-    }
-
-    const extra = Object.create(null);
-    for (const prop of EXPORT_DATA_EXTRA_PROPERTIES) {
-      const value = this[prop];
-      if (value !== undefined) {
-        extra[prop] = value;
-      }
-    }
-    return { data, extra };
+  exportData() {
+    return {
+      buffer: compileFontInfo(this.#getExportData(EXPORT_DATA_PROPERTIES)),
+      charProcOperatorList: this.charProcOperatorList,
+      extra: this.fontExtraProperties
+        ? this.#getExportData(EXPORT_DATA_EXTRA_PROPERTIES)
+        : undefined,
+    };
   }
 
   fallbackToSystemFont(properties) {

src/core/obj_bin_transform_core.js

@@ -169,7 +169,6 @@ function compileFontInfo(font) {
     view.setUint8(offset++, 0);
     offset += 2 * 4; // TODO: optimize this padding away
   }
-
   assert(
     offset === FONT_INFO.OFFSET_FONT_MATRIX,
     "compileFontInfo: BBox properties offset mismatch"
@@ -185,7 +184,6 @@ function compileFontInfo(font) {
     view.setUint8(offset++, 0);
     offset += 8 * 6; // TODO: optimize this padding away
   }
-
   assert(
     offset === FONT_INFO.OFFSET_DEFAULT_VMETRICS,
     "compileFontInfo: FontMatrix properties offset mismatch"
@@ -201,7 +199,6 @@ function compileFontInfo(font) {
     view.setUint8(offset++, 0);
     offset += 3 * 2; // TODO: optimize this padding away
   }
-
   assert(
     offset === FONT_INFO.OFFSET_STRINGS,
     "compileFontInfo: DefaultVMetrics properties offset mismatch"

src/display/api.js

@@ -2890,8 +2890,8 @@ class WorkerTransport {
           const font = new FontFaceObject(
             fontData,
             inspectFont,
-            exportedData.extra,
-            exportedData.charProcOperatorList
+            exportedData.charProcOperatorList,
+            exportedData.extra
           );
 
           this.fontLoader

src/display/font_loader.js

@@ -359,7 +359,7 @@ class FontFaceObject {
 
   #fontData;
 
-  constructor(translatedData, inspectFont = null, extra, charProcOperatorList) {
+  constructor(translatedData, inspectFont = null, charProcOperatorList, extra) {
     if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
       assert(
         typeof translatedData.disableFontFace === "boolean",
@@ -372,12 +372,13 @@ class FontFaceObject {
     }
     this.#fontData = translatedData;
     this._inspectFont = inspectFont;
-    if (extra) {
-      Object.assign(this, extra);
-    }
+
     if (charProcOperatorList) {
       this.charProcOperatorList = charProcOperatorList;
     }
+    if (extra) {
+      Object.assign(this, extra);
+    }
   }
 
   createNativeFontFace() {

src/display/obj_bin_transform_display.js

@@ -30,7 +30,7 @@ class CssFontInfo {
 
   constructor(buffer) {
     this.#buffer = buffer;
-    this.#view = new DataView(this.#buffer);
+    this.#view = new DataView(buffer);
   }
 
   #readString(index) {
@@ -67,7 +67,7 @@ class SystemFontInfo {
 
   constructor(buffer) {
     this.#buffer = buffer;
-    this.#view = new DataView(this.#buffer);
+    this.#view = new DataView(buffer);
   }
 
   get guessFallback() {
@@ -125,9 +125,9 @@ class FontInfo {
 
   #view;
 
-  constructor({ data, extra }) {
-    this.#buffer = data;
-    this.#view = new DataView(this.#buffer);
+  constructor({ buffer, extra }) {
+    this.#buffer = buffer;
+    this.#view = new DataView(buffer);
     if (extra) {
       Object.assign(this, extra);
     }

test/unit/obj_bin_transform_spec.js

@@ -133,7 +133,7 @@ describe("obj_bin_transform", function () {
           sizeEstimate += 4 + fontInfo.data.length;
           const buffer = compileFontInfo(fontInfo);
           expect(buffer.byteLength).toEqual(sizeEstimate);
-          const deserialized = new FontInfo({ data: buffer });
+          const deserialized = new FontInfo({ buffer });
           expect(deserialized.black).toEqual(true);
           expect(deserialized.bold).toEqual(true);
           expect(deserialized.disableFontFace).toEqual(true);
@@ -168,7 +168,7 @@ describe("obj_bin_transform", function () {
             cssFontInfo,
             systemFontInfo,
           });
-          const deserialized = new FontInfo({ data: buffer });
+          const deserialized = new FontInfo({ buffer });
           expect(deserialized.cssFontInfo.fontWeight).toEqual("not a number");
           expect(deserialized.systemFontInfo.src).toEqual("source");
         });