Move the transfers computation into the AnnotationStorage class

Rather than having to *manually* determine the potential `transfers` at various spots in the API, we can let the `AnnotationStorage.serializable` getter include this.
To further simplify things, we can also let the `serializable` getter compute and include the `hash`-string as well.

src/display/annotation_storage.js

@@ -17,6 +17,12 @@ import { objectFromMap, unreachable } from "../shared/util.js";
 import { AnnotationEditor } from "./editor/editor.js";
 import { MurmurHash3_64 } from "../shared/murmurhash3.js";
 
+const SerializableEmpty = Object.freeze({
+  map: null,
+  hash: "",
+  transfers: undefined,
+});
+
 /**
  * Key/value storage for annotation data in forms.
  */
@@ -171,34 +177,27 @@ class AnnotationStorage {
    */
   get serializable() {
     if (this.#storage.size === 0) {
-      return null;
+      return SerializableEmpty;
     }
-    const clone = new Map();
-
+    const map = new Map(),
+      hash = new MurmurHash3_64(),
+      transfers = [];
     for (const [key, val] of this.#storage) {
       const serialized =
         val instanceof AnnotationEditor ? val.serialize() : val;
       if (serialized) {
-        clone.set(key, serialized);
+        map.set(key, serialized);
+
+        hash.update(`${key}:${JSON.stringify(serialized)}`);
+
+        if (serialized.bitmap) {
+          transfers.push(serialized.bitmap);
+        }
       }
     }
-    return clone;
-  }
-
-  /**
-   * PLEASE NOTE: Only intended for usage within the API itself.
-   * @ignore
-   */
-  static getHash(map) {
-    if (!map) {
-      return "";
-    }
-    const hash = new MurmurHash3_64();
-
-    for (const [key, val] of map) {
-      hash.update(`${key}:${JSON.stringify(val)}`);
-    }
-    return hash.hexdigest();
+    return map.size > 0
+      ? { map, hash: hash.hexdigest(), transfers }
+      : SerializableEmpty;
   }
 }
 
@@ -208,12 +207,21 @@ class AnnotationStorage {
  * contents. (Necessary since printing is triggered synchronously in browsers.)
  */
 class PrintAnnotationStorage extends AnnotationStorage {
-  #serializable = null;
+  #serializable;
 
   constructor(parent) {
     super();
+    const { map, hash, transfers } = parent.serializable;
     // Create a *copy* of the data, since Objects are passed by reference in JS.
-    this.#serializable = structuredClone(parent.serializable);
+    const clone = structuredClone(
+      map,
+      (typeof PDFJSDev === "undefined" ||
+        PDFJSDev.test("SKIP_BABEL || TESTING")) &&
+        transfers
+        ? { transfer: transfers }
+        : null
+    );
+    this.#serializable = { map: clone, hash, transfers };
   }
 
   /**
@@ -233,4 +241,4 @@ class PrintAnnotationStorage extends AnnotationStorage {
   }
 }
 
-export { AnnotationStorage, PrintAnnotationStorage };
+export { AnnotationStorage, PrintAnnotationStorage, SerializableEmpty };

src/display/api.js

@@ -41,6 +41,7 @@ import {
 import {
   AnnotationStorage,
   PrintAnnotationStorage,
+  SerializableEmpty,
 } from "./annotation_storage.js";
 import {
   deprecated,
@@ -1811,22 +1812,18 @@ class PDFPageProxy {
   /**
    * @private
    */
-  _pumpOperatorList({ renderingIntent, cacheKey, annotationStorageMap }) {
+  _pumpOperatorList({
+    renderingIntent,
+    cacheKey,
+    annotationStorageSerializable,
+  }) {
     if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
       assert(
         Number.isInteger(renderingIntent) && renderingIntent > 0,
         '_pumpOperatorList: Expected valid "renderingIntent" argument.'
       );
     }
-
-    const transfers = [];
-    if (annotationStorageMap) {
-      for (const annotation of annotationStorageMap.values()) {
-        if (annotation.bitmap) {
-          transfers.push(annotation.bitmap);
-        }
-      }
-    }
+    const { map, transfers } = annotationStorageSerializable;
 
     const readableStream = this._transport.messageHandler.sendWithStream(
       "GetOperatorList",
@@ -1834,7 +1831,7 @@ class PDFPageProxy {
         pageIndex: this._pageIndex,
         intent: renderingIntent,
         cacheKey,
-        annotationStorage: annotationStorageMap,
+        annotationStorage: map,
       },
       transfers
     );
@@ -2459,7 +2456,7 @@ class WorkerTransport {
     isOpList = false
   ) {
     let renderingIntent = RenderingIntentFlag.DISPLAY; // Default value.
-    let annotationMap = null;
+    let annotationStorageSerializable = SerializableEmpty;
 
     switch (intent) {
       case "any":
@@ -2492,7 +2489,7 @@ class WorkerTransport {
             ? printAnnotationStorage
             : this.annotationStorage;
 
-        annotationMap = annotationStorage.serializable;
+        annotationStorageSerializable = annotationStorage.serializable;
         break;
       default:
         warn(`getRenderingIntent - invalid annotationMode: ${annotationMode}`);
@@ -2504,10 +2501,8 @@ class WorkerTransport {
 
     return {
       renderingIntent,
-      cacheKey: `${renderingIntent}_${AnnotationStorage.getHash(
-        annotationMap
-      )}`,
-      annotationStorageMap: annotationMap,
+      cacheKey: `${renderingIntent}_${annotationStorageSerializable.hash}`,
+      annotationStorageSerializable,
     };
   }
 
@@ -2915,22 +2910,15 @@ class WorkerTransport {
           "please use the getData-method instead."
       );
     }
-    const annotationStorage = this.annotationStorage.serializable;
-    const transfers = [];
-    if (annotationStorage) {
-      for (const annotation of annotationStorage.values()) {
-        if (annotation.bitmap) {
-          transfers.push(annotation.bitmap);
-        }
-      }
-    }
+    const { map, transfers } = this.annotationStorage.serializable;
+
     return this.messageHandler
       .sendWithPromise(
         "SaveDocument",
         {
           isPureXfa: !!this._htmlForXfa,
           numPages: this._numPages,
-          annotationStorage,
+          annotationStorage: map,
           filename: this._fullReader?.filename ?? null,
         },
         transfers