[api-minor] Move the page reference/number caching into the API

Rather than having to handle this *manually* throughout the viewer, this functionality can instead be moved into the API which simplifies the code slightly.

src/core/worker.js

@@ -419,6 +419,7 @@ class WorkerMessageHandler {
           return {
             rotate,
             ref,
+            refStr: ref?.toString() ?? null,
             userUnit,
             view,
           };

src/display/api.js

@@ -560,6 +560,16 @@ function getDataProp(val) {
   );
 }
 
+function isRefProxy(ref) {
+  return (
+    typeof ref === "object" &&
+    Number.isInteger(ref?.num) &&
+    ref.num >= 0 &&
+    Number.isInteger(ref?.gen) &&
+    ref.gen >= 0
+  );
+}
+
 /**
  * @typedef {Object} OnProgressParameters
  * @property {number} loaded - Currently loaded number of bytes.
@@ -1066,6 +1076,14 @@ class PDFDocumentProxy {
     return this.loadingTask.destroy();
   }
 
+  /**
+   * @param {RefProxy} ref - The page reference.
+   * @returns {number | null} The page number, if it's cached.
+   */
+  cachedPageNumber(ref) {
+    return this._transport.cachedPageNumber(ref);
+  }
+
   /**
    * @type {DocumentInitParameters} A subset of the current
    *   {DocumentInitParameters}, which are needed in the viewer.
@@ -2340,6 +2358,8 @@ class WorkerTransport {
 
   #pagePromises = new Map();
 
+  #pageRefCache = new Map();
+
   #passwordCapability = null;
 
   constructor(messageHandler, loadingTask, networkStream, params, factory) {
@@ -2483,6 +2503,7 @@ class WorkerTransport {
     }
     this.#pageCache.clear();
     this.#pagePromises.clear();
+    this.#pageRefCache.clear();
     // Allow `AnnotationStorage`-related clean-up when destroying the document.
     if (this.hasOwnProperty("annotationStorage")) {
       this.annotationStorage.resetModified();
@@ -2915,6 +2936,10 @@ class WorkerTransport {
         if (this.destroyed) {
           throw new Error("Transport destroyed");
         }
+        if (pageInfo.refStr) {
+          this.#pageRefCache.set(pageInfo.refStr, pageNumber);
+        }
+
         const page = new PDFPageProxy(
           pageIndex,
           pageInfo,
@@ -2929,13 +2954,7 @@ class WorkerTransport {
   }
 
   getPageIndex(ref) {
-    if (
-      typeof ref !== "object" ||
-      !Number.isInteger(ref?.num) ||
-      ref.num < 0 ||
-      !Number.isInteger(ref?.gen) ||
-      ref.gen < 0
-    ) {
+    if (!isRefProxy(ref)) {
       return Promise.reject(new Error("Invalid pageIndex request."));
     }
     return this.messageHandler.sendWithPromise("GetPageIndex", {
@@ -3076,6 +3095,14 @@ class WorkerTransport {
     cleanupTextLayer();
   }
 
+  cachedPageNumber(ref) {
+    if (!isRefProxy(ref)) {
+      return null;
+    }
+    const refStr = ref.gen === 0 ? `${ref.num}R` : `${ref.num}R${ref.gen}`;
+    return this.#pageRefCache.get(refStr) ?? null;
+  }
+
   get loadingParams() {
     const { disableAutoFetch, enableXfa } = this._params;
     return shadow(this, "loadingParams", {

web/interfaces.js

@@ -106,12 +106,6 @@ class IPDFLinkService {
    * @param {Object} action
    */
   executeSetOCGState(action) {}
-
-  /**
-   * @param {number} pageNum - page number.
-   * @param {Object} pageRef - reference to the page.
-   */
-  cachePageRef(pageNum, pageRef) {}
 }
 
 /**

web/pdf_link_service.js

@@ -49,8 +49,6 @@ const LinkTarget = {
 class PDFLinkService {
   externalLinkEnabled = true;
 
-  #pagesRefCache = new Map();
-
   /**
    * @param {PDFLinkServiceOptions} options
    */
@@ -74,7 +72,6 @@ class PDFLinkService {
   setDocument(pdfDocument, baseUrl = null) {
     this.baseUrl = baseUrl;
     this.pdfDocument = pdfDocument;
-    this.#pagesRefCache.clear();
   }
 
   setViewer(pdfViewer) {
@@ -157,15 +154,14 @@ class PDFLinkService {
     // Dest array looks like that: <page-ref> </XYZ|/FitXXX> <args..>
     const [destRef] = explicitDest;
 
-    if (typeof destRef === "object" && destRef !== null) {
-      pageNumber = this._cachedPageNumber(destRef);
+    if (destRef && typeof destRef === "object") {
+      pageNumber = this.pdfDocument.cachedPageNumber(destRef);
 
       if (!pageNumber) {
         // Fetch the page reference if it's not yet available. This could
         // only occur during loading, before all pages have been resolved.
         try {
           pageNumber = (await this.pdfDocument.getPageIndex(destRef)) + 1;
-          this.cachePageRef(pageNumber, destRef);
         } catch {
           console.error(
             `goToDestination: "${destRef}" is not a valid page reference, for dest="${dest}".`
@@ -496,31 +492,6 @@ class PDFLinkService {
     );
   }
 
-  /**
-   * @param {number} pageNum - page number.
-   * @param {Object} pageRef - reference to the page.
-   */
-  cachePageRef(pageNum, pageRef) {
-    if (!pageRef) {
-      return;
-    }
-    const refStr =
-      pageRef.gen === 0 ? `${pageRef.num}R` : `${pageRef.num}R${pageRef.gen}`;
-    this.#pagesRefCache.set(refStr, pageNum);
-  }
-
-  /**
-   * @ignore
-   */
-  _cachedPageNumber(pageRef) {
-    if (!pageRef) {
-      return null;
-    }
-    const refStr =
-      pageRef.gen === 0 ? `${pageRef.num}R` : `${pageRef.num}R${pageRef.gen}`;
-    return this.#pagesRefCache.get(refStr) || null;
-  }
-
   static #isValidExplicitDest(dest) {
     if (!Array.isArray(dest) || dest.length < 2) {
       return false;
@@ -580,12 +551,6 @@ class PDFLinkService {
  */
 class SimpleLinkService extends PDFLinkService {
   setDocument(pdfDocument, baseUrl = null) {}
-
-  /**
-   * @param {number} pageNum - page number.
-   * @param {Object} pageRef - reference to the page.
-   */
-  cachePageRef(pageNum, pageRef) {}
 }
 
 export { LinkTarget, PDFLinkService, SimpleLinkService };

web/pdf_outline_viewer.js

@@ -325,21 +325,10 @@ class PDFOutlineViewer extends BaseTreeViewer {
         if (Array.isArray(explicitDest)) {
           const [destRef] = explicitDest;
 
-          if (typeof destRef === "object" && destRef !== null) {
-            pageNumber = this.linkService._cachedPageNumber(destRef);
-
-            if (!pageNumber) {
-              try {
-                pageNumber = (await pdfDocument.getPageIndex(destRef)) + 1;
-
-                if (pdfDocument !== this._pdfDocument) {
-                  return null; // The document was closed while the data resolved.
-                }
-                this.linkService.cachePageRef(pageNumber, destRef);
-              } catch {
-                // Invalid page reference, ignore it and continue parsing.
-              }
-            }
+          if (destRef && typeof destRef === "object") {
+            // The page reference must be available, since the current method
+            // won't be invoked until all pages have been loaded.
+            pageNumber = pdfDocument.cachedPageNumber(destRef);
           } else if (Number.isInteger(destRef)) {
             pageNumber = destRef + 1;
           }

web/pdf_viewer.js

@@ -935,11 +935,7 @@ class PDFViewer {
         // Set the first `pdfPage` immediately, since it's already loaded,
         // rather than having to repeat the `PDFDocumentProxy.getPage` call in
         // the `this.#ensurePdfPageLoaded` method before rendering can start.
-        const firstPageView = this._pages[0];
-        if (firstPageView) {
-          firstPageView.setPdfPage(firstPdfPage);
-          this.linkService.cachePageRef(1, firstPdfPage.ref);
-        }
+        this._pages[0]?.setPdfPage(firstPdfPage);
 
         if (this._scrollMode === ScrollMode.PAGE) {
           // Ensure that the current page becomes visible on document load.
@@ -994,7 +990,6 @@ class PDFViewer {
                 if (!pageView.pdfPage) {
                   pageView.setPdfPage(pdfPage);
                 }
-                this.linkService.cachePageRef(pageNum, pdfPage.ref);
                 if (--getPagesLeft === 0) {
                   this._pagesCapability.resolve();
                 }
@@ -1718,9 +1713,6 @@ class PDFViewer {
       if (!pageView.pdfPage) {
         pageView.setPdfPage(pdfPage);
       }
-      if (!this.linkService._cachedPageNumber?.(pdfPage.ref)) {
-        this.linkService.cachePageRef(pageView.id, pdfPage.ref);
-      }
       return pdfPage;
     } catch (reason) {
       console.error("Unable to get page for page view", reason);