Improve how we disable PDFThumbnailView.setImage for documents with Optional Content (PR 12170 follow-up)

Rather than always disable `PDFThumbnailView.setImage` as soon as user has changed the visibility of the Optional Content, we can utilize the new method added in the previous patch to improve thumbnail performance. Note in particular how, in the old code, even *resetting* of the Optional Content to its default state wouldn't enable `PDFThumbnailView.setImage` again.

While slightly unrelated, this patch also removes the `PDFThumbnailViewer._optionalContentConfigPromise`-property since it's completely unused.

web/base_viewer.js

@@ -1824,6 +1824,7 @@ class BaseViewer {
       return Promise.resolve(null);
     }
     if (!this._optionalContentConfigPromise) {
+      console.error("optionalContentConfigPromise: Not initialized yet.");
       // Prevent issues if the getter is accessed *before* the `onePageRendered`
       // promise has resolved; won't (normally) happen in the default viewer.
       return this.pdfDocument.getOptionalContentConfig();

web/pdf_page_view.js

@@ -99,6 +99,8 @@ const MAX_CANVAS_PIXELS = compatibilityParams.maxCanvasPixels || 16777216;
 class PDFPageView {
   #annotationMode = AnnotationMode.ENABLE_FORMS;
 
+  #useThumbnailCanvas = true;
+
   /**
    * @param {PDFPageViewOptions} options
    */
@@ -174,6 +176,22 @@ class PDFPageView {
     this.div = div;
 
     container?.append(div);
+
+    if (this._isStandalone) {
+      const { optionalContentConfigPromise } = options;
+      if (optionalContentConfigPromise) {
+        // Ensure that the thumbnails always display the *initial* document
+        // state.
+        optionalContentConfigPromise.then(optionalContentConfig => {
+          if (
+            optionalContentConfigPromise !== this._optionalContentConfigPromise
+          ) {
+            return;
+          }
+          this.#useThumbnailCanvas = optionalContentConfig.hasInitialVisibility;
+        });
+      }
+    }
   }
 
   setPdfPage(pdfPage) {
@@ -376,6 +394,16 @@ class PDFPageView {
     }
     if (optionalContentConfigPromise instanceof Promise) {
       this._optionalContentConfigPromise = optionalContentConfigPromise;
+
+      // Ensure that the thumbnails always display the *initial* document state.
+      optionalContentConfigPromise.then(optionalContentConfig => {
+        if (
+          optionalContentConfigPromise !== this._optionalContentConfigPromise
+        ) {
+          return;
+        }
+        this.#useThumbnailCanvas = optionalContentConfig.hasInitialVisibility;
+      });
     }
 
     const totalRotation = (this.rotation + this.pdfPageRotate) % 360;
@@ -1003,6 +1031,14 @@ class PDFPageView {
       this.div.removeAttribute("data-page-label");
     }
   }
+
+  /**
+   * For use by the `PDFThumbnailView.setImage`-method.
+   * @ignore
+   */
+  get thumbnailCanvas() {
+    return this.#useThumbnailCanvas ? this.canvas : null;
+  }
 }
 
 export { PDFPageView };

web/pdf_thumbnail_view.js

@@ -37,7 +37,6 @@ const THUMBNAIL_WIDTH = 98; // px
  *   The default value is `null`.
  * @property {IPDFLinkService} linkService - The navigation/linking service.
  * @property {PDFRenderingQueue} renderingQueue - The rendering queue object.
- * @property {function} checkSetImageDisabled
  * @property {IL10n} l10n - Localization service.
  * @property {Object} [pageColors] - Overwrites background and foreground colors
  *   with user defined ones in order to improve readability in high contrast
@@ -88,7 +87,6 @@ class PDFThumbnailView {
     optionalContentConfigPromise,
     linkService,
     renderingQueue,
-    checkSetImageDisabled,
     l10n,
     pageColors,
   }) {
@@ -109,11 +107,6 @@ class PDFThumbnailView {
     this.renderTask = null;
     this.renderingState = RenderingStates.INITIAL;
     this.resume = null;
-    this._checkSetImageDisabled =
-      checkSetImageDisabled ||
-      function () {
-        return false;
-      };
 
     const pageWidth = this.viewport.width,
       pageHeight = this.viewport.height,
@@ -356,13 +349,10 @@ class PDFThumbnailView {
   }
 
   setImage(pageView) {
-    if (this._checkSetImageDisabled()) {
-      return;
-    }
     if (this.renderingState !== RenderingStates.INITIAL) {
       return;
     }
-    const { canvas, pdfPage } = pageView;
+    const { thumbnailCanvas: canvas, pdfPage } = pageView;
     if (!canvas) {
       return;
     }

web/pdf_thumbnail_viewer.js

@@ -85,12 +85,6 @@ class PDFThumbnailViewer {
 
     this.scroll = watchScroll(this.container, this._scrollUpdated.bind(this));
     this._resetView();
-
-    eventBus._on("optionalcontentconfigchanged", () => {
-      // Ensure that the thumbnails always render with the *default* optional
-      // content configuration.
-      this._setImageDisabled = true;
-    });
   }
 
   /**
@@ -195,8 +189,6 @@ class PDFThumbnailViewer {
     this._currentPageNumber = 1;
     this._pageLabels = null;
     this._pagesRotation = 0;
-    this._optionalContentConfigPromise = null;
-    this._setImageDisabled = false;
 
     // Remove the thumbnails from the DOM.
     this.container.textContent = "";
@@ -220,13 +212,8 @@ class PDFThumbnailViewer {
 
     firstPagePromise
       .then(firstPdfPage => {
-        this._optionalContentConfigPromise = optionalContentConfigPromise;
-
         const pagesCount = pdfDocument.numPages;
         const viewport = firstPdfPage.getViewport({ scale: 1 });
-        const checkSetImageDisabled = () => {
-          return this._setImageDisabled;
-        };
 
         for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
           const thumbnail = new PDFThumbnailView({
@@ -236,7 +223,6 @@ class PDFThumbnailViewer {
             optionalContentConfigPromise,
             linkService: this.linkService,
             renderingQueue: this.renderingQueue,
-            checkSetImageDisabled,
             l10n: this.l10n,
             pageColors: this.pageColors,
           });