Ensure that any pending rendering operations in `PDFViewer`/`PDFThumbnailViewer` are cancelled when the viewer is closed

web/app.js

@@ -1583,6 +1583,19 @@ function webViewerPageRendered(e) {
   var pageIndex = pageNumber - 1;
   var pageView = PDFViewerApplication.pdfViewer.getPageView(pageIndex);
 
+  // If the page is still visible when it has finished rendering,
+  // ensure that the page number input loading indicator is hidden.
+  if (pageNumber === PDFViewerApplication.page) {
+    var pageNumberInput = PDFViewerApplication.appConfig.toolbar.pageNumber;
+    pageNumberInput.classList.remove(PAGE_NUMBER_LOADING_INDICATOR);
+  }
+
+  // Prevent errors in the edge-case where the PDF document is removed *before*
+  // the 'pagerendered' event handler is invoked.
+  if (!pageView) {
+    return;
+  }
+
   // Use the rendered page to set the corresponding thumbnail image.
   if (PDFViewerApplication.pdfSidebar.isThumbnailViewVisible) {
     var thumbnailView = PDFViewerApplication.pdfThumbnailViewer.
@@ -1599,13 +1612,6 @@ function webViewerPageRendered(e) {
       'An error occurred while rendering the page.'), pageView.error);
   }
 
-  // If the page is still visible when it has finished rendering,
-  // ensure that the page number input loading indicator is hidden.
-  if (pageNumber === PDFViewerApplication.page) {
-    var pageNumberInput = PDFViewerApplication.appConfig.toolbar.pageNumber;
-    pageNumberInput.classList.remove(PAGE_NUMBER_LOADING_INDICATOR);
-  }
-
 //#if !PRODUCTION
   if (true) {
     return;

web/pdf_page_view.js

@@ -92,6 +92,7 @@ var PDFPageView = (function PDFPageViewClosure() {
     this.textLayerFactory = textLayerFactory;
     this.annotationLayerFactory = annotationLayerFactory;
 
+    this.renderTask = null;
     this.renderingState = RenderingStates.INITIAL;
     this.resume = null;
 
@@ -135,11 +136,7 @@ var PDFPageView = (function PDFPageViewClosure() {
     },
 
     reset: function PDFPageView_reset(keepZoomLayer, keepAnnotations) {
-      if (this.renderTask) {
-        this.renderTask.cancel();
-      }
-      this.resume = null;
-      this.renderingState = RenderingStates.INITIAL;
+      this.cancelRendering();
 
       var div = this.div;
       div.style.width = Math.floor(this.viewport.width) + 'px';
@@ -225,6 +222,15 @@ var PDFPageView = (function PDFPageViewClosure() {
       this.reset(/* keepZoomLayer = */ true, /* keepAnnotations = */ true);
     },
 
+    cancelRendering: function PDFPageView_cancelRendering() {
+      if (this.renderTask) {
+        this.renderTask.cancel();
+        this.renderTask = null;
+      }
+      this.renderingState = RenderingStates.INITIAL;
+      this.resume = null;
+    },
+
     /**
      * Called when moved in the parent's container.
      */
@@ -320,6 +326,7 @@ var PDFPageView = (function PDFPageViewClosure() {
     draw: function PDFPageView_draw() {
       if (this.renderingState !== RenderingStates.INITIAL) {
         console.error('Must be in new state before drawing');
+        this.reset(); // Ensure that we reset all state to prevent issues.
       }
 
       this.renderingState = RenderingStates.RUNNING;

web/pdf_thumbnail_view.js

@@ -98,8 +98,9 @@ var PDFThumbnailView = (function PDFThumbnailViewClosure() {
     this.linkService = linkService;
     this.renderingQueue = renderingQueue;
 
-    this.resume = null;
+    this.renderTask = null;
     this.renderingState = RenderingStates.INITIAL;
+    this.resume = null;
     this.disableCanvasToImageConversion = disableCanvasToImageConversion;
 
     this.pageWidth = this.viewport.width;
@@ -151,11 +152,7 @@ var PDFThumbnailView = (function PDFThumbnailViewClosure() {
     },
 
     reset: function PDFThumbnailView_reset() {
-      if (this.renderTask) {
-        this.renderTask.cancel();
-      }
-      this.resume = null;
-      this.renderingState = RenderingStates.INITIAL;
+      this.cancelRendering();
 
       this.pageWidth = this.viewport.width;
       this.pageHeight = this.viewport.height;
@@ -199,6 +196,15 @@ var PDFThumbnailView = (function PDFThumbnailViewClosure() {
       this.reset();
     },
 
+    cancelRendering: function PDFThumbnailView_cancelRendering() {
+      if (this.renderTask) {
+        this.renderTask.cancel();
+        this.renderTask = null;
+      }
+      this.renderingState = RenderingStates.INITIAL;
+      this.resume = null;
+    },
+
     /**
      * @private
      */

web/pdf_thumbnail_viewer.js

@@ -135,15 +135,14 @@ var PDFThumbnailViewer = (function PDFThumbnailViewerClosure() {
       this.thumbnails = [];
       this._pagesRotation = 0;
       this._pagesRequests = [];
+
+      // Remove the thumbnails from the DOM.
+      this.container.textContent = '';
     },
 
     setDocument: function PDFThumbnailViewer_setDocument(pdfDocument) {
       if (this.pdfDocument) {
-        // cleanup of the elements and views
-        var thumbsView = this.container;
-        while (thumbsView.hasChildNodes()) {
-          thumbsView.removeChild(thumbsView.lastChild);
-        }
+        this._cancelRendering();
         this._resetView();
       }
 
@@ -169,6 +168,17 @@ var PDFThumbnailViewer = (function PDFThumbnailViewerClosure() {
       }.bind(this));
     },
 
+    /**
+     * @private
+     */
+    _cancelRendering: function PDFThumbnailViewer_cancelRendering() {
+      for (var i = 0, ii = this.thumbnails.length; i < ii; i++) {
+        if (this.thumbnails[i]) {
+          this.thumbnails[i].cancelRendering();
+        }
+      }
+    },
+
     /**
      * @param {PDFThumbnailView} thumbView
      * @returns {PDFPage}

web/pdf_viewer.js

@@ -299,6 +299,7 @@ var PDFViewer = (function pdfViewer() {
      */
     setDocument: function (pdfDocument) {
       if (this.pdfDocument) {
+        this._cancelRendering();
         this._resetView();
       }
 
@@ -424,10 +425,8 @@ var PDFViewer = (function pdfViewer() {
       this._pagesRequests = [];
       this._pageViewsReady = false;
 
-      var container = this.viewer;
-      while (container.hasChildNodes()) {
-        container.removeChild(container.lastChild);
-      }
+      // Remove the pages from the DOM.
+      this.viewer.textContent = '';
     },
 
     _scrollUpdate: function PDFViewer_scrollUpdate() {
@@ -802,6 +801,17 @@ var PDFViewer = (function pdfViewer() {
       }
     },
 
+    /**
+     * @private
+     */
+    _cancelRendering: function PDFViewer_cancelRendering() {
+      for (var i = 0, ii = this._pages.length; i < ii; i++) {
+        if (this._pages[i]) {
+          this._pages[i].cancelRendering();
+        }
+      }
+    },
+
     /**
      * @param {PDFPageView} pageView
      * @returns {PDFPage}