fix(a11y): screen reader support for view only file preview

src/lib/viewers/doc/DocBaseViewer.js

@@ -177,6 +177,7 @@ class DocBaseViewer extends BaseViewer {
 
         this.viewerEl = this.docEl.appendChild(document.createElement('div'));
         this.viewerEl.classList.add('pdfViewer');
+
         this.loadTimeout = LOAD_TIMEOUT_MS;
 
         this.startPageNum = this.getStartPage(this.startAt);
@@ -795,7 +796,15 @@ class DocBaseViewer extends BaseViewer {
         const { AnnotationMode: PDFAnnotationMode = {} } = this.pdfjsLib;
         const assetUrlCreator = createAssetUrlCreator(location);
         const hasDownload = checkPermission(file, PERMISSION_DOWNLOAD);
-        const hasTextLayer = hasDownload && !this.getViewerOption('disableTextLayer');
+        const hasTextLayer = !this.getViewerOption('disableTextLayer');
+        const enabledTextLayerMode = hasDownload
+            ? PDFJS_TEXT_LAYER_MODE.ENABLE
+            : PDFJS_TEXT_LAYER_MODE.ENABLE_PERMISSIONS; // This mode will prevent default behavior for copy events in the TextLayerBuilder
+
+        // Text layer should be rendered for a11y reasons thats why we will block user from selecting content when no download permissions was granted
+        if (!hasDownload) {
+            this.viewerEl.classList.add('pdfViewer--viewOnly');
+        }
 
         return new PdfViewerClass({
             annotationMode: PDFAnnotationMode.ENABLE, // Show annotations, but not forms
@@ -806,7 +815,7 @@ class DocBaseViewer extends BaseViewer {
             linkService: this.pdfLinkService,
             maxCanvasPixels: this.isMobile ? MOBILE_MAX_CANVAS_SIZE : -1,
             renderInteractiveForms: false, // Enabling prevents unverified signatures from being displayed
-            textLayerMode: hasTextLayer ? PDFJS_TEXT_LAYER_MODE.ENABLE : PDFJS_TEXT_LAYER_MODE.DISABLE,
+            textLayerMode: hasTextLayer ? enabledTextLayerMode : PDFJS_TEXT_LAYER_MODE.DISABLE,
         });
     }
 

src/lib/viewers/doc/__tests__/DocBaseViewer-test.js

@@ -1140,43 +1140,65 @@ describe('src/lib/viewers/doc/DocBaseViewer', () => {
                 });
             });
 
-            test('should enable the text layer based on download permissions', () => {
+            test('should enable the text layer if the user is on mobile', () => {
+                docBase.isMobile = true;
                 stubs.checkPermission.mockReturnValueOnce(true);
 
                 return docBase.initViewer('').then(() => {
-                    expect(stubs.checkPermission).toBeCalledWith(docBase.options.file, PERMISSION_DOWNLOAD);
+                    expect(stubs.getViewerOption).toBeCalledWith('disableTextLayer');
                     // Text Layer mode 1 = enabled
                     expect(stubs.pdfViewerClass).toBeCalledWith(expect.objectContaining({ textLayerMode: 1 }));
                 });
             });
 
-            test('should enable the text layer if the user is on mobile', () => {
-                docBase.isMobile = true;
+            test('should add view only class if user does not have download permissions', () => {
+                docBase.containerEl = containerEl;
+                stubs.checkPermission.mockReturnValueOnce(false);
+
+                return docBase.initViewer('').then(() => {
+                    expect(stubs.checkPermission).toBeCalledWith(docBase.options.file, PERMISSION_DOWNLOAD);
+                    expect(docBase.viewerEl).toHaveClass('pdfViewer--viewOnly');
+                });
+            });
+
+            test('should not add view only class if user has download permissions', () => {
+                docBase.containerEl = containerEl;
+                stubs.checkPermission.mockReturnValueOnce(true);
+
+                return docBase.initViewer('').then(() => {
+                    expect(stubs.checkPermission).toBeCalledWith(docBase.options.file, PERMISSION_DOWNLOAD);
+                    expect(docBase.viewerEl).not.toHaveClass('pdfViewer--viewOnly');
+                });
+            });
+
+            test('should use proper text layer mode if user has download permissions and disableTextLayer viewer option is not set', () => {
+                stubs.getViewerOption.mockReturnValue(false);
                 stubs.checkPermission.mockReturnValueOnce(true);
 
                 return docBase.initViewer('').then(() => {
                     expect(stubs.checkPermission).toBeCalledWith(docBase.options.file, PERMISSION_DOWNLOAD);
+                    expect(stubs.getViewerOption).toBeCalledWith('disableTextLayer');
                     // Text Layer mode 1 = enabled
                     expect(stubs.pdfViewerClass).toBeCalledWith(expect.objectContaining({ textLayerMode: 1 }));
                 });
             });
 
-            test('should disable the text layer based on download permissions', () => {
+            test('should use proper text layer mode if user does not have download permissions and disableTextLayer viewer option is not set', () => {
+                stubs.getViewerOption.mockReturnValue(false);
                 stubs.checkPermission.mockReturnValueOnce(false);
 
                 return docBase.initViewer('').then(() => {
                     expect(stubs.checkPermission).toBeCalledWith(docBase.options.file, PERMISSION_DOWNLOAD);
-                    // Text Layer mode 0 = disabled
-                    expect(stubs.pdfViewerClass).toBeCalledWith(expect.objectContaining({ textLayerMode: 0 }));
+                    expect(stubs.getViewerOption).toBeCalledWith('disableTextLayer');
+                    // Text Layer mode 2 = enabled permissions
+                    expect(stubs.pdfViewerClass).toBeCalledWith(expect.objectContaining({ textLayerMode: 2 }));
                 });
             });
 
             test('should disable the text layer if disableTextLayer viewer option is set', () => {
-                stubs.checkPermission.mockReturnValueOnce(true);
                 stubs.getViewerOption.mockReturnValue(true);
 
                 return docBase.initViewer('').then(() => {
-                    expect(stubs.checkPermission).toBeCalledWith(docBase.options.file, PERMISSION_DOWNLOAD);
                     expect(stubs.getViewerOption).toBeCalledWith('disableTextLayer');
                     // Text Layer mode 0 = disabled
                     expect(stubs.pdfViewerClass).toBeCalledWith(expect.objectContaining({ textLayerMode: 0 }));

src/lib/viewers/doc/_docBase.scss

@@ -304,6 +304,17 @@ $thumbnail-sidebar-width: 191px; // Extra pixel to account for sidebar border
         }
     }
 
+    .pdfViewer {
+        &.pdfViewer--viewOnly {
+            .textLayer {
+                span {
+                    cursor: unset;
+                    user-select: none;
+                }
+            }
+        }
+    }
+
     .textLayer {
         caret-color: black; // Required for caret navigation on transparent text
         top: $pdfjs-page-padding;