Replace the disableTextLayer and enhanceTextSelection options/preferences with a single textLayerMode option/preference

Rather than having two different (but connected) options for the textLayer, I think that it makes sense to try and unify this. For example: currently if `disableTextLayer === true`, then the value of `enhanceTextSelection` is simply ignored.

Since PDF.js version `2.0` already won't be backwards compatible in lots of ways, I don't think that we need to worry about migrating existing preferences here.

examples/mobile-viewer/viewer.js

@@ -22,7 +22,7 @@ if (typeof PDFJS === 'undefined' || !PDFJS.PDFViewer || !PDFJS.getDocument) {
 }
 
 var USE_ONLY_CSS_ZOOM = true;
-PDFJS.disableTextLayer = true;
+var TEXT_LAYER_MODE = 0; // DISABLE
 PDFJS.maxImageSize = 1024 * 1024;
 PDFJS.workerSrc = '../../node_modules/pdfjs-dist/build/pdf.worker.js';
 PDFJS.cMapUrl = '../../node_modules/pdfjs-dist/cmaps/';
@@ -299,6 +299,7 @@ var PDFViewerApplication = {
       linkService: linkService,
       l10n: this.l10n,
       useOnlyCssZoom: USE_ONLY_CSS_ZOOM,
+      textLayerMode: TEXT_LAYER_MODE,
     });
     this.pdfViewer = pdfViewer;
     linkService.setViewer(pdfViewer);

extensions/chromium/preferences_schema.json

@@ -75,11 +75,16 @@
       "type": "boolean",
       "default": false
     },
-    "disableTextLayer": {
+    "textLayerMode": {
-      "title": "Disable text selection layer",
+      "title": "Text layer mode",
-      "description": "Whether to disable the text selection layer.",
+      "description": "Controls if the text layer is enabled, and the selection mode that is used.\n 0 = Disabled.\n 1 = Enabled.\n 2 = (Experimental) Enabled, with enhanced text selection.",
-      "type": "boolean",
+      "type": "integer",
-      "default": false
+      "enum": [
+        0,
+        1,
+        2
+      ],
+      "default": 1
     },
     "useOnlyCssZoom": {
       "type": "boolean",
@@ -112,10 +117,6 @@
       "description": "Whether to prevent the extension from reporting the extension and browser version to the extension developers.",
       "default": false
     },
-    "enhanceTextSelection": {
-      "type": "boolean",
-      "default": false
-    },
     "renderer": {
       "type": "string",
       "enum": [

web/app.js

@@ -18,7 +18,7 @@ import {
   animationStarted, DEFAULT_SCALE_VALUE, getPDFFileNameFromURL, isFileSchema,
   isValidRotation, MAX_SCALE, MIN_SCALE, noContextMenuHandler,
   normalizeWheelEventDelta, parseQueryString, PresentationModeState,
-  ProgressBar, RendererType
+  ProgressBar, RendererType, TextLayerMode
 } from './ui_utils';
 import {
   build, createBlob, getDocument, getFilenameFromUrl, InvalidPDFException,
@@ -146,7 +146,7 @@ let PDFViewerApplication = {
     disablePageMode: false,
     disablePageLabels: false,
     renderer: 'canvas',
-    enhanceTextSelection: false,
+    textLayerMode: TextLayerMode.ENABLE,
     renderInteractiveForms: false,
     enablePrintAutoRotate: false,
   },
@@ -217,14 +217,11 @@ let PDFViewerApplication = {
       preferences.get('defaultZoomValue').then(function resolved(value) {
         viewerPrefs['defaultZoomValue'] = value;
       }),
-      preferences.get('enhanceTextSelection').then(function resolved(value) {
+      preferences.get('textLayerMode').then(function resolved(value) {
-        viewerPrefs['enhanceTextSelection'] = value;
+        if (viewerPrefs['textLayerMode'] === TextLayerMode.DISABLE) {
-      }),
-      preferences.get('disableTextLayer').then(function resolved(value) {
-        if (PDFJS.disableTextLayer === true) {
           return;
         }
-        PDFJS.disableTextLayer = value;
+        viewerPrefs['textLayerMode'] = value;
       }),
       preferences.get('disableRange').then(function resolved(value) {
         if (PDFJS.disableRange === true) {
@@ -323,7 +320,7 @@ let PDFViewerApplication = {
       if ('textlayer' in hashParams) {
         switch (hashParams['textlayer']) {
           case 'off':
-            PDFJS.disableTextLayer = true;
+            viewerPrefs['textLayerMode'] = TextLayerMode.DISABLE;
             break;
           case 'visible':
           case 'shadow':
@@ -398,7 +395,7 @@ let PDFViewerApplication = {
         downloadManager,
         renderer: viewerPrefs['renderer'],
         l10n: this.l10n,
-        enhanceTextSelection: viewerPrefs['enhanceTextSelection'],
+        textLayerMode: viewerPrefs['textLayerMode'],
         imageResourcesPath: PDFJS.imageResourcesPath,
         renderInteractiveForms: viewerPrefs['renderInteractiveForms'],
         enablePrintAutoRotate: viewerPrefs['enablePrintAutoRotate'],

web/base_viewer.js

@@ -17,7 +17,7 @@ import { createPromiseCapability, PDFJS } from 'pdfjs-lib';
 import {
   CSS_UNITS, DEFAULT_SCALE, DEFAULT_SCALE_VALUE, isValidRotation,
   MAX_AUTO_SCALE, NullL10n, PresentationModeState, RendererType,
-  SCROLLBAR_PADDING, UNKNOWN_SCALE, VERTICAL_PADDING, watchScroll
+  SCROLLBAR_PADDING, TextLayerMode, UNKNOWN_SCALE, VERTICAL_PADDING, watchScroll
 } from './ui_utils';
 import { PDFRenderingQueue, RenderingStates } from './pdf_rendering_queue';
 import { AnnotationLayerBuilder } from './annotation_layer_builder';
@@ -39,9 +39,11 @@ const DEFAULT_CACHE_SIZE = 10;
  * @property {PDFRenderingQueue} renderingQueue - (optional) The rendering
  *   queue object.
  * @property {boolean} removePageBorders - (optional) Removes the border shadow
- *   around the pages. The default is false.
+ *   around the pages. The default value is `false`.
- * @property {boolean} enhanceTextSelection - (optional) Enables the improved
+ * @property {number} textLayerMode - (optional) Controls if the text layer used
- *   text selection behaviour. The default is `false`.
+ *   for selection and searching is created, and if the improved text selection
+ *   behaviour is enabled. The constants from {TextLayerMode} should be used.
+ *   The default value is `TextLayerMode.ENABLE`.
  * @property {string} imageResourcesPath - (optional) Path for image resources,
  *   mainly for annotation icons. Include trailing slash.
  * @property {boolean} renderInteractiveForms - (optional) Enables rendering of
@@ -114,6 +116,8 @@ class BaseViewer {
     this.linkService = options.linkService || new SimpleLinkService();
     this.downloadManager = options.downloadManager || null;
     this.removePageBorders = options.removePageBorders || false;
+    this.textLayerMode = Number.isInteger(options.textLayerMode) ?
+      options.textLayerMode : TextLayerMode.ENABLE;
     this.enhanceTextSelection = options.enhanceTextSelection || false;
     this.imageResourcesPath = options.imageResourcesPath || '';
     this.renderInteractiveForms = options.renderInteractiveForms || false;
@@ -372,7 +376,7 @@ class BaseViewer {
       let viewport = pdfPage.getViewport(scale * CSS_UNITS);
       for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
         let textLayerFactory = null;
-        if (!PDFJS.disableTextLayer) {
+        if (this.textLayerMode !== TextLayerMode.DISABLE) {
           textLayerFactory = this;
         }
         let pageView = new PDFPageView({
@@ -383,8 +387,8 @@ class BaseViewer {
           defaultViewport: viewport.clone(),
           renderingQueue: this.renderingQueue,
           textLayerFactory,
+          textLayerMode: this.textLayerMode,
           annotationLayerFactory: this,
-          enhanceTextSelection: this.enhanceTextSelection,
           imageResourcesPath: this.imageResourcesPath,
           renderInteractiveForms: this.renderInteractiveForms,
           renderer: this.renderer,

web/default_preferences.json

@@ -10,10 +10,9 @@
   "disableStream": false,
   "disableAutoFetch": false,
   "disableFontFace": false,
-  "disableTextLayer": false,
+  "textLayerMode": 1,
   "useOnlyCssZoom": false,
   "externalLinkTarget": 0,
-  "enhanceTextSelection": false,
   "renderer": "canvas",
   "renderInteractiveForms": false,
   "enablePrintAutoRotate": false,

web/pdf_page_view.js

@@ -15,7 +15,7 @@
 
 import {
   approximateFraction, CSS_UNITS, DEFAULT_SCALE, getOutputScale, NullL10n,
-  RendererType, roundToDivide
+  RendererType, roundToDivide, TextLayerMode
 } from './ui_utils';
 import {
   createPromiseCapability, RenderingCancelledException, SVGGraphics
@@ -33,9 +33,11 @@ import { viewerCompatibilityParams } from './viewer_compatibility';
  * @property {PageViewport} defaultViewport - The page viewport.
  * @property {PDFRenderingQueue} renderingQueue - The rendering queue object.
  * @property {IPDFTextLayerFactory} textLayerFactory
+ * @property {number} textLayerMode - (optional) Controls if the text layer used
+ *   for selection and searching is created, and if the improved text selection
+ *   behaviour is enabled. The constants from {TextLayerMode} should be used.
+ *   The default value is `TextLayerMode.ENABLE`.
  * @property {IPDFAnnotationLayerFactory} annotationLayerFactory
- * @property {boolean} enhanceTextSelection - Turns on the text selection
- *   enhancement. The default is `false`.
  * @property {string} imageResourcesPath - (optional) Path for image resources,
  *   mainly for annotation icons. Include trailing slash.
  * @property {boolean} renderInteractiveForms - Turns on rendering of
@@ -72,7 +74,8 @@ class PDFPageView {
     this.viewport = defaultViewport;
     this.pdfPageRotate = defaultViewport.rotation;
     this.hasRestrictedScaling = false;
-    this.enhanceTextSelection = options.enhanceTextSelection || false;
+    this.textLayerMode = Number.isInteger(options.textLayerMode) ?
+      options.textLayerMode : TextLayerMode.ENABLE;
     this.imageResourcesPath = options.imageResourcesPath || '';
     this.renderInteractiveForms = options.renderInteractiveForms || false;
     this.useOnlyCssZoom = options.useOnlyCssZoom || false;
@@ -384,7 +387,7 @@ class PDFPageView {
     }
 
     let textLayer = null;
-    if (this.textLayerFactory) {
+    if (this.textLayerMode !== TextLayerMode.DISABLE && this.textLayerFactory) {
       let textLayerDiv = document.createElement('div');
       textLayerDiv.className = 'textLayer';
       textLayerDiv.style.width = canvasWrapper.style.width;
@@ -398,7 +401,7 @@ class PDFPageView {
 
       textLayer = this.textLayerFactory.
         createTextLayerBuilder(textLayerDiv, this.id - 1, this.viewport,
-                               this.enhanceTextSelection);
+            this.textLayerMode === TextLayerMode.ENABLE_ENHANCE);
     }
     this.textLayer = textLayer;
 

web/ui_utils.js

@@ -37,6 +37,12 @@ const RendererType = {
   SVG: 'svg',
 };
 
+const TextLayerMode = {
+  DISABLE: 0,
+  ENABLE: 1,
+  ENABLE_ENHANCE: 2,
+};
+
 // Replaces {{arguments}} with their values.
 function formatL10nValue(text, args) {
   if (!args) {
@@ -87,13 +93,6 @@ PDFJS.maxCanvasPixels = (PDFJS.maxCanvasPixels === undefined ?
 PDFJS.disableHistory = (PDFJS.disableHistory === undefined ?
                         false : PDFJS.disableHistory);
 
-/**
- * Disables creation of the text layer that used for text selection and search.
- * @var {boolean}
- */
-PDFJS.disableTextLayer = (PDFJS.disableTextLayer === undefined ?
-                          false : PDFJS.disableTextLayer);
-
 if (typeof PDFJSDev === 'undefined' ||
     !PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
   /**
@@ -669,6 +668,7 @@ export {
   cloneObj,
   PresentationModeState,
   RendererType,
+  TextLayerMode,
   mozL10n,
   NullL10n,
   EventBus,