Merge pull request #8582 from timvandermeij/es6-text-layer-builder

Convert the text layer builder to ES6 syntax

web/text_layer_builder.js

@@ -16,7 +16,7 @@
 import { getGlobalEventBus } from './dom_events';
 import { renderTextLayer } from 'pdfjs-lib';
 
-var EXPAND_DIVS_TIMEOUT = 300; // ms
+const EXPAND_DIVS_TIMEOUT = 300; // ms
 
 /**
  * @typedef {Object} TextLayerBuilderOptions
@@ -30,40 +30,40 @@ var EXPAND_DIVS_TIMEOUT = 300; // ms
  */
 
 /**
- * TextLayerBuilder provides text-selection functionality for the PDF.
+ * The text layer builder provides text selection functionality for the PDF.
- * It does this by creating overlay divs over the PDF text. These divs
+ * It does this by creating overlay divs over the PDF's text. These divs
  * contain text that matches the PDF text they are overlaying. This object
  * also provides a way to highlight text that is being searched for.
- * @class
  */
-var TextLayerBuilder = (function TextLayerBuilderClosure() {
+class TextLayerBuilder {
-  function TextLayerBuilder(options) {
+  constructor({ textLayerDiv, eventBus, pageIndex, viewport,
-    this.textLayerDiv = options.textLayerDiv;
+                findController = null, enhanceTextSelection = false, }) {
-    this.eventBus = options.eventBus || getGlobalEventBus();
+    this.textLayerDiv = textLayerDiv;
+    this.eventBus = eventBus || getGlobalEventBus();
     this.textContent = null;
     this.textContentItemsStr = [];
     this.textContentStream = null;
     this.renderingDone = false;
-    this.pageIdx = options.pageIndex;
+    this.pageIdx = pageIndex;
     this.pageNumber = this.pageIdx + 1;
     this.matches = [];
-    this.viewport = options.viewport;
+    this.viewport = viewport;
     this.textDivs = [];
-    this.findController = options.findController || null;
+    this.findController = findController;
     this.textLayerRenderTask = null;
-    this.enhanceTextSelection = options.enhanceTextSelection;
+    this.enhanceTextSelection = enhanceTextSelection;
+
     this._bindMouse();
   }
 
-  TextLayerBuilder.prototype = {
   /**
    * @private
    */
-    _finishRendering: function TextLayerBuilder_finishRendering() {
+  _finishRendering() {
     this.renderingDone = true;
 
     if (!this.enhanceTextSelection) {
-        var endOfContent = document.createElement('div');
+      let endOfContent = document.createElement('div');
       endOfContent.className = 'endOfContent';
       this.textLayerDiv.appendChild(endOfContent);
     }
@@ -73,21 +73,22 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
       pageNumber: this.pageNumber,
       numTextDivs: this.textDivs.length,
     });
-    },
+  }
 
   /**
    * Renders the text layer.
-     * @param {number} timeout (optional) if specified, the rendering waits
+   *
-     *   for specified amount of ms.
+   * @param {number} timeout - (optional) wait for a specified amount of
+   *                           milliseconds before rendering
    */
-    render: function TextLayerBuilder_render(timeout) {
+  render(timeout = 0) {
     if (!(this.textContent || this.textContentStream) || this.renderingDone) {
       return;
     }
     this.cancel();
 
     this.textDivs = [];
-      var textLayerFrag = document.createDocumentFragment();
+    let textLayerFrag = document.createDocumentFragment();
     this.textLayerRenderTask = renderTextLayer({
       textContent: this.textContent,
       textContentStream: this.textContentStream,
@@ -103,45 +104,44 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
       this._finishRendering();
       this.updateMatches();
     }, function (reason) {
-        // cancelled or failed to render text layer -- skipping errors
+      // Cancelled or failed to render text layer; skipping errors.
     });
-    },
+  }
 
   /**
-     * Cancels rendering of the text layer.
+   * Cancel rendering of the text layer.
    */
-    cancel: function TextLayerBuilder_cancel() {
+  cancel() {
     if (this.textLayerRenderTask) {
       this.textLayerRenderTask.cancel();
       this.textLayerRenderTask = null;
     }
-    },
+  }
 
   setTextContentStream(readableStream) {
     this.cancel();
     this.textContentStream = readableStream;
-    },
+  }
 
-    setTextContent: function TextLayerBuilder_setTextContent(textContent) {
+  setTextContent(textContent) {
     this.cancel();
     this.textContent = textContent;
-    },
+  }
 
-    convertMatches: function TextLayerBuilder_convertMatches(matches,
+  convertMatches(matches, matchesLength) {
-                                                             matchesLength) {
+    let i = 0;
-      var i = 0;
+    let iIndex = 0;
-      var iIndex = 0;
     let textContentItemsStr = this.textContentItemsStr;
-      var end = textContentItemsStr.length - 1;
+    let end = textContentItemsStr.length - 1;
-      var queryLen = (this.findController === null ?
+    let queryLen = (this.findController === null ?
                     0 : this.findController.state.query.length);
-      var ret = [];
+    let ret = [];
     if (!matches) {
       return ret;
     }
-      for (var m = 0, len = matches.length; m < len; m++) {
+    for (let m = 0, len = matches.length; m < len; m++) {
       // Calculate the start position.
-        var matchIdx = matches[m];
+      let matchIdx = matches[m];
 
       // Loop over the divIdxs.
       while (i !== end && matchIdx >=
@@ -154,7 +154,7 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
         console.error('Could not find a matching mapping');
       }
 
-        var match = {
+      let match = {
         begin: {
           divIdx: i,
           offset: matchIdx - iIndex,
@@ -162,9 +162,9 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
       };
 
       // Calculate the end position.
-        if (matchesLength) { // multiterm search
+      if (matchesLength) { // Multiterm search.
         matchIdx += matchesLength[m];
-        } else { // phrase search
+      } else { // Phrase search.
         matchIdx += queryLen;
       }
 
@@ -184,42 +184,41 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
     }
 
     return ret;
-    },
+  }
 
-    renderMatches: function TextLayerBuilder_renderMatches(matches) {
+  renderMatches(matches) {
     // Early exit if there is nothing to render.
     if (matches.length === 0) {
       return;
     }
 
     let textContentItemsStr = this.textContentItemsStr;
-      var textDivs = this.textDivs;
+    let textDivs = this.textDivs;
-      var prevEnd = null;
+    let prevEnd = null;
-      var pageIdx = this.pageIdx;
+    let pageIdx = this.pageIdx;
-      var isSelectedPage = (this.findController === null ?
+    let isSelectedPage = (this.findController === null ?
       false : (pageIdx === this.findController.selected.pageIdx));
-      var selectedMatchIdx = (this.findController === null ?
+    let selectedMatchIdx = (this.findController === null ?
                             -1 : this.findController.selected.matchIdx);
-      var highlightAll = (this.findController === null ?
+    let highlightAll = (this.findController === null ?
                         false : this.findController.state.highlightAll);
-      var infinity = {
+    let infinity = {
       divIdx: -1,
       offset: undefined,
     };
 
     function beginText(begin, className) {
-        var divIdx = begin.divIdx;
+      let divIdx = begin.divIdx;
       textDivs[divIdx].textContent = '';
       appendTextToDiv(divIdx, 0, begin.offset, className);
     }
 
     function appendTextToDiv(divIdx, fromOffset, toOffset, className) {
-        var div = textDivs[divIdx];
+      let div = textDivs[divIdx];
-        var content =
+      let content = textContentItemsStr[divIdx].substring(fromOffset, toOffset);
-          textContentItemsStr[divIdx].substring(fromOffset, toOffset);
+      let node = document.createTextNode(content);
-        var node = document.createTextNode(content);
       if (className) {
-          var span = document.createElement('span');
+        let span = document.createElement('span');
         span.className = className;
         span.appendChild(node);
         div.appendChild(span);
@@ -228,7 +227,7 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
       div.appendChild(node);
     }
 
-      var i0 = selectedMatchIdx, i1 = i0 + 1;
+    let i0 = selectedMatchIdx, i1 = i0 + 1;
     if (highlightAll) {
       i0 = 0;
       i1 = matches.length;
@@ -237,12 +236,12 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
       return;
     }
 
-      for (var i = i0; i < i1; i++) {
+    for (let i = i0; i < i1; i++) {
-        var match = matches[i];
+      let match = matches[i];
-        var begin = match.begin;
+      let begin = match.begin;
-        var end = match.end;
+      let end = match.end;
-        var isSelected = (isSelectedPage && i === selectedMatchIdx);
+      let isSelected = (isSelectedPage && i === selectedMatchIdx);
-        var highlightSuffix = (isSelected ? ' selected' : '');
+      let highlightSuffix = (isSelected ? ' selected' : '');
 
       if (this.findController) {
         this.findController.updateMatchPosition(pageIdx, i, textDivs,
@@ -267,7 +266,7 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
       } else {
         appendTextToDiv(begin.divIdx, begin.offset, infinity.offset,
                         'highlight begin' + highlightSuffix);
-          for (var n0 = begin.divIdx + 1, n1 = end.divIdx; n0 < n1; n0++) {
+        for (let n0 = begin.divIdx + 1, n1 = end.divIdx; n0 < n1; n0++) {
           textDivs[n0].className = 'highlight middle' + highlightSuffix;
         }
         beginText(end, 'highlight end' + highlightSuffix);
@@ -278,26 +277,26 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
     if (prevEnd) {
       appendTextToDiv(prevEnd.divIdx, prevEnd.offset, infinity.offset);
     }
-    },
+  }
 
-    updateMatches: function TextLayerBuilder_updateMatches() {
+  updateMatches() {
     // Only show matches when all rendering is done.
     if (!this.renderingDone) {
       return;
     }
 
     // Clear all matches.
-      var matches = this.matches;
+    let matches = this.matches;
-      var textDivs = this.textDivs;
+    let textDivs = this.textDivs;
     let textContentItemsStr = this.textContentItemsStr;
-      var clearedUntilDivIdx = -1;
+    let clearedUntilDivIdx = -1;
 
     // Clear all current matches.
-      for (var i = 0, len = matches.length; i < len; i++) {
+    for (let i = 0, len = matches.length; i < len; i++) {
-        var match = matches[i];
+      let match = matches[i];
-        var begin = Math.max(clearedUntilDivIdx, match.begin.divIdx);
+      let begin = Math.max(clearedUntilDivIdx, match.begin.divIdx);
-        for (var n = begin, end = match.end.divIdx; n <= end; n++) {
+      for (let n = begin, end = match.end.divIdx; n <= end; n++) {
-          var div = textDivs[n];
+        let div = textDivs[n];
         div.textContent = textContentItemsStr[n];
         div.className = '';
       }
@@ -310,7 +309,7 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
 
     // Convert the matches on the page controller into the match format
     // used for the textLayer.
-      var pageMatches, pageMatchesLength;
+    let pageMatches, pageMatchesLength;
     if (this.findController !== null) {
       pageMatches = this.findController.pageMatches[this.pageIdx] || null;
       pageMatchesLength = (this.findController.pageMatchesLength) ?
@@ -319,21 +318,22 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
 
     this.matches = this.convertMatches(pageMatches, pageMatchesLength);
     this.renderMatches(this.matches);
-    },
+  }
 
   /**
-     * Fixes text selection: adds additional div where mouse was clicked.
+   * Improves text selection by adding an additional div where the mouse was
-     * This reduces flickering of the content if mouse slowly dragged down/up.
+   * clicked. This reduces flickering of the content if the mouse is slowly
+   * dragged up or down.
+   *
    * @private
    */
-    _bindMouse: function TextLayerBuilder_bindMouse() {
+  _bindMouse() {
-      var div = this.textLayerDiv;
+    let div = this.textLayerDiv;
-      var self = this;
+    let expandDivsTimer = null;
-      var expandDivsTimer = null;
+
-
+    div.addEventListener('mousedown', (evt) => {
-      div.addEventListener('mousedown', function (e) {
+      if (this.enhanceTextSelection && this.textLayerRenderTask) {
-        if (self.enhanceTextSelection && self.textLayerRenderTask) {
+        this.textLayerRenderTask.expandTextDivs(true);
-          self.textLayerRenderTask.expandTextDivs(true);
         if ((typeof PDFJSDev === 'undefined' ||
              !PDFJSDev.test('FIREFOX || MOZCENTRAL')) &&
             expandDivsTimer) {
@@ -342,46 +342,48 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
         }
         return;
       }
-        var end = div.querySelector('.endOfContent');
+
+      let end = div.querySelector('.endOfContent');
       if (!end) {
         return;
       }
       if (typeof PDFJSDev === 'undefined' ||
           !PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
         // On non-Firefox browsers, the selection will feel better if the height
-        // of the endOfContent div will be adjusted to start at mouse click
+        // of the `endOfContent` div is adjusted to start at mouse click
-        // location -- this will avoid flickering when selections moves up.
+        // location. This avoids flickering when the selection moves up.
-        // However it does not work when selection started on empty space.
+        // However it does not work when selection is started on empty space.
-        var adjustTop = e.target !== div;
+        let adjustTop = evt.target !== div;
         if (typeof PDFJSDev === 'undefined' || PDFJSDev.test('GENERIC')) {
           adjustTop = adjustTop && window.getComputedStyle(end).
             getPropertyValue('-moz-user-select') !== 'none';
         }
         if (adjustTop) {
-          var divBounds = div.getBoundingClientRect();
+          let divBounds = div.getBoundingClientRect();
-          var r = Math.max(0, (e.pageY - divBounds.top) / divBounds.height);
+          let r = Math.max(0, (evt.pageY - divBounds.top) / divBounds.height);
           end.style.top = (r * 100).toFixed(2) + '%';
         }
       }
       end.classList.add('active');
     });
 
-      div.addEventListener('mouseup', function (e) {
+    div.addEventListener('mouseup', () => {
-        if (self.enhanceTextSelection && self.textLayerRenderTask) {
+      if (this.enhanceTextSelection && this.textLayerRenderTask) {
         if (typeof PDFJSDev === 'undefined' ||
             !PDFJSDev.test('FIREFOX || MOZCENTRAL')) {
-            expandDivsTimer = setTimeout(function() {
+          expandDivsTimer = setTimeout(() => {
-              if (self.textLayerRenderTask) {
+            if (this.textLayerRenderTask) {
-                self.textLayerRenderTask.expandTextDivs(false);
+              this.textLayerRenderTask.expandTextDivs(false);
             }
             expandDivsTimer = null;
           }, EXPAND_DIVS_TIMEOUT);
         } else {
-            self.textLayerRenderTask.expandTextDivs(false);
+          this.textLayerRenderTask.expandTextDivs(false);
         }
         return;
       }
-        var end = div.querySelector('.endOfContent');
+
+      let end = div.querySelector('.endOfContent');
       if (!end) {
         return;
       }
@@ -391,17 +393,13 @@ var TextLayerBuilder = (function TextLayerBuilderClosure() {
       }
       end.classList.remove('active');
     });
-    },
+  }
-  };
+}
-  return TextLayerBuilder;
-})();
 
 /**
- * @constructor
  * @implements IPDFTextLayerFactory
  */
-function DefaultTextLayerFactory() {}
+class DefaultTextLayerFactory {
-DefaultTextLayerFactory.prototype = {
   /**
    * @param {HTMLDivElement} textLayerDiv
    * @param {number} pageIndex
@@ -417,8 +415,8 @@ DefaultTextLayerFactory.prototype = {
       viewport,
       enhanceTextSelection,
     });
-  },
+  }
-};
+}
 
 export {
   TextLayerBuilder,