chrome/browser/resources/chromeos/chromevox/common/content_editable_extractor.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview Defines the ContentEditableExtractor class.
   7  */
   8
   9 goog.provide('cvox.ContentEditableExtractor');
  10
  11 goog.require('cvox.Cursor');
  12 goog.require('cvox.TraverseUtil');
  13
  14 /**
  15  * Extracts the text and line break information from a contenteditable region.
  16  * @constructor
  17  */
  18 cvox.ContentEditableExtractor = function() {
  19   /**
  20    * The extracted, flattened, text.
  21    * @type {string}
  22    * @private
  23    */
  24   this.text_ = '';
  25
  26   /**
  27    * The start cursor/selection index.
  28    * @type {number}
  29    * @private
  30    */
  31   this.start_ = 0;
  32
  33   /**
  34    * The end cursor/selection index.
  35    * @type {number}
  36    * @private
  37    */
  38   this.end_ = 0;
  39
  40   /**
  41    * Map from line index to a data structure containing the start
  42    * and end index within the line.
  43    * @type {Object<number, {startIndex: number, endIndex: number}>}
  44    * @private
  45    */
  46   this.lines_ = {};
  47
  48   /**
  49    * Map from 0-based character index to 0-based line index.
  50    * @type {Array<number>}
  51    * @private
  52    */
  53   this.characterToLineMap_ = [];
  54 };
  55
  56 /**
  57  * Update the metadata.
  58  * @param {Element} element The DOM element that's contentEditable.
  59  */
  60 cvox.ContentEditableExtractor.prototype.update = function(element) {
  61   /**
  62    * Map from line index to a data structure containing the start
  63    * and end index within the line.
  64    * @type {Object<number, {startIndex: number, endIndex: number}>}
  65    */
  66   var lines = {0: {startIndex: 0, endIndex: 0}};
  67   var startCursor = new cvox.Cursor(element, 0, '');
  68   var endCursor = startCursor.clone();
  69   var range = document.createRange();
  70   var rect;
  71   var lineIndex = 0;
  72   var lastBottom = null;
  73   var text = '';
  74   var textSize = 0;
  75   var selectionStartIndex = -1;
  76   var selectionEndIndex = -1;
  77   var sel = window.getSelection();
  78   var selectionStart = new cvox.Cursor(sel.baseNode, sel.baseOffset, '');
  79   var selectionEnd = new cvox.Cursor(sel.extentNode, sel.extentOffset, '');
  80   var setStart = false;
  81   var setEnd = false;
  82   while (true) {
  83     var entered = [];
  84     var left = [];
  85     var c = cvox.TraverseUtil.forwardsChar(endCursor, entered, left);
  86     var done = false;
  87     if (!c) {
  88       done = true;
  89     }
  90     for (var i = 0; i < left.length && !done; i++) {
  91       if (left[i] == element) {
  92         done = true;
  93       }
  94     }
  95     if (done) {
  96       break;
  97     }
  98
  99     range.setStart(startCursor.node, startCursor.index);
 100     range.setEnd(endCursor.node, endCursor.index);
 101     rect = range.getBoundingClientRect();
 102     if (!rect || rect.width == 0 || rect.height == 0) {
 103       continue;
 104     }
 105
 106     if (lastBottom !== null &&
 107         rect.bottom != lastBottom &&
 108         textSize > 0 &&
 109         text.substr(-1).match(/\S/) &&
 110         c.match(/\S/)) {
 111       text += '\n';
 112       textSize++;
 113     }
 114
 115     if (startCursor.node != endCursor.node && endCursor.index > 0) {
 116       range.setStart(endCursor.node, endCursor.index - 1);
 117       rect = range.getBoundingClientRect();
 118       if (!rect || rect.width == 0 || rect.height == 0) {
 119         continue;
 120       }
 121     }
 122
 123     if (!setStart &&
 124         selectionStartIndex == -1 &&
 125         endCursor.node == selectionStart.node &&
 126         endCursor.index >= selectionStart.index) {
 127       if (endCursor.index > selectionStart.index) {
 128         selectionStartIndex = textSize;
 129       } else {
 130         setStart = true;
 131       }
 132     }
 133     if (!setEnd &&
 134         selectionEndIndex == -1 &&
 135         endCursor.node == selectionEnd.node &&
 136         endCursor.index >= selectionEnd.index) {
 137       if (endCursor.index > selectionEnd.index) {
 138         selectionEndIndex = textSize;
 139       } else {
 140         setEnd = true;
 141       }
 142     }
 143
 144     if (lastBottom === null) {
 145       // This is the first character we've successfully measured on this
 146       // line. Save the vertical position but don't do anything else.
 147       lastBottom = rect.bottom;
 148     } else if (rect.bottom != lastBottom) {
 149       lines[lineIndex].endIndex = textSize;
 150       lineIndex++;
 151       lines[lineIndex] = {startIndex: textSize, endIndex: textSize};
 152       lastBottom = rect.bottom;
 153     }
 154     text += c;
 155     textSize++;
 156     startCursor = endCursor.clone();
 157
 158     if (setStart) {
 159       selectionStartIndex = textSize;
 160       setStart = false;
 161     }
 162     if (setEnd) {
 163       selectionEndIndex = textSize;
 164       setEnd = false;
 165     }
 166   }
 167
 168   // Finish up the last line.
 169   lines[lineIndex].endIndex = textSize;
 170
 171   // Create a map from character index to line number.
 172   var characterToLineMap = [];
 173   for (var i = 0; i <= lineIndex; i++) {
 174     for (var j = lines[i].startIndex; j <= lines[i].endIndex; j++) {
 175       characterToLineMap[j] = i;
 176     }
 177   }
 178
 179   // Finish updating fields.
 180   this.text_ = text;
 181   this.characterToLineMap_ = characterToLineMap;
 182   this.lines_ = lines;
 183
 184   this.start_ = selectionStartIndex >= 0 ? selectionStartIndex : text.length;
 185   this.end_ = selectionEndIndex >= 0 ? selectionEndIndex : text.length;
 186 };
 187
 188 /**
 189  * Get the text.
 190  * @return {string} The extracted, flattened, text.
 191  */
 192 cvox.ContentEditableExtractor.prototype.getText = function() {
 193   return this.text_;
 194 };
 195
 196 /**
 197  * @return {number} The start cursor/selection index.
 198  */
 199 cvox.ContentEditableExtractor.prototype.getStartIndex = function() {
 200   return this.start_;
 201 };
 202
 203 /**
 204  * @return {number} The end cursor/selection index.
 205  */
 206 cvox.ContentEditableExtractor.prototype.getEndIndex = function() {
 207   return this.end_;
 208 };
 209
 210 /**
 211  * Get the line number corresponding to a particular index.
 212  * @param {number} index The 0-based character index.
 213  * @return {number} The 0-based line number corresponding to that character.
 214  */
 215 cvox.ContentEditableExtractor.prototype.getLineIndex = function(index) {
 216   return this.characterToLineMap_[index];
 217 };
 218
 219 /**
 220  * Get the start character index of a line.
 221  * @param {number} index The 0-based line index.
 222  * @return {number} The 0-based index of the first character in this line.
 223  */
 224 cvox.ContentEditableExtractor.prototype.getLineStart = function(index) {
 225   return this.lines_[index].startIndex;
 226 };
 227
 228 /**
 229  * Get the end character index of a line.
 230  * @param {number} index The 0-based line index.
 231  * @return {number} The 0-based index of the end of this line.
 232  */
 233 cvox.ContentEditableExtractor.prototype.getLineEnd = function(index) {
 234   return this.lines_[index].endIndex;
 235 };