modules/documentCanvas/canvas/canvas.js

   1 define([
   2 'libs/jquery-1.9.1.min',
   3 'libs/underscore-min',
   4 'libs/backbone-min',
   5 'modules/documentCanvas/canvas/documentElement',
   6 'modules/documentCanvas/canvas/utils'
   7 ], function($, _, Backbone, documentElement, utils) {
   8
   9 'use strict';
  10
  11 var Canvas = function(wlxml, publisher) {
  12     this.eventBus = _.extend({}, Backbone.Events);
  13     this.loadWlxml(wlxml);
  14     this.publisher = publisher ? publisher : function() {};
  15 };
  16
  17 $.extend(Canvas.prototype, {
  18
  19     loadWlxml: function(wlxml) {
  20         var d = wlxml ? $($.trim(wlxml)) : null;
  21         if(d) {
  22             this.wrapper = $('<div>').addClass('canvas-wrapper').attr('contenteditable', true);
  23             this.wrapper.append(d);
  24             var canvas = this;
  25
  26             this.wrapper.find('*').replaceWith(function() {
  27                 var currentTag = $(this);
  28                 if(currentTag.attr('wlxml-tag'))
  29                     return;
  30
  31                 var meta = {}, others = {};
  32                 for(var i = 0; i < this.attributes.length; i++) {
  33                     var attr = this.attributes[i];
  34                     if(attr.name.substr(0, 5) === 'meta-')
  35                         meta[attr.name.substr(5)] = attr.value;
  36                     else if(attr.name !== 'class')
  37                         others[attr.name] = attr.value;
  38                 }
  39
  40                 var element = documentElement.DocumentNodeElement.create({
  41                     tag: currentTag.prop('tagName').toLowerCase(),
  42                     klass: currentTag.attr('class'),
  43                     meta: meta,
  44                     others: others,
  45                     rawChildren: currentTag.contents()
  46                 }, canvas);
  47
  48                 ['orig-before', 'orig-after', 'orig-begin', 'orig-end'].forEach(function(attr) {
  49                     element.data(attr, '');
  50                 });
  51                 return element.dom();
  52             });
  53
  54             var FIRST_CONTENT_INDEX = 0;
  55
  56             // @@ TODO - refactor!
  57             var getNode = function(element) {
  58                 return element.children('[document-element-content]');
  59             }
  60
  61             this.wrapper.find(':not(iframe)').addBack().contents()
  62                 .filter(function() {return this.nodeType === Node.TEXT_NODE})
  63                 .each(function() {
  64
  65                     // TODO: use DocumentElement API
  66
  67                     var el = $(this),
  68                         text = {original: el.text(), trimmed: $.trim(el.text())},
  69                         elParent = el.parent(),
  70                         hasSpanParent = elParent.attr('wlxml-tag') === 'span',
  71                         hasSpanBefore = el.prev().length > 0  && getNode($(el.prev()[0])).attr('wlxml-tag') === 'span',
  72                         hasSpanAfter = el.next().length > 0 && getNode($(el.next()[0])).attr('wlxml-tag') === 'span';
  73
  74                     if(el.parent().hasClass('canvas-widget'))
  75                         return true; // continue
  76
  77                     var addInfo = function(toAdd, where) {
  78                         var parentContents = elParent.contents(),
  79                             idx = parentContents.index(el[0]),
  80                             prev = idx > FIRST_CONTENT_INDEX ? parentContents[idx-1] : null,
  81                             next = idx < parentContents.length - 1 ? parentContents[idx+1] : null,
  82                             target, key;
  83
  84                         if(where === 'above') {
  85                             target = prev ? $(prev) : elParent.parent();
  86                             key = prev ? 'orig-after' : 'orig-begin';
  87                         } else if(where === 'below') {
  88                             target = next ? $(next) : elParent.parent();
  89                             key = next ? 'orig-before' : 'orig-end';
  90                         } else { throw new Object;}
  91
  92                         target.data(key, toAdd);
  93                     }
  94
  95                     text.transformed = text.trimmed;
  96
  97                     if(hasSpanParent || hasSpanBefore || hasSpanAfter) {
  98                         var startSpace = /\s/g.test(text.original.substr(0,1)),
  99                             endSpace = /\s/g.test(text.original.substr(-1)) && text.original.length > 1;
 100                         text.transformed = (startSpace && (hasSpanParent || hasSpanBefore) ? ' ' : '')
 101                                     + text.trimmed
 102                                     + (endSpace && (hasSpanParent || hasSpanAfter) ? ' ' : '');
 103                     } else {
 104                         if(text.trimmed.length === 0 && text.original.length > 0 && elParent.contents().length === 1)
 105                             text.transformed = ' ';
 106                     }
 107
 108                     if(!text.transformed) {
 109                         addInfo(text.original, 'below');
 110                         el.remove();
 111                         return true; // continue
 112                     }
 113
 114                     if(text.transformed !== text.original) {
 115                         if(!text.trimmed) {
 116                             addInfo(text.original, 'below');
 117                         } else {
 118                             var startingMatch = text.original.match(/^\s+/g),
 119                                 endingMatch = text.original.match(/\s+$/g),
 120                                 startingWhiteSpace = startingMatch ? startingMatch[0] : null,
 121                                 endingWhiteSpace = endingMatch ? endingMatch[0] : null;
 122
 123                             if(endingWhiteSpace) {
 124                                 if(text.transformed[text.transformed.length - 1] === ' ' && endingWhiteSpace[0] === ' ')
 125                                     endingWhiteSpace = endingWhiteSpace.substr(1);
 126                                 addInfo(endingWhiteSpace, 'below');
 127                             }
 128
 129                             if(startingWhiteSpace) {
 130                                 if(text.transformed[0] === ' ' && startingWhiteSpace[startingWhiteSpace.length-1] === ' ')
 131                                     startingWhiteSpace = startingWhiteSpace.substr(0, startingWhiteSpace.length -1);
 132                                 addInfo(startingWhiteSpace, 'above');
 133                             }
 134                         }
 135                     }
 136
 137                     var element = documentElement.DocumentTextElement.create({text: text.transformed});
 138                     el.replaceWith(element.dom());
 139                 });
 140
 141             this.d = this.wrapper.children(0);
 142
 143             this.wrapper.on('keydown', function(e) {
 144                 if(e.which === 13) {
 145                     e.preventDefault();
 146                     var cursor = canvas.getCursor();
 147                     if(!cursor.isSelecting()) {
 148                         var position = cursor.getPosition(),
 149                             elements = position.element.split({offset: position.offset}),
 150                             newEmpty,
 151                             goto;
 152
 153                         if(position.offsetAtBeginning)
 154                             newEmpty = elements.first;
 155                         else if(position.offsetAtEnd)
 156                             newEmpty = elements.second;
 157                         if(newEmpty) {
 158                             goto = newEmpty.append(documentElement.DocumentTextElement.create({text: ''}, this));
 159                             canvas.setCurrentElement(goto);
 160                         }
 161                     }
 162                 }
 163             });
 164
 165
 166             var KEYS = {
 167                 ARROW_LEFT: 37,
 168                 ARROW_UP: 38,
 169                 ARROW_RIGHT: 39,
 170                 ARROW_DOWN: 40
 171             }
 172
 173             this.wrapper.on('keyup', function(e) {
 174                 if(e.which >= 37 && e.which <= 40) {
 175                     var element = canvas.getCursor().getPosition().element,
 176                         caretTo = false;
 177                     if(!element) {
 178                         // Chrome hack
 179                         var direction;
 180                         if(e.which === KEYS.ARROW_LEFT  || e.which === KEYS.ARROW_UP) {
 181                             direction = 'above';
 182                             caretTo = 'end';
 183                         } else {
 184                             direction = 'below';
 185                             caretTo = 'start';
 186                         }
 187                         element = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]:visible', direction, window.getSelection().focusNode));
 188                     }
 189                     canvas.setCurrentElement(element, {caretTo: caretTo});
 190                 }
 191             });
 192
 193             this.wrapper.on('keydown', function(e) {
 194                 if(e.which >= 37 && e.which <= 40) {
 195                     var position = canvas.getCursor().getPosition(),
 196                         element = position.element;
 197                     if(element && (element instanceof documentElement.DocumentTextElement)) {
 198                         if(element.isEmpty()) {
 199                             var direction, caretTo;
 200                             if(e.which === KEYS.ARROW_LEFT  || e.which === KEYS.ARROW_UP) {
 201                                 direction = 'above';
 202                                 caretTo = 'end';
 203                             } else {
 204                                 direction = 'below';
 205                                 caretTo = 'start';
 206                             }
 207                             var el = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]', direction, window.getSelection().focusNode))
 208                             canvas.setCurrentElement(element, {caretTo: caretTo});
 209                         } else {
 210                             var txt = element.dom().contents()[0].data;
 211                             if(e.which === KEYS.ARROW_LEFT && position.offset > 1 && txt.charAt(position.offset-2) === utils.unicode.ZWS) {
 212                                 e.preventDefault();
 213                                 canvas._moveCaretToTextElement(element, position.offset-2);
 214                             }
 215                             if(e.which === KEYS.ARROW_RIGHT && position.offset < txt.length - 1 && txt.charAt(position.offset+1) === utils.unicode.ZWS) {
 216                                 e.preventDefault();
 217                                 canvas._moveCaretToTextElement(element, position.offset+2);
 218                             }
 219                         }
 220                     }
 221
 222
 223                 }
 224             });
 225
 226             this.wrapper.on('click', '[document-node-element], [document-text-element]', function(e) {
 227                 e.stopPropagation();
 228                 canvas.setCurrentElement(canvas.getDocumentElement(e.currentTarget), {caretTo: false});
 229             });
 230
 231             var observer = new MutationObserver(function(mutations) {
 232                 mutations.forEach(function(mutation) {
 233                     if(documentElement.DocumentTextElement.isContentContainer(mutation.target) && mutation.target.data === '')
 234                         mutation.target.data = utils.unicode.ZWS;
 235                 });
 236             });
 237             var config = { attributes: false, childList: false, characterData: true, subtree: true, characterDataOldValue: true};
 238             observer.observe(this.d[0], config);
 239
 240
 241             this.wrapper.on('mouseover', '[document-node-element], [document-text-element]', function(e) {
 242                 var el = canvas.getDocumentElement(e.currentTarget);
 243                 if(!el)
 244                     return;
 245                 e.stopPropagation();
 246                 if(el instanceof documentElement.DocumentTextElement)
 247                     el = el.parent();
 248                 el.toggleLabel(true);
 249             });
 250             this.wrapper.on('mouseout', '[document-node-element], [document-text-element]', function(e) {
 251                 var el = canvas.getDocumentElement(e.currentTarget);
 252                 if(!el)
 253                     return;
 254                 e.stopPropagation();
 255                 if(el instanceof documentElement.DocumentTextElement)
 256                     el = el.parent();
 257                 el.toggleLabel(false);
 258             });
 259
 260             this.eventBus.on('elementToggled', function(toggle, element) {
 261                 if(!toggle) {
 262                     element = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]:visible', 'above', element.dom()[0]));
 263                     canvas.setCurrentElement(element);
 264                 }
 265             })
 266
 267         } else {
 268             this.d = null;
 269         }
 270     },
 271
 272     view: function() {
 273         return this.wrapper;
 274     },
 275
 276     doc: function() {
 277         if(this.d === null)
 278             return null;
 279         return documentElement.DocumentNodeElement.fromHTMLElement(this.d.get(0), this); //{wlxmlTag: this.d.prop('tagName')};
 280     },
 281
 282     wrapText: function(params) {
 283         params = _.extend({textNodeIdx: 0}, params);
 284         if(typeof params.textNodeIdx === 'number')
 285             params.textNodeIdx = [params.textNodeIdx];
 286
 287         var childrenInside = params.inside.children(),
 288             idx1 = Math.min.apply(Math, params.textNodeIdx),
 289             idx2 = Math.max.apply(Math, params.textNodeIdx),
 290             textNode1 = childrenInside[idx1],
 291             textNode2 = childrenInside[idx2],
 292             sameNode = textNode1.sameNode(textNode2),
 293             prefixOutside = textNode1.getText().substr(0, params.offsetStart),
 294             prefixInside = textNode1.getText().substr(params.offsetStart),
 295             suffixInside = textNode2.getText().substr(0, params.offsetEnd),
 296             suffixOutside = textNode2.getText().substr(params.offsetEnd)
 297         ;
 298
 299         var wrapperElement = documentElement.DocumentNodeElement.create({tag: params._with.tag, klass: params._with.klass});
 300         textNode1.after(wrapperElement);
 301         textNode1.detach();
 302
 303         if(prefixOutside.length > 0)
 304             wrapperElement.before({text:prefixOutside});
 305         if(sameNode) {
 306             var core = textNode1.getText().substr(params.offsetStart, params.offsetEnd - params.offsetStart);
 307             wrapperElement.append({text: core});
 308         } else {
 309             textNode2.detach();
 310             if(prefixInside.length > 0)
 311                 wrapperElement.append({text: prefixInside});
 312             for(var i = idx1 + 1; i < idx2; i++) {
 313                 wrapperElement.append(childrenInside[i]);
 314             }
 315             if(suffixInside.length > 0)
 316                 wrapperElement.append({text: suffixInside});
 317         }
 318         if(suffixOutside.length > 0)
 319             wrapperElement.after({text: suffixOutside});
 320         return wrapperElement;
 321     },
 322     getDocumentElement: function(from) {
 323         if(from instanceof HTMLElement || from instanceof Text) {
 324            return documentElement.DocumentElement.fromHTMLElement(from, this);
 325         }
 326     },
 327     getCursor: function() {
 328         return new Cursor(this);
 329     },
 330
 331     list: {},
 332
 333
 334     getCurrentNodeElement: function() {
 335         return this.getDocumentElement(this.wrapper.find('.current-node-element').parent()[0]);
 336     },
 337
 338     getCurrentTextElement: function() {
 339         return this.getDocumentElement(this.wrapper.find('.current-text-element')[0]);
 340     },
 341
 342
 343
 344     setCurrentElement: function(element, params) {
 345         params = _.extend({caretTo: 'end'}, params);
 346         var findFirstDirectTextChild = function(e, nodeToLand) {
 347             var byBrowser = this.getCursor().getPosition().element;
 348             if(byBrowser && byBrowser.parent().sameNode(nodeToLand))
 349                 return byBrowser;
 350             var children = e.children();
 351             for(var i = 0; i < children.length; i++) {
 352                 if(children[i] instanceof documentElement.DocumentTextElement)
 353                     return children[i];
 354             }
 355             return null;
 356         }.bind(this);
 357         var _markAsCurrent = function(element) {
 358             if(element instanceof documentElement.DocumentTextElement) {
 359                 this.wrapper.find('.current-text-element').removeClass('current-text-element');
 360                 element.dom().addClass('current-text-element');
 361             } else {
 362                 this.wrapper.find('.current-node-element').removeClass('current-node-element')
 363                 element._container().addClass('current-node-element');
 364                 this.publisher('currentElementChanged', element);
 365             }
 366         }.bind(this);
 367
 368
 369         var isTextElement = element instanceof documentElement.DocumentTextElement,
 370             nodeElementToLand = isTextElement ? element.parent() : element,
 371             textElementToLand = isTextElement ? element : findFirstDirectTextChild(element, nodeElementToLand),
 372             currentTextElement = this.getCurrentTextElement(),
 373             currentNodeElement = this.getCurrentNodeElement();
 374
 375         if(currentTextElement && !(currentTextElement.sameNode(textElementToLand)))
 376             this.wrapper.find('.current-text-element').removeClass('current-text-element');
 377
 378         if(textElementToLand) {
 379             _markAsCurrent(textElementToLand);
 380             if(params.caretTo || !textElementToLand.sameNode(this.getCursor().getPosition().element))
 381                 this._moveCaretToTextElement(textElementToLand, params.caretTo); // as method on element?
 382             if(!(textElementToLand.sameNode(currentTextElement)))
 383                 this.publisher('currentTextElementSet', textElementToLand);
 384         } else {
 385             document.getSelection().removeAllRanges();
 386         }
 387
 388         if(!(currentNodeElement && currentNodeElement.sameNode(nodeElementToLand))) {
 389             _markAsCurrent(nodeElementToLand);
 390
 391             this.publisher('currentNodeElementSet', nodeElementToLand);
 392         }
 393     },
 394
 395     _moveCaretToTextElement: function(element, where) {
 396         var range = document.createRange(),
 397             node = element.dom().contents()[0];
 398
 399         if(typeof where !== 'number') {
 400             range.selectNodeContents(node);
 401         } else {
 402             range.setStart(node, where);
 403         }
 404
 405         var collapseArg = true;
 406         if(where === 'end')
 407             collapseArg = false;
 408         range.collapse(collapseArg);
 409
 410         var selection = document.getSelection();
 411
 412         selection.removeAllRanges();
 413         selection.addRange(range);
 414         this.wrapper.focus(); // FF requires this for caret to be put where range colllapses, Chrome doesn't.
 415     },
 416
 417     setCursorPosition: function(position) {
 418         if(position.element)
 419             this._moveCaretToTextElement(position.element, position.offset);
 420     },
 421
 422     toXML: function() {
 423         var parent = $('<div>'),
 424             parts = this.doc().toXML(0);
 425         parent.append(parts);
 426         return parent.html();
 427     }
 428 });
 429
 430 $.extend(Canvas.prototype.list, {
 431     create: function(params) {
 432         if(!(params.element1.parent().sameNode(params.element2.parent())))
 433             return false;
 434
 435         var parent = params.element1.parent();
 436
 437         if(parent.childIndex(params.element1) > parent.childIndex(params.element2)) {
 438             var tmp = params.element1;
 439             params.element1 = params.element2;
 440             params.element2 = tmp;
 441         }
 442
 443         var elementsToWrap = [];
 444
 445         var place = 'before';
 446         var canvas = this;
 447         parent.children().some(function(element) {
 448             var _e = element;
 449             if(element.sameNode(params.element1))
 450                 place = 'inside';
 451             if(place === 'inside') {
 452                 if(element instanceof documentElement.DocumentTextElement) {
 453                     element = element.wrapWithNodeElement({tag: 'div', klass: 'list.item'});
 454                     if(element.children()[0].sameNode(params.element1))
 455                         params.element1 = element;
 456                 }
 457                 element.setWlxmlClass('item');
 458                 elementsToWrap.push(element);
 459             }
 460             if(_e.sameNode(params.element2))
 461                 return true;
 462         });
 463
 464         var listElement = documentElement.DocumentNodeElement.create({tag: 'div', klass: 'list-items' + (params.type === 'enum' ? '-enum' : '')});
 465
 466         var toret;
 467         if(parent.is('list')) {
 468             listElement.wrapWithNodeElement({tag: 'div', klass: 'item'});
 469             toret = listElement.parent();
 470         } else {
 471             toret = listElement;
 472         }
 473
 474         params.element1.before(toret);
 475
 476         elementsToWrap.forEach(function(element) {
 477             element.detach();
 478             listElement.append(element);
 479         });
 480     },
 481     extractItems: function(params) {
 482         params = _.extend({merge: true}, params);
 483         var list = params.element1.parent();
 484         if(!list.is('list') || !(list.sameNode(params.element2.parent())))
 485             return false;
 486
 487         var idx1 = list.childIndex(params.element1),
 488             idx2 = list.childIndex(params.element2),
 489             precedingItems = [],
 490             extractedItems = [],
 491             succeedingItems = [],
 492             items = list.children(),
 493             listIsNested = list.parent().getWlxmlClass() === 'item',
 494             i;
 495
 496         if(idx1 > idx2) {
 497             var tmp = idx1; idx1 = idx2; idx2 = tmp;
 498         }
 499
 500         items.forEach(function(item, idx) {
 501             if(idx < idx1)
 502                 precedingItems.push(item);
 503             else if(idx >= idx1 && idx <= idx2) {
 504                 extractedItems.push(item);
 505             }
 506             else {
 507                 succeedingItems.push(item);
 508             }
 509         });
 510
 511         var reference = listIsNested ? list.parent() : list;
 512         if(succeedingItems.length === 0) {
 513             var reference_orig = reference;
 514             extractedItems.forEach(function(item) {
 515                 reference.after(item);
 516                 reference = item;
 517                 if(!listIsNested)
 518                     item.setWlxmlClass(null);
 519             });
 520             if(precedingItems.length === 0)
 521                 reference_orig.detach();
 522         } else if(precedingItems.length === 0) {
 523             extractedItems.forEach(function(item) {
 524                 reference.before(item);
 525                 if(!listIsNested)
 526                     item.setWlxmlClass(null);
 527             });
 528         } else {
 529             extractedItems.forEach(function(item) {
 530                 reference.after(item);
 531                 if(!listIsNested)
 532                     item.setWlxmlClass(null);
 533                 reference = item;
 534             });
 535             var secondList = documentElement.DocumentNodeElement.create({tag: 'div', klass:'list-items'}, this),
 536                 toAdd = secondList;
 537
 538             if(listIsNested) {
 539                 toAdd = secondList.wrapWithNodeElement({tag: 'div', klass:'item'});
 540             }
 541             succeedingItems.forEach(function(item) {
 542                 secondList.append(item);
 543             });
 544
 545             reference.after(toAdd);
 546         }
 547         if(!params.merge && listIsNested) {
 548             return this.extractItems({element1: extractedItems[0], element2: extractedItems[extractedItems.length-1]});
 549         }
 550         return true;
 551     },
 552     areItemsOfTheSameList: function(params) {
 553         var e1 = params.element1,
 554             e2 = params.element2;
 555         return e1.parent().sameNode(e2.parent())
 556             && e1.parent().is('list');
 557     }
 558 });
 559
 560
 561 var Cursor = function(canvas) {
 562     this.canvas = canvas;
 563 };
 564
 565 $.extend(Cursor.prototype, {
 566     isSelecting: function() {
 567         var selection = window.getSelection();
 568         return !selection.isCollapsed;
 569     },
 570     isSelectingWithinElement: function() {
 571         return this.isSelecting() && this.getSelectionStart().element.sameNode(this.getSelectionEnd().element);
 572     },
 573     isSelectingSiblings: function() {
 574         return this.isSelecting() && this.getSelectionStart().element.parent().sameNode(this.getSelectionEnd().element.parent());
 575     },
 576     getPosition: function() {
 577         return this.getSelectionAnchor();
 578     },
 579     getSelectionStart: function() {
 580         return this.getSelectionBoundry('start');
 581     },
 582     getSelectionEnd: function() {
 583         return this.getSelectionBoundry('end');
 584     },
 585     getSelectionAnchor: function() {
 586         return this.getSelectionBoundry('anchor');
 587     },
 588     getSelectionFocus: function() {
 589         return this.getSelectionBoundry('focus');
 590     },
 591     getSelectionBoundry: function(which) {
 592         var selection = window.getSelection(),
 593             anchorElement = this.canvas.getDocumentElement(selection.anchorNode),
 594             focusElement = this.canvas.getDocumentElement(selection.focusNode);
 595
 596         var getOffset = function(where) {
 597             var toret, node;
 598             if(where === 'anchor') {
 599                 node = selection.anchorNode;
 600                 toret = selection.anchorOffset;
 601             } else {
 602                 node = selection.focusNode;
 603                 toret = selection.focusOffset;
 604             }
 605
 606             if(toret === 1 && node.data.charAt(0) === utils.unicode.ZWS)
 607                 toret = 0;
 608             else if((toret === node.data.length - 1) && (node.data.charAt(node.data.length - 1) === utils.unicode.ZWS))
 609                 toret++;
 610             return toret;
 611         }
 612
 613         if((!anchorElement) || (anchorElement instanceof documentElement.DocumentNodeElement) || (!focusElement) || focusElement instanceof documentElement.DocumentNodeElement)
 614             return {};
 615
 616         if(which === 'anchor') {
 617             return {
 618                 element: anchorElement,
 619                 offset: getOffset('anchor'),
 620                 offsetAtBeginning: getOffset('anchor') === 0,
 621                 offsetAtEnd: selection.anchorNode.data.length === getOffset('anchor')
 622             };
 623         }
 624         if(which === 'focus') {
 625             return {
 626                 element: focusElement,
 627                 offset: getOffset('focus'),
 628                 offsetAtBeginning: getOffset('focus') === 0,
 629                 offsetAtEnd: selection.focusNode.data.length === getOffset('focus')
 630             };
 631         }
 632
 633         var element,
 634             offset;
 635
 636         if(anchorElement.parent().sameNode(focusElement.parent())) {
 637             var parent = anchorElement.parent(),
 638                 anchorFirst = parent.childIndex(anchorElement) < parent.childIndex(focusElement);
 639             if(anchorFirst) {
 640                 if(which === 'start') {
 641                     element = anchorElement;
 642                     offset = getOffset('anchor')
 643                 }
 644                 else if(which === 'end') {
 645                     element = focusElement,
 646                     offset = getOffset('focus')
 647                 }
 648             } else {
 649                 if(which === 'start') {
 650                     element = focusElement,
 651                     offset = getOffset('focus')
 652                 }
 653                 else if(which === 'end') {
 654                     element = anchorElement;
 655                     offset = getOffset('anchor')
 656                 }
 657             }
 658         } else {
 659             // TODO: Handle order via https://developer.mozilla.org/en-US/docs/Web/API/Node.compareDocumentPosition
 660             if(which === 'start') {
 661                 element = anchorElement;
 662                 offset = getOffset('anchor')
 663             } else {
 664                 element = focusElement;
 665                 offset = getOffset('focus')
 666             }
 667         }
 668
 669         var nodeLen = (element.sameNode(focusElement) ? selection.focusNode : selection.anchorNode).length;
 670         return {
 671             element: element,
 672             offset: offset,
 673             offsetAtBeginning: offset === 0,
 674             offsetAtEnd: nodeLen === offset
 675         }
 676     }
 677 })
 678
 679 return {
 680     fromXML: function(xml, publisher) {
 681         return new Canvas(xml, publisher);
 682     }
 683 };
 684
 685 });