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
 323     wrapElements: function(params) {
 324         if(!(params.element1.parent().sameNode(params.element2.parent())))
 325             return;
 326
 327         var parent = params.element1.parent(),
 328             parentChildren = parent.children(),
 329             wrapper = documentElement.DocumentNodeElement.create({
 330                 tag: params._with.tag,
 331                 klass: params._with.klass}),
 332             idx1 = parent.childIndex(params.element1),
 333             idx2 = parent.childIndex(params.element2);
 334
 335         if(idx1 > idx2) {
 336             var tmp = idx1;
 337             idx1 = idx2;
 338             idx2 = tmp;
 339         }
 340
 341         var insertingMethod, insertingTarget;
 342         if(idx1 === 0) {
 343             insertingMethod = 'prepend';
 344             insertingTarget = parent;
 345         } else {
 346             insertingMethod = 'after';
 347             insertingTarget = parentChildren[idx1-1];
 348         }
 349
 350         for(var i = idx1; i <= idx2; i++) {
 351             wrapper.append(parentChildren[i].detach());
 352         }
 353
 354         insertingTarget[insertingMethod](wrapper);
 355         return wrapper;
 356     },
 357
 358     getSiblingParents: function(params) {
 359         var parents1 = [params.element1].concat(params.element1.parents()).reverse(),
 360             parents2 = [params.element2].concat(params.element2.parents()).reverse(),
 361             noSiblingParents = null;
 362
 363         if(parents1.length === 0 || parents2.length === 0 || !(parents1[0].sameNode(parents2[0])))
 364             return noSiblingParents;
 365
 366         var i;
 367         for(i = 0; i < Math.min(parents1.length, parents2.length); i++) {
 368             if(parents1[i].sameNode(parents2[i]))
 369                 continue;
 370             break;
 371         }
 372         return {element1: parents1[i], element2: parents2[i]};
 373     },
 374
 375     getDocumentElement: function(from) {
 376         if(from instanceof HTMLElement || from instanceof Text) {
 377            return documentElement.DocumentElement.fromHTMLElement(from, this);
 378         }
 379     },
 380     getCursor: function() {
 381         return new Cursor(this);
 382     },
 383
 384     list: {},
 385
 386
 387     getCurrentNodeElement: function() {
 388         return this.getDocumentElement(this.wrapper.find('.current-node-element').parent()[0]);
 389     },
 390
 391     getCurrentTextElement: function() {
 392         return this.getDocumentElement(this.wrapper.find('.current-text-element')[0]);
 393     },
 394
 395
 396
 397     setCurrentElement: function(element, params) {
 398         params = _.extend({caretTo: 'end'}, params);
 399         var findFirstDirectTextChild = function(e, nodeToLand) {
 400             var byBrowser = this.getCursor().getPosition().element;
 401             if(byBrowser && byBrowser.parent().sameNode(nodeToLand))
 402                 return byBrowser;
 403             var children = e.children();
 404             for(var i = 0; i < children.length; i++) {
 405                 if(children[i] instanceof documentElement.DocumentTextElement)
 406                     return children[i];
 407             }
 408             return null;
 409         }.bind(this);
 410         var _markAsCurrent = function(element) {
 411             if(element instanceof documentElement.DocumentTextElement) {
 412                 this.wrapper.find('.current-text-element').removeClass('current-text-element');
 413                 element.dom().addClass('current-text-element');
 414             } else {
 415                 this.wrapper.find('.current-node-element').removeClass('current-node-element')
 416                 element._container().addClass('current-node-element');
 417                 this.publisher('currentElementChanged', element);
 418             }
 419         }.bind(this);
 420
 421
 422         var isTextElement = element instanceof documentElement.DocumentTextElement,
 423             nodeElementToLand = isTextElement ? element.parent() : element,
 424             textElementToLand = isTextElement ? element : findFirstDirectTextChild(element, nodeElementToLand),
 425             currentTextElement = this.getCurrentTextElement(),
 426             currentNodeElement = this.getCurrentNodeElement();
 427
 428         if(currentTextElement && !(currentTextElement.sameNode(textElementToLand)))
 429             this.wrapper.find('.current-text-element').removeClass('current-text-element');
 430
 431         if(textElementToLand) {
 432             _markAsCurrent(textElementToLand);
 433             if(params.caretTo || !textElementToLand.sameNode(this.getCursor().getPosition().element))
 434                 this._moveCaretToTextElement(textElementToLand, params.caretTo); // as method on element?
 435             if(!(textElementToLand.sameNode(currentTextElement)))
 436                 this.publisher('currentTextElementSet', textElementToLand);
 437         } else {
 438             document.getSelection().removeAllRanges();
 439         }
 440
 441         if(!(currentNodeElement && currentNodeElement.sameNode(nodeElementToLand))) {
 442             _markAsCurrent(nodeElementToLand);
 443
 444             this.publisher('currentNodeElementSet', nodeElementToLand);
 445         }
 446     },
 447
 448     _moveCaretToTextElement: function(element, where) {
 449         var range = document.createRange(),
 450             node = element.dom().contents()[0];
 451
 452         if(typeof where !== 'number') {
 453             range.selectNodeContents(node);
 454         } else {
 455             range.setStart(node, where);
 456         }
 457
 458         var collapseArg = true;
 459         if(where === 'end')
 460             collapseArg = false;
 461         range.collapse(collapseArg);
 462
 463         var selection = document.getSelection();
 464
 465         selection.removeAllRanges();
 466         selection.addRange(range);
 467         this.wrapper.focus(); // FF requires this for caret to be put where range colllapses, Chrome doesn't.
 468     },
 469
 470     setCursorPosition: function(position) {
 471         if(position.element)
 472             this._moveCaretToTextElement(position.element, position.offset);
 473     },
 474
 475     toXML: function() {
 476         var parent = $('<div>'),
 477             parts = this.doc().toXML(0);
 478         parent.append(parts);
 479         return parent.html();
 480     }
 481 });
 482
 483 $.extend(Canvas.prototype.list, {
 484     create: function(params) {
 485         if(!(params.element1.parent().sameNode(params.element2.parent())))
 486             return false;
 487
 488         var parent = params.element1.parent();
 489
 490         if(parent.childIndex(params.element1) > parent.childIndex(params.element2)) {
 491             var tmp = params.element1;
 492             params.element1 = params.element2;
 493             params.element2 = tmp;
 494         }
 495
 496         var elementsToWrap = [];
 497
 498         var place = 'before';
 499         var canvas = this;
 500         parent.children().some(function(element) {
 501             var _e = element;
 502             if(element.sameNode(params.element1))
 503                 place = 'inside';
 504             if(place === 'inside') {
 505                 if(element instanceof documentElement.DocumentTextElement) {
 506                     element = element.wrapWithNodeElement({tag: 'div', klass: 'list.item'});
 507                     if(element.children()[0].sameNode(params.element1))
 508                         params.element1 = element;
 509                 }
 510                 element.setWlxmlClass('item');
 511                 elementsToWrap.push(element);
 512             }
 513             if(_e.sameNode(params.element2))
 514                 return true;
 515         });
 516
 517         var listElement = documentElement.DocumentNodeElement.create({tag: 'div', klass: 'list-items' + (params.type === 'enum' ? '-enum' : '')});
 518
 519         var toret;
 520         if(parent.is('list')) {
 521             listElement.wrapWithNodeElement({tag: 'div', klass: 'item'});
 522             toret = listElement.parent();
 523         } else {
 524             toret = listElement;
 525         }
 526
 527         params.element1.before(toret);
 528
 529         elementsToWrap.forEach(function(element) {
 530             element.detach();
 531             listElement.append(element);
 532         });
 533     },
 534     extractItems: function(params) {
 535         params = _.extend({merge: true}, params);
 536         var list = params.element1.parent();
 537         if(!list.is('list') || !(list.sameNode(params.element2.parent())))
 538             return false;
 539
 540         var idx1 = list.childIndex(params.element1),
 541             idx2 = list.childIndex(params.element2),
 542             precedingItems = [],
 543             extractedItems = [],
 544             succeedingItems = [],
 545             items = list.children(),
 546             listIsNested = list.parent().getWlxmlClass() === 'item',
 547             i;
 548
 549         if(idx1 > idx2) {
 550             var tmp = idx1; idx1 = idx2; idx2 = tmp;
 551         }
 552
 553         items.forEach(function(item, idx) {
 554             if(idx < idx1)
 555                 precedingItems.push(item);
 556             else if(idx >= idx1 && idx <= idx2) {
 557                 extractedItems.push(item);
 558             }
 559             else {
 560                 succeedingItems.push(item);
 561             }
 562         });
 563
 564         var reference = listIsNested ? list.parent() : list;
 565         if(succeedingItems.length === 0) {
 566             var reference_orig = reference;
 567             extractedItems.forEach(function(item) {
 568                 reference.after(item);
 569                 reference = item;
 570                 if(!listIsNested)
 571                     item.setWlxmlClass(null);
 572             });
 573             if(precedingItems.length === 0)
 574                 reference_orig.detach();
 575         } else if(precedingItems.length === 0) {
 576             extractedItems.forEach(function(item) {
 577                 reference.before(item);
 578                 if(!listIsNested)
 579                     item.setWlxmlClass(null);
 580             });
 581         } else {
 582             extractedItems.forEach(function(item) {
 583                 reference.after(item);
 584                 if(!listIsNested)
 585                     item.setWlxmlClass(null);
 586                 reference = item;
 587             });
 588             var secondList = documentElement.DocumentNodeElement.create({tag: 'div', klass:'list-items'}, this),
 589                 toAdd = secondList;
 590
 591             if(listIsNested) {
 592                 toAdd = secondList.wrapWithNodeElement({tag: 'div', klass:'item'});
 593             }
 594             succeedingItems.forEach(function(item) {
 595                 secondList.append(item);
 596             });
 597
 598             reference.after(toAdd);
 599         }
 600         if(!params.merge && listIsNested) {
 601             return this.extractItems({element1: extractedItems[0], element2: extractedItems[extractedItems.length-1]});
 602         }
 603         return true;
 604     },
 605     areItemsOfTheSameList: function(params) {
 606         var e1 = params.element1,
 607             e2 = params.element2;
 608         return e1.parent().sameNode(e2.parent())
 609             && e1.parent().is('list');
 610     }
 611 });
 612
 613
 614 var Cursor = function(canvas) {
 615     this.canvas = canvas;
 616 };
 617
 618 $.extend(Cursor.prototype, {
 619     isSelecting: function() {
 620         var selection = window.getSelection();
 621         return !selection.isCollapsed;
 622     },
 623     isSelectingWithinElement: function() {
 624         return this.isSelecting() && this.getSelectionStart().element.sameNode(this.getSelectionEnd().element);
 625     },
 626     isSelectingSiblings: function() {
 627         return this.isSelecting() && this.getSelectionStart().element.parent().sameNode(this.getSelectionEnd().element.parent());
 628     },
 629     getPosition: function() {
 630         return this.getSelectionAnchor();
 631     },
 632     getSelectionStart: function() {
 633         return this.getSelectionBoundry('start');
 634     },
 635     getSelectionEnd: function() {
 636         return this.getSelectionBoundry('end');
 637     },
 638     getSelectionAnchor: function() {
 639         return this.getSelectionBoundry('anchor');
 640     },
 641     getSelectionFocus: function() {
 642         return this.getSelectionBoundry('focus');
 643     },
 644     getSelectionBoundry: function(which) {
 645         var selection = window.getSelection(),
 646             anchorElement = this.canvas.getDocumentElement(selection.anchorNode),
 647             focusElement = this.canvas.getDocumentElement(selection.focusNode);
 648
 649         var getOffset = function(where) {
 650             var toret, node;
 651             if(where === 'anchor') {
 652                 node = selection.anchorNode;
 653                 toret = selection.anchorOffset;
 654             } else {
 655                 node = selection.focusNode;
 656                 toret = selection.focusOffset;
 657             }
 658
 659             if(toret === 1 && node.data.charAt(0) === utils.unicode.ZWS)
 660                 toret = 0;
 661             else if((toret === node.data.length - 1) && (node.data.charAt(node.data.length - 1) === utils.unicode.ZWS))
 662                 toret++;
 663             return toret;
 664         }
 665
 666         if((!anchorElement) || (anchorElement instanceof documentElement.DocumentNodeElement) || (!focusElement) || focusElement instanceof documentElement.DocumentNodeElement)
 667             return {};
 668
 669         if(which === 'anchor') {
 670             return {
 671                 element: anchorElement,
 672                 offset: getOffset('anchor'),
 673                 offsetAtBeginning: getOffset('anchor') === 0,
 674                 offsetAtEnd: selection.anchorNode.data.length === getOffset('anchor')
 675             };
 676         }
 677         if(which === 'focus') {
 678             return {
 679                 element: focusElement,
 680                 offset: getOffset('focus'),
 681                 offsetAtBeginning: getOffset('focus') === 0,
 682                 offsetAtEnd: selection.focusNode.data.length === getOffset('focus')
 683             };
 684         }
 685
 686         var element,
 687             offset;
 688
 689         if(anchorElement.parent().sameNode(focusElement.parent())) {
 690             var parent = anchorElement.parent(),
 691                 anchorFirst = parent.childIndex(anchorElement) < parent.childIndex(focusElement);
 692             if(anchorFirst) {
 693                 if(which === 'start') {
 694                     element = anchorElement;
 695                     offset = getOffset('anchor')
 696                 }
 697                 else if(which === 'end') {
 698                     element = focusElement,
 699                     offset = getOffset('focus')
 700                 }
 701             } else {
 702                 if(which === 'start') {
 703                     element = focusElement,
 704                     offset = getOffset('focus')
 705                 }
 706                 else if(which === 'end') {
 707                     element = anchorElement;
 708                     offset = getOffset('anchor')
 709                 }
 710             }
 711         } else {
 712             // TODO: Handle order via https://developer.mozilla.org/en-US/docs/Web/API/Node.compareDocumentPosition
 713             if(which === 'start') {
 714                 element = anchorElement;
 715                 offset = getOffset('anchor')
 716             } else {
 717                 element = focusElement;
 718                 offset = getOffset('focus')
 719             }
 720         }
 721
 722         var nodeLen = (element.sameNode(focusElement) ? selection.focusNode : selection.anchorNode).length;
 723         return {
 724             element: element,
 725             offset: offset,
 726             offsetAtBeginning: offset === 0,
 727             offsetAtEnd: nodeLen === offset
 728         }
 729     }
 730 })
 731
 732 return {
 733     fromXML: function(xml, publisher) {
 734         return new Canvas(xml, publisher);
 735     }
 736 };
 737
 738 });