modules/documentCanvas/canvas/canvas.js

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