Refactoring
[fnpeditor.git] / 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             var KEYS = {
144                 ENTER: 13,
145                 ARROW_LEFT: 37,
146                 ARROW_UP: 38,
147                 ARROW_RIGHT: 39,
148                 ARROW_DOWN: 40,
149                 BACKSPACE: 8,
150                 DELETE: 46,
151                 X: 88
152             }
153
154             this.wrapper.on('keyup', function(e) {
155                 if(e.which >= 37 && e.which <= 40) {
156                     var element = canvas.getCursor().getPosition().element,
157                         caretTo = false;
158                     if(!element) {
159                         // Chrome hack
160                         var direction;
161                         if(e.which === KEYS.ARROW_LEFT  || e.which === KEYS.ARROW_UP) {
162                             direction = 'above';
163                             caretTo = 'end';
164                         } else {
165                             direction = 'below';
166                             caretTo = 'start';
167                         }
168                         element = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]:visible', direction, window.getSelection().focusNode));
169                     }
170                     canvas.setCurrentElement(element, {caretTo: caretTo});
171                 }
172             });
173          
174             this.wrapper.on('keydown', function(e) {
175                 var cursor = canvas.getCursor(),
176                     position = canvas.getCursor().getPosition(),
177                     element = position.element;
178                 if(e.which >= 37 && e.which <= 40) {
179
180                     if(element && (element instanceof documentElement.DocumentTextElement)) {
181                         if(element.isEmpty()) {
182                             var direction, caretTo;
183                             if(e.which === KEYS.ARROW_LEFT  || e.which === KEYS.ARROW_UP) {
184                                 direction = 'above';
185                                 caretTo = 'end';
186                             } else {
187                                 direction = 'below';
188                                 caretTo = 'start';
189                             }
190                             var el = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]', direction, window.getSelection().focusNode))
191                             canvas.setCurrentElement(element, {caretTo: caretTo});
192                         } else {
193                             var txt = element.dom().contents()[0].data;
194                             if(e.which === KEYS.ARROW_LEFT && position.offset > 1 && txt.charAt(position.offset-2) === utils.unicode.ZWS) {
195                                 e.preventDefault();
196                                 canvas._moveCaretToTextElement(element, position.offset-2);
197                             }
198                             if(e.which === KEYS.ARROW_RIGHT && position.offset < txt.length - 1 && txt.charAt(position.offset+1) === utils.unicode.ZWS) {
199                                 e.preventDefault();
200                                 canvas._moveCaretToTextElement(element, position.offset+2);
201                             }
202                         }
203                     }
204
205
206                 }
207
208                 var selectsWholeTextElement = function() {
209                     if(cursor.isSelecting() && cursor.getSelectionStart().offsetAtBeginning && cursor.getSelectionEnd().offsetAtEnd)
210                         return true;
211                     return false;
212                 }
213
214                 if(e.which === KEYS.X && e.ctrlKey && selectsWholeTextElement()) {
215                     e.preventDefault();
216                 }
217
218                 if(e.which === KEYS.BACKSPACE || e.which === KEYS.DELETE) {
219                     if(cursor.isSelecting() && !cursor.isSelectingWithinElement()) {
220                         e.preventDefault();
221                         return;
222                     }
223                         
224                     var cursorAtOperationEdge = position.offsetAtBeginning;
225                     if(e.which === KEYS.DELETE) {
226                         cursorAtOperationEdge = position.offsetAtEnd;
227                     }
228
229                     if(element.getText().length === 1 || selectsWholeTextElement()) {
230                         e.preventDefault();
231                         element.setText('');
232                     }
233                     else if(element.isEmpty()) {
234
235                         var direction = 'above',
236                             caretTo = 'end';
237                             
238                         if(e.which === KEYS.DELETE) {
239                             direction = 'below';
240                             caretTo = 'start';
241                         }
242
243                         e.preventDefault();
244
245                         var parent = element.parent(),
246                             grandParent = parent ? parent.parent() : null,
247                             goto;
248                         if(parent.children().length === 1) {
249                             if(grandParent && grandParent.children().length === 1) {
250                                 goto = grandParent.append({text: ''});
251                             } else {
252                                 goto = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]', direction, element.dom()[0]));
253                             }
254                             parent.detach();
255                         } else {
256                             goto = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]', direction, element.dom()[0]));
257                             element.detach();
258                         }
259                         canvas.setCurrentElement(goto, {caretTo: caretTo});
260                     }
261                     else if(cursorAtOperationEdge) {
262                         // todo
263                         e.preventDefault();
264                     }
265                 }
266
267                 if(e.which === KEYS.ENTER) {
268                     e.preventDefault();
269                     var cursor = canvas.getCursor();
270                     if(!cursor.isSelecting()) {
271                         var position = cursor.getPosition(),
272                             element = position.element;
273
274                         if(!(element.parent().parent())) {
275                             return false; // top level element is unsplittable
276                         }
277
278                         var elements = position.element.split({offset: position.offset}),
279                             newEmpty,
280                             goto;
281
282                         if(position.offsetAtBeginning)
283                             newEmpty = elements.first;
284                         else if(position.offsetAtEnd)
285                             newEmpty = elements.second;
286                         if(newEmpty) {
287                             goto = newEmpty.append(documentElement.DocumentTextElement.create({text: ''}, this));
288                             canvas.setCurrentElement(goto);
289                         }
290                     }
291                 }
292             });
293
294             this.wrapper.on('click', '[document-node-element], [document-text-element]', function(e) {
295                 e.stopPropagation();
296                 canvas.setCurrentElement(canvas.getDocumentElement(e.currentTarget), {caretTo: false});
297             });
298
299             var observer = new MutationObserver(function(mutations) {
300                 mutations.forEach(function(mutation) {
301                     if(documentElement.DocumentTextElement.isContentContainer(mutation.target) && mutation.target.data === '')
302                         mutation.target.data = utils.unicode.ZWS;
303                 });
304             });
305             var config = { attributes: false, childList: false, characterData: true, subtree: true, characterDataOldValue: true};
306             observer.observe(this.d[0], config);
307
308
309             this.wrapper.on('mouseover', '[document-node-element], [document-text-element]', function(e) {
310                 var el = canvas.getDocumentElement(e.currentTarget);
311                 if(!el)
312                     return;
313                 e.stopPropagation();
314                 if(el instanceof documentElement.DocumentTextElement)
315                     el = el.parent();
316                 el.toggleLabel(true);
317             });
318             this.wrapper.on('mouseout', '[document-node-element], [document-text-element]', function(e) {
319                 var el = canvas.getDocumentElement(e.currentTarget);
320                 if(!el)
321                     return;
322                 e.stopPropagation();
323                 if(el instanceof documentElement.DocumentTextElement)
324                     el = el.parent();
325                 el.toggleLabel(false);
326             });
327
328             this.eventBus.on('elementToggled', function(toggle, element) {
329                 if(!toggle) {
330                     element = canvas.getDocumentElement(utils.nearestInDocumentOrder('[document-text-element]:visible', 'above', element.dom()[0]));
331                     canvas.setCurrentElement(element);
332                 }
333             })
334
335         } else {
336             this.d = null;
337         }
338     },
339
340     view: function() {
341         return this.wrapper;
342     },
343
344     doc: function() {
345         if(this.d === null)
346             return null;
347         return documentElement.DocumentNodeElement.fromHTMLElement(this.d.get(0), this); //{wlxmlTag: this.d.prop('tagName')};
348     },
349
350     wrapText: function(params) {
351         params = _.extend({textNodeIdx: 0}, params);
352         if(typeof params.textNodeIdx === 'number')
353             params.textNodeIdx = [params.textNodeIdx];
354         
355         var childrenInside = params.inside.children(),
356             idx1 = Math.min.apply(Math, params.textNodeIdx),
357             idx2 = Math.max.apply(Math, params.textNodeIdx),
358             textNode1 = childrenInside[idx1],
359             textNode2 = childrenInside[idx2],
360             sameNode = textNode1.sameNode(textNode2),
361             prefixOutside = textNode1.getText().substr(0, params.offsetStart),
362             prefixInside = textNode1.getText().substr(params.offsetStart),
363             suffixInside = textNode2.getText().substr(0, params.offsetEnd),
364             suffixOutside = textNode2.getText().substr(params.offsetEnd)
365         ;
366         
367         var wrapperElement = documentElement.DocumentNodeElement.create({tag: params._with.tag, klass: params._with.klass});
368         textNode1.after(wrapperElement);
369         textNode1.detach();
370         
371         if(prefixOutside.length > 0)
372             wrapperElement.before({text:prefixOutside});
373         if(sameNode) {
374             var core = textNode1.getText().substr(params.offsetStart, params.offsetEnd - params.offsetStart);
375             wrapperElement.append({text: core});
376         } else {
377             textNode2.detach();
378             if(prefixInside.length > 0)
379                 wrapperElement.append({text: prefixInside});
380             for(var i = idx1 + 1; i < idx2; i++) {
381                 wrapperElement.append(childrenInside[i]);
382             }
383             if(suffixInside.length > 0)
384                 wrapperElement.append({text: suffixInside});
385         }
386         if(suffixOutside.length > 0)
387             wrapperElement.after({text: suffixOutside});
388         return wrapperElement;
389     },
390
391     wrapElements: function(params) {
392         if(!(params.element1.parent().sameNode(params.element2.parent())))
393             return;
394
395         var parent = params.element1.parent(),
396             parentChildren = parent.children(),
397             wrapper = documentElement.DocumentNodeElement.create({
398                 tag: params._with.tag,
399                 klass: params._with.klass}),
400             idx1 = parent.childIndex(params.element1),
401             idx2 = parent.childIndex(params.element2);
402
403         if(idx1 > idx2) {
404             var tmp = idx1;
405             idx1 = idx2;
406             idx2 = tmp;
407         }
408
409         var insertingMethod, insertingTarget;
410         if(idx1 === 0) {
411             insertingMethod = 'prepend';
412             insertingTarget = parent;
413         } else {
414             insertingMethod = 'after';
415             insertingTarget = parentChildren[idx1-1];
416         }
417
418         for(var i = idx1; i <= idx2; i++) {
419             wrapper.append(parentChildren[i].detach());
420         }
421
422         insertingTarget[insertingMethod](wrapper);
423         return wrapper;
424     },
425
426     getSiblingParents: function(params) {
427         var parents1 = [params.element1].concat(params.element1.parents()).reverse(),
428             parents2 = [params.element2].concat(params.element2.parents()).reverse(),
429             noSiblingParents = null;
430
431         if(parents1.length === 0 || parents2.length === 0 || !(parents1[0].sameNode(parents2[0])))
432             return noSiblingParents;
433
434         var i;
435         for(i = 0; i < Math.min(parents1.length, parents2.length); i++) {
436             if(parents1[i].sameNode(parents2[i]))
437                 continue;
438             break;
439         }
440         return {element1: parents1[i], element2: parents2[i]};
441     },
442
443     getDocumentElement: function(from) {
444         if(from instanceof HTMLElement || from instanceof Text) {
445            return documentElement.DocumentElement.fromHTMLElement(from, this);
446         }
447     },
448     getCursor: function() {
449         return new Cursor(this);
450     },
451
452     list: {},
453
454     
455     getCurrentNodeElement: function() {
456         return this.getDocumentElement(this.wrapper.find('.current-node-element').parent()[0]);
457     },
458
459     getCurrentTextElement: function() {
460         return this.getDocumentElement(this.wrapper.find('.current-text-element')[0]);
461     },
462
463
464
465     setCurrentElement: function(element, params) {
466         params = _.extend({caretTo: 'end'}, params);
467         var findFirstDirectTextChild = function(e, nodeToLand) {
468             var byBrowser = this.getCursor().getPosition().element;
469             if(byBrowser && byBrowser.parent().sameNode(nodeToLand))
470                 return byBrowser;
471             var children = e.children();
472             for(var i = 0; i < children.length; i++) {
473                 if(children[i] instanceof documentElement.DocumentTextElement)
474                     return children[i];
475             }
476             return null;
477         }.bind(this);
478         var _markAsCurrent = function(element) {
479             if(element instanceof documentElement.DocumentTextElement) {
480                 this.wrapper.find('.current-text-element').removeClass('current-text-element');
481                 element.dom().addClass('current-text-element');
482             } else {
483                 this.wrapper.find('.current-node-element').removeClass('current-node-element')
484                 element._container().addClass('current-node-element');
485                 this.publisher('currentElementChanged', element);
486             }
487         }.bind(this);
488
489
490         var isTextElement = element instanceof documentElement.DocumentTextElement,
491             nodeElementToLand = isTextElement ? element.parent() : element,
492             textElementToLand = isTextElement ? element : findFirstDirectTextChild(element, nodeElementToLand),
493             currentTextElement = this.getCurrentTextElement(),
494             currentNodeElement = this.getCurrentNodeElement();
495
496         if(currentTextElement && !(currentTextElement.sameNode(textElementToLand)))
497             this.wrapper.find('.current-text-element').removeClass('current-text-element');
498
499         if(textElementToLand) {
500             _markAsCurrent(textElementToLand);
501             if(params.caretTo || !textElementToLand.sameNode(this.getCursor().getPosition().element))
502                 this._moveCaretToTextElement(textElementToLand, params.caretTo); // as method on element?
503             if(!(textElementToLand.sameNode(currentTextElement)))
504                 this.publisher('currentTextElementSet', textElementToLand);
505         } else {
506             document.getSelection().removeAllRanges();
507         }
508
509         if(!(currentNodeElement && currentNodeElement.sameNode(nodeElementToLand))) {
510             _markAsCurrent(nodeElementToLand);
511
512             this.publisher('currentNodeElementSet', nodeElementToLand);
513         }
514     },
515
516     _moveCaretToTextElement: function(element, where) {
517         var range = document.createRange(),
518             node = element.dom().contents()[0];
519
520         if(typeof where !== 'number') {
521             range.selectNodeContents(node);
522         } else {
523             range.setStart(node, where);
524         }
525         
526         var collapseArg = true;
527         if(where === 'end')
528             collapseArg = false;
529         range.collapse(collapseArg);
530         
531         var selection = document.getSelection();
532
533         selection.removeAllRanges();
534         selection.addRange(range);
535         this.wrapper.focus(); // FF requires this for caret to be put where range colllapses, Chrome doesn't.
536     },
537
538     setCursorPosition: function(position) {
539         if(position.element)
540             this._moveCaretToTextElement(position.element, position.offset);
541     },
542
543     toXML: function() {
544         var parent = $('<div>'),
545             parts = this.doc().toXML(0);
546         parent.append(parts);
547         return parent.html();
548     }
549 });
550
551 $.extend(Canvas.prototype.list, {
552     create: function(params) {
553         if(!(params.element1.parent().sameNode(params.element2.parent())))
554             return false;
555             
556         var parent = params.element1.parent();
557         
558         if(parent.childIndex(params.element1) > parent.childIndex(params.element2)) {
559             var tmp = params.element1;
560             params.element1 = params.element2;
561             params.element2 = tmp;
562         }
563         
564         var elementsToWrap = [];
565         
566         var place = 'before';
567         var canvas = this;
568         parent.children().some(function(element) {
569             var _e = element;
570             if(element.sameNode(params.element1))
571                 place = 'inside';
572             if(place === 'inside') {
573                 if(element instanceof documentElement.DocumentTextElement) {
574                     element = element.wrapWithNodeElement({tag: 'div', klass: 'list.item'});
575                     if(element.children()[0].sameNode(params.element1))
576                         params.element1 = element;
577                 }
578                 element.setWlxmlClass('item');
579                 elementsToWrap.push(element);
580             }
581             if(_e.sameNode(params.element2))
582                 return true;
583         });
584         
585         var listElement = documentElement.DocumentNodeElement.create({tag: 'div', klass: 'list-items' + (params.type === 'enum' ? '-enum' : '')});
586         
587         var toret;
588         if(parent.is('list')) {
589             listElement.wrapWithNodeElement({tag: 'div', klass: 'item'});
590             toret = listElement.parent();
591         } else {
592             toret = listElement;
593         }  
594         
595         params.element1.before(toret);
596         
597         elementsToWrap.forEach(function(element) {
598             element.detach();
599             listElement.append(element);
600         });
601     },
602     extractItems: function(params) {
603         params = _.extend({merge: true}, params);
604         var list = params.element1.parent();
605         if(!list.is('list') || !(list.sameNode(params.element2.parent())))
606             return false;
607
608         var idx1 = list.childIndex(params.element1),
609             idx2 = list.childIndex(params.element2),
610             precedingItems = [],
611             extractedItems = [],
612             succeedingItems = [],
613             items = list.children(),
614             listIsNested = list.parent().getWlxmlClass() === 'item',
615             i;
616
617         if(idx1 > idx2) {
618             var tmp = idx1; idx1 = idx2; idx2 = tmp;
619         }
620
621         items.forEach(function(item, idx) {
622             if(idx < idx1)
623                 precedingItems.push(item);
624             else if(idx >= idx1 && idx <= idx2) {
625                 extractedItems.push(item);
626             }
627             else {
628                 succeedingItems.push(item);
629             }
630         });
631
632         var reference = listIsNested ? list.parent() : list;
633         if(succeedingItems.length === 0) {
634             var reference_orig = reference;
635             extractedItems.forEach(function(item) {
636                 reference.after(item);
637                 reference = item;
638                 if(!listIsNested)
639                     item.setWlxmlClass(null);
640             });
641             if(precedingItems.length === 0)
642                 reference_orig.detach();
643         } else if(precedingItems.length === 0) {
644             extractedItems.forEach(function(item) {
645                 reference.before(item);
646                 if(!listIsNested)
647                     item.setWlxmlClass(null);
648             });
649         } else {
650             extractedItems.forEach(function(item) {
651                 reference.after(item);
652                 if(!listIsNested)
653                     item.setWlxmlClass(null);
654                 reference = item;
655             });
656             var secondList = documentElement.DocumentNodeElement.create({tag: 'div', klass:'list-items'}, this),
657                 toAdd = secondList;
658             
659             if(listIsNested) {
660                 toAdd = secondList.wrapWithNodeElement({tag: 'div', klass:'item'});
661             }
662             succeedingItems.forEach(function(item) {
663                 secondList.append(item);
664             });
665
666             reference.after(toAdd);
667         }
668         if(!params.merge && listIsNested) {
669             return this.extractItems({element1: extractedItems[0], element2: extractedItems[extractedItems.length-1]});
670         }
671         return true;
672     },
673     areItemsOfTheSameList: function(params) {
674         var e1 = params.element1,
675             e2 = params.element2;
676         return e1.parent().sameNode(e2.parent())
677             && e1.parent().is('list');
678     }
679 });
680
681
682 var Cursor = function(canvas) {
683     this.canvas = canvas;
684 };
685
686 $.extend(Cursor.prototype, {
687     isSelecting: function() {
688         var selection = window.getSelection();
689         return !selection.isCollapsed;
690     },
691     isSelectingWithinElement: function() {
692         return this.isSelecting() && this.getSelectionStart().element.sameNode(this.getSelectionEnd().element);
693     },
694     isSelectingSiblings: function() {
695         return this.isSelecting() && this.getSelectionStart().element.parent().sameNode(this.getSelectionEnd().element.parent());
696     },
697     getPosition: function() {
698         return this.getSelectionAnchor();
699     },
700     getSelectionStart: function() {
701         return this.getSelectionBoundry('start');
702     },
703     getSelectionEnd: function() {
704         return this.getSelectionBoundry('end');
705     },
706     getSelectionAnchor: function() {
707         return this.getSelectionBoundry('anchor');
708     },
709     getSelectionFocus: function() {
710         return this.getSelectionBoundry('focus');
711     },
712     getSelectionBoundry: function(which) {
713         var selection = window.getSelection(),
714             anchorElement = this.canvas.getDocumentElement(selection.anchorNode),
715             focusElement = this.canvas.getDocumentElement(selection.focusNode);
716         
717         var getOffset = function(where) {
718             var toret, node;
719             if(where === 'anchor') {
720                 node = selection.anchorNode;
721                 toret = selection.anchorOffset;
722             } else {
723                 node = selection.focusNode;
724                 toret = selection.focusOffset;
725             }
726                         
727             if(toret === 1 && node.data.charAt(0) === utils.unicode.ZWS)
728                 toret = 0;
729             else if((toret === node.data.length - 1) && (node.data.charAt(node.data.length - 1) === utils.unicode.ZWS))
730                 toret++;
731             return toret;
732         }
733
734         if((!anchorElement) || (anchorElement instanceof documentElement.DocumentNodeElement) || (!focusElement) || focusElement instanceof documentElement.DocumentNodeElement)
735             return {};
736
737         if(which === 'anchor') {
738             return {
739                 element: anchorElement,
740                 offset: getOffset('anchor'),
741                 offsetAtBeginning: getOffset('anchor') === 0,
742                 offsetAtEnd: selection.anchorNode.data.length === getOffset('anchor')
743             };
744         }
745         if(which === 'focus') {
746             return {
747                 element: focusElement,
748                 offset: getOffset('focus'),
749                 offsetAtBeginning: getOffset('focus') === 0,
750                 offsetAtEnd: selection.focusNode.data.length === getOffset('focus')
751             };
752         }
753         
754         var element,
755             offset;
756
757         if(anchorElement.parent().sameNode(focusElement.parent())) {
758             var parent = anchorElement.parent(),
759                 anchorFirst = parent.childIndex(anchorElement) < parent.childIndex(focusElement);
760             if(anchorFirst) {
761                 if(which === 'start') {
762                     element = anchorElement;
763                     offset = getOffset('anchor')
764                 }
765                 else if(which === 'end') {
766                     element = focusElement,
767                     offset = getOffset('focus')
768                 }
769             } else {
770                 if(which === 'start') {
771                     element = focusElement,
772                     offset = getOffset('focus')
773                 }
774                 else if(which === 'end') {
775                     element = anchorElement;
776                     offset = getOffset('anchor')
777                 }
778             }
779         } else {
780             // TODO: Handle order via https://developer.mozilla.org/en-US/docs/Web/API/Node.compareDocumentPosition
781             if(which === 'start') {
782                 element = anchorElement;
783                 offset = getOffset('anchor')
784             } else {
785                 element = focusElement;
786                 offset = getOffset('focus')
787             }
788         }
789
790         var nodeLen = (element.sameNode(focusElement) ? selection.focusNode : selection.anchorNode).length;
791         return {
792             element: element,
793             offset: offset,
794             offsetAtBeginning: offset === 0,
795             offsetAtEnd: nodeLen === offset
796         }
797     }
798 })
799
800 return {
801     fromXML: function(xml, publisher) {
802         return new Canvas(xml, publisher);
803     }
804 };
805
806 });