1 /*
  2     Copyright 2008-2023
  3         Matthias Ehmann,
  4         Michael Gerhaeuser,
  5         Carsten Miller,
  6         Bianca Valentin,
  7         Andreas Walter,
  8         Alfred Wassermann,
  9         Peter Wilfahrt
 10 
 11     This file is part of JSXGraph.
 12 
 13     JSXGraph is free software dual licensed under the GNU LGPL or MIT License.
 14 
 15     You can redistribute it and/or modify it under the terms of the
 16 
 17       * GNU Lesser General Public License as published by
 18         the Free Software Foundation, either version 3 of the License, or
 19         (at your option) any later version
 20       OR
 21       * MIT License: https://github.com/jsxgraph/jsxgraph/blob/master/LICENSE.MIT
 22 
 23     JSXGraph is distributed in the hope that it will be useful,
 24     but WITHOUT ANY WARRANTY; without even the implied warranty of
 25     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 26     GNU Lesser General Public License for more details.
 27 
 28     You should have received a copy of the GNU Lesser General Public License and
 29     the MIT License along with JSXGraph. If not, see <https://www.gnu.org/licenses/>
 30     and <https://opensource.org/licenses/MIT/>.
 31  */
 32 
 33 /*global JXG: true, define: true, window: true, document: true, navigator: true, module: true, global: true, self: true, require: true*/
 34 /*jslint nomen: true, plusplus: true*/
 35 
 36 /**
 37  * @fileoverview The functions in this file help with the detection of the environment JSXGraph runs in. We can distinguish
 38  * between node.js, windows 8 app and browser, what rendering techniques are supported and (most of the time) if the device
 39  * the browser runs on is a tablet/cell or a desktop computer.
 40  */
 41 
 42 import JXG from "../jxg";
 43 import Type from "./type";
 44 
 45 JXG.extendConstants(
 46     JXG,
 47     /** @lends JXG */ {
 48         /**
 49          * Determines the property that stores the relevant information in the event object.
 50          * @type String
 51          * @default 'touches'
 52          * @private
 53          */
 54         touchProperty: "touches"
 55     }
 56 );
 57 
 58 JXG.extend(
 59     JXG,
 60     /** @lends JXG */ {
 61         /**
 62          * Determines whether evt is a touch event.
 63          * @param evt {Event}
 64          * @returns {Boolean}
 65          */
 66         isTouchEvent: function (evt) {
 67             return JXG.exists(evt[JXG.touchProperty]);
 68         },
 69 
 70         /**
 71          * Determines whether evt is a pointer event.
 72          * @param evt {Event}
 73          * @returns {Boolean}
 74          */
 75         isPointerEvent: function (evt) {
 76             return JXG.exists(evt.pointerId);
 77         },
 78 
 79         /**
 80          * Determines whether evt is neither a touch event nor a pointer event.
 81          * @param evt {Event}
 82          * @returns {Boolean}
 83          */
 84         isMouseEvent: function (evt) {
 85             return !JXG.isTouchEvent(evt) && !JXG.isPointerEvent(evt);
 86         },
 87 
 88         /**
 89          * Determines the number of touch points in a touch event.
 90          * For other events, -1 is returned.
 91          * @param evt {Event}
 92          * @returns {Number}
 93          */
 94         getNumberOfTouchPoints: function (evt) {
 95             var n = -1;
 96 
 97             if (JXG.isTouchEvent(evt)) {
 98                 n = evt[JXG.touchProperty].length;
 99             }
100 
101             return n;
102         },
103 
104         /**
105          * Checks whether an mouse, pointer or touch event evt is the first event of a multitouch event.
106          * Attention: When two or more pointer device types are being used concurrently,
107          *            it is only checked whether the passed event is the first one of its type!
108          * @param evt {Event}
109          * @returns {boolean}
110          */
111         isFirstTouch: function (evt) {
112             var touchPoints = JXG.getNumberOfTouchPoints(evt);
113 
114             if (JXG.isPointerEvent(evt)) {
115                 return evt.isPrimary;
116             }
117 
118             return touchPoints === 1;
119         },
120 
121         /**
122          * A document/window environment is available.
123          * @type Boolean
124          * @default false
125          */
126         isBrowser: typeof window === "object" && typeof document === "object",
127 
128         /**
129          * Features of ECMAScript 6+ are available.
130          * @type Boolean
131          * @default false
132          */
133         supportsES6: function () {
134             // var testMap;
135             /* jshint ignore:start */
136             try {
137                 // This would kill the old uglifyjs: testMap = (a = 0) => a;
138                 new Function("(a = 0) => a");
139                 return true;
140             } catch (err) {
141                 return false;
142             }
143             /* jshint ignore:end */
144         },
145 
146         /**
147          * Detect browser support for VML.
148          * @returns {Boolean} True, if the browser supports VML.
149          */
150         supportsVML: function () {
151             // From stackoverflow.com
152             return this.isBrowser && !!document.namespaces;
153         },
154 
155         /**
156          * Detect browser support for SVG.
157          * @returns {Boolean} True, if the browser supports SVG.
158          */
159         supportsSVG: function () {
160             var svgSupport;
161             if (!this.isBrowser) {
162                 return false;
163             }
164             svgSupport = !!document.createElementNS && !!document.createElementNS('http://www.w3.org/2000/svg', 'svg').createSVGRect;
165             return svgSupport;
166         },
167 
168         /**
169          * Detect browser support for Canvas.
170          * @returns {Boolean} True, if the browser supports HTML canvas.
171          */
172         supportsCanvas: function () {
173             var hasCanvas = false;
174 
175             // if (this.isNode()) {
176             //     try {
177             //         // c = typeof module === "object" ? module.require("canvas") : $__canvas;
178             //         c = typeof module === "object" ? module.require("canvas") : import('canvas');
179             //         hasCanvas = !!c;
180             //     } catch (err) {}
181             // }
182 
183             if (this.isNode()) {
184                 //try {
185                 //    JXG.createCanvas(500, 500);
186                     hasCanvas = true;
187                 // } catch (err) {
188                 //     throw new Error('JXG.createCanvas not available.\n' +
189                 //         'Install the npm package `canvas`\n' +
190                 //         'and call:\n' +
191                 //         '    import { createCanvas } from "canvas";\n' +
192                 //         '    JXG.createCanvas = createCanvas;\n');
193                 // }
194             }
195 
196             return (
197                 hasCanvas || (this.isBrowser && !!document.createElement("canvas").getContext)
198             );
199         },
200 
201         /**
202          * True, if run inside a node.js environment.
203          * @returns {Boolean}
204          */
205         isNode: function () {
206             // This is not a 100% sure but should be valid in most cases
207             // We are not inside a browser
208             /* eslint-disable no-undef */
209             return (
210                 !this.isBrowser &&
211                 (typeof process !== 'undefined') &&
212                 (process.release.name.search(/node|io.js/) !== -1)
213             /* eslint-enable no-undef */
214 
215                 // there is a module object (plain node, no requirejs)
216                 // ((typeof module === "object" && !!module.exports) ||
217                 //     // there is a global object and requirejs is loaded
218                 //     (typeof global === "object" &&
219                 //         global.requirejsVars &&
220                 //         !global.requirejsVars.isBrowser)
221                 // )
222             );
223         },
224 
225         /**
226          * True if run inside a webworker environment.
227          * @returns {Boolean}
228          */
229         isWebWorker: function () {
230             return (
231                 !this.isBrowser &&
232                 typeof self === "object" &&
233                 typeof self.postMessage === "function"
234             );
235         },
236 
237         /**
238          * Checks if the environments supports the W3C Pointer Events API {@link https://www.w3.org/TR/pointerevents/}
239          * @returns {Boolean}
240          */
241         supportsPointerEvents: function () {
242             return !!(
243                 (
244                     this.isBrowser &&
245                     window.navigator &&
246                     (window.PointerEvent || // Chrome/Edge/IE11+
247                         window.navigator.pointerEnabled || // IE11+
248                         window.navigator.msPointerEnabled)
249                 ) // IE10-
250             );
251         },
252 
253         /**
254          * Determine if the current browser supports touch events
255          * @returns {Boolean} True, if the browser supports touch events.
256          */
257         isTouchDevice: function () {
258             return this.isBrowser && window.ontouchstart !== undefined;
259         },
260 
261         /**
262          * Detects if the user is using an Android powered device.
263          * @returns {Boolean}
264          */
265         isAndroid: function () {
266             return (
267                 Type.exists(navigator) &&
268                 navigator.userAgent.toLowerCase().indexOf("android") > -1
269             );
270         },
271 
272         /**
273          * Detects if the user is using the default Webkit browser on an Android powered device.
274          * @returns {Boolean}
275          */
276         isWebkitAndroid: function () {
277             return this.isAndroid() && navigator.userAgent.indexOf(" AppleWebKit/") > -1;
278         },
279 
280         /**
281          * Detects if the user is using a Apple iPad / iPhone.
282          * @returns {Boolean}
283          */
284         isApple: function () {
285             return (
286                 Type.exists(navigator) &&
287                 (navigator.userAgent.indexOf("iPad") > -1 ||
288                     navigator.userAgent.indexOf("iPhone") > -1)
289             );
290         },
291 
292         /**
293          * Detects if the user is using Safari on an Apple device.
294          * @returns {Boolean}
295          */
296         isWebkitApple: function () {
297             return (
298                 this.isApple() && navigator.userAgent.search(/Mobile\/[0-9A-Za-z.]*Safari/) > -1
299             );
300         },
301 
302         /**
303          * Returns true if the run inside a Windows 8 "Metro" App.
304          * @returns {Boolean}
305          */
306         isMetroApp: function () {
307             return (
308                 typeof window === "object" &&
309                 window.clientInformation &&
310                 window.clientInformation.appVersion &&
311                 window.clientInformation.appVersion.indexOf("MSAppHost") > -1
312             );
313         },
314 
315         /**
316          * Detects if the user is using a Mozilla browser
317          * @returns {Boolean}
318          */
319         isMozilla: function () {
320             return (
321                 Type.exists(navigator) &&
322                 navigator.userAgent.toLowerCase().indexOf("mozilla") > -1 &&
323                 navigator.userAgent.toLowerCase().indexOf("apple") === -1
324             );
325         },
326 
327         /**
328          * Detects if the user is using a firefoxOS powered device.
329          * @returns {Boolean}
330          */
331         isFirefoxOS: function () {
332             return (
333                 Type.exists(navigator) &&
334                 navigator.userAgent.toLowerCase().indexOf("android") === -1 &&
335                 navigator.userAgent.toLowerCase().indexOf("apple") === -1 &&
336                 navigator.userAgent.toLowerCase().indexOf("mobile") > -1 &&
337                 navigator.userAgent.toLowerCase().indexOf("mozilla") > -1
338             );
339         },
340 
341         /**
342          * Internet Explorer version. Works only for IE > 4.
343          * @type Number
344          */
345         ieVersion: (function () {
346             var div,
347                 all,
348                 v = 3;
349 
350             if (typeof document !== "object") {
351                 return 0;
352             }
353 
354             div = document.createElement("div");
355             all = div.getElementsByTagName("i");
356 
357             do {
358                 div.innerHTML = "<!--[if gt IE " + ++v + "]><" + "i><" + "/i><![endif]-->";
359             } while (all[0]);
360 
361             return v > 4 ? v : undefined;
362         })(),
363 
364         /**
365          * Reads the width and height of an HTML element.
366          * @param {String|Object} elementId id of or reference to an HTML DOM node.
367          * @returns {Object} An object with the two properties width and height.
368          */
369         getDimensions: function (elementId, doc) {
370             var element,
371                 display,
372                 els,
373                 originalVisibility,
374                 originalPosition,
375                 originalDisplay,
376                 originalWidth,
377                 originalHeight,
378                 style,
379                 pixelDimRegExp = /\d+(\.\d*)?px/;
380 
381             if (!this.isBrowser || elementId === null) {
382                 return {
383                     width: 500,
384                     height: 500
385                 };
386             }
387 
388             doc = doc || document;
389             // Borrowed from prototype.js
390             element = (Type.isString(elementId)) ? doc.getElementById(elementId) : elementId;
391             if (!Type.exists(element)) {
392                 throw new Error(
393                     "\nJSXGraph: HTML container element '" + elementId + "' not found."
394                 );
395             }
396 
397             display = element.style.display;
398 
399             // Work around a bug in Safari
400             if (display !== "none" && display !== null) {
401                 if (element.clientWidth > 0 && element.clientHeight > 0) {
402                     return { width: element.clientWidth, height: element.clientHeight };
403                 }
404 
405                 // A parent might be set to display:none; try reading them from styles
406                 style = window.getComputedStyle ? window.getComputedStyle(element) : element.style;
407                 return {
408                     width: pixelDimRegExp.test(style.width) ? parseFloat(style.width) : 0,
409                     height: pixelDimRegExp.test(style.height) ? parseFloat(style.height) : 0
410                 };
411             }
412 
413             // All *Width and *Height properties give 0 on elements with display set to none,
414             // hence we show the element temporarily
415             els = element.style;
416 
417             // save style
418             originalVisibility = els.visibility;
419             originalPosition = els.position;
420             originalDisplay = els.display;
421 
422             // show element
423             els.visibility = "hidden";
424             els.position = "absolute";
425             els.display = "block";
426 
427             // read the dimension
428             originalWidth = element.clientWidth;
429             originalHeight = element.clientHeight;
430 
431             // restore original css values
432             els.display = originalDisplay;
433             els.position = originalPosition;
434             els.visibility = originalVisibility;
435 
436             return {
437                 width: originalWidth,
438                 height: originalHeight
439             };
440         },
441 
442         /**
443          * Adds an event listener to a DOM element.
444          * @param {Object} obj Reference to a DOM node.
445          * @param {String} type The event to catch, without leading 'on', e.g. 'mousemove' instead of 'onmousemove'.
446          * @param {Function} fn The function to call when the event is triggered.
447          * @param {Object} owner The scope in which the event trigger is called.
448          * @param {Object|Boolean} [options=false] This parameter is passed as the third parameter to the method addEventListener. Depending on the data type it is either
449          * an options object or the useCapture Boolean.
450          *
451          */
452         addEvent: function (obj, type, fn, owner, options) {
453             var el = function () {
454                 return fn.apply(owner, arguments);
455             };
456 
457             el.origin = fn;
458             // Check if owner is a board
459             if (typeof owner === 'object' && Type.exists(owner.BOARD_MODE_NONE)) {
460                 owner['x_internal' + type] = owner['x_internal' + type] || [];
461                 owner['x_internal' + type].push(el);
462             }
463 
464             // Non-IE browser
465             if (Type.exists(obj) && Type.exists(obj.addEventListener)) {
466                 options = options || false;  // options or useCapture
467                 obj.addEventListener(type, el, options);
468             }
469 
470             // IE
471             if (Type.exists(obj) && Type.exists(obj.attachEvent)) {
472                 obj.attachEvent("on" + type, el);
473             }
474         },
475 
476         /**
477          * Removes an event listener from a DOM element.
478          * @param {Object} obj Reference to a DOM node.
479          * @param {String} type The event to catch, without leading 'on', e.g. 'mousemove' instead of 'onmousemove'.
480          * @param {Function} fn The function to call when the event is triggered.
481          * @param {Object} owner The scope in which the event trigger is called.
482          */
483         removeEvent: function (obj, type, fn, owner) {
484             var i;
485 
486             if (!Type.exists(owner)) {
487                 JXG.debug("no such owner");
488                 return;
489             }
490 
491             if (!Type.exists(owner["x_internal" + type])) {
492                 JXG.debug("no such type: " + type);
493                 return;
494             }
495 
496             if (!Type.isArray(owner["x_internal" + type])) {
497                 JXG.debug("owner[x_internal + " + type + "] is not an array");
498                 return;
499             }
500 
501             i = Type.indexOf(owner["x_internal" + type], fn, "origin");
502 
503             if (i === -1) {
504                 JXG.debug("removeEvent: no such event function in internal list: " + fn);
505                 return;
506             }
507 
508             try {
509                 // Non-IE browser
510                 if (Type.exists(obj) && Type.exists(obj.removeEventListener)) {
511                     obj.removeEventListener(type, owner["x_internal" + type][i], false);
512                 }
513 
514                 // IE
515                 if (Type.exists(obj) && Type.exists(obj.detachEvent)) {
516                     obj.detachEvent("on" + type, owner["x_internal" + type][i]);
517                 }
518             } catch (e) {
519                 JXG.debug("event not registered in browser: (" + type + " -- " + fn + ")");
520             }
521 
522             owner["x_internal" + type].splice(i, 1);
523         },
524 
525         /**
526          * Removes all events of the given type from a given DOM node; Use with caution and do not use it on a container div
527          * of a {@link JXG.Board} because this might corrupt the event handling system.
528          * @param {Object} obj Reference to a DOM node.
529          * @param {String} type The event to catch, without leading 'on', e.g. 'mousemove' instead of 'onmousemove'.
530          * @param {Object} owner The scope in which the event trigger is called.
531          */
532         removeAllEvents: function (obj, type, owner) {
533             var i, len;
534             if (owner["x_internal" + type]) {
535                 len = owner["x_internal" + type].length;
536 
537                 for (i = len - 1; i >= 0; i--) {
538                     JXG.removeEvent(obj, type, owner["x_internal" + type][i].origin, owner);
539                 }
540 
541                 if (owner["x_internal" + type].length > 0) {
542                     JXG.debug("removeAllEvents: Not all events could be removed.");
543                 }
544             }
545         },
546 
547         /**
548          * Cross browser mouse / pointer / touch coordinates retrieval relative to the documents's top left corner.
549          * This method might be a bit outdated today, since pointer events and clientX/Y are omnipresent.
550          *
551          * @param {Object} [e] The browsers event object. If omitted, <tt>window.event</tt> will be used.
552          * @param {Number} [index] If <tt>e</tt> is a touch event, this provides the index of the touch coordinates, i.e. it determines which finger.
553          * @param {Object} [doc] The document object.
554          * @returns {Array} Contains the position as x,y-coordinates in the first resp. second component.
555          */
556         getPosition: function (e, index, doc) {
557             var i,
558                 len,
559                 evtTouches,
560                 posx = 0,
561                 posy = 0;
562 
563             if (!e) {
564                 e = window.event;
565             }
566 
567             doc = doc || document;
568             evtTouches = e[JXG.touchProperty];
569 
570             // touchend events have their position in "changedTouches"
571             if (Type.exists(evtTouches) && evtTouches.length === 0) {
572                 evtTouches = e.changedTouches;
573             }
574 
575             if (Type.exists(index) && Type.exists(evtTouches)) {
576                 if (index === -1) {
577                     len = evtTouches.length;
578 
579                     for (i = 0; i < len; i++) {
580                         if (evtTouches[i]) {
581                             e = evtTouches[i];
582                             break;
583                         }
584                     }
585                 } else {
586                     e = evtTouches[index];
587                 }
588             }
589 
590             // Scrolling is ignored.
591             // e.clientX is supported since IE6
592             if (e.clientX) {
593                 posx = e.clientX;
594                 posy = e.clientY;
595             }
596 
597             return [posx, posy];
598         },
599 
600         /**
601          * Calculates recursively the offset of the DOM element in which the board is stored.
602          * @param {Object} obj A DOM element
603          * @returns {Array} An array with the elements left and top offset.
604          */
605         getOffset: function (obj) {
606             var cPos,
607                 o = obj,
608                 o2 = obj,
609                 l = o.offsetLeft - o.scrollLeft,
610                 t = o.offsetTop - o.scrollTop;
611 
612             cPos = this.getCSSTransform([l, t], o);
613             l = cPos[0];
614             t = cPos[1];
615 
616             /*
617              * In Mozilla and Webkit: offsetParent seems to jump at least to the next iframe,
618              * if not to the body. In IE and if we are in an position:absolute environment
619              * offsetParent walks up the DOM hierarchy.
620              * In order to walk up the DOM hierarchy also in Mozilla and Webkit
621              * we need the parentNode steps.
622              */
623             o = o.offsetParent;
624             while (o) {
625                 l += o.offsetLeft;
626                 t += o.offsetTop;
627 
628                 if (o.offsetParent) {
629                     l += o.clientLeft - o.scrollLeft;
630                     t += o.clientTop - o.scrollTop;
631                 }
632 
633                 cPos = this.getCSSTransform([l, t], o);
634                 l = cPos[0];
635                 t = cPos[1];
636 
637                 o2 = o2.parentNode;
638 
639                 while (o2 !== o) {
640                     l += o2.clientLeft - o2.scrollLeft;
641                     t += o2.clientTop - o2.scrollTop;
642 
643                     cPos = this.getCSSTransform([l, t], o2);
644                     l = cPos[0];
645                     t = cPos[1];
646 
647                     o2 = o2.parentNode;
648                 }
649                 o = o.offsetParent;
650             }
651 
652             return [l, t];
653         },
654 
655         /**
656          * Access CSS style sheets.
657          * @param {Object} obj A DOM element
658          * @param {String} stylename The CSS property to read.
659          * @returns The value of the CSS property and <tt>undefined</tt> if it is not set.
660          */
661         getStyle: function (obj, stylename) {
662             var r,
663                 doc = obj.ownerDocument;
664 
665             // Non-IE
666             if (doc.defaultView && doc.defaultView.getComputedStyle) {
667                 r = doc.defaultView.getComputedStyle(obj, null).getPropertyValue(stylename);
668                 // IE
669             } else if (obj.currentStyle && JXG.ieVersion >= 9) {
670                 r = obj.currentStyle[stylename];
671             } else {
672                 if (obj.style) {
673                     // make stylename lower camelcase
674                     stylename = stylename.replace(/-([a-z]|[0-9])/gi, function (all, letter) {
675                         return letter.toUpperCase();
676                     });
677                     r = obj.style[stylename];
678                 }
679             }
680 
681             return r;
682         },
683 
684         /**
685          * Reads css style sheets of a given element. This method is a getStyle wrapper and
686          * defaults the read value to <tt>0</tt> if it can't be parsed as an integer value.
687          * @param {DOMElement} el
688          * @param {string} css
689          * @returns {number}
690          */
691         getProp: function (el, css) {
692             var n = parseInt(this.getStyle(el, css), 10);
693             return isNaN(n) ? 0 : n;
694         },
695 
696         /**
697          * Correct position of upper left corner in case of
698          * a CSS transformation. Here, only translations are
699          * extracted. All scaling transformations are corrected
700          * in {@link JXG.Board#getMousePosition}.
701          * @param {Array} cPos Previously determined position
702          * @param {Object} obj A DOM element
703          * @returns {Array} The corrected position.
704          */
705         getCSSTransform: function (cPos, obj) {
706             var i,
707                 j,
708                 str,
709                 arrStr,
710                 start,
711                 len,
712                 len2,
713                 arr,
714                 t = [
715                     "transform",
716                     "webkitTransform",
717                     "MozTransform",
718                     "msTransform",
719                     "oTransform"
720                 ];
721 
722             // Take the first transformation matrix
723             len = t.length;
724 
725             for (i = 0, str = ""; i < len; i++) {
726                 if (Type.exists(obj.style[t[i]])) {
727                     str = obj.style[t[i]];
728                     break;
729                 }
730             }
731 
732             /**
733              * Extract the coordinates and apply the transformation
734              * to cPos
735              */
736             if (str !== "") {
737                 start = str.indexOf("(");
738 
739                 if (start > 0) {
740                     len = str.length;
741                     arrStr = str.substring(start + 1, len - 1);
742                     arr = arrStr.split(",");
743 
744                     for (j = 0, len2 = arr.length; j < len2; j++) {
745                         arr[j] = parseFloat(arr[j]);
746                     }
747 
748                     if (str.indexOf("matrix") === 0) {
749                         cPos[0] += arr[4];
750                         cPos[1] += arr[5];
751                     } else if (str.indexOf("translateX") === 0) {
752                         cPos[0] += arr[0];
753                     } else if (str.indexOf("translateY") === 0) {
754                         cPos[1] += arr[0];
755                     } else if (str.indexOf("translate") === 0) {
756                         cPos[0] += arr[0];
757                         cPos[1] += arr[1];
758                     }
759                 }
760             }
761 
762             // Zoom is used by reveal.js
763             if (Type.exists(obj.style.zoom)) {
764                 str = obj.style.zoom;
765                 if (str !== "") {
766                     cPos[0] *= parseFloat(str);
767                     cPos[1] *= parseFloat(str);
768                 }
769             }
770 
771             return cPos;
772         },
773 
774         /**
775          * Scaling CSS transformations applied to the div element containing the JSXGraph constructions
776          * are determined. In IE prior to 9, 'rotate', 'skew', 'skewX', 'skewY' are not supported.
777          * @returns {Array} 3x3 transformation matrix without translation part. See {@link JXG.Board#updateCSSTransforms}.
778          */
779         getCSSTransformMatrix: function (obj) {
780             var i, j, str, arrstr, arr,
781                 start, len, len2, st,
782                 doc = obj.ownerDocument,
783                 t = [
784                     "transform",
785                     "webkitTransform",
786                     "MozTransform",
787                     "msTransform",
788                     "oTransform"
789                 ],
790                 mat = [
791                     [1, 0, 0],
792                     [0, 1, 0],
793                     [0, 0, 1]
794                 ];
795 
796             // This should work on all browsers except IE 6-8
797             if (doc.defaultView && doc.defaultView.getComputedStyle) {
798                 st = doc.defaultView.getComputedStyle(obj, null);
799                 str =
800                     st.getPropertyValue("-webkit-transform") ||
801                     st.getPropertyValue("-moz-transform") ||
802                     st.getPropertyValue("-ms-transform") ||
803                     st.getPropertyValue("-o-transform") ||
804                     st.getPropertyValue("transform");
805             } else {
806                 // Take the first transformation matrix
807                 len = t.length;
808                 for (i = 0, str = ""; i < len; i++) {
809                     if (Type.exists(obj.style[t[i]])) {
810                         str = obj.style[t[i]];
811                         break;
812                     }
813                 }
814             }
815 
816             // Convert and reorder the matrix for JSXGraph
817             if (str !== "") {
818                 start = str.indexOf("(");
819 
820                 if (start > 0) {
821                     len = str.length;
822                     arrstr = str.substring(start + 1, len - 1);
823                     arr = arrstr.split(",");
824 
825                     for (j = 0, len2 = arr.length; j < len2; j++) {
826                         arr[j] = parseFloat(arr[j]);
827                     }
828 
829                     if (str.indexOf("matrix") === 0) {
830                         mat = [
831                             [1, 0, 0],
832                             [0, arr[0], arr[1]],
833                             [0, arr[2], arr[3]]
834                         ];
835                     } else if (str.indexOf("scaleX") === 0) {
836                         mat[1][1] = arr[0];
837                     } else if (str.indexOf("scaleY") === 0) {
838                         mat[2][2] = arr[0];
839                     } else if (str.indexOf("scale") === 0) {
840                         mat[1][1] = arr[0];
841                         mat[2][2] = arr[1];
842                     }
843                 }
844             }
845 
846             // CSS style zoom is used by reveal.js
847             // Recursively search for zoom style entries.
848             // This is necessary for reveal.js on webkit.
849             // It fails if the user does zooming
850             if (Type.exists(obj.style.zoom)) {
851                 str = obj.style.zoom;
852                 if (str !== "") {
853                     mat[1][1] *= parseFloat(str);
854                     mat[2][2] *= parseFloat(str);
855                 }
856             }
857 
858             return mat;
859         },
860 
861         /**
862          * Process data in timed chunks. Data which takes long to process, either because it is such
863          * a huge amount of data or the processing takes some time, causes warnings in browsers about
864          * irresponsive scripts. To prevent these warnings, the processing is split into smaller pieces
865          * called chunks which will be processed in serial order.
866          * Copyright 2009 Nicholas C. Zakas. All rights reserved. MIT Licensed
867          * @param {Array} items to do
868          * @param {Function} process Function that is applied for every array item
869          * @param {Object} context The scope of function process
870          * @param {Function} callback This function is called after the last array element has been processed.
871          */
872         timedChunk: function (items, process, context, callback) {
873             //create a clone of the original
874             var todo = items.concat(),
875                 timerFun = function () {
876                     var start = +new Date();
877 
878                     do {
879                         process.call(context, todo.shift());
880                     } while (todo.length > 0 && +new Date() - start < 300);
881 
882                     if (todo.length > 0) {
883                         window.setTimeout(timerFun, 1);
884                     } else {
885                         callback(items);
886                     }
887                 };
888 
889             window.setTimeout(timerFun, 1);
890         },
891 
892         /**
893          * Scale and vertically shift a DOM element (usually a JSXGraph div)
894          * inside of a parent DOM
895          * element which is set to fullscreen.
896          * This is realized with a CSS transformation.
897          *
898          * @param  {String} wrap_id  id of the parent DOM element which is in fullscreen mode
899          * @param  {String} inner_id id of the DOM element which is scaled and shifted
900          * @param  {Object} doc      document object or shadow root
901          * @param  {Number} scale    Relative size of the JSXGraph board in the fullscreen window.
902          *
903          * @private
904          * @see JXG.Board#toFullscreen
905          * @see JXG.Board#fullscreenListener
906          *
907          */
908         scaleJSXGraphDiv: function (wrap_id, inner_id, doc, scale) {
909             var w, h, b,
910                 wi, hi,
911                 wo, ho, inner,
912                 scale_l, vshift_l,
913                 f = scale,
914                 ratio,
915                 pseudo_keys = [
916                     ":fullscreen",
917                     ":-webkit-full-screen",
918                     ":-moz-full-screen",
919                     ":-ms-fullscreen"
920                 ],
921                 len_pseudo = pseudo_keys.length,
922                 i;
923 
924             b = doc.getElementById(wrap_id).getBoundingClientRect();
925             h = b.height;
926             w = b.width;
927 
928             inner = doc.getElementById(inner_id);
929             wo = inner._cssFullscreenStore.w;
930             ho = inner._cssFullscreenStore.h;
931             ratio = ho / wo;
932 
933             // Scale the div such that fits into the fullscreen.
934             if (wo > w * f) {
935                 wo = w * f;
936                 ho = wo * ratio;
937             }
938             if (ho > h * f) {
939                 ho = h * f;
940                 wo = ho / ratio;
941             }
942 
943             wi = wo;
944             hi = ho;
945             // Compare the code in this.setBoundingBox()
946             if (ratio > 1) {
947                 // h > w
948                 if (ratio < h / w) {
949                     scale_l =  w * f / wo;
950                 } else {
951                     scale_l =  h * f / ho;
952                 }
953             } else {
954                 // h <= w
955                 if (ratio < h / w) {
956                     scale_l = w * f / wo;
957                 } else {
958                     scale_l = h * f / ho;
959                 }
960             }
961             vshift_l = (h - hi) * 0.5;
962 
963             // Set a CSS properties to center the JSXGraph div horizontally and vertically
964             // at the first position of the fullscreen pseudo classes.
965             for (i = 0; i < len_pseudo; i++) {
966                 try {
967                     inner.style.width = wi + 'px !important';
968                     inner.style.height = hi + 'px !important';
969                     inner.style.margin = '0 auto';
970                     // Add the transform to a possibly already existing transform
971                     inner.style.transform = inner._cssFullscreenStore.transform +
972                         ' matrix(' + scale_l + ',0,0,' + scale_l + ',0,' + vshift_l + ')';
973                     break;
974                 } catch (err) {
975                     JXG.debug("JXG.scaleJSXGraphDiv:\n" + err);
976                 }
977             }
978             if (i === len_pseudo) {
979                 JXG.debug("JXG.scaleJSXGraphDiv: Could not set any CSS property.");
980             }
981         }
982 
983     }
984 );
985 
986 export default JXG;
987