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} elementId The HTML id of 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 = doc.getElementById(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,
781                 j,
782                 str,
783                 arrstr,
784                 start,
785                 len,
786                 len2,
787                 arr,
788                 st,
789                 doc = obj.ownerDocument,
790                 t = [
791                     "transform",
792                     "webkitTransform",
793                     "MozTransform",
794                     "msTransform",
795                     "oTransform"
796                 ],
797                 mat = [
798                     [1, 0, 0],
799                     [0, 1, 0],
800                     [0, 0, 1]
801                 ];
802 
803             // This should work on all browsers except IE 6-8
804             if (doc.defaultView && doc.defaultView.getComputedStyle) {
805                 st = doc.defaultView.getComputedStyle(obj, null);
806                 str =
807                     st.getPropertyValue("-webkit-transform") ||
808                     st.getPropertyValue("-moz-transform") ||
809                     st.getPropertyValue("-ms-transform") ||
810                     st.getPropertyValue("-o-transform") ||
811                     st.getPropertyValue("transform");
812             } else {
813                 // Take the first transformation matrix
814                 len = t.length;
815                 for (i = 0, str = ""; i < len; i++) {
816                     if (Type.exists(obj.style[t[i]])) {
817                         str = obj.style[t[i]];
818                         break;
819                     }
820                 }
821             }
822 
823             if (str !== "") {
824                 start = str.indexOf("(");
825 
826                 if (start > 0) {
827                     len = str.length;
828                     arrstr = str.substring(start + 1, len - 1);
829                     arr = arrstr.split(",");
830 
831                     for (j = 0, len2 = arr.length; j < len2; j++) {
832                         arr[j] = parseFloat(arr[j]);
833                     }
834 
835                     if (str.indexOf("matrix") === 0) {
836                         mat = [
837                             [1, 0, 0],
838                             [0, arr[0], arr[1]],
839                             [0, arr[2], arr[3]]
840                         ];
841                     } else if (str.indexOf("scaleX") === 0) {
842                         mat[1][1] = arr[0];
843                     } else if (str.indexOf("scaleY") === 0) {
844                         mat[2][2] = arr[0];
845                     } else if (str.indexOf("scale") === 0) {
846                         mat[1][1] = arr[0];
847                         mat[2][2] = arr[1];
848                     }
849                 }
850             }
851 
852             // CSS style zoom is used by reveal.js
853             // Recursively search for zoom style entries.
854             // This is necessary for reveal.js on webkit.
855             // It fails if the user does zooming
856             if (Type.exists(obj.style.zoom)) {
857                 str = obj.style.zoom;
858                 if (str !== "") {
859                     mat[1][1] *= parseFloat(str);
860                     mat[2][2] *= parseFloat(str);
861                 }
862             }
863 
864             return mat;
865         },
866 
867         /**
868          * Process data in timed chunks. Data which takes long to process, either because it is such
869          * a huge amount of data or the processing takes some time, causes warnings in browsers about
870          * irresponsive scripts. To prevent these warnings, the processing is split into smaller pieces
871          * called chunks which will be processed in serial order.
872          * Copyright 2009 Nicholas C. Zakas. All rights reserved. MIT Licensed
873          * @param {Array} items to do
874          * @param {Function} process Function that is applied for every array item
875          * @param {Object} context The scope of function process
876          * @param {Function} callback This function is called after the last array element has been processed.
877          */
878         timedChunk: function (items, process, context, callback) {
879             //create a clone of the original
880             var todo = items.concat(),
881                 timerFun = function () {
882                     var start = +new Date();
883 
884                     do {
885                         process.call(context, todo.shift());
886                     } while (todo.length > 0 && +new Date() - start < 300);
887 
888                     if (todo.length > 0) {
889                         window.setTimeout(timerFun, 1);
890                     } else {
891                         callback(items);
892                     }
893                 };
894 
895             window.setTimeout(timerFun, 1);
896         },
897 
898         /**
899          * Scale and vertically shift a DOM element (usually a JSXGraph div)
900          * inside of a parent DOM
901          * element which is set to fullscreen.
902          * This is realized with a CSS transformation.
903          *
904          * @param  {String} wrap_id  id of the parent DOM element which is in fullscreen mode
905          * @param  {String} inner_id id of the DOM element which is scaled and shifted
906          * @param  {Object} doc      document object or shadow root
907          * @param  {Number} scale    Relative size of the JSXGraph board in the fullscreen window.
908          *
909          * @private
910          * @see JXG.Board#toFullscreen
911          * @see JXG.Board#fullscreenListener
912          *
913          */
914         scaleJSXGraphDiv: function (wrap_id, inner_id, doc, scale) {
915             var len = doc.styleSheets.length, style, rule, w, h, b, wi, hi, bi,
916                 scale_l, vshift_l, // scale_p, vshift_p,
917                 f = scale,
918                 rule_inner_l, // rule_inner_p,
919                 pseudo_keys = [
920                     ":fullscreen",
921                     ":-webkit-full-screen",
922                     ":-moz-full-screen",
923                     ":-ms-fullscreen"
924                 ],
925                 len_pseudo = pseudo_keys.length,
926                 i,
927                 // A previously installed CSS rule to center the JSXGraph div has to
928                 // be searched and removed again.
929                 regex = new RegExp(
930                     ".*#" +
931                         wrap_id +
932                         ":.*full.*screen.*#" +
933                         inner_id +
934                         ".*auto;.*transform:.*matrix"
935                 );
936 
937             b = doc.getElementById(wrap_id).getBoundingClientRect();
938             h = b.height;
939             w = b.width;
940 
941             bi = doc.getElementById(inner_id).getBoundingClientRect();
942             hi = bi.height;
943             wi = bi.width;
944 
945             if (wi / hi >= w / h) {
946                 scale_l = (f * w) / wi;
947             } else {
948                 scale_l = (f * h) / hi;
949             }
950             vshift_l = (h - hi) * 0.5;
951 
952             // CSS rules to center the inner div horizontally and vertically.
953             rule_inner_l =
954                 "{margin:0 auto;transform:matrix(" +
955                 scale_l +
956                 ",0,0," +
957                 scale_l +
958                 ",0," +
959                 vshift_l +
960                 ");}";
961 
962             if (len === 0) {
963                 // In case there is not a single CSS rule defined at all.
964                 style = document.createElement("style");
965                 // WebKit hack :(
966                 style.appendChild(document.createTextNode(""));
967                 // Add the <style> element to the page
968                 doc.appendChild(style);
969                 len = doc.styleSheets.length;
970             }
971 
972             // Remove a previously installed CSS rule.
973             if (
974                 doc.styleSheets[len - 1].cssRules.length > 0 &&
975                 regex.test(doc.styleSheets[len - 1].cssRules[0].cssText) &&
976                 doc.styleSheets[len - 1].deleteRule
977             ) {
978                 doc.styleSheets[len - 1].deleteRule(0);
979             }
980 
981             // Install a CSS rule to center the JSXGraph div at the first position of the list.
982             for (i = 0; i < len_pseudo; i++) {
983                 try {
984                     rule = "#" + wrap_id + pseudo_keys[i] + " #" + inner_id + rule_inner_l;
985                     // rule = '@media all and (orientation:landscape) {' + rule + '}';
986                     doc.styleSheets[len - 1].insertRule(rule, 0);
987 
988                     break;
989                 } catch (err) {
990                     // console.log('JXG.scaleJSXGraphDiv: Could not add CSS rule "' + pseudo_keys[i] + '".');
991                     // console.log('One possible reason could be that the id of the JSXGraph container does not start with a letter.');
992                 }
993             }
994             if (i === len_pseudo) {
995                 console.log("JXG.scaleJSXGraphDiv: Could not add any CSS rule.");
996                 console.log(
997                     "One possible reason could be that the id of the JSXGraph container does not start with a letter."
998                 );
999             }
1000         }
1001 
1002     }
1003 );
1004 
1005 export default JXG;
1006