/*
    Copyright 2008-2013
        Matthias Ehmann,
        Michael Gerhaeuser,
        Carsten Miller,
        Bianca Valentin,
        Alfred Wassermann,
        Peter Wilfahrt

    This file is part of JSXGraph.

    JSXGraph is free software dual licensed under the GNU LGPL or MIT License.

    You can redistribute it and/or modify it under the terms of the

      * GNU Lesser General Public License as published by
        the Free Software Foundation, either version 3 of the License, or
        (at your option) any later version
      OR
      * MIT License: https://github.com/jsxgraph/jsxgraph/blob/master/LICENSE.MIT

    JSXGraph is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License and
    the MIT License along with JSXGraph. If not, see <http://www.gnu.org/licenses/>
    and <http://opensource.org/licenses/MIT/>.
 */

/*global JXG: true, XMLSerializer: true, Image: true*/
/*jslint nomen: true, plusplus: true*/

/* depends:
 jxg
 base/constants
 base/group
 parser/geonext
 utils/type
 utils/color
 utils/zip
 utils/base64
 utils/xml
  elements:
   image
   transform
   point
   line
   circle
   glider
   intersection
   arrowparallel
   bisector
   circumcircle
   circumcenter
   midpoint
   reflection
   mirrorpoint
   perpendicularsegment
   parallelpoint
   perpendicularpoint
   sector
   segment
   polygon
   curve
   arrow
   arc
   angle
   text
   tracecurve
   grid
   axis
 */

(function () {

    "use strict";

    JXG.GeonextReader = function (board, str) {
        var content;

        this.board = board;
        content = this.prepareString(str);
        this.tree = JXG.XML.parse(content);
    };

    JXG.extend(JXG.GeonextReader.prototype, /** @lends JXG.GeonextReader.prototype */ {
        changeOriginIds: function (board, id) {
            if ((id === 'gOOe0') || (id === 'gXOe0') || (id === 'gYOe0') || (id === 'gXLe0') || (id === 'gYLe0')) {
                return board.id + id;
            }

            return id;
        },

        /**
         * Retrieves data by TagName from an XML node.
         * @param {Object} node The Node that contains the data we want to get.
         * @param {String} tag The Name of the tag we are looking for.
         * @param {Number} [idx=0] getElementsByTagName returns an array; This parameter decides which element to use.
         * @param {Boolean} [fc=true] If True, the result will be the <tt>data</tt> of <tt>firstChild</tt> instead of the result node.
         * @returns {Object|Array|String} The gathered data
         */
        gEBTN: function (node, tag, idx, fc) {
            var tmp = [];

            if (!JXG.exists(node || !node.getElementsByTagName)) {
                return node;
            }

            // Default values for optional parameters idx and fc
            if (!JXG.exists(fc)) {
                fc = true;
            }

            idx = idx || 0;

            if (node.getElementsByTagName) {
                tmp = node.getElementsByTagName(tag);
            }
            if (tmp.length > 0) {
                tmp = tmp[idx];
                if (fc && tmp.firstChild) {
                    tmp = tmp.firstChild.data;
                }
            }

            return tmp;
        },

        /**
         * Set color properties of a geonext element.
         * Set stroke, fill, lighting, label and draft color attributes.
         * @param {Object} gxtEl element of which attributes are to set
         * @param {Object} Data
         * @returns {Object} Returns gxtEl
         */
        colorProperties: function (gxtEl, Data) {
            var rgbo,
                color = this.gEBTN(Data, 'color', 0, false);

            //gxtEl.strokewidth = Data.getElementsByTagName('strokewidth')[0].firstChild.data;
            // colorStroke = strokeColor etc. is here for downwards compatibility:
            // once upon a time we used to create elements in here using the "new JXG.Element" constructor mechanism
            // then we changed to board.create + setProperty afterwords
            // now i want to use the board.create method with an appropriate attributes object to avoid setProperty calls
            // and as gxtEl happens to be somewhat like an attributes object it's  just slightly different so we adjust it
            // for downwards compatibility during the transformation of this reader we use both properties

            rgbo = JXG.rgba2rgbo(this.gEBTN(color, 'stroke'));
            gxtEl.strokeColor = rgbo[0];
            gxtEl.strokeOpacity = rgbo[1];

            rgbo = JXG.rgba2rgbo(this.gEBTN(color, 'lighting'));
            gxtEl.highlightStrokeColor = rgbo[0];
            gxtEl.highlightStrokeOpacity = rgbo[1];

            rgbo = JXG.rgba2rgbo(this.gEBTN(color, 'fill'));
            gxtEl.fillColor = rgbo[0];
            gxtEl.fillOpacity = rgbo[1];

            gxtEl.highlightFillColor = gxtEl.fillColor;
            gxtEl.highlightFillOpacity = gxtEl.fillOpacity;

            rgbo = JXG.rgba2rgbo(this.gEBTN(color, 'label'));
            gxtEl.labelColor = rgbo[0];
            gxtEl.withLabel = rgbo[1] > 0;
            gxtEl.labelOpacity = rgbo[1];
            
            gxtEl.colorDraft = JXG.rgba2rgbo(this.gEBTN(color, 'draft'))[0];

            // backwards compatibility
            gxtEl.colorStroke = gxtEl.strokeColor;
            gxtEl.colorFill = gxtEl.fillColor;
            gxtEl.colorLabel = gxtEl.labelColor;

            return gxtEl;
        },

        firstLevelProperties: function (gxtEl, Data) {
            var n, key, arr;

            if (!JXG.exists(Data) || !JXG.exists(Data.childNodes)) {
                return gxtEl;
            }

            arr = Data.childNodes;

            for (n = 0; n < arr.length; n++) {
                if (JXG.exists(arr[n].firstChild) && arr[n].nodeName !== 'data' && arr[n].nodeName !== 'straight') {
                    key = arr[n].nodeName;

                    if (key === 'width') {
                        key = 'strokewidth';
                    }
                    gxtEl[key] = arr[n].firstChild.data;
                }
            }

            return gxtEl;
        },

        /**
         * Set the defining properties of a geonext element.
         * Writing the nodeName to ident; setting the name attribute and defining the element id.
         * @param {Object} gxtEl element of which attributes are to set
         * @param {Object} Data
         */
        defProperties: function (gxtEl, Data) {
            // 3==TEXT_NODE, 8==COMMENT_NODE
            if (Data.nodeType === 3 || Data.nodeType === 8) {
                return null;
            }

            gxtEl.ident = Data.nodeName;

            if (gxtEl.ident === "text" || gxtEl.ident === "intersection" || gxtEl.ident === "composition") {
                gxtEl.name = '';
            } else {
                gxtEl.name = this.gEBTN(Data, 'name');
            }

            gxtEl.id = this.gEBTN(Data, 'id');

            return gxtEl;
        },

        visualProperties: function (gxtEl, Data) {
            gxtEl.visible = JXG.str2Bool(this.gEBTN(Data, 'visible'));
            gxtEl.trace = JXG.str2Bool(this.gEBTN(Data, 'trace'));

            return gxtEl;
        },

        /**
         * Transforms the Geonext properties to jsxgraph properties
         * @param {Object} gxtEl
         * @param {String} [type]
         * @return {Object} gxtEl
         */
        transformProperties: function (gxtEl, type) {
            var i,
                facemap = [
                    // 0-2
                    'cross', 'cross', 'cross',
                    // 3-6
                    'circle', 'circle', 'circle', 'circle',
                    // 7-9
                    'square', 'square', 'square',
                    // 10-12
                    'plus', 'plus', 'plus'
                ],
                sizemap = [
                    // 0-2
                    2, 3, 4,
                    // 3-6
                    1, 2, 3, 4,
                    // 7-9
                    2, 3, 4,
                    // 10-12
                    2, 3, 4
                ],
                remove = [
                    'color', 'dash', 'style', 'style', 'ident', 'colordraft', 'colorstroke', 'colorfill',
                    'colorlabel', 'active', 'area', 'showinfo', 'showcoord', 'fix'
                ];

            gxtEl.strokeWidth = gxtEl.strokewidth;
            gxtEl.face = facemap[parseInt(gxtEl.style, 10)] || 'cross';
            gxtEl.size = sizemap[parseInt(gxtEl.style, 10)] || 3;

            gxtEl.straightFirst = JXG.str2Bool(gxtEl.straightFirst);
            gxtEl.straightLast = JXG.str2Bool(gxtEl.straightLast);

            gxtEl.visible = JXG.str2Bool(gxtEl.visible);
            //gxtEl.withLabel = gxtEl.visible;           // withLabel is set in colorProperties()
            gxtEl.draft = JXG.str2Bool(gxtEl.draft);
            gxtEl.trace = JXG.str2Bool(gxtEl.trace);

            if (type === 'point') {
                // Fill properties are ignored by GEONExT
                gxtEl.fillColor = gxtEl.strokeColor;
                gxtEl.highlightFillColor = gxtEl.highlightStrokeColor;
                gxtEl.fillOpacity = gxtEl.strokeOpacity;
                gxtEl.highlightFillOpacity = gxtEl.highlightStrokeOpacity;
            }

            if (typeof gxtEl.label === 'string') {
                delete gxtEl.label;
            }
            gxtEl.label = gxtEl.label || {
                opacity: gxtEl.labelOpacity
            };

            // clean up
            for (i = 0; i < remove.length; i++) {
                delete gxtEl[remove[i]];
            }

            return gxtEl;
        },

        readNodes: function (gxtEl, Data, nodeType, prefix) {
            var key, n,
                arr = this.gEBTN(Data, nodeType, 0, false).childNodes;

            for (n = 0; n < arr.length; n++) {
                if (JXG.exists(arr[n].firstChild)) {
                    if (JXG.exists(prefix)) {
                        key = prefix + JXG.capitalize(arr[n].nodeName);
                    } else {
                        key = arr[n].nodeName;
                    }
                    gxtEl[key] = arr[n].firstChild.data;
                }
            }
            return gxtEl;
        },

        subtreeToString: function (root) {
            try {
                // firefox
                return (new XMLSerializer()).serializeToString(root);
            } catch (e) {
                // IE
                return root.xml;
            }
        },

        readImage: function (node) {
            var pic = '',
                nod = node;

            if (JXG.exists(nod)) {
                pic = nod.data;
                while (JXG.exists(nod.nextSibling)) {
                    nod = nod.nextSibling;
                    pic += nod.data;
                }
            }
            return pic;
        },

        parseImage: function (board, fileNode, level, x, y, w, h, el) {
            var tag, id, picStr, tmpImg,
                im = null;

            if (fileNode === null) {
                return im;
            }

            // Background image
            if (JXG.exists(fileNode.getElementsByTagName('src')[0])) {
                tag = 'src';
            } else if (JXG.exists(fileNode.getElementsByTagName('image')[0]) &&
                    JXG.exists(this.gEBTN(fileNode, 'image'))) {
                tag = 'image';
            } else {
                return im;
            }

            picStr = this.readImage(this.gEBTN(fileNode, tag, 0, false).firstChild);
            if (picStr !== '') {
                picStr = 'data:image/png;base64,' + picStr;

                // Background image
                if (tag === 'src') {
                    x = this.gEBTN(fileNode, 'x');
                    y = this.gEBTN(fileNode, 'y');
                    w = this.gEBTN(fileNode, 'width');
                    h = this.gEBTN(fileNode, 'height');
                    im = board.create('image', [picStr, [x, y], [w, h]], {
                        anchor: el,
                        layer: level
                    });

                    return im;
                }
                // Image bound to an element
                // Read the original dimensions, i.e. the ratio h/w with the help of a temporary image.
                // We have to wait until the image is loaded, therefore
                // we need "onload".
                tmpImg = new Image();
                tmpImg.src = picStr;
                id = el.id + '_image';
                tmpImg.onload = function () {
                    // Now, we can read the original dimensions of the image.
                    var xf, yf, wf, hf, im, tRot,
                        wOrg = this.width,
                        hOrg = this.height;

                    if (el.elementClass === JXG.OBJECT_CLASS_LINE) {
                        // A line containing an image, runs through the horizontal middle
                        // of the image.
                        xf = function () {
                            return el.point1.X();
                        };
                        wf = function () {
                            return el.point1.Dist(el.point2);
                        };
                        hf = function () {
                            return wf() * hOrg / wOrg;
                        };
                        yf = function () {
                            return el.point1.Y() - hf() * 0.5;
                        };

                        im = board.create('image', [picStr, [xf, yf], [wf, hf]], {
                            layer: level,
                            id: id,
                            anchor: el
                        });

                        tRot = board.create('transform', [
                            function () {
                                return Math.atan2(el.point2.Y() - el.point1.Y(), el.point2.X() - el.point1.X());
                            },
                            el.point1
                        ], {type: 'rotate'});

                        tRot.bindTo(im);
                        el.image = im;
                    } else if (el.elementClass === JXG.OBJECT_CLASS_POINT) {
                        wf = function () {
                            return wOrg / board.unitX;
                        };
                        hf = function () {
                            return hOrg / board.unitY;
                        };
                        xf = function () {
                            return el.X() - wf() * 0.5;
                        };
                        yf = function () {
                            return el.Y() - hf() * 0.5;
                        };

                        im = board.create('image', [picStr, [xf, yf], [wf, hf]], {
                            layer: level,
                            id: id,
                            anchor: el
                        });
                        board.renderer.hide(el.label);
                        el.image = im;
                    } else if (el.elementClass === JXG.OBJECT_CLASS_CIRCLE) {
                        // A circle containing an image
                        wf = function () {
                            return 2.0 * el.Radius();
                        };
                        hf = function () {
                            return wf() * hOrg / wOrg;
                        };
                        xf = function () {
                            return el.center.X() - wf() * 0.5;
                        };
                        yf = function () {
                            return el.center.Y() - hf() * 0.5;
                        };

                        im = board.create('image', [picStr, [xf, yf], [wf, hf]], {
                            layer: level,
                            id: id,
                            anchor: el
                        });
                        el.image = im;
                    } else {
                        im = board.create('image', [picStr, [x, y], [w, h]], {
                            layer: level,
                            id: id,
                            anchor: el
                        });
                        el.image = im;
                    }
                };

                return im;
            }
        },

        readConditions: function (node) {
            var i, s, ob,
                conditions = '';

            if (JXG.exists(node)) {
                for (i = 0; i < node.getElementsByTagName('data').length; i++) {
                    ob = node.getElementsByTagName('data')[i];
                    s = this.subtreeToString(ob);
                    conditions += s;
                }
            }

            return conditions;
        },

        readViewPort: function (node) {
            var no,
                arr = [];

            no = this.gEBTN(node, 'viewport', 0, false);

            if (no) {
                arr[0] = parseFloat(this.gEBTN(no, 'left'));
                arr[1] = parseFloat(this.gEBTN(no, 'top'));
                arr[2] = parseFloat(this.gEBTN(no, 'right'));
                arr[3] = parseFloat(this.gEBTN(no, 'bottom'));
                return arr;
            }

            return [];
        },

        printDebugMessage: function (outputEl, gxtEl, nodetyp, success) {
            JXG.debug("* " + success + ":  " + nodetyp + " " + gxtEl.name + " " + gxtEl.id);
        },

        readNode: function (elChildNodes, s, board) {
            var dataVertex, i, l, x, c, numberDefEls, el, p, inter, rgbo, tmp, v, Data, xmlNode,
                gxtEl = {};

            Data = elChildNodes[s];
            gxtEl = this.defProperties(gxtEl, Data);

            // Skip text nodes
            if (!JXG.exists(gxtEl)) {
                return;
            }

            this.printDebugMessage('debug', gxtEl, Data.nodeName.toLowerCase(), 'READ:');
            switch (Data.nodeName.toLowerCase()) {
            case "point":
                gxtEl.strokewidth = 1; // Old file format
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl = this.readNodes(gxtEl, Data, 'data');
                gxtEl.fixed = JXG.str2Bool(this.gEBTN(Data, 'fix'));
                gxtEl = this.transformProperties(gxtEl, 'point');

                //try {
                p = board.create('point', [parseFloat(gxtEl.x), parseFloat(gxtEl.y)], gxtEl);

                v = function () {
                    return p.visProp.visible;
                };
                el = this.parseImage(board, Data, board.options.layer.image, 0, 0, 0, 0, p);
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "line":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl = this.readNodes(gxtEl, Data, 'data');
                gxtEl = this.readNodes(gxtEl, Data, 'straight', 'straight');
                gxtEl = this.transformProperties(gxtEl);

                gxtEl.first = this.changeOriginIds(board, gxtEl.first);
                gxtEl.last = this.changeOriginIds(board, gxtEl.last);

                l = board.create('line', [gxtEl.first, gxtEl.last], gxtEl);

                this.parseImage(board, Data, board.options.layer.image, 0, 0, 0, 0, l);
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "circle":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);

                tmp = this.gEBTN(Data, 'data', 0, false);
                gxtEl.center = this.changeOriginIds(board, this.gEBTN(tmp, 'midpoint'));

                if (tmp.getElementsByTagName('radius').length > 0) {
                    gxtEl.radius = this.changeOriginIds(board, this.gEBTN(tmp, 'radius'));
                } else if (tmp.getElementsByTagName('radiusvalue').length > 0) {
                    gxtEl.radius = this.gEBTN(tmp, 'radiusvalue');
                }
                gxtEl = this.transformProperties(gxtEl);
                c = board.create('circle', [gxtEl.center, gxtEl.radius], gxtEl);

                this.parseImage(board, Data, board.options.layer.image, 0, 0, 0, 0, c);
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "slider":
                gxtEl.strokewidth = 1; // Old file format
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);

                gxtEl = this.readNodes(gxtEl, Data, 'data');
                gxtEl.fixed = JXG.str2Bool(this.gEBTN(Data, 'fix'));
                gxtEl = this.readNodes(gxtEl, Data, 'animate', 'animate');
                gxtEl = this.transformProperties(gxtEl, 'point');
                try {
                    gxtEl.parent = this.changeOriginIds(board, gxtEl.parent);
                    gxtEl.isGeonext = true;
                    
                    p = board.create('glider', [parseFloat(gxtEl.x), parseFloat(gxtEl.y), gxtEl.parent], gxtEl);
                    p.onPolygon = JXG.exists(gxtEl.onpolygon) && JXG.str2Bool(gxtEl.onpolygon);

                    this.parseImage(board, Data, board.options.layer.point, 0, 0, 0, 0, p);

                    this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                } catch (e) {
                    JXG.debug("* Err:  Slider " + gxtEl.name + " " + gxtEl.id + ': ' + gxtEl.parent);
                }
                break;
            case "cas":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl.fixed = JXG.str2Bool(Data.getElementsByTagName('fix')[0].firstChild.data);
                gxtEl = this.readNodes(gxtEl, Data, 'data');
                gxtEl = this.transformProperties(gxtEl, 'point');

                p = board.create('point', [gxtEl.x, gxtEl.y], gxtEl);
                this.parseImage(board, Data, board.options.layer.point, 0, 0, 0, 0, p);
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "intersection":
                gxtEl.strokewidth = 1; // Old file format
                gxtEl = this.readNodes(gxtEl, Data, 'data');
                xmlNode = Data.getElementsByTagName('first')[1];

                gxtEl.outFirst = {};
                gxtEl.outFirst = this.colorProperties(gxtEl.outFirst, xmlNode);
                gxtEl.outFirst = this.visualProperties(gxtEl.outFirst, xmlNode);
                gxtEl.outFirst = this.firstLevelProperties(gxtEl.outFirst, xmlNode);
                gxtEl.outFirst.fixed = JXG.str2Bool(xmlNode.getElementsByTagName('fix')[0].firstChild.data);
                gxtEl.outFirst = this.transformProperties(gxtEl.outFirst, 'point');
                gxtEl.first = this.changeOriginIds(board, gxtEl.first);
                gxtEl.last = this.changeOriginIds(board, gxtEl.last);

                if ((board.select(gxtEl.first).elementClass === JXG.OBJECT_CLASS_LINE) &&
                        (board.select(gxtEl.last).elementClass === JXG.OBJECT_CLASS_LINE)) {
                    inter = board.create('intersection', [board.objects[gxtEl.first], board.objects[gxtEl.last], 0], gxtEl.outFirst);
                    /* for some reason this if is required */
                    if (gxtEl.outFirst.visible === "false") {
                        inter.hideElement();
                    }
                } else {
                    xmlNode = Data.getElementsByTagName('last')[1];
                    if (JXG.exists(xmlNode)) {
                        gxtEl.outLast = {};
                        gxtEl.outLast = this.colorProperties(gxtEl.outLast, xmlNode);
                        gxtEl.outLast = this.visualProperties(gxtEl.outLast, xmlNode);
                        gxtEl.outLast = this.firstLevelProperties(gxtEl.outLast, xmlNode);
                        gxtEl.outLast.fixed = JXG.str2Bool(xmlNode.getElementsByTagName('fix')[0].firstChild.data);
                        gxtEl.outLast = this.transformProperties(gxtEl.outLast, 'point');

                        inter = board.create('intersection', [board.objects[gxtEl.first], board.objects[gxtEl.last], 0], gxtEl.outFirst);
                        inter = board.create('intersection', [board.objects[gxtEl.first], board.objects[gxtEl.last], 1], gxtEl.outLast);
                    }
                }
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "composition":
                gxtEl = this.readNodes(gxtEl, Data, 'data');
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl.defEl = [];
                numberDefEls = 0;
                xmlNode = Data.getElementsByTagName('data')[0].getElementsByTagName('input');
                for (i = 0; i < xmlNode.length; i++) {
                    gxtEl.defEl[i] = xmlNode[i].firstChild.data;
                    numberDefEls = i + 1;
                }

                // every composition produces at least one element and the data for this element is stored
                // in gxtEl.out. if additional elements are created their data is read in the according case.
                xmlNode = Data.getElementsByTagName('output')[0];
                gxtEl.out = {};
                gxtEl.out = this.colorProperties(gxtEl.out, xmlNode);
                gxtEl.out = this.visualProperties(gxtEl.out, xmlNode);
                gxtEl.out = this.firstLevelProperties(gxtEl.out, xmlNode);
                gxtEl.out = this.transformProperties(gxtEl.out);

                gxtEl.defEl[0] = this.changeOriginIds(board, gxtEl.defEl[0]);
                gxtEl.defEl[1] = this.changeOriginIds(board, gxtEl.defEl[1]);
                gxtEl.defEl[2] = this.changeOriginIds(board, gxtEl.defEl[2]);

                switch (gxtEl.type) {
                // ARROW_PARALLEL
                case "210070":
                    gxtEl.out.fixed = this.gEBTN(xmlNode, 'fix');

                    xmlNode = Data.getElementsByTagName('output')[1];
                    gxtEl.outPoint = {};
                    gxtEl.outPoint = this.defProperties(gxtEl.outPoint, xmlNode);
                    gxtEl.outPoint = this.colorProperties(gxtEl.outPoint, xmlNode);
                    gxtEl.outPoint = this.visualProperties(gxtEl.outPoint, xmlNode);
                    gxtEl.outPoint = this.firstLevelProperties(gxtEl.outPoint, xmlNode);
                    gxtEl.outPoint = this.transformProperties(gxtEl.outPoint);

                    // construct this by hand, because arrowparallel uses projective geometry now
                    p =  board.create('parallelpoint', [gxtEl.defEl[1], gxtEl.defEl[0]], gxtEl.outPoint);
                    gxtEl.out.firstArrow = false;
                    gxtEl.out.lastArrow = true;
                    el = board.create('segment', [gxtEl.defEl[0], p], gxtEl.out);
                    el.parallelpoint = p;
                    break;

                // BISECTOR
                case "210080":
                    gxtEl.out.straightFirst = false;
                    board.create('bisector', [gxtEl.defEl[0], gxtEl.defEl[1], gxtEl.defEl[2]], gxtEl.out);
                    break;

                // CIRCUMCIRCLE
                case "210090":
                    xmlNode = Data.getElementsByTagName('output')[1];
                    gxtEl.outCircle = {};
                    gxtEl.outCircle = this.defProperties(gxtEl.outCircle, xmlNode);
                    gxtEl.outCircle = this.colorProperties(gxtEl.outCircle, xmlNode);
                    gxtEl.outCircle = this.visualProperties(gxtEl.outCircle, xmlNode);
                    gxtEl.outCircle = this.firstLevelProperties(gxtEl.outCircle, xmlNode);
                    gxtEl.outCircle = this.transformProperties(gxtEl.outCircle);
                    gxtEl.outCircle.point = gxtEl.out;
                    board.create('circumcircle', [gxtEl.defEl[0], gxtEl.defEl[1], gxtEl.defEl[2]], gxtEl.outCircle);
                    break;

                // CIRCUMCIRCLE_CENTER
                case "210100":
                    board.create('circumcenter', [gxtEl.defEl[0], gxtEl.defEl[1], gxtEl.defEl[2]], gxtEl.out);
                    break;

                // MIDPOINT
                case "210110":
                    board.create('midpoint', gxtEl.defEl.slice(0, numberDefEls), gxtEl.out);
                    break;

                // MIRRORLINE
                case "210120":
                    board.create('reflection', [gxtEl.defEl[1], gxtEl.defEl[0]], gxtEl.out);
                    break;

                // MIRROR_POINT
                case "210125":
                    board.create('mirrorpoint', [gxtEl.defEl[0], gxtEl.defEl[1]], gxtEl.out);
                    break;

                // NORMAL
                case "210130":
                    //board.create('normal', [gxtEl.defEl[1], gxtEl.defEl[0]], gxtEl.out);
                    board.create('perpendicularsegment', [gxtEl.defEl[0], gxtEl.defEl[1]], gxtEl.out);
                    break;

                // PARALLEL
                case "210140":
                    p =  board.create('parallelpoint', [gxtEl.defEl[1], gxtEl.defEl[0]], {
                        withLabel: false,
                        visible: false,
                        name: '',
                        fixed: true
                    });

                    // GEONExT uses its own parallel construction to make the order
                    // of intersection points compatible.
                    // el = board.create('parallel', [gxtEl.defEl[1], gxtEl.defEl[0]], gxtEl.out);
                    el = board.create('line', [gxtEl.defEl[0], p], gxtEl.out);
                    el.parallelpoint = p;
                    break;

                // PARALLELOGRAM_POINT
                case "210150":
                    board.create('parallelpoint', gxtEl.defEl.slice(0, numberDefEls), gxtEl.out);
                    break;

                // PERPENDICULAR
                case "210160":
                    // output[0] was already read and is stored in gxtEl.out
                    gxtEl.out.fixed = this.gEBTN(xmlNode, 'fix');

                    xmlNode = Data.getElementsByTagName('output')[1];
                    gxtEl.outLine = {};
                    gxtEl.outLine = this.defProperties(gxtEl.outLine, xmlNode);
                    gxtEl.outLine = this.colorProperties(gxtEl.outLine, xmlNode);
                    gxtEl.outLine = this.visualProperties(gxtEl.outLine, xmlNode);
                    gxtEl.outLine = this.firstLevelProperties(gxtEl.outLine, xmlNode);
                    gxtEl.outLine = this.readNodes(gxtEl.outLine, xmlNode, 'straight', 'straight');
                    gxtEl.outLine = this.transformProperties(gxtEl.outLine);
                    gxtEl.outLine.point = gxtEl.out;

                    board.create('perpendicularsegment', [gxtEl.defEl[1], gxtEl.defEl[0]], gxtEl.outLine);
                    break;

                // PERPENDICULAR_POINT
                case "210170":
                    board.create('perpendicularpoint', [gxtEl.defEl[1], gxtEl.defEl[0]], gxtEl.out);
                    break;

                // ROTATION
                case "210180":
                    throw new Error('JSXGraph: Element ROTATION not yet implemented.');

                // SECTOR
                case "210190":
                    // sectors usually provide more than one output element but JSXGraph is not fully compatible
                    // to GEONExT sector elements. GEONExT sectors consist of two lines, a point, and a sector,
                    // JSXGraph uses a curve to display the sector incl. the borders, and
                    // a point and two lines.
                    // Gliders on sectors also run through the borders.
                    gxtEl.out = this.defProperties(gxtEl.out, xmlNode);
                    gxtEl.out.firstArrow = JXG.str2Bool(this.gEBTN(xmlNode, 'firstarrow'));
                    gxtEl.out.lastArrow = JXG.str2Bool(this.gEBTN(xmlNode, 'lastarrow'));

                    xmlNode = [];
                    c = [];

                    for (i = 0; i < 4; i++) {
                        xmlNode[i] = Data.getElementsByTagName('output')[i];
                        gxtEl.out = {};
                        gxtEl.out = this.defProperties(gxtEl.out, xmlNode[i]);
                        gxtEl.out = this.colorProperties(gxtEl.out, xmlNode[i]);
                        gxtEl.out = this.visualProperties(gxtEl.out, xmlNode[i]);
                        gxtEl.out = this.firstLevelProperties(gxtEl.out, xmlNode[i]);
                        gxtEl.out = this.transformProperties(gxtEl.out);
                        c[i] = gxtEl.out;
                    }

                    // i === 0
                    el = board.create('sector', gxtEl.defEl, c[0]);

                    // i === 1
                    p = board.create('point', [
                        function () {
                            var p1 = board.select(gxtEl.defEl[1]),
                                p2 = board.select(gxtEl.defEl[2]);

                            return p1.X() + (p2.X() - p1.X()) * el.Radius / p1.Dist(p2);
                        },
                        function () {
                            var p1 = board.select(gxtEl.defEl[1]),
                                p2 = board.select(gxtEl.defEl[2]);

                            return p1.Y() + (p2.Y() - p1.Y()) * el.Radius / p1.Dist(p2);
                        }
                    ], c[1]);

                    // i === 2
                    el = board.create('segment', [gxtEl.defEl[0], gxtEl.defEl[1]], c[2]);

                    // i === 3
                    el = board.create('segment', [gxtEl.defEl[1], p], c[3]);
                    break;
                default:
                    throw new Error('JSXGraph: GEONExT -- element ' + gxtEl.type + ' not implemented.');
                }
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "polygon":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                dataVertex = [];

                // In Geonext file format the first vertex is equal to the last vertex:
                for (i = 0; i < Data.getElementsByTagName('data')[0].getElementsByTagName('vertex').length - 1; i++) {
                    dataVertex[i] = Data.getElementsByTagName('data')[0].getElementsByTagName('vertex')[i].firstChild.data;
                    dataVertex[i] = this.changeOriginIds(board, dataVertex[i]);
                }
                gxtEl.border = [];
                gxtEl.borders = {
                    ids: [],
                    names: []
                };
                for (i = 0; i < Data.getElementsByTagName('border').length; i++) {
                    gxtEl.border[i] = {};
                    xmlNode = Data.getElementsByTagName('border')[i];
                    gxtEl.border[i].id = xmlNode.getElementsByTagName('id')[0].firstChild.data;
                    gxtEl.borders.ids.push(gxtEl.border[i].id);
                    gxtEl.border[i].name = xmlNode.getElementsByTagName('name')[0].firstChild.data;
                    gxtEl.borders.names.push(gxtEl.border[i].name);

                    gxtEl.border[i].straightFirst = JXG.str2Bool(xmlNode.getElementsByTagName('straight')[0].getElementsByTagName('first')[0].firstChild.data);
                    gxtEl.border[i].straightLast = JXG.str2Bool(xmlNode.getElementsByTagName('straight')[0].getElementsByTagName('last')[0].firstChild.data);
                    try {
                        gxtEl.border[i].strokeWidth = xmlNode.getElementsByTagName('strokewidth')[0].firstChild.data;
                    } catch (ex) {
                        gxtEl.border[i].strokeWidth = xmlNode.getElementsByTagName('width')[0].firstChild.data;
                    }
                    try {
                        gxtEl.border[i].dash = JXG.str2Bool(xmlNode.getElementsByTagName('dash')[0].firstChild.data);
                    } catch (exc) {}

                    gxtEl.border[i].visible = JXG.str2Bool(xmlNode.getElementsByTagName('visible')[0].firstChild.data);
                    gxtEl.border[i].draft = JXG.str2Bool(xmlNode.getElementsByTagName('draft')[0].firstChild.data);
                    gxtEl.border[i].trace = JXG.str2Bool(xmlNode.getElementsByTagName('trace')[0].firstChild.data);

                    xmlNode = Data.getElementsByTagName('border')[i].getElementsByTagName('color')[0];
                    rgbo = JXG.rgba2rgbo(xmlNode.getElementsByTagName('stroke')[0].firstChild.data);
                    gxtEl.border[i].strokeColor = rgbo[0];
                    gxtEl.border[i].strokeOpacity = rgbo[1];

                    rgbo = JXG.rgba2rgbo(xmlNode.getElementsByTagName('lighting')[0].firstChild.data);
                    gxtEl.border[i].highlightStrokeColor = rgbo[0];
                    gxtEl.border[i].highlightStrokeOpacity = rgbo[1];

                    rgbo = JXG.rgba2rgbo(xmlNode.getElementsByTagName('fill')[0].firstChild.data);
                    gxtEl.border[i].fillColor = rgbo[0];
                    gxtEl.border[i].fillOpacity = rgbo[1];

                    gxtEl.border[i].highlightFillColor = gxtEl.border[i].fillColor;
                    gxtEl.border[i].highlightFillOpacity = gxtEl.border[i].fillOpacity;

                    gxtEl.border[i].labelColor = xmlNode.getElementsByTagName('label')[0].firstChild.data;
                    gxtEl.border[i].colorDraft = xmlNode.getElementsByTagName('draft')[0].firstChild.data;
                }
                gxtEl = this.transformProperties(gxtEl);
                p = board.create('polygon', dataVertex, gxtEl);

                // to emulate the geonext behaviour on invisible polygons
                // A.W.: Why do we need this?
                /*
                 if (!gxtEl.visible) {
                 p.setProperty({
                 fillColor: 'none',
                 highlightFillColor: 'none'
                 });
                 }
                 */
                for (i = 0; i < p.borders.length; i++) {
                    p.borders[i].setProperty(gxtEl.border[i]);
                }

                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "graph":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl.funct = Data.getElementsByTagName('data')[0].getElementsByTagName('function')[0].firstChild.data;
                gxtEl.funct = board.jc.snippet(gxtEl.funct, true, 'x', true);

                c = board.create('plot', [gxtEl.funct], {
                    id: gxtEl.id,
                    name: gxtEl.name,
                    strokeColor: gxtEl.strokeColor,
                    strokeWidth: gxtEl.strokeWidth,
                    fillColor: 'none',
                    highlightFillColor: 'none',
                    highlightStrokeColor: gxtEl.highlightStrokeColor,
                    visible: JXG.str2Bool(gxtEl.visible)
                });

                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "arrow":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl = this.readNodes(gxtEl, Data, 'data');
                gxtEl = this.readNodes(gxtEl, Data, 'straight', 'straight');

                gxtEl = this.transformProperties(gxtEl);
                gxtEl.first = this.changeOriginIds(board, gxtEl.first);
                gxtEl.last = this.changeOriginIds(board, gxtEl.last);

                l = board.create('arrow', [gxtEl.first, gxtEl.last], gxtEl);

                this.printDebugMessage('debug', l, Data.nodeName, 'OK');
                break;
            case "arc":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl = this.readNodes(gxtEl, Data, 'data');

                // It seems that JSXGraph and GEONExT use opposite directions.
                gxtEl.firstArrow = JXG.str2Bool(Data.getElementsByTagName('lastarrow')[0].firstChild.data);
                gxtEl.lastArrow = JXG.str2Bool(Data.getElementsByTagName('firstarrow')[0].firstChild.data);

                gxtEl = this.transformProperties(gxtEl);

                gxtEl.center = this.changeOriginIds(board, gxtEl.midpoint);
                gxtEl.angle = this.changeOriginIds(board, gxtEl.angle);
                gxtEl.radius = this.changeOriginIds(board, gxtEl.radius);

                c = board.create('arc', [gxtEl.center, gxtEl.radius, gxtEl.angle], gxtEl);

                this.printDebugMessage('debug', c, Data.nodeName, 'OK');
                break;
            case "angle":
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl = this.readNodes(gxtEl, Data, 'data');
                gxtEl = this.transformProperties(gxtEl);
                gxtEl.radius *= 1.0;

                c = board.create('angle', [gxtEl.first, gxtEl.middle, gxtEl.last], gxtEl);
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case "text":
                if (gxtEl.id.match(/oldVersion/)) {
                    break;
                }
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);

                gxtEl = this.readNodes(gxtEl, Data, 'data');
                try {
                    gxtEl.mpStr = this.subtreeToString(Data.getElementsByTagName('data')[0].getElementsByTagName('mp')[0]);
                    gxtEl.mpStr = gxtEl.mpStr.replace(/<\/?mp>/g, '');
                } catch (ex1) {
                    gxtEl.mpStr = this.subtreeToString(Data.getElementsByTagName('data')[0].getElementsByTagName('content')[0]);
                    gxtEl.mpStr = gxtEl.mpStr.replace(/<\/?content>/g, '');
                }
                gxtEl.fixed = false;
                try {
                    if (Data.getElementsByTagName('data')[0].getElementsByTagName('parent')[0].firstChild) {
                        gxtEl.parent = Data.getElementsByTagName('data')[0].getElementsByTagName('parent')[0].firstChild.data;
                        gxtEl.fixed = true;
                    }
                } catch (ex2) {}

                try {
                    gxtEl.condition = Data.getElementsByTagName('condition')[0].firstChild.data;
                } catch (ex3) {
                    gxtEl.condition = "";
                }
                gxtEl.content = Data.getElementsByTagName('content')[0].firstChild.data;
                try {
                    gxtEl.fixed = Data.getElementsByTagName('fix')[0].firstChild.data;
                } catch (ex4) {
                    gxtEl.fixed = false;
                }
                // not used: gxtEl.digits = Data.getElementsByTagName('cs')[0].firstChild.data;
                try {
                    gxtEl.autodigits = Data.getElementsByTagName('digits')[0].firstChild.data;
                } catch (ex5) {
                    gxtEl.autodigits = 2;
                }
                gxtEl.parent = this.changeOriginIds(board, gxtEl.parent);

                c = board.create('text', [parseFloat(gxtEl.x), parseFloat(gxtEl.y), gxtEl.mpStr], {
                    anchor: gxtEl.parent,
                    id: gxtEl.id,
                    name: gxtEl.name,
                    digits: gxtEl.autodigits,
                    isLabel: false,
                    strokeColor: gxtEl.colorLabel,
                    fixed: gxtEl.fixed,
                    visible: JXG.str2Bool(gxtEl.visible)
                });
                break;
            case 'parametercurve':
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.visualProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl = this.transformProperties(gxtEl);
                gxtEl.functionx = Data.getElementsByTagName('functionx')[0].firstChild.data;
                gxtEl.functiony = Data.getElementsByTagName('functiony')[0].firstChild.data;
                gxtEl.min = Data.getElementsByTagName('min')[0].firstChild.data;
                gxtEl.max = Data.getElementsByTagName('max')[0].firstChild.data;
                gxtEl.fillColor = 'none';
                gxtEl.highlightFillColor = 'none';

                // intentional
                /*jslint evil:true*/
                board.create('curve', [
                    board.jc.snippet(gxtEl.functionx, true, 't', true),
                    board.jc.snippet(gxtEl.functiony, true, 't', true),
                    board.jc.snippet(gxtEl.min, true, '', true),
                    board.jc.snippet(gxtEl.max, true, '', true)
                ], gxtEl);
                /*jslint evil:false*/
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case 'tracecurve':
                gxtEl.tracepoint = Data.getElementsByTagName('tracepoint')[0].firstChild.data;
                gxtEl.traceslider = Data.getElementsByTagName('traceslider')[0].firstChild.data;
                board.create('tracecurve', [gxtEl.traceslider, gxtEl.tracepoint], gxtEl);
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            case 'group':
                gxtEl = this.colorProperties(gxtEl, Data);
                gxtEl = this.firstLevelProperties(gxtEl, Data);
                gxtEl.members = [];

                for (i = 0; i < Data.getElementsByTagName('data')[0].getElementsByTagName('member').length; i++) {
                    gxtEl.members[i] = Data.getElementsByTagName('data')[0].getElementsByTagName('member')[i].firstChild.data;
                    gxtEl.members[i] = this.changeOriginIds(board, gxtEl.members[i]);
                }

                c = new JXG.Group(board, gxtEl.id, gxtEl.name, gxtEl.members);
                this.printDebugMessage('debug', gxtEl, Data.nodeName, 'OK');
                break;
            default:
                JXG.debug("* Err: " + Data.nodeName + " not yet implemented");
            }
        },

        /**
         * Reading the elements of a geonext file
         */
        read: function () {
            var xmlNode, elChildNodes, s, boardData, conditions, tmp,
                tree = this.tree,
                board = this.board,
                strTrue = 'true';

            // maybe this is not necessary as we already provide layer options for sectors and circles via JXG.Options but
            // maybe these have to be the same for geonext.
            board.options.layer.sector = board.options.layer.angle;
            board.options.layer.circle = board.options.layer.angle;

            board.options.line.label.position = 'top';

            boardData = this.gEBTN(tree, 'board', 0, false);
            conditions = this.readConditions(boardData.getElementsByTagName('conditions')[0]);

            // set the board background color
            s = this.gEBTN(boardData, 'background', 0, false);
            s = this.gEBTN(s, 'color', 0, true);
            tmp = JXG.rgba2rgbo(s);
            s = JXG.rgbParser(tmp[0]);
            board.containerObj.style.backgroundColor = 'rgba(' + s[0] + ', ' + s[1] + ', ' + s[2] + ', ' + tmp[1] + ')';

            // resize board
            if (board.attr.takeSizeFromFile) {
                board.resizeContainer(this.gEBTN(boardData, 'width'), this.gEBTN(boardData, 'height'));
            }

            xmlNode = this.gEBTN(boardData, 'coordinates', 0, false);

            tmp = this.readViewPort(xmlNode);
            
            if (tmp.length === 4) {
                board.setBoundingBox(tmp, true);
            } else {
                // zoom level
                tmp = this.gEBTN(xmlNode, 'zoom', 0, false);
                board.zoomX = parseFloat(this.gEBTN(tmp, 'x'));
                board.zoomY = parseFloat(this.gEBTN(tmp, 'y'));

                // set the origin
                tmp = this.gEBTN(xmlNode, 'origin', 0, false);
                board.origin = {
                    usrCoords: [1, 0, 0],
                    scrCoords: [1, parseFloat(this.gEBTN(tmp, 'x')) * board.zoomX, parseFloat(this.gEBTN(tmp, 'y')) * board.zoomY]
                };

                // screen to user coordinates conversion
                tmp = this.gEBTN(xmlNode, 'unit', 0, false);
                board.unitX = parseFloat(this.gEBTN(tmp, 'x')) * board.zoomX;
                board.unitY = parseFloat(this.gEBTN(tmp, 'y')) * board.zoomY;
            }

            if (board.attr.takeSizeFromFile) {
                board.resizeContainer(this.gEBTN(boardData, 'width'), this.gEBTN(boardData, 'height'));
            }

            // check and set fontSize
            if (parseFloat(board.options.text.fontSize) < 0) {
                board.options.text.fontSize = 12;
            }

            board.geonextCompatibilityMode = true;

            // jsxgraph chooses an id for the board but we don't want to use it, we want to use
            // the id stored in the geonext file. if you know why this is required, please note it here.
            delete JXG.boards[board.id];

            board.id = this.gEBTN(boardData, 'id');

            JXG.boards[board.id] = board;

            // this creates some basic elements present in every geonext construction but not explicitly present in the file
            board.initGeonextBoard();

            // Update of properties during update() is not necessary in GEONExT files
            // But it maybe necessary if we construct with JavaScript afterwards
            board.renderer.enhancedRendering = true;

            // Read background image
            this.parseImage(board, this.gEBTN(boardData, 'file', 0, false), board.options.layer.image);

            board.options.point.snapToGrid = (this.gEBTN(this.gEBTN(boardData, 'coordinates', 0, false), 'snap') === strTrue);

            // If snapToGrid and snapToPoint are both true, point snapping is enabled
            if (board.options.point.snapToGrid && this.gEBTN(this.gEBTN(boardData, 'grid', 1, false), 'pointsnap') === strTrue) {
                board.options.point.snapToGrid = false;
                board.options.point.snapToPoints = true;
                board.options.point.attractorDistance = 0.5;
            }

            xmlNode = this.gEBTN(boardData, 'grid', 1, false);
            tmp = this.gEBTN(xmlNode,  'x');
            if (tmp) {
                board.options.grid.gridX = 1 / parseFloat(tmp);
                board.options.point.snapSizeX = 1 / parseFloat(tmp);
            }
            tmp = this.gEBTN(xmlNode,  'y');
            if (tmp) {
                board.options.grid.gridY = 1 / parseFloat(tmp);
                board.options.point.snapSizeY = 1 / parseFloat(tmp);
            }

            board.options.grid.gridDash = JXG.str2Bool(this.gEBTN(xmlNode, 'dash'));

            tmp = JXG.rgba2rgbo(this.gEBTN(xmlNode, 'color'));
            board.options.grid.gridColor = tmp[0];
            board.options.grid.gridOpacity = tmp[1];

            xmlNode = this.gEBTN(boardData, 'coordinates', 0, false);
            if (this.gEBTN(xmlNode, 'grid') === strTrue) {
                board.create('grid', []);
            }

            if (this.gEBTN(xmlNode, 'coord') === strTrue) {
                // Hard coded default option
                board.options.axis.ticks.majorHeight = 10;

                // Hard coded default option
                board.options.axis.ticks.minorHeight = 4;
                board.create('axis', [[0, 0], [1, 0]]);
                board.create('axis', [[0, 0], [0, 1]]);
            }

            tmp = this.gEBTN(this.gEBTN(boardData, 'background', 0, false), 'color');
            if (tmp.length === 8) {
                tmp = '#' + tmp;
            }
            board.containerObj.style.backgroundColor = JXG.rgba2rgbo(tmp)[0];

            elChildNodes = tree.getElementsByTagName("elements")[0].childNodes;
            for (s = 0; s < elChildNodes.length; s++) {
                this.readNode(elChildNodes, s, board);
            }
            board.addConditions(conditions);
        },

        decodeString: function (str) {
            var unz;

            if (str.indexOf("<GEONEXT>") < 0) {
                unz = (new JXG.Util.Unzip(JXG.Util.Base64.decodeAsArray(str))).unzip();
                if (unz === "") {
                    return str;
                }

                return unz;
            }

            return str;
        },

        prepareString: function (fileStr) {
            try {
                if (fileStr.indexOf('GEONEXT') < 0) {
                    // Base64 decoding
                    fileStr = (this.decodeString(fileStr))[0][0];
                }
                // Hacks to enable not well formed XML. Will be redone in geonext2JS and Board.addConditions
                fileStr = this.fixXML(fileStr);
            } catch (exc2) {
                fileStr = '';
            }
            return fileStr;
        },

        fixXML: function (str) {
            var arr = ["active", "angle", "animate", "animated", "arc", "area", "arrow", "author", "autodigits", "axis",
                    "back", "background", "board", "border", "bottom", "buttonsize", "cas", "circle", "color",
                    "comment", "composition", "condition", "conditions", "content", "continuous", "control", "coord",
                    "coordinates", "cross", "cs", "dash", "data", "description", "digits", "direction", "draft",
                    "editable", "elements", "event", "file", "fill", "first", "firstarrow", "fix", "fontsize", "free",
                    "full", "function", "functionx", "functiony", "GEONEXT", "graph", "grid", "group", "height", "id",
                    "image", "info", "information", "input", "intersection", "item", "jsf", "label", "last",
                    "lastarrow", "left", "lefttoolbar", "lighting", "line", "loop", "max", "maximized", "member",
                    "middle", "midpoint", "min", "modifier", "modus", "mp", "mpx", "multi", "name", "onpolygon",
                    "order", "origin", "output", "overline", "parametercurve", "parent", "point", "pointsnap",
                    "polygon", "position", "radius", "radiusnum", "radiusvalue", "right", "section",
                    "selectedlefttoolbar", "showconstruction", "showcoord", "showinfo", "showunit", "showx", "showy",
                    "size", "slider", "snap", "speed", "src", "start", "stop", "straight", "stroke", "strokewidth",
                    "style", "term", "text", "top", "trace", "tracecurve", "tracepoint", "traceslider", "type", "unit",
                    "value", "VERSION", "vertex", "viewport", "visible", "width", "wot", "x", "xooy", "xval", "y",
                    "yval", "zoom"],

                list = arr.join('|'),
                regex = '&lt;(/?(' + list + '))&gt;',
                expr = new RegExp(regex, 'g');

            // First, we convert all < to &lt; and > to &gt;
            str = JXG.escapeHTML(str);
            // Second, we convert all GEONExT tags of the form &lt;tag&gt; back to <tag>
            str = str.replace(expr, '<$1>');

            // intentional
            /*jslint regexp:true*/
            str = str.replace(/(<content>.*)<arc>(.*<\/content>)/g, '$1&lt;arc&gt;$2');
            str = str.replace(/(<mp>.*)<arc>(.*<\/mpx>)/g, '$1&lt;arc&gt;$2');
            str = str.replace(/(<mpx>.*)<arc>(.*<\/mpx>)/g, '$1&lt;arc&gt;$2');
            /*jslint regexp:false*/

            return str;
        }
    });

    JXG.registerReader(JXG.GeonextReader, ['gxt', 'geonext']);
}());
