(function(global) {

  'use strict';

  /**
   * @name fabric
   * @namespace
   */

  var fabric = global.fabric || (global.fabric = { }),
      extend = fabric.util.object.extend,
      clone = fabric.util.object.clone,
      toFixed = fabric.util.toFixed,
      parseUnit = fabric.util.parseUnit,
      multiplyTransformMatrices = fabric.util.multiplyTransformMatrices,

      svgValidTagNames = ['path', 'circle', 'polygon', 'polyline', 'ellipse', 'rect', 'line',
        'image', 'text'],
      svgViewBoxElements = ['symbol', 'image', 'marker', 'pattern', 'view', 'svg'],
      svgInvalidAncestors = ['pattern', 'defs', 'symbol', 'metadata', 'clipPath', 'mask', 'desc'],
      svgValidParents = ['symbol', 'g', 'a', 'svg', 'clipPath', 'defs'],

      attributesMap = {
        cx:                   'left',
        x:                    'left',
        r:                    'radius',
        cy:                   'top',
        y:                    'top',
        display:              'visible',
        visibility:           'visible',
        transform:            'transformMatrix',
        'fill-opacity':       'fillOpacity',
        'fill-rule':          'fillRule',
        'font-family':        'fontFamily',
        'font-size':          'fontSize',
        'font-style':         'fontStyle',
        'font-weight':        'fontWeight',
        'letter-spacing':     'charSpacing',
        'paint-order':        'paintFirst',
        'stroke-dasharray':   'strokeDashArray',
        'stroke-dashoffset':  'strokeDashOffset',
        'stroke-linecap':     'strokeLineCap',
        'stroke-linejoin':    'strokeLineJoin',
        'stroke-miterlimit':  'strokeMiterLimit',
        'stroke-opacity':     'strokeOpacity',
        'stroke-width':       'strokeWidth',
        'text-decoration':    'textDecoration',
        'text-anchor':        'textAnchor',
        opacity:              'opacity',
        'clip-path':          'clipPath',
        'clip-rule':          'clipRule',
        'vector-effect':      'strokeUniform',
        'image-rendering':    'imageSmoothing',
      },

      colorAttributes = {
        stroke: 'strokeOpacity',
        fill:   'fillOpacity'
      },

      fSize = 'font-size', cPath = 'clip-path';

  fabric.svgValidTagNamesRegEx = getSvgRegex(svgValidTagNames);
  fabric.svgViewBoxElementsRegEx = getSvgRegex(svgViewBoxElements);
  fabric.svgInvalidAncestorsRegEx = getSvgRegex(svgInvalidAncestors);
  fabric.svgValidParentsRegEx = getSvgRegex(svgValidParents);

  fabric.cssRules = { };
  fabric.gradientDefs = { };
  fabric.clipPaths = { };

  function normalizeAttr(attr) {
    // transform attribute names
    if (attr in attributesMap) {
      return attributesMap[attr];
    }
    return attr;
  }

  function normalizeValue(attr, value, parentAttributes, fontSize) {
    var isArray = Object.prototype.toString.call(value) === '[object Array]',
        parsed;

    if ((attr === 'fill' || attr === 'stroke') && value === 'none') {
      value = '';
    }
    else if (attr === 'strokeUniform') {
      return (value === 'non-scaling-stroke');
    }
    else if (attr === 'strokeDashArray') {
      if (value === 'none') {
        value = null;
      }
      else {
        value = value.replace(/,/g, ' ').split(/\s+/).map(parseFloat);
      }
    }
    else if (attr === 'transformMatrix') {
      if (parentAttributes && parentAttributes.transformMatrix) {
        value = multiplyTransformMatrices(
          parentAttributes.transformMatrix, fabric.parseTransformAttribute(value));
      }
      else {
        value = fabric.parseTransformAttribute(value);
      }
    }
    else if (attr === 'visible') {
      value = value !== 'none' && value !== 'hidden';
      // display=none on parent element always takes precedence over child element
      if (parentAttributes && parentAttributes.visible === false) {
        value = false;
      }
    }
    else if (attr === 'opacity') {
      value = parseFloat(value);
      if (parentAttributes && typeof parentAttributes.opacity !== 'undefined') {
        value *= parentAttributes.opacity;
      }
    }
    else if (attr === 'textAnchor' /* text-anchor */) {
      value = value === 'start' ? 'left' : value === 'end' ? 'right' : 'center';
    }
    else if (attr === 'charSpacing') {
      // parseUnit returns px and we convert it to em
      parsed = parseUnit(value, fontSize) / fontSize * 1000;
    }
    else if (attr === 'paintFirst') {
      var fillIndex = value.indexOf('fill');
      var strokeIndex = value.indexOf('stroke');
      var value = 'fill';
      if (fillIndex > -1 && strokeIndex > -1 && strokeIndex < fillIndex) {
        value = 'stroke';
      }
      else if (fillIndex === -1 && strokeIndex > -1) {
        value = 'stroke';
      }
    }
    else if (attr === 'href' || attr === 'xlink:href' || attr === 'font') {
      return value;
    }
    else if (attr === 'imageSmoothing') {
      return (value === 'optimizeQuality' ? true : false);
    }
    else {
      parsed = isArray ? value.map(parseUnit) : parseUnit(value, fontSize);
    }

    return (!isArray && isNaN(parsed) ? value : parsed);
  }

  /**
    * @private
    */
  function getSvgRegex(arr) {
    return new RegExp('^(' + arr.join('|') + ')\\b', 'i');
  }

  /**
   * @private
   * @param {Object} attributes Array of attributes to parse
   */
  function _setStrokeFillOpacity(attributes) {
    for (var attr in colorAttributes) {

      if (typeof attributes[colorAttributes[attr]] === 'undefined' || attributes[attr] === '') {
        continue;
      }

      if (typeof attributes[attr] === 'undefined') {
        if (!fabric.Object.prototype[attr]) {
          continue;
        }
        attributes[attr] = fabric.Object.prototype[attr];
      }

      if (attributes[attr].indexOf('url(') === 0) {
        continue;
      }

      var color = new fabric.Color(attributes[attr]);
      attributes[attr] = color.setAlpha(toFixed(color.getAlpha() * attributes[colorAttributes[attr]], 2)).toRgba();
    }
    return attributes;
  }

  /**
   * @private
   */
  function _getMultipleNodes(doc, nodeNames) {
    var nodeName, nodeArray = [], nodeList, i, len;
    for (i = 0, len = nodeNames.length; i < len; i++) {
      nodeName = nodeNames[i];
      nodeList = doc.getElementsByTagName(nodeName);
      nodeArray = nodeArray.concat(Array.prototype.slice.call(nodeList));
    }
    return nodeArray;
  }

  /**
   * Parses "transform" attribute, returning an array of values
   * @static
   * @function
   * @memberOf fabric
   * @param {String} attributeValue String containing attribute value
   * @return {Array} Array of 6 elements representing transformation matrix
   */
  fabric.parseTransformAttribute = (function() {
    function rotateMatrix(matrix, args) {
      var cos = fabric.util.cos(args[0]), sin = fabric.util.sin(args[0]),
          x = 0, y = 0;
      if (args.length === 3) {
        x = args[1];
        y = args[2];
      }

      matrix[0] = cos;
      matrix[1] = sin;
      matrix[2] = -sin;
      matrix[3] = cos;
      matrix[4] = x - (cos * x - sin * y);
      matrix[5] = y - (sin * x + cos * y);
    }

    function scaleMatrix(matrix, args) {
      var multiplierX = args[0],
          multiplierY = (args.length === 2) ? args[1] : args[0];

      matrix[0] = multiplierX;
      matrix[3] = multiplierY;
    }

    function skewMatrix(matrix, args, pos) {
      matrix[pos] = Math.tan(fabric.util.degreesToRadians(args[0]));
    }

    function translateMatrix(matrix, args) {
      matrix[4] = args[0];
      if (args.length === 2) {
        matrix[5] = args[1];
      }
    }

    // identity matrix
    var iMatrix = fabric.iMatrix,

        // == begin transform regexp
        number = fabric.reNum,

        commaWsp = fabric.commaWsp,

        skewX = '(?:(skewX)\\s*\\(\\s*(' + number + ')\\s*\\))',

        skewY = '(?:(skewY)\\s*\\(\\s*(' + number + ')\\s*\\))',

        rotate = '(?:(rotate)\\s*\\(\\s*(' + number + ')(?:' +
                    commaWsp + '(' + number + ')' +
                    commaWsp + '(' + number + '))?\\s*\\))',

        scale = '(?:(scale)\\s*\\(\\s*(' + number + ')(?:' +
                    commaWsp + '(' + number + '))?\\s*\\))',

        translate = '(?:(translate)\\s*\\(\\s*(' + number + ')(?:' +
                    commaWsp + '(' + number + '))?\\s*\\))',

        matrix = '(?:(matrix)\\s*\\(\\s*' +
                  '(' + number + ')' + commaWsp +
                  '(' + number + ')' + commaWsp +
                  '(' + number + ')' + commaWsp +
                  '(' + number + ')' + commaWsp +
                  '(' + number + ')' + commaWsp +
                  '(' + number + ')' +
                  '\\s*\\))',

        transform = '(?:' +
                    matrix + '|' +
                    translate + '|' +
                    scale + '|' +
                    rotate + '|' +
                    skewX + '|' +
                    skewY +
                    ')',

        transforms = '(?:' + transform + '(?:' + commaWsp + '*' + transform + ')*' + ')',

        transformList = '^\\s*(?:' + transforms + '?)\\s*$',

        // http://www.w3.org/TR/SVG/coords.html#TransformAttribute
        reTransformList = new RegExp(transformList),
        // == end transform regexp

        reTransform = new RegExp(transform, 'g');

    return function(attributeValue) {

      // start with identity matrix
      var matrix = iMatrix.concat(),
          matrices = [];

      // return if no argument was given or
      // an argument does not match transform attribute regexp
      if (!attributeValue || (attributeValue && !reTransformList.test(attributeValue))) {
        return matrix;
      }

      attributeValue.replace(reTransform, function(match) {

        var m = new RegExp(transform).exec(match).filter(function (match) {
              // match !== '' && match != null
              return (!!match);
            }),
            operation = m[1],
            args = m.slice(2).map(parseFloat);

        switch (operation) {
          case 'translate':
            translateMatrix(matrix, args);
            break;
          case 'rotate':
            args[0] = fabric.util.degreesToRadians(args[0]);
            rotateMatrix(matrix, args);
            break;
          case 'scale':
            scaleMatrix(matrix, args);
            break;
          case 'skewX':
            skewMatrix(matrix, args, 2);
            break;
          case 'skewY':
            skewMatrix(matrix, args, 1);
            break;
          case 'matrix':
            matrix = args;
            break;
        }

        // snapshot current matrix into matrices array
        matrices.push(matrix.concat());
        // reset
        matrix = iMatrix.concat();
      });

      var combinedMatrix = matrices[0];
      while (matrices.length > 1) {
        matrices.shift();
        combinedMatrix = fabric.util.multiplyTransformMatrices(combinedMatrix, matrices[0]);
      }
      return combinedMatrix;
    };
  })();

  /**
   * @private
   */
  function parseStyleString(style, oStyle) {
    var attr, value;
    style.replace(/;\s*$/, '').split(';').forEach(function (chunk) {
      var pair = chunk.split(':');

      attr = pair[0].trim().toLowerCase();
      value =  pair[1].trim();

      oStyle[attr] = value;
    });
  }

  /**
   * @private
   */
  function parseStyleObject(style, oStyle) {
    var attr, value;
    for (var prop in style) {
      if (typeof style[prop] === 'undefined') {
        continue;
      }

      attr = prop.toLowerCase();
      value = style[prop];

      oStyle[attr] = value;
    }
  }

  /**
   * @private
   */
  function getGlobalStylesForElement(element, svgUid) {
    var styles = { };
    for (var rule in fabric.cssRules[svgUid]) {
      if (elementMatchesRule(element, rule.split(' '))) {
        for (var property in fabric.cssRules[svgUid][rule]) {
          styles[property] = fabric.cssRules[svgUid][rule][property];
        }
      }
    }
    return styles;
  }

  /**
   * @private
   */
  function elementMatchesRule(element, selectors) {
    var firstMatching, parentMatching = true;
    //start from rightmost selector.
    firstMatching = selectorMatches(element, selectors.pop());
    if (firstMatching && selectors.length) {
      parentMatching = doesSomeParentMatch(element, selectors);
    }
    return firstMatching && parentMatching && (selectors.length === 0);
  }

  function doesSomeParentMatch(element, selectors) {
    var selector, parentMatching = true;
    while (element.parentNode && element.parentNode.nodeType === 1 && selectors.length) {
      if (parentMatching) {
        selector = selectors.pop();
      }
      element = element.parentNode;
      parentMatching = selectorMatches(element, selector);
    }
    return selectors.length === 0;
  }

  /**
   * @private
   */
  function selectorMatches(element, selector) {
    var nodeName = element.nodeName,
        classNames = element.getAttribute('class'),
        id = element.getAttribute('id'), matcher, i;
    // i check if a selector matches slicing away part from it.
    // if i get empty string i should match
    matcher = new RegExp('^' + nodeName, 'i');
    selector = selector.replace(matcher, '');
    if (id && selector.length) {
      matcher = new RegExp('#' + id + '(?![a-zA-Z\\-]+)', 'i');
      selector = selector.replace(matcher, '');
    }
    if (classNames && selector.length) {
      classNames = classNames.split(' ');
      for (i = classNames.length; i--;) {
        matcher = new RegExp('\\.' + classNames[i] + '(?![a-zA-Z\\-]+)', 'i');
        selector = selector.replace(matcher, '');
      }
    }
    return selector.length === 0;
  }

  /**
   * @private
   * to support IE8 missing getElementById on SVGdocument and on node xmlDOM
   */
  function elementById(doc, id) {
    var el;
    doc.getElementById && (el = doc.getElementById(id));
    if (el) {
      return el;
    }
    var node, i, len, nodelist = doc.getElementsByTagName('*');
    for (i = 0, len = nodelist.length; i < len; i++) {
      node = nodelist[i];
      if (id === node.getAttribute('id')) {
        return node;
      }
    }
  }

  /**
   * @private
   */
  function parseUseDirectives(doc) {
    var nodelist = _getMultipleNodes(doc, ['use', 'svg:use']), i = 0;
    while (nodelist.length && i < nodelist.length) {
      var el = nodelist[i],
          xlink = (el.getAttribute('xlink:href') || el.getAttribute('href')).substr(1),
          x = el.getAttribute('x') || 0,
          y = el.getAttribute('y') || 0,
          el2 = elementById(doc, xlink).cloneNode(true),
          currentTrans = (el2.getAttribute('transform') || '') + ' translate(' + x + ', ' + y + ')',
          parentNode, oldLength = nodelist.length, attr, j, attrs, len, namespace = fabric.svgNS;

      applyViewboxTransform(el2);
      if (/^svg$/i.test(el2.nodeName)) {
        var el3 = el2.ownerDocument.createElementNS(namespace, 'g');
        for (j = 0, attrs = el2.attributes, len = attrs.length; j < len; j++) {
          attr = attrs.item(j);
          el3.setAttributeNS(namespace, attr.nodeName, attr.nodeValue);
        }
        // el2.firstChild != null
        while (el2.firstChild) {
          el3.appendChild(el2.firstChild);
        }
        el2 = el3;
      }

      for (j = 0, attrs = el.attributes, len = attrs.length; j < len; j++) {
        attr = attrs.item(j);
        if (attr.nodeName === 'x' || attr.nodeName === 'y' ||
          attr.nodeName === 'xlink:href' || attr.nodeName === 'href') {
          continue;
        }

        if (attr.nodeName === 'transform') {
          currentTrans = attr.nodeValue + ' ' + currentTrans;
        }
        else {
          el2.setAttribute(attr.nodeName, attr.nodeValue);
        }
      }

      el2.setAttribute('transform', currentTrans);
      el2.setAttribute('instantiated_by_use', '1');
      el2.removeAttribute('id');
      parentNode = el.parentNode;
      parentNode.replaceChild(el2, el);
      // some browsers do not shorten nodelist after replaceChild (IE8)
      if (nodelist.length === oldLength) {
        i++;
      }
    }
  }

  // http://www.w3.org/TR/SVG/coords.html#ViewBoxAttribute
  // matches, e.g.: +14.56e-12, etc.
  var reViewBoxAttrValue = new RegExp(
    '^' +
    '\\s*(' + fabric.reNum + '+)\\s*,?' +
    '\\s*(' + fabric.reNum + '+)\\s*,?' +
    '\\s*(' + fabric.reNum + '+)\\s*,?' +
    '\\s*(' + fabric.reNum + '+)\\s*' +
    '$'
  );

  /**
   * Add a <g> element that envelop all child elements and makes the viewbox transformMatrix descend on all elements
   */
  function applyViewboxTransform(element) {
    if (!fabric.svgViewBoxElementsRegEx.test(element.nodeName)) {
      return;
    }
    var viewBoxAttr = element.getAttribute('viewBox'),
        scaleX = 1,
        scaleY = 1,
        minX = 0,
        minY = 0,
        viewBoxWidth, viewBoxHeight, matrix, el,
        widthAttr = element.getAttribute('width'),
        heightAttr = element.getAttribute('height'),
        x = element.getAttribute('x') || 0,
        y = element.getAttribute('y') || 0,
        preserveAspectRatio = element.getAttribute('preserveAspectRatio') || '',
        missingViewBox = (!viewBoxAttr || !(viewBoxAttr = viewBoxAttr.match(reViewBoxAttrValue))),
        missingDimAttr = (!widthAttr || !heightAttr || widthAttr === '100%' || heightAttr === '100%'),
        toBeParsed = missingViewBox && missingDimAttr,
        parsedDim = { }, translateMatrix = '', widthDiff = 0, heightDiff = 0;

    parsedDim.width = 0;
    parsedDim.height = 0;
    parsedDim.toBeParsed = toBeParsed;

    if (missingViewBox) {
      if (((x || y) && element.parentNode.nodeName !== '#document')) {
        translateMatrix = ' translate(' + parseUnit(x) + ' ' + parseUnit(y) + ') ';
        matrix = (element.getAttribute('transform') || '') + translateMatrix;
        element.setAttribute('transform', matrix);
        element.removeAttribute('x');
        element.removeAttribute('y');
      }
    }

    if (toBeParsed) {
      return parsedDim;
    }

    if (missingViewBox) {
      parsedDim.width = parseUnit(widthAttr);
      parsedDim.height = parseUnit(heightAttr);
      // set a transform for elements that have x y and are inner(only) SVGs
      return parsedDim;
    }
    minX = -parseFloat(viewBoxAttr[1]);
    minY = -parseFloat(viewBoxAttr[2]);
    viewBoxWidth = parseFloat(viewBoxAttr[3]);
    viewBoxHeight = parseFloat(viewBoxAttr[4]);
    parsedDim.minX = minX;
    parsedDim.minY = minY;
    parsedDim.viewBoxWidth = viewBoxWidth;
    parsedDim.viewBoxHeight = viewBoxHeight;
    if (!missingDimAttr) {
      parsedDim.width = parseUnit(widthAttr);
      parsedDim.height = parseUnit(heightAttr);
      scaleX = parsedDim.width / viewBoxWidth;
      scaleY = parsedDim.height / viewBoxHeight;
    }
    else {
      parsedDim.width = viewBoxWidth;
      parsedDim.height = viewBoxHeight;
    }

    // default is to preserve aspect ratio
    preserveAspectRatio = fabric.util.parsePreserveAspectRatioAttribute(preserveAspectRatio);
    if (preserveAspectRatio.alignX !== 'none') {
      //translate all container for the effect of Mid, Min, Max
      if (preserveAspectRatio.meetOrSlice === 'meet') {
        scaleY = scaleX = (scaleX > scaleY ? scaleY : scaleX);
        // calculate additional translation to move the viewbox
      }
      if (preserveAspectRatio.meetOrSlice === 'slice') {
        scaleY = scaleX = (scaleX > scaleY ? scaleX : scaleY);
        // calculate additional translation to move the viewbox
      }
      widthDiff = parsedDim.width - viewBoxWidth * scaleX;
      heightDiff = parsedDim.height - viewBoxHeight * scaleX;
      if (preserveAspectRatio.alignX === 'Mid') {
        widthDiff /= 2;
      }
      if (preserveAspectRatio.alignY === 'Mid') {
        heightDiff /= 2;
      }
      if (preserveAspectRatio.alignX === 'Min') {
        widthDiff = 0;
      }
      if (preserveAspectRatio.alignY === 'Min') {
        heightDiff = 0;
      }
    }

    if (scaleX === 1 && scaleY === 1 && minX === 0 && minY === 0 && x === 0 && y === 0) {
      return parsedDim;
    }
    if ((x || y) && element.parentNode.nodeName !== '#document') {
      translateMatrix = ' translate(' + parseUnit(x) + ' ' + parseUnit(y) + ') ';
    }

    matrix = translateMatrix + ' matrix(' + scaleX +
                  ' 0' +
                  ' 0 ' +
                  scaleY + ' ' +
                  (minX * scaleX + widthDiff) + ' ' +
                  (minY * scaleY + heightDiff) + ') ';
    // seems unused.
    // parsedDim.viewboxTransform = fabric.parseTransformAttribute(matrix);
    if (element.nodeName === 'svg') {
      el = element.ownerDocument.createElementNS(fabric.svgNS, 'g');
      // element.firstChild != null
      while (element.firstChild) {
        el.appendChild(element.firstChild);
      }
      element.appendChild(el);
    }
    else {
      el = element;
      el.removeAttribute('x');
      el.removeAttribute('y');
      matrix = el.getAttribute('transform') + matrix;
    }
    el.setAttribute('transform', matrix);
    return parsedDim;
  }

  function hasAncestorWithNodeName(element, nodeName) {
    while (element && (element = element.parentNode)) {
      if (element.nodeName && nodeName.test(element.nodeName.replace('svg:', ''))
        && !element.getAttribute('instantiated_by_use')) {
        return true;
      }
    }
    return false;
  }

  /**
   * Parses an SVG document, converts it to an array of corresponding fabric.* instances and passes them to a callback
   * @static
   * @function
   * @memberOf fabric
   * @param {SVGDocument} doc SVG document to parse
   * @param {Function} callback Callback to call when parsing is finished;
   * It's being passed an array of elements (parsed from a document).
   * @param {Function} [reviver] Method for further parsing of SVG elements, called after each fabric object created.
   * @param {Object} [parsingOptions] options for parsing document
   * @param {String} [parsingOptions.crossOrigin] crossOrigin settings
   */
  fabric.parseSVGDocument = function(doc, callback, reviver, parsingOptions) {
    if (!doc) {
      return;
    }

    parseUseDirectives(doc);

    var svgUid =  fabric.Object.__uid++, i, len,
        options = applyViewboxTransform(doc),
        descendants = fabric.util.toArray(doc.getElementsByTagName('*'));
    options.crossOrigin = parsingOptions && parsingOptions.crossOrigin;
    options.svgUid = svgUid;

    if (descendants.length === 0 && fabric.isLikelyNode) {
      // we're likely in node, where "o3-xml" library fails to gEBTN("*")
      // https://github.com/ajaxorg/node-o3-xml/issues/21
      descendants = doc.selectNodes('//*[name(.)!="svg"]');
      var arr = [];
      for (i = 0, len = descendants.length; i < len; i++) {
        arr[i] = descendants[i];
      }
      descendants = arr;
    }

    var elements = descendants.filter(function(el) {
      applyViewboxTransform(el);
      return fabric.svgValidTagNamesRegEx.test(el.nodeName.replace('svg:', '')) &&
            !hasAncestorWithNodeName(el, fabric.svgInvalidAncestorsRegEx); // http://www.w3.org/TR/SVG/struct.html#DefsElement
    });
    if (!elements || (elements && !elements.length)) {
      callback && callback([], {});
      return;
    }
    var clipPaths = { };
    descendants.filter(function(el) {
      return el.nodeName.replace('svg:', '') === 'clipPath';
    }).forEach(function(el) {
      var id = el.getAttribute('id');
      clipPaths[id] = fabric.util.toArray(el.getElementsByTagName('*')).filter(function(el) {
        return fabric.svgValidTagNamesRegEx.test(el.nodeName.replace('svg:', ''));
      });
    });
    fabric.gradientDefs[svgUid] = fabric.getGradientDefs(doc);
    fabric.cssRules[svgUid] = fabric.getCSSRules(doc);
    fabric.clipPaths[svgUid] = clipPaths;
    // Precedence of rules:   style > class > attribute
    fabric.parseElements(elements, function(instances, elements) {
      if (callback) {
        callback(instances, options, elements, descendants);
        delete fabric.gradientDefs[svgUid];
        delete fabric.cssRules[svgUid];
        delete fabric.clipPaths[svgUid];
      }
    }, clone(options), reviver, parsingOptions);
  };

  function recursivelyParseGradientsXlink(doc, gradient) {
    var gradientsAttrs = ['gradientTransform', 'x1', 'x2', 'y1', 'y2', 'gradientUnits', 'cx', 'cy', 'r', 'fx', 'fy'],
        xlinkAttr = 'xlink:href',
        xLink = gradient.getAttribute(xlinkAttr).substr(1),
        referencedGradient = elementById(doc, xLink);
    if (referencedGradient && referencedGradient.getAttribute(xlinkAttr)) {
      recursivelyParseGradientsXlink(doc, referencedGradient);
    }
    gradientsAttrs.forEach(function(attr) {
      if (referencedGradient && !gradient.hasAttribute(attr) && referencedGradient.hasAttribute(attr)) {
        gradient.setAttribute(attr, referencedGradient.getAttribute(attr));
      }
    });
    if (!gradient.children.length) {
      var referenceClone = referencedGradient.cloneNode(true);
      while (referenceClone.firstChild) {
        gradient.appendChild(referenceClone.firstChild);
      }
    }
    gradient.removeAttribute(xlinkAttr);
  }

  var reFontDeclaration = new RegExp(
    '(normal|italic)?\\s*(normal|small-caps)?\\s*' +
    '(normal|bold|bolder|lighter|100|200|300|400|500|600|700|800|900)?\\s*(' +
      fabric.reNum +
    '(?:px|cm|mm|em|pt|pc|in)*)(?:\\/(normal|' + fabric.reNum + '))?\\s+(.*)');

  extend(fabric, {
    /**
     * Parses a short font declaration, building adding its properties to a style object
     * @static
     * @function
     * @memberOf fabric
     * @param {String} value font declaration
     * @param {Object} oStyle definition
     */
    parseFontDeclaration: function(value, oStyle) {
      var match = value.match(reFontDeclaration);

      if (!match) {
        return;
      }
      var fontStyle = match[1],
          // font variant is not used
          // fontVariant = match[2],
          fontWeight = match[3],
          fontSize = match[4],
          lineHeight = match[5],
          fontFamily = match[6];

      if (fontStyle) {
        oStyle.fontStyle = fontStyle;
      }
      if (fontWeight) {
        oStyle.fontWeight = isNaN(parseFloat(fontWeight)) ? fontWeight : parseFloat(fontWeight);
      }
      if (fontSize) {
        oStyle.fontSize = parseUnit(fontSize);
      }
      if (fontFamily) {
        oStyle.fontFamily = fontFamily;
      }
      if (lineHeight) {
        oStyle.lineHeight = lineHeight === 'normal' ? 1 : lineHeight;
      }
    },

    /**
     * Parses an SVG document, returning all of the gradient declarations found in it
     * @static
     * @function
     * @memberOf fabric
     * @param {SVGDocument} doc SVG document to parse
     * @return {Object} Gradient definitions; key corresponds to element id, value -- to gradient definition element
     */
    getGradientDefs: function(doc) {
      var tagArray = [
            'linearGradient',
            'radialGradient',
            'svg:linearGradient',
            'svg:radialGradient'],
          elList = _getMultipleNodes(doc, tagArray),
          el, j = 0, gradientDefs = { };
      j = elList.length;
      while (j--) {
        el = elList[j];
        if (el.getAttribute('xlink:href')) {
          recursivelyParseGradientsXlink(doc, el);
        }
        gradientDefs[el.getAttribute('id')] = el;
      }
      return gradientDefs;
    },

    /**
     * Returns an object of attributes' name/value, given element and an array of attribute names;
     * Parses parent "g" nodes recursively upwards.
     * @static
     * @memberOf fabric
     * @param {DOMElement} element Element to parse
     * @param {Array} attributes Array of attributes to parse
     * @return {Object} object containing parsed attributes' names/values
     */
    parseAttributes: function(element, attributes, svgUid) {

      if (!element) {
        return;
      }

      var value,
          parentAttributes = { },
          fontSize, parentFontSize;

      if (typeof svgUid === 'undefined') {
        svgUid = element.getAttribute('svgUid');
      }
      // if there's a parent container (`g` or `a` or `symbol` node), parse its attributes recursively upwards
      if (element.parentNode && fabric.svgValidParentsRegEx.test(element.parentNode.nodeName)) {
        parentAttributes = fabric.parseAttributes(element.parentNode, attributes, svgUid);
      }

      var ownAttributes = attributes.reduce(function(memo, attr) {
        value = element.getAttribute(attr);
        if (value) { // eslint-disable-line
          memo[attr] = value;
        }
        return memo;
      }, { });
      // add values parsed from style, which take precedence over attributes
      // (see: http://www.w3.org/TR/SVG/styling.html#UsingPresentationAttributes)
      var cssAttrs = extend(
        getGlobalStylesForElement(element, svgUid),
        fabric.parseStyleAttribute(element)
      );
      ownAttributes = extend(
        ownAttributes,
        cssAttrs
      );
      if (cssAttrs[cPath]) {
        element.setAttribute(cPath, cssAttrs[cPath]);
      }
      fontSize = parentFontSize = parentAttributes.fontSize || fabric.Text.DEFAULT_SVG_FONT_SIZE;
      if (ownAttributes[fSize]) {
        // looks like the minimum should be 9px when dealing with ems. this is what looks like in browsers.
        ownAttributes[fSize] = fontSize = parseUnit(ownAttributes[fSize], parentFontSize);
      }

      var normalizedAttr, normalizedValue, normalizedStyle = {};
      for (var attr in ownAttributes) {
        normalizedAttr = normalizeAttr(attr);
        normalizedValue = normalizeValue(normalizedAttr, ownAttributes[attr], parentAttributes, fontSize);
        normalizedStyle[normalizedAttr] = normalizedValue;
      }
      if (normalizedStyle && normalizedStyle.font) {
        fabric.parseFontDeclaration(normalizedStyle.font, normalizedStyle);
      }
      var mergedAttrs = extend(parentAttributes, normalizedStyle);
      return fabric.svgValidParentsRegEx.test(element.nodeName) ? mergedAttrs : _setStrokeFillOpacity(mergedAttrs);
    },

    /**
     * Transforms an array of svg elements to corresponding fabric.* instances
     * @static
     * @memberOf fabric
     * @param {Array} elements Array of elements to parse
     * @param {Function} callback Being passed an array of fabric instances (transformed from SVG elements)
     * @param {Object} [options] Options object
     * @param {Function} [reviver] Method for further parsing of SVG elements, called after each fabric object created.
     */
    parseElements: function(elements, callback, options, reviver, parsingOptions) {
      new fabric.ElementsParser(elements, callback, options, reviver, parsingOptions).parse();
    },

    /**
     * Parses "style" attribute, retuning an object with values
     * @static
     * @memberOf fabric
     * @param {SVGElement} element Element to parse
     * @return {Object} Objects with values parsed from style attribute of an element
     */
    parseStyleAttribute: function(element) {
      var oStyle = { },
          style = element.getAttribute('style');

      if (!style) {
        return oStyle;
      }

      if (typeof style === 'string') {
        parseStyleString(style, oStyle);
      }
      else {
        parseStyleObject(style, oStyle);
      }

      return oStyle;
    },

    /**
     * Parses "points" attribute, returning an array of values
     * @static
     * @memberOf fabric
     * @param {String} points points attribute string
     * @return {Array} array of points
     */
    parsePointsAttribute: function(points) {

      // points attribute is required and must not be empty
      if (!points) {
        return null;
      }

      // replace commas with whitespace and remove bookending whitespace
      points = points.replace(/,/g, ' ').trim();

      points = points.split(/\s+/);
      var parsedPoints = [], i, len;

      for (i = 0, len = points.length; i < len; i += 2) {
        parsedPoints.push({
          x: parseFloat(points[i]),
          y: parseFloat(points[i + 1])
        });
      }

      // odd number of points is an error
      // if (parsedPoints.length % 2 !== 0) {
      //   return null;
      // }

      return parsedPoints;
    },

    /**
     * Returns CSS rules for a given SVG document
     * @static
     * @function
     * @memberOf fabric
     * @param {SVGDocument} doc SVG document to parse
     * @return {Object} CSS rules of this document
     */
    getCSSRules: function(doc) {
      var styles = doc.getElementsByTagName('style'), i, len,
          allRules = { }, rules;

      // very crude parsing of style contents
      for (i = 0, len = styles.length; i < len; i++) {
        // <style/> could produce `undefined`, covering this case with ''
        var styleContents = styles[i].textContent || '';

        // remove comments
        styleContents = styleContents.replace(/\/\*[\s\S]*?\*\//g, '');
        if (styleContents.trim() === '') {
          continue;
        }
        rules = styleContents.match(/[^{]*\{[\s\S]*?\}/g);
        rules = rules.map(function(rule) { return rule.trim(); });
        // eslint-disable-next-line no-loop-func
        rules.forEach(function(rule) {

          var match = rule.match(/([\s\S]*?)\s*\{([^}]*)\}/),
              ruleObj = { }, declaration = match[2].trim(),
              propertyValuePairs = declaration.replace(/;$/, '').split(/\s*;\s*/);

          for (i = 0, len = propertyValuePairs.length; i < len; i++) {
            var pair = propertyValuePairs[i].split(/\s*:\s*/),
                property = pair[0],
                value = pair[1];
            ruleObj[property] = value;
          }
          rule = match[1];
          rule.split(',').forEach(function(_rule) {
            _rule = _rule.replace(/^svg/i, '').trim();
            if (_rule === '') {
              return;
            }
            if (allRules[_rule]) {
              fabric.util.object.extend(allRules[_rule], ruleObj);
            }
            else {
              allRules[_rule] = fabric.util.object.clone(ruleObj);
            }
          });
        });
      }
      return allRules;
    },

    /**
     * Takes url corresponding to an SVG document, and parses it into a set of fabric objects.
     * Note that SVG is fetched via XMLHttpRequest, so it needs to conform to SOP (Same Origin Policy)
     * @memberOf fabric
     * @param {String} url
     * @param {Function} callback
     * @param {Function} [reviver] Method for further parsing of SVG elements, called after each fabric object created.
     * @param {Object} [options] Object containing options for parsing
     * @param {String} [options.crossOrigin] crossOrigin crossOrigin setting to use for external resources
     */
    loadSVGFromURL: function(url, callback, reviver, options) {

      url = url.replace(/^\n\s*/, '').trim();
      new fabric.util.request(url, {
        method: 'get',
        onComplete: onComplete
      });

      function onComplete(r) {

        var xml = r.responseXML;
        if (!xml || !xml.documentElement) {
          callback && callback(null);
          return false;
        }

        fabric.parseSVGDocument(xml.documentElement, function (results, _options, elements, allElements) {
          callback && callback(results, _options, elements, allElements);
        }, reviver, options);
      }
    },

    /**
     * Takes string corresponding to an SVG document, and parses it into a set of fabric objects
     * @memberOf fabric
     * @param {String} string
     * @param {Function} callback
     * @param {Function} [reviver] Method for further parsing of SVG elements, called after each fabric object created.
     * @param {Object} [options] Object containing options for parsing
     * @param {String} [options.crossOrigin] crossOrigin crossOrigin setting to use for external resources
     */
    loadSVGFromString: function(string, callback, reviver, options) {
      var parser = new fabric.window.DOMParser(),
          doc = parser.parseFromString(string.trim(), 'text/xml');
      fabric.parseSVGDocument(doc.documentElement, function (results, _options, elements, allElements) {
        callback(results, _options, elements, allElements);
      }, reviver, options);
    }
  });

})(typeof exports !== 'undefined' ? exports : this);