svgcanvas/context.js

/*!!
 *  SVGCanvas v2.0.3
 *  Draw on SVG using Canvas's 2D Context API.
 *
 *  Licensed under the MIT license:
 *  http://www.opensource.org/licenses/mit-license.php
 *
 *  Author:
 *  Kerry Liu
 *  Zeno Zeng
 *
 *  Copyright (c) 2014 Gliffy Inc.
 *  Copyright (c) 2021 Zeno Zeng
 */

import * as utils from "./utils";
import { format } from "./utils";
import imageUtils from "./image";
import Path2D from "./path2d";

export default (function () {
  "use strict";

  var STYLES, Context, CanvasGradient, CanvasPattern, namedEntities;

  //helper function that generates a random string
  function randomString(holder) {
    var chars, randomstring, i;
    if (!holder) {
      throw new Error(
        "cannot create a random attribute name for an undefined object"
      );
    }
    chars = "ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
    randomstring = "";
    do {
      randomstring = "";
      for (i = 0; i < 12; i++) {
        randomstring += chars[Math.floor(Math.random() * chars.length)];
      }
    } while (holder[randomstring]);
    return randomstring;
  }

  //helper function to map named to numbered entities
  function createNamedToNumberedLookup(items, radix) {
    var i,
      entity,
      lookup = {},
      base10,
      base16;
    items = items.split(",");
    radix = radix || 10;
    // Map from named to numbered entities.
    for (i = 0; i < items.length; i += 2) {
      entity = "&" + items[i + 1] + ";";
      base10 = parseInt(items[i], radix);
      lookup[entity] = "&#" + base10 + ";";
    }
    //FF and IE need to create a regex from hex values ie &nbsp; == \xa0
    lookup["\\xa0"] = "&#160;";
    return lookup;
  }

  //helper function to map canvas-textAlign to svg-textAnchor
  function getTextAnchor(textAlign) {
    //TODO: support rtl languages
    var mapping = {
      left: "start",
      right: "end",
      center: "middle",
      start: "start",
      end: "end",
    };
    return mapping[textAlign] || mapping.start;
  }

  //helper function to map canvas-textBaseline to svg-dominantBaseline
  function getDominantBaseline(textBaseline) {
    //INFO: not supported in all browsers
    var mapping = {
      alphabetic: "alphabetic",
      hanging: "hanging",
      top: "text-before-edge",
      bottom: "text-after-edge",
      middle: "central",
    };
    return mapping[textBaseline] || mapping.alphabetic;
  }

  // Unpack entities lookup where the numbers are in radix 32 to reduce the size
  // entity mapping courtesy of tinymce
  namedEntities = createNamedToNumberedLookup(
    "50,nbsp,51,iexcl,52,cent,53,pound,54,curren,55,yen,56,brvbar,57,sect,58,uml,59,copy," +
    "5a,ordf,5b,laquo,5c,not,5d,shy,5e,reg,5f,macr,5g,deg,5h,plusmn,5i,sup2,5j,sup3,5k,acute," +
    "5l,micro,5m,para,5n,middot,5o,cedil,5p,sup1,5q,ordm,5r,raquo,5s,frac14,5t,frac12,5u,frac34," +
    "5v,iquest,60,Agrave,61,Aacute,62,Acirc,63,Atilde,64,Auml,65,Aring,66,AElig,67,Ccedil," +
    "68,Egrave,69,Eacute,6a,Ecirc,6b,Euml,6c,Igrave,6d,Iacute,6e,Icirc,6f,Iuml,6g,ETH,6h,Ntilde," +
    "6i,Ograve,6j,Oacute,6k,Ocirc,6l,Otilde,6m,Ouml,6n,times,6o,Oslash,6p,Ugrave,6q,Uacute," +
    "6r,Ucirc,6s,Uuml,6t,Yacute,6u,THORN,6v,szlig,70,agrave,71,aacute,72,acirc,73,atilde,74,auml," +
    "75,aring,76,aelig,77,ccedil,78,egrave,79,eacute,7a,ecirc,7b,euml,7c,igrave,7d,iacute,7e,icirc," +
    "7f,iuml,7g,eth,7h,ntilde,7i,ograve,7j,oacute,7k,ocirc,7l,otilde,7m,ouml,7n,divide,7o,oslash," +
    "7p,ugrave,7q,uacute,7r,ucirc,7s,uuml,7t,yacute,7u,thorn,7v,yuml,ci,fnof,sh,Alpha,si,Beta," +
    "sj,Gamma,sk,Delta,sl,Epsilon,sm,Zeta,sn,Eta,so,Theta,sp,Iota,sq,Kappa,sr,Lambda,ss,Mu," +
    "st,Nu,su,Xi,sv,Omicron,t0,Pi,t1,Rho,t3,Sigma,t4,Tau,t5,Upsilon,t6,Phi,t7,Chi,t8,Psi," +
    "t9,Omega,th,alpha,ti,beta,tj,gamma,tk,delta,tl,epsilon,tm,zeta,tn,eta,to,theta,tp,iota," +
    "tq,kappa,tr,lambda,ts,mu,tt,nu,tu,xi,tv,omicron,u0,pi,u1,rho,u2,sigmaf,u3,sigma,u4,tau," +
    "u5,upsilon,u6,phi,u7,chi,u8,psi,u9,omega,uh,thetasym,ui,upsih,um,piv,812,bull,816,hellip," +
    "81i,prime,81j,Prime,81u,oline,824,frasl,88o,weierp,88h,image,88s,real,892,trade,89l,alefsym," +
    "8cg,larr,8ch,uarr,8ci,rarr,8cj,darr,8ck,harr,8dl,crarr,8eg,lArr,8eh,uArr,8ei,rArr,8ej,dArr," +
    "8ek,hArr,8g0,forall,8g2,part,8g3,exist,8g5,empty,8g7,nabla,8g8,isin,8g9,notin,8gb,ni,8gf,prod," +
    "8gh,sum,8gi,minus,8gn,lowast,8gq,radic,8gt,prop,8gu,infin,8h0,ang,8h7,and,8h8,or,8h9,cap,8ha,cup," +
    "8hb,int,8hk,there4,8hs,sim,8i5,cong,8i8,asymp,8j0,ne,8j1,equiv,8j4,le,8j5,ge,8k2,sub,8k3,sup,8k4," +
    "nsub,8k6,sube,8k7,supe,8kl,oplus,8kn,otimes,8l5,perp,8m5,sdot,8o8,lceil,8o9,rceil,8oa,lfloor,8ob," +
    "rfloor,8p9,lang,8pa,rang,9ea,loz,9j0,spades,9j3,clubs,9j5,hearts,9j6,diams,ai,OElig,aj,oelig,b0," +
    "Scaron,b1,scaron,bo,Yuml,m6,circ,ms,tilde,802,ensp,803,emsp,809,thinsp,80c,zwnj,80d,zwj,80e,lrm," +
    "80f,rlm,80j,ndash,80k,mdash,80o,lsquo,80p,rsquo,80q,sbquo,80s,ldquo,80t,rdquo,80u,bdquo,810,dagger," +
    "811,Dagger,81g,permil,81p,lsaquo,81q,rsaquo,85c,euro",
    32
  );

  //Some basic mappings for attributes and default values.
  STYLES = {
    strokeStyle: {
      svgAttr: "stroke", //corresponding svg attribute
      canvas: "#000000", //canvas default
      svg: "none", //svg default
      apply: "stroke", //apply on stroke() or fill()
    },
    fillStyle: {
      svgAttr: "fill",
      canvas: "#000000",
      svg: null, //svg default is black, but we need to special case this to handle canvas stroke without fill
      apply: "fill",
    },
    lineCap: {
      svgAttr: "stroke-linecap",
      canvas: "butt",
      svg: "butt",
      apply: "stroke",
    },
    lineJoin: {
      svgAttr: "stroke-linejoin",
      canvas: "miter",
      svg: "miter",
      apply: "stroke",
    },
    miterLimit: {
      svgAttr: "stroke-miterlimit",
      canvas: 10,
      svg: 4,
      apply: "stroke",
    },
    lineWidth: {
      svgAttr: "stroke-width",
      canvas: 1,
      svg: 1,
      apply: "stroke",
    },
    globalAlpha: {
      svgAttr: "opacity",
      canvas: 1,
      svg: 1,
      apply: "fill stroke",
    },
    font: {
      //font converts to multiple svg attributes, there is custom logic for this
      canvas: "10px sans-serif",
    },
    shadowColor: {
      canvas: "#000000",
    },
    shadowOffsetX: {
      canvas: 0,
    },
    shadowOffsetY: {
      canvas: 0,
    },
    shadowBlur: {
      canvas: 0,
    },
    textAlign: {
      canvas: "start",
    },
    textBaseline: {
      canvas: "alphabetic",
    },
    lineDash: {
      svgAttr: "stroke-dasharray",
      canvas: [],
      svg: null,
      apply: "stroke",
    },
  };

  /**
   *
   * @param gradientNode - reference to the gradient
   * @constructor
   */
  CanvasGradient = function (gradientNode, ctx) {
    this.__root = gradientNode;
    this.__ctx = ctx;
  };

  /**
   * Adds a color stop to the gradient root
   */
  CanvasGradient.prototype.addColorStop = function (offset, color) {
    var stop = this.__ctx.__createElement("stop"),
      regex,
      matches;
    stop.setAttribute("offset", offset);
    if (utils.toString(color).indexOf("rgba") !== -1) {
      //separate alpha value, since webkit can't handle it
      regex =
        /rgba\(\s*(\d*\.?\d+)\s*,\s*(\d*\.?\d+)\s*,\s*(\d*\.?\d+)\s*,\s*(\d?\.?\d*)\s*\)/gi;
      matches = regex.exec(color);
      stop.setAttribute(
        "stop-color",
        format("rgb({r},{g},{b})", {
          r: matches[1],
          g: matches[2],
          b: matches[3],
        })
      );
      stop.setAttribute("stop-opacity", matches[4]);
    } else {
      stop.setAttribute("stop-color", utils.toString(color));
    }
    this.__root.appendChild(stop);
  };

  CanvasPattern = function (pattern, ctx) {
    this.__root = pattern;
    this.__ctx = ctx;
  };

  /**
   * The mock canvas context
   * @param o - options include:
   * ctx - existing Context2D to wrap around
   * width - width of your canvas (defaults to 500)
   * height - height of your canvas (defaults to 500)
   * enableMirroring - enables canvas mirroring (get image data) (defaults to false)
   * document - the document object (defaults to the current document)
   */
  Context = function (o) {
    var defaultOptions = { width: 500, height: 500, enableMirroring: false },
      options;

    // keep support for this way of calling Context: new Context(width, height)
    if (arguments.length > 1) {
      options = defaultOptions;
      options.width = arguments[0];
      options.height = arguments[1];
    } else if (!o) {
      options = defaultOptions;
    } else {
      options = o;
    }

    if (!(this instanceof Context)) {
      //did someone call this without new?
      return new Context(options);
    }

    //setup options
    this.width = options.width || defaultOptions.width;
    this.height = options.height || defaultOptions.height;
    this.enableMirroring =
      options.enableMirroring !== undefined
        ? options.enableMirroring
        : defaultOptions.enableMirroring;

    this.canvas = this; ///point back to this instance!
    this.__document = options.document || document;

    // allow passing in an existing context to wrap around
    // if a context is passed in, we know a canvas already exist
    if (options.ctx) {
      this.__ctx = options.ctx;
    } else {
      this.__canvas = this.__document.createElement("canvas");
      this.__ctx = this.__canvas.getContext("2d");
    }

    this.__setDefaultStyles();
    this.__styleStack = [this.__getStyleState()];
    this.__groupStack = [];

    //the root svg element
    this.__root = this.__document.createElementNS(
      "http://www.w3.org/2000/svg",
      "svg"
    );
    this.__root.setAttribute("version", 1.1);
    this.__root.setAttribute("xmlns", "http://www.w3.org/2000/svg");
    this.__root.setAttributeNS(
      "http://www.w3.org/2000/xmlns/",
      "xmlns:xlink",
      "http://www.w3.org/1999/xlink"
    );
    this.__root.setAttribute("width", this.width);
    this.__root.setAttribute("height", this.height);

    //make sure we don't generate the same ids in defs
    this.__ids = {};

    //defs tag
    this.__defs = this.__document.createElementNS(
      "http://www.w3.org/2000/svg",
      "defs"
    );
    this.__root.appendChild(this.__defs);

    //also add a group child. the svg element can't use the transform attribute
    this.__currentElement = this.__document.createElementNS(
      "http://www.w3.org/2000/svg",
      "g"
    );
    this.__root.appendChild(this.__currentElement);

    // init transformation matrix
    this.resetTransform();

    this.__options = options;
    this.__id = Math.random().toString(16).substring(2, 8);
    this.__debug(`new`, o);
  };

  /**
   * Log
   *
   * @private
   */
  Context.prototype.__debug = function (...data) {
    if (!this.__options.debug) {
      return;
    }
    console.debug(`svgcanvas#${this.__id}:`, ...data);
  };

  /**
   * Creates the specified svg element
   * @private
   */
  Context.prototype.__createElement = function (
    elementName,
    properties,
    resetFill
  ) {
    if (typeof properties === "undefined") {
      properties = {};
    }

    var element = this.__document.createElementNS(
      "http://www.w3.org/2000/svg",
      elementName
    ),
      keys = Object.keys(properties),
      i,
      key;
    if (resetFill) {
      //if fill or stroke is not specified, the svg element should not display. By default SVG's fill is black.
      element.setAttribute("fill", "none");
      element.setAttribute("stroke", "none");
    }
    for (i = 0; i < keys.length; i++) {
      key = keys[i];
      element.setAttribute(key, properties[key]);
    }
    return element;
  };

  /**
   * Applies default canvas styles to the context
   * @private
   */
  Context.prototype.__setDefaultStyles = function () {
    //default 2d canvas context properties see:http://www.w3.org/TR/2dcontext/
    var keys = Object.keys(STYLES),
      i,
      key;
    for (i = 0; i < keys.length; i++) {
      key = keys[i];
      this[key] = STYLES[key].canvas;
    }
  };

  /**
   * Applies styles on restore
   * @param styleState
   * @private
   */
  Context.prototype.__applyStyleState = function (styleState) {
    var keys = Object.keys(styleState),
      i,
      key;
    for (i = 0; i < keys.length; i++) {
      key = keys[i];
      this[key] = styleState[key];
    }
  };

  /**
   * Gets the current style state
   * @return {Object}
   * @private
   */
  Context.prototype.__getStyleState = function () {
    var i,
      styleState = {},
      keys = Object.keys(STYLES),
      key;
    for (i = 0; i < keys.length; i++) {
      key = keys[i];
      styleState[key] = this[key];
    }
    return styleState;
  };

  /**
   * @see https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/transform
   */
  Context.prototype.__applyTransformation = function (element, matrix) {
    const { a, b, c, d, e, f } = matrix || this.getTransform();
    element.setAttribute("transform", `matrix(${a} ${b} ${c} ${d} ${e} ${f})`);
  };

  /**
   * Apples the current styles to the current SVG element. On "ctx.fill" or "ctx.stroke"
   * @param type
   * @private
   */
  Context.prototype.__applyStyleToElement = function (element, type) {
    var currentElement = element;
    var currentStyleGroup = this.__currentElementsToStyle;
    if (currentStyleGroup) {
      currentElement.setAttribute(type, "");
      currentElement = currentStyleGroup.element;
      currentStyleGroup.children.forEach(function (node) {
        node.setAttribute(type, "");
      });
    }

    var keys = Object.keys(STYLES),
      i,
      style,
      value,
      regex,
      matches,
      id,
      nodeIndex,
      node;
    for (i = 0; i < keys.length; i++) {
      style = STYLES[keys[i]];
      value = this[keys[i]];
      if (style.apply) {
        //is this a gradient or pattern?
        if (value instanceof CanvasPattern) {
          //pattern
          if (value.__ctx) {
            //copy over defs
            for (
              nodeIndex = 0;
              nodeIndex < value.__ctx.__defs.childNodes.length;
              nodeIndex++
            ) {
              node = value.__ctx.__defs.childNodes[nodeIndex];
              id = node.getAttribute("id");
              this.__ids[id] = id;
              this.__defs.appendChild(node);
            }
          }
          currentElement.setAttribute(
            style.apply,
            format("url(#{id})", { id: value.__root.getAttribute("id") })
          );
        } else if (value instanceof CanvasGradient) {
          //gradient
          currentElement.setAttribute(
            style.apply,
            format("url(#{id})", { id: value.__root.getAttribute("id") })
          );
        } else if (style.apply.indexOf(type) !== -1 && style.svg !== value) {
          if (
            (style.svgAttr === "stroke" || style.svgAttr === "fill") &&
            value.indexOf("rgba") !== -1
          ) {
            //separate alpha value, since illustrator can't handle it
            regex =
              /rgba\(\s*(\d*\.?\d+)\s*,\s*(\d*\.?\d+)\s*,\s*(\d*\.?\d+)\s*,\s*(\d?\.?\d*)\s*\)/gi;
            matches = regex.exec(value);
            currentElement.setAttribute(
              style.svgAttr,
              format("rgb({r},{g},{b})", {
                r: matches[1],
                g: matches[2],
                b: matches[3],
              })
            );
            //should take globalAlpha here
            var opacity = matches[4];
            var globalAlpha = this.globalAlpha;
            if (globalAlpha != null) {
              opacity *= globalAlpha;
            }
            currentElement.setAttribute(style.svgAttr + "-opacity", opacity);
          } else {
            var attr = style.svgAttr;
            if (keys[i] === "globalAlpha") {
              attr = type + "-" + style.svgAttr;
              if (currentElement.getAttribute(attr)) {
                //fill-opacity or stroke-opacity has already been set by stroke or fill.
                continue;
              }
            } else if (keys[i] === "lineWidth") {
              var scale = this.__getTransformScale();
              value = value * Math.max(scale.x, scale.y);
            }
            //otherwise only update attribute if right type, and not svg default
            currentElement.setAttribute(attr, value);
          }
        }
      }
    }
  };

  /**
   * Will return the closest group or svg node. May return the current element.
   * @private
   */
  Context.prototype.__closestGroupOrSvg = function (node) {
    node = node || this.__currentElement;
    if (node.nodeName === "g" || node.nodeName === "svg") {
      return node;
    } else {
      return this.__closestGroupOrSvg(node.parentNode);
    }
  };

  /**
   * Returns the serialized value of the svg so far
   * @param fixNamedEntities - Standalone SVG doesn't support named entities, which document.createTextNode encodes.
   *                           If true, we attempt to find all named entities and encode it as a numeric entity.
   * @return serialized svg
   */
  Context.prototype.getSerializedSvg = function (fixNamedEntities) {
    var serialized = new XMLSerializer().serializeToString(this.__root),
      keys,
      i,
      key,
      value,
      regexp,
      xmlns;

    //IE search for a duplicate xmnls because they didn't implement setAttributeNS correctly
    xmlns =
      /xmlns="http:\/\/www\.w3\.org\/2000\/svg".+xmlns="http:\/\/www\.w3\.org\/2000\/svg/gi;
    if (xmlns.test(serialized)) {
      serialized = serialized.replace(
        'xmlns="http://www.w3.org/2000/svg',
        'xmlns:xlink="http://www.w3.org/1999/xlink'
      );
    }

    if (fixNamedEntities) {
      keys = Object.keys(namedEntities);
      //loop over each named entity and replace with the proper equivalent.
      for (i = 0; i < keys.length; i++) {
        key = keys[i];
        value = namedEntities[key];
        regexp = new RegExp(key, "gi");
        if (regexp.test(serialized)) {
          serialized = serialized.replace(regexp, value);
        }
      }
    }

    return serialized;
  };

  Context.prototype.createPath = function (arg) {
    return new Path2D(this, arg);
  };

  /**
   * Returns the root svg
   * @return
   */
  Context.prototype.getSvg = function () {
    return this.__root;
  };

  /**
   * Will generate a group tag.
   */
  Context.prototype.save = function () {
    var group = this.__createElement("g");
    var parent = this.__closestGroupOrSvg();
    this.__groupStack.push(parent);
    parent.appendChild(group);
    this.__currentElement = group;
    const style = this.__getStyleState();

    this.__debug("save style", style);
    this.__styleStack.push(style);
    if (!this.__transformMatrixStack) {
      this.__transformMatrixStack = [];
    }
    this.__transformMatrixStack.push(this.getTransform());
  };

  /**
   * Sets current element to parent, or just root if already root
   */
  Context.prototype.restore = function () {
    this.__currentElement = this.__groupStack.pop();
    this.__currentElementsToStyle = null;
    //Clearing canvas will make the poped group invalid, currentElement is set to the root group node.
    if (!this.__currentElement) {
      this.__currentElement = this.__root.childNodes[1];
    }
    var state = this.__styleStack.pop();
    this.__debug("restore style", state);
    this.__applyStyleState(state);
    if (this.__transformMatrixStack && this.__transformMatrixStack.length > 0) {
      this.setTransform(this.__transformMatrixStack.pop());
    }
  };

  Context.prototype.__createPathElement = function () {
    var path = this.__createElement("path", {}, true);
    var parent = this.__closestGroupOrSvg();
    parent.appendChild(path);
    return path;
  };

  /**
   * Create a new Path Element
   */
  Context.prototype.beginPath = function () {
    // Note that there is only one current default path, it is not part of the drawing state.
    // See also: https://html.spec.whatwg.org/multipage/scripting.html#current-default-path
    this.__currentDefaultPath = new Path2D(this);
    this.__currentPosition = {};
  };

  Context.prototype.closePath = function () {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.closePath();
  };

  Context.prototype.moveTo = function (x, y) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.moveTo(x, y);
  };

  Context.prototype.lineTo = function (x, y) {
    if (!this.__currentDefaultPath) {
      this.moveTo(x, y);
    }
    this.__currentDefaultPath.lineTo(x, y);
  };

  Context.prototype.rect = function (x, y, width, height) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.rect(x, y, width, height);
  };

  Context.prototype.roundRect = function (x, y, width, height, radii) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.roundRect(x, y, width, height, radii);
  };

  Context.prototype.bezierCurveTo = function (cp1x, cp1y, cp2x, cp2y, x, y) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.bezierCurveTo(cp1x, cp1y, cp2x, cp2y, x, y);
  };

  Context.prototype.quadraticCurveTo = function (cpx, cpy, x, y) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.quadraticCurveTo(cpx, cpy, x, y);
  };

  Context.prototype.arc = function (
    x,
    y,
    radius,
    startAngle,
    endAngle,
    counterClockwise
  ) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.arc(
      x,
      y,
      radius,
      startAngle,
      endAngle,
      counterClockwise
    );
  };

  Context.prototype.arcTo = function (x1, y1, x2, y2, radius) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.arcTo(x1, y1, x2, y2, radius);
  };

  Context.prototype.ellipse = function (
    x,
    y,
    radiusX,
    radiusY,
    rotation,
    startAngle,
    endAngle,
    counterClockwise
  ) {
    if (!this.__currentDefaultPath) {
      this.beginPath();
    }
    this.__currentDefaultPath.ellipse(
      x,
      y,
      radiusX,
      radiusY,
      rotation,
      startAngle,
      endAngle,
      counterClockwise
    );
  };

  /**
   * Sets the stroke property on the current element
   */
  Context.prototype.stroke = function (path2d) {
    this.__strokeOrFill(path2d, "stroke");
  };

  /**
   * Sets fill properties on the current element
   */
  Context.prototype.fill = function (path2d) {
    this.__strokeOrFill(path2d, "fill");
  };

  Context.prototype.__strokeOrFill = function (path2d, action) {
    var path;

    if (path2d) {
      path = path2d;
    } else {
      if (!this.__currentDefaultPath) {
        this.beginPath();
      }
      path = this.__currentDefaultPath;
    }

    if (path.__pathString.length > 0) {
      var pathElement = this.__createPathElement();
      this.__applyStyleToElement(pathElement, action);
      pathElement.setAttribute("paint-order", "fill stroke markers");
      pathElement.setAttribute("d", path.__pathString);
      if (path2d) {
        this.__applyTransformation(pathElement);
      }
    }

    if (path2d) {
      path2d.__subPaths.forEach((subPath) => {
        var pathElement = this.__createPathElement();
        this.__applyStyleToElement(pathElement, action);
        pathElement.setAttribute("paint-order", "fill stroke markers");
        pathElement.setAttribute("d", subPath.path.__pathString);
        if (subPath.transform) {
          this.__applyTransformation(pathElement, this.getTransform().multiply(subPath.transform));
        }
      });
    }
  };

  /**
   * adds a rectangle element
   */
  Context.prototype.fillRect = function (x, y, width, height) {
    let { a, b, c, d, e, f } = this.getTransform();
    if (
      JSON.stringify([a, b, c, d, e, f]) === JSON.stringify([1, 0, 0, 1, 0, 0])
    ) {
      //clear entire canvas
      if (
        x === 0 &&
        y === 0 &&
        width === this.width &&
        height === this.height
      ) {
        this.__clearCanvas();
      }
    }
    var rect, parent;
    rect = this.__createElement(
      "rect",
      {
        x: x,
        y: y,
        width: width,
        height: height,
      },
      true
    );
    parent = this.__closestGroupOrSvg();
    parent.appendChild(rect);
    this.__currentElement = rect;
    this.__applyTransformation(rect);
    this.__applyStyleToElement(this.__currentElement, "fill");
  };

  /**
   * Draws a rectangle with no fill
   * @param x
   * @param y
   * @param width
   * @param height
   */
  Context.prototype.strokeRect = function (x, y, width, height) {
    var rect, parent;
    rect = this.__createElement(
      "rect",
      {
        x: x,
        y: y,
        width: width,
        height: height,
      },
      true
    );
    parent = this.__closestGroupOrSvg();
    parent.appendChild(rect);
    this.__currentElement = rect;
    this.__applyTransformation(rect);
    this.__applyStyleToElement(this.__currentElement, "stroke");
  };

  /**
   * Clear entire canvas:
   * 1. save current transforms
   * 2. remove all the childNodes of the root g element
   */
  Context.prototype.__clearCanvas = function () {
    var rootGroup = this.__root.childNodes[1];
    this.__root.removeChild(rootGroup);
    this.__currentElement = this.__document.createElementNS(
      "http://www.w3.org/2000/svg",
      "g"
    );
    this.__root.appendChild(this.__currentElement);
    //reset __groupStack as all the child group nodes are all removed.
    this.__groupStack = [];
  };

  /**
   * "Clears" a canvas by just drawing a white rectangle in the current group.
   */
  Context.prototype.clearRect = function (x, y, width, height) {
    let { a, b, c, d, e, f } = this.getTransform();
    if (
      JSON.stringify([a, b, c, d, e, f]) === JSON.stringify([1, 0, 0, 1, 0, 0])
    ) {
      //clear entire canvas
      if (
        x === 0 &&
        y === 0 &&
        width === this.width &&
        height === this.height
      ) {
        this.__clearCanvas();
        return;
      }
    }
    var rect,
      parent = this.__closestGroupOrSvg();
    rect = this.__createElement(
      "rect",
      {
        x: x,
        y: y,
        width: width,
        height: height,
        fill: "#FFFFFF",
      },
      true
    );
    this.__applyTransformation(rect);
    parent.appendChild(rect);
  };

  /**
   * Adds a linear gradient to a defs tag.
   * Returns a canvas gradient object that has a reference to it's parent def
   */
  Context.prototype.createLinearGradient = function (x1, y1, x2, y2) {
    var grad = this.__createElement(
      "linearGradient",
      {
        id: randomString(this.__ids),
        x1: x1 + "px",
        x2: x2 + "px",
        y1: y1 + "px",
        y2: y2 + "px",
        gradientUnits: "userSpaceOnUse",
      },
      false
    );
    this.__defs.appendChild(grad);
    return new CanvasGradient(grad, this);
  };

  /**
   * Adds a radial gradient to a defs tag.
   * Returns a canvas gradient object that has a reference to it's parent def
   */
  Context.prototype.createRadialGradient = function (x0, y0, r0, x1, y1, r1) {
    var grad = this.__createElement(
      "radialGradient",
      {
        id: randomString(this.__ids),
        cx: x1 + "px",
        cy: y1 + "px",
        r: r1 + "px",
        fx: x0 + "px",
        fy: y0 + "px",
        gradientUnits: "userSpaceOnUse",
      },
      false
    );
    this.__defs.appendChild(grad);
    return new CanvasGradient(grad, this);
  };

  /**
   * Fills or strokes text
   * @param text
   * @param x
   * @param y
   * @param action - stroke or fill
   * @private
   */
  Context.prototype.__applyText = function (text, x, y, action) {
    var el = document.createElement("span");
    el.setAttribute("style", "font:" + this.font);

    var style = el.style, // CSSStyleDeclaration object
      parent = this.__closestGroupOrSvg(),
      textElement = this.__createElement(
        "text",
        {
          "font-family": style.fontFamily,
          "font-size": style.fontSize,
          "font-style": style.fontStyle,
          "font-weight": style.fontWeight,

          // canvas doesn't support underline natively, but we do :)
          "text-decoration": this.__fontUnderline,
          x: x,
          y: y,
          "text-anchor": getTextAnchor(this.textAlign),
          "dominant-baseline": getDominantBaseline(this.textBaseline),
        },
        true
      );

    textElement.appendChild(this.__document.createTextNode(text));
    this.__currentElement = textElement;
    this.__applyTransformation(textElement);
    this.__applyStyleToElement(this.__currentElement, action);

    if (this.__fontHref) {
      var a = this.__createElement("a");
      // canvas doesn't natively support linking, but we do :)
      a.setAttributeNS(
        "http://www.w3.org/1999/xlink",
        "xlink:href",
        this.__fontHref
      );
      a.appendChild(textElement);
      textElement = a;
    }

    parent.appendChild(textElement);
  };

  /**
   * Creates a text element
   * @param text
   * @param x
   * @param y
   */
  Context.prototype.fillText = function (text, x, y) {
    this.__applyText(text, x, y, "fill");
  };

  /**
   * Strokes text
   * @param text
   * @param x
   * @param y
   */
  Context.prototype.strokeText = function (text, x, y) {
    this.__applyText(text, x, y, "stroke");
  };

  /**
   * No need to implement this for svg.
   * @param text
   * @return {TextMetrics}
   */
  Context.prototype.measureText = function (text) {
    this.__ctx.font = this.font;
    return this.__ctx.measureText(text);
  };

  /**
   * Generates a ClipPath from the clip command.
   */
  Context.prototype.clip = function (fillRule) {
    var group = this.__closestGroupOrSvg(),
      clipPath = this.__createElement("clipPath"),
      id = randomString(this.__ids);

    var pathElement = this.__createPathElement();
    pathElement.setAttribute("d", this.__currentDefaultPath.__pathString);
    // this.__applyTransformation(pathElement);

    clipPath.setAttribute("id", id);

    if (typeof fillRule === "string") {
      clipPath.setAttribute("clip-rule", fillRule);
    }

    clipPath.appendChild(pathElement);

    this.__defs.appendChild(clipPath);

    //set the clip path to this group
    group.setAttribute("clip-path", format("url(#{id})", { id: id }));

    this.__currentElement = group;
  };

  /**
   * Draws a canvas, image or mock context to this canvas.
   * Note that all svg dom manipulation uses node.childNodes rather than node.children for IE support.
   * http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-drawimage
   */
  Context.prototype.drawImage = function () {
    //convert arguments to a real array
    var args = Array.prototype.slice.call(arguments),
      image = args[0],
      dx,
      dy,
      dw,
      dh,
      sx = 0,
      sy = 0,
      sw,
      sh,
      parent,
      svg,
      defs,
      group,
      currentElement,
      svgImage,
      canvas,
      context,
      id;

    if (args.length === 3) {
      dx = args[1];
      dy = args[2];
      sw = image.width;
      sh = image.height;
      dw = sw;
      dh = sh;
    } else if (args.length === 5) {
      dx = args[1];
      dy = args[2];
      dw = args[3];
      dh = args[4];
      sw = image.width;
      sh = image.height;
    } else if (args.length === 9) {
      sx = args[1];
      sy = args[2];
      sw = args[3];
      sh = args[4];
      dx = args[5];
      dy = args[6];
      dw = args[7];
      dh = args[8];
    } else {
      throw new Error(
        "Invalid number of arguments passed to drawImage: " + arguments.length
      );
    }

    parent = this.__closestGroupOrSvg();
    currentElement = this.__currentElement;
    const matrix = this.getTransform().translate(dx, dy);
    if (image instanceof Context) {
      //canvas2svg mock canvas context. In the future we may want to clone nodes instead.
      //also I'm currently ignoring dw, dh, sw, sh, sx, sy for a mock context.
      svg = image.getSvg().cloneNode(true);
      if (svg.childNodes && svg.childNodes.length > 1) {
        defs = svg.childNodes[0];
        while (defs.childNodes.length) {
          id = defs.childNodes[0].getAttribute("id");
          this.__ids[id] = id;
          this.__defs.appendChild(defs.childNodes[0]);
        }
        group = svg.childNodes[1];
        if (group) {
          this.__applyTransformation(group, matrix);
          parent.appendChild(group);
        }
      }
    } else if (image.nodeName === "CANVAS" || image.nodeName === "IMG") {
      //canvas or image
      svgImage = this.__createElement("image");
      svgImage.setAttribute("width", dw);
      svgImage.setAttribute("height", dh);
      svgImage.setAttribute("preserveAspectRatio", "none");

      // Crop the image using a temporary canvas and convert to a bitmap
      canvas = this.__document.createElement("canvas");
      canvas.width = dw;
      canvas.height = dh;
      context = canvas.getContext("2d");
      context.drawImage(image, sx, sy, sw, sh, 0, 0, dw, dh);
      image = canvas;

      this.__applyTransformation(svgImage, matrix);
      svgImage.setAttributeNS(
        "http://www.w3.org/1999/xlink",
        "xlink:href",
        image.nodeName === "CANVAS"
          ? image.toDataURL()
          : image.getAttribute("src")
      );
      parent.appendChild(svgImage);
    }
  };

  /**
   * Generates a pattern tag
   */
  Context.prototype.createPattern = function (image, repetition) {
    var pattern = this.__document.createElementNS(
      "http://www.w3.org/2000/svg",
      "pattern"
    ),
      id = randomString(this.__ids),
      img;
    pattern.setAttribute("id", id);
    pattern.setAttribute("width", image.width);
    pattern.setAttribute("height", image.height);
    // We want the pattern sizing to be absolute, and not relative
    // https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Patterns
    // https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/patternUnits
    pattern.setAttribute("patternUnits", "userSpaceOnUse");

    if (image.nodeName === "CANVAS" || image.nodeName === "IMG") {
      img = this.__document.createElementNS(
        "http://www.w3.org/2000/svg",
        "image"
      );
      img.setAttribute("width", image.width);
      img.setAttribute("height", image.height);
      img.setAttributeNS(
        "http://www.w3.org/1999/xlink",
        "xlink:href",
        image.nodeName === "CANVAS"
          ? image.toDataURL()
          : image.getAttribute("src")
      );
      pattern.appendChild(img);
      this.__defs.appendChild(pattern);
    } else if (image instanceof Context) {
      pattern.appendChild(image.__root.childNodes[1]);
      this.__defs.appendChild(pattern);
    }
    return new CanvasPattern(pattern, this);
  };

  Context.prototype.setLineDash = function (dashArray) {
    if (dashArray && dashArray.length > 0) {
      this.lineDash = dashArray.join(",");
    } else {
      this.lineDash = null;
    }
  };

  Context.prototype.isPointInStroke = function (path2d, x, y) {
    if (this.__ctx) {
      return this.__ctx.isPointInStroke(path2d, x, y);
    }

    // TODO: method stub
    return false;
  }

  /**
   * SetTransform changes the current transformation matrix to
   * the matrix given by the arguments as described below.
   *
   * @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/setTransform
   */
  Context.prototype.setTransform = function (a, b, c, d, e, f) {
    if (a instanceof DOMMatrix) {
      this.__transformMatrix = new DOMMatrix([a.a, a.b, a.c, a.d, a.e, a.f]);
    } else {
      this.__transformMatrix = new DOMMatrix([a, b, c, d, e, f]);
    }
  };

  /**
   * GetTransform Returns a copy of the current transformation matrix,
   * as a newly created DOMMAtrix Object
   *
   * @returns A DOMMatrix Object
   */
  Context.prototype.getTransform = function () {
    let { a, b, c, d, e, f } = this.__transformMatrix;
    return new DOMMatrix([a, b, c, d, e, f]);
  };

  /**
   * ResetTransform resets the current transformation matrix to the identity matrix
   *
   * @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/resetTransform
   */
  Context.prototype.resetTransform = function () {
    this.setTransform(1, 0, 0, 1, 0, 0);
  };

  /**
   * Add the scaling transformation described by the arguments to the current transformation matrix.
   *
   * @param x The x argument represents the scale factor in the horizontal direction
   * @param y The y argument represents the scale factor in the vertical direction.
   * @see https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-scale
   */
  Context.prototype.scale = function (x, y) {
    if (y === undefined) {
      y = x;
    }
    // If either of the arguments are infinite or NaN, then return.
    if (isNaN(x) || isNaN(y) || !isFinite(x) || !isFinite(y)) {
      return;
    }
    let matrix = this.getTransform().scale(x, y);
    this.setTransform(matrix);
  };

  /**
   * Rotate adds a rotation to the transformation matrix.
   *
   * @param angle The rotation angle, clockwise in radians. You can use degree * Math.PI / 180 to calculate a radian from a degree.
   * @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/rotate
   * @see https://www.w3.org/TR/css-transforms-1
   */
  Context.prototype.rotate = function (angle) {
    let matrix = this.getTransform().multiply(
      new DOMMatrix([
        Math.cos(angle),
        Math.sin(angle),
        -Math.sin(angle),
        Math.cos(angle),
        0,
        0,
      ])
    );
    this.setTransform(matrix);
  };

  /**
   * Translate adds a translation transformation to the current matrix.
   *
   * @param x Distance to move in the horizontal direction. Positive values are to the right, and negative to the left.
   * @param y Distance to move in the vertical direction. Positive values are down, and negative are up.
   * @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/translate
   */
  Context.prototype.translate = function (x, y) {
    const matrix = this.getTransform().translate(x, y);
    this.setTransform(matrix);
  };

  /**
   * Transform multiplies the current transformation with the matrix described by the arguments of this method.
   * This lets you scale, rotate, translate (move), and skew the context.
   *
   * @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/transform
   */
  Context.prototype.transform = function (a, b, c, d, e, f) {
    const matrix = this.getTransform().multiply(
      new DOMMatrix([a, b, c, d, e, f])
    );
    this.setTransform(matrix);
  };

  Context.prototype.__matrixTransform = function (x, y) {
    return new DOMPoint(x, y).matrixTransform(this.__transformMatrix);
  };

  /**
   *
   * @returns The scale component of the transform matrix as {x,y}.
   */
  Context.prototype.__getTransformScale = function () {
    return {
      x: Math.hypot(this.__transformMatrix.a, this.__transformMatrix.b),
      y: Math.hypot(this.__transformMatrix.c, this.__transformMatrix.d),
    };
  };

  /**
   *
   * @returns The rotation component of the transform matrix in radians.
   */
  Context.prototype.__getTransformRotation = function () {
    return Math.atan2(this.__transformMatrix.b, this.__transformMatrix.a);
  };

  /**
   *
   * @param {*} sx The x-axis coordinate of the top-left corner of the rectangle from which the ImageData will be extracted.
   * @param {*} sy The y-axis coordinate of the top-left corner of the rectangle from which the ImageData will be extracted.
   * @param {*} sw The width of the rectangle from which the ImageData will be extracted. Positive values are to the right, and negative to the left.
   * @param {*} sh The height of the rectangle from which the ImageData will be extracted. Positive values are down, and negative are up.
   * @param {Boolean} options.async Will return a Promise<ImageData> if true, must be set to true
   * @returns An ImageData object containing the image data for the rectangle of the canvas specified. The coordinates of the rectangle's top-left corner are (sx, sy), while the coordinates of the bottom corner are (sx + sw, sy + sh).
   */
  Context.prototype.getImageData = function (sx, sy, sw, sh, options) {
    return imageUtils.getImageData(
      this.getSvg(),
      this.width,
      this.height,
      sx,
      sy,
      sw,
      sh,
      options
    );
  };

  /**
   * Not yet implemented
   */
  Context.prototype.drawFocusRing = function () { };
  Context.prototype.createImageData = function () { };
  Context.prototype.putImageData = function () { };
  Context.prototype.globalCompositeOperation = function () { };

  return Context;
})();