text: // Copyright 2006 Google Inc.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  
  // Known Issues:
  //
  // * Patterns only support repeat.
  // * Radial gradient are not implemented. The VML version of these look very
  //   different from the canvas one.
  // * Clipping paths are not implemented.
  // * Coordsize. The width and height attribute have higher priority than the
  //   width and height style values which isn't correct.
  // * Painting mode isn't implemented.
  // * Canvas width/height should is using content-box by default. IE in
  //   Quirks mode will draw the canvas using border-box. Either change your
  //   doctype to HTML5
  //   (http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
  //   or use Box Sizing Behavior from WebFX
  //   (http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
  // * Non uniform scaling does not correctly scale strokes.
  // * Filling very large shapes (above 5000 points) is buggy.
  // * Optimize. There is always room for speed improvements.
  
  // Only add this code if we do not already have a canvas implementation
  if (!document.createElement('canvas').getContext) {
  
      (function () {
  
          // alias some functions to make (compiled) code shorter
          var m = Math;
          var mr = m.round;
          var ms = m.sin;
          var mc = m.cos;
          var abs = m.abs;
          var sqrt = m.sqrt;
  
          // this is used for sub pixel precision
          var Z = 10;
          var Z2 = Z / 2;
  
          var IE_VERSION = +navigator.userAgent.match(/MSIE ([\d.]+)?/)[1];
  
          /**
           * This funtion is assigned to the <canvas> elements as element.getContext().
           * @this {HTMLElement}
           * @return {CanvasRenderingContext2D_}
           */
          function getContext() {
              return this.context_ ||
                  (this.context_ = new CanvasRenderingContext2D_(this));
          }
  
          var slice = Array.prototype.slice;
  
          /**
           * Binds a function to an object. The returned function will always use the
           * passed in {@code obj} as {@code this}.
           *
           * Example:
           *
           *   g = bind(f, obj, a, b)
           *   g(c, d) // will do f.call(obj, a, b, c, d)
           *
           * @param {Function} f The function to bind the object to
           * @param {Object} obj The object that should act as this when the function
           *     is called
           * @param {*} var_args Rest arguments that will be used as the initial
           *     arguments when the function is called
           * @return {Function} A new function that has bound this
           */
          function bind(f, obj, var_args) {
              var a = slice.call(arguments, 2);
              return function () {
                  return f.apply(obj, a.concat(slice.call(arguments)));
              };
          }
  
          function encodeHtmlAttribute(s) {
              return String(s).replace(/&/g, '&amp;').replace(/"/g, '&quot;');
          }
  
          function addNamespace(doc, prefix, urn) {
              if (!doc.namespaces[prefix]) {
                  doc.namespaces.add(prefix, urn, '#default#VML');
              }
          }
  
          function addNamespacesAndStylesheet(doc) {
              addNamespace(doc, 'g_vml_', 'urn:schemas-microsoft-com:vml');
              addNamespace(doc, 'g_o_', 'urn:schemas-microsoft-com:office:office');
  
              // Setup default CSS.  Only add one style sheet per document
              if (!doc.styleSheets['ex_canvas_']) {
                  var ss = doc.createStyleSheet();
                  ss.owningElement.id = 'ex_canvas_';
                  ss.cssText = 'canvas{display:inline-block;overflow:hidden;' +
                      // default size is 300x150 in Gecko and Opera
                  'text-align:left;width:300px;height:150px}';
              }
          }
  
          // Add namespaces and stylesheet at startup.
          addNamespacesAndStylesheet(document);
  
          var G_vmlCanvasManager_ = {
              init: function (opt_doc) {
                  var doc = opt_doc || document;
                  // Create a dummy element so that IE will allow canvas elements to be
                  // recognized.
                  doc.createElement('canvas');
                  doc.attachEvent('onreadystatechange', bind(this.init_, this, doc));
              },
  
              init_: function (doc) {
                  // find all canvas elements
                  var els = doc.getElementsByTagName('canvas');
                  for (var i = 0; i < els.length; i++) {
                      this.initElement(els[i]);
                  }
              },
  
              /**
               * Public initializes a canvas element so that it can be used as canvas
               * element from now on. This is called automatically before the page is
               * loaded but if you are creating elements using createElement you need to
               * make sure this is called on the element.
               * @param {HTMLElement} el The canvas element to initialize.
               * @return {HTMLElement} the element that was created.
               */
              initElement: function (el) {
                  if (!el.getContext) {
                      el.getContext = getContext;
  
                      // Add namespaces and stylesheet to document of the element.
                      addNamespacesAndStylesheet(el.ownerDocument);
  
                      // Remove fallback content. There is no way to hide text nodes so we
                      // just remove all childNodes. We could hide all elements and remove
                      // text nodes but who really cares about the fallback content.
                      el.innerHTML = '';
  
                      // do not use inline function because that will leak memory
                      el.attachEvent('onpropertychange', onPropertyChange);
                      el.attachEvent('onresize', onResize);
  
                      var attrs = el.attributes;
                      if (attrs.width && attrs.width.specified) {
                          // TODO: use runtimeStyle and coordsize
                          // el.getContext().setWidth_(attrs.width.nodeValue);
                          el.style.width = attrs.width.nodeValue + 'px';
                      } else {
                          el.width = el.clientWidth;
                      }
                      if (attrs.height && attrs.height.specified) {
                          // TODO: use runtimeStyle and coordsize
                          // el.getContext().setHeight_(attrs.height.nodeValue);
                          el.style.height = attrs.height.nodeValue + 'px';
                      } else {
                          el.height = el.clientHeight;
                      }
                      //el.getContext().setCoordsize_()
                  }
                  return el;
              }
          };
  
          function onPropertyChange(e) {
              var el = e.srcElement;
  
              switch (e.propertyName) {
                  case 'width':
                      el.getContext().clearRect();
                      el.style.width = el.attributes.width.nodeValue + 'px';
                      // In IE8 this does not trigger onresize.
                      el.firstChild.style.width = el.clientWidth + 'px';
                      break;
                  case 'height':
                      el.getContext().clearRect();
                      el.style.height = el.attributes.height.nodeValue + 'px';
                      el.firstChild.style.height = el.clientHeight + 'px';
                      break;
              }
          }
  
          function onResize(e) {
              var el = e.srcElement;
              if (el.firstChild) {
                  el.firstChild.style.width = el.clientWidth + 'px';
                  el.firstChild.style.height = el.clientHeight + 'px';
              }
          }
  
          G_vmlCanvasManager_.init();
  
          // precompute "00" to "FF"
          var decToHex = [];
          for (var i = 0; i < 16; i++) {
              for (var j = 0; j < 16; j++) {
                  decToHex[i * 16 + j] = i.toString(16) + j.toString(16);
              }
          }
  
          function createMatrixIdentity() {
              return [
                  [1, 0, 0],
                  [0, 1, 0],
                  [0, 0, 1]
              ];
          }
  
          function matrixMultiply(m1, m2) {
              var result = createMatrixIdentity();
  
              for (var x = 0; x < 3; x++) {
                  for (var y = 0; y < 3; y++) {
                      var sum = 0;
  
                      for (var z = 0; z < 3; z++) {
                          sum += m1[x][z] * m2[z][y];
                      }
  
                      result[x][y] = sum;
                  }
              }
              return result;
          }
  
          function copyState(o1, o2) {
              o2.fillStyle = o1.fillStyle;
              o2.lineCap = o1.lineCap;
              o2.lineJoin = o1.lineJoin;
              o2.lineWidth = o1.lineWidth;
              o2.miterLimit = o1.miterLimit;
              o2.shadowBlur = o1.shadowBlur;
              o2.shadowColor = o1.shadowColor;
              o2.shadowOffsetX = o1.shadowOffsetX;
              o2.shadowOffsetY = o1.shadowOffsetY;
              o2.strokeStyle = o1.strokeStyle;
              o2.globalAlpha = o1.globalAlpha;
              o2.font = o1.font;
              o2.textAlign = o1.textAlign;
              o2.textBaseline = o1.textBaseline;
              o2.arcScaleX_ = o1.arcScaleX_;
              o2.arcScaleY_ = o1.arcScaleY_;
              o2.lineScale_ = o1.lineScale_;
          }
  
          var colorData = {
              aliceblue: '#F0F8FF',
              antiquewhite: '#FAEBD7',
              aquamarine: '#7FFFD4',
              azure: '#F0FFFF',
              beige: '#F5F5DC',
              bisque: '#FFE4C4',
              black: '#000000',
              blanchedalmond: '#FFEBCD',
              blueviolet: '#8A2BE2',
              brown: '#A52A2A',
              burlywood: '#DEB887',
              cadetblue: '#5F9EA0',
              chartreuse: '#7FFF00',
              chocolate: '#D2691E',
              coral: '#FF7F50',
              cornflowerblue: '#6495ED',
              cornsilk: '#FFF8DC',
              crimson: '#DC143C',
              cyan: '#00FFFF',
              darkblue: '#00008B',
              darkcyan: '#008B8B',
              darkgoldenrod: '#B8860B',
              darkgray: '#A9A9A9',
              darkgreen: '#006400',
              darkgrey: '#A9A9A9',
              darkkhaki: '#BDB76B',
              darkmagenta: '#8B008B',
              darkolivegreen: '#556B2F',
              darkorange: '#FF8C00',
              darkorchid: '#9932CC',
              darkred: '#8B0000',
              darksalmon: '#E9967A',
              darkseagreen: '#8FBC8F',
              darkslateblue: '#483D8B',
              darkslategray: '#2F4F4F',
              darkslategrey: '#2F4F4F',
              darkturquoise: '#00CED1',
              darkviolet: '#9400D3',
              deeppink: '#FF1493',
              deepskyblue: '#00BFFF',
              dimgray: '#696969',
              dimgrey: '#696969',
              dodgerblue: '#1E90FF',
              firebrick: '#B22222',
              floralwhite: '#FFFAF0',
              forestgreen: '#228B22',
              gainsboro: '#DCDCDC',
              ghostwhite: '#F8F8FF',
              gold: '#FFD700',
              goldenrod: '#DAA520',
              grey: '#808080',
              greenyellow: '#ADFF2F',
              honeydew: '#F0FFF0',
              hotpink: '#FF69B4',
              indianred: '#CD5C5C',
              indigo: '#4B0082',
              ivory: '#FFFFF0',
              khaki: '#F0E68C',
              lavender: '#E6E6FA',
              lavenderblush: '#FFF0F5',
              lawngreen: '#7CFC00',
              lemonchiffon: '#FFFACD',
              lightblue: '#ADD8E6',
              lightcoral: '#F08080',
              lightcyan: '#E0FFFF',
              lightgoldenrodyellow: '#FAFAD2',
              lightgreen: '#90EE90',
              lightgrey: '#D3D3D3',
              lightpink: '#FFB6C1',
              lightsalmon: '#FFA07A',
              lightseagreen: '#20B2AA',
              lightskyblue: '#87CEFA',
              lightslategray: '#778899',
              lightslategrey: '#778899',
              lightsteelblue: '#B0C4DE',
              lightyellow: '#FFFFE0',
              limegreen: '#32CD32',
              linen: '#FAF0E6',
              magenta: '#FF00FF',
              mediumaquamarine: '#66CDAA',
              mediumblue: '#0000CD',
              mediumorchid: '#BA55D3',
              mediumpurple: '#9370DB',
              mediumseagreen: '#3CB371',
              mediumslateblue: '#7B68EE',
              mediumspringgreen: '#00FA9A',
              mediumturquoise: '#48D1CC',
              mediumvioletred: '#C71585',
              midnightblue: '#191970',
              mintcream: '#F5FFFA',
              mistyrose: '#FFE4E1',
              moccasin: '#FFE4B5',
              navajowhite: '#FFDEAD',
              oldlace: '#FDF5E6',
              olivedrab: '#6B8E23',
              orange: '#FFA500',
              orangered: '#FF4500',
              orchid: '#DA70D6',
              palegoldenrod: '#EEE8AA',
              palegreen: '#98FB98',
              paleturquoise: '#AFEEEE',
              palevioletred: '#DB7093',
              papayawhip: '#FFEFD5',
              peachpuff: '#FFDAB9',
              peru: '#CD853F',
              pink: '#FFC0CB',
              plum: '#DDA0DD',
              powderblue: '#B0E0E6',
              rosybrown: '#BC8F8F',
              royalblue: '#4169E1',
              saddlebrown: '#8B4513',
              salmon: '#FA8072',
              sandybrown: '#F4A460',
              seagreen: '#2E8B57',
              seashell: '#FFF5EE',
              sienna: '#A0522D',
              skyblue: '#87CEEB',
              slateblue: '#6A5ACD',
              slategray: '#708090',
              slategrey: '#708090',
              snow: '#FFFAFA',
              springgreen: '#00FF7F',
              steelblue: '#4682B4',
              tan: '#D2B48C',
              thistle: '#D8BFD8',
              tomato: '#FF6347',
              turquoise: '#40E0D0',
              violet: '#EE82EE',
              wheat: '#F5DEB3',
              whitesmoke: '#F5F5F5',
              yellowgreen: '#9ACD32'
          };
  
  
          function getRgbHslContent(styleString) {
              var start = styleString.indexOf('(', 3);
              var end = styleString.indexOf(')', start + 1);
              var parts = styleString.substring(start + 1, end).split(',');
              // add alpha if needed
              if (parts.length != 4 || styleString.charAt(3) != 'a') {
                  parts[3] = 1;
              }
              return parts;
          }
  
          function percent(s) {
              return parseFloat(s) / 100;
          }
  
          function clamp(v, min, max) {
              return Math.min(max, Math.max(min, v));
          }
  
          function hslToRgb(parts) {
              var r, g, b, h, s, l;
              h = parseFloat(parts[0]) / 360 % 360;
              if (h < 0)
                  h++;
              s = clamp(percent(parts[1]), 0, 1);
              l = clamp(percent(parts[2]), 0, 1);
              if (s == 0) {
                  r = g = b = l; // achromatic
              } else {
                  var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
                  var p = 2 * l - q;
                  r = hueToRgb(p, q, h + 1 / 3);
                  g = hueToRgb(p, q, h);
                  b = hueToRgb(p, q, h - 1 / 3);
              }
  
              return '#' + decToHex[Math.floor(r * 255)] +
                  decToHex[Math.floor(g * 255)] +
                  decToHex[Math.floor(b * 255)];
          }
  
          function hueToRgb(m1, m2, h) {
              if (h < 0)
                  h++;
              if (h > 1)
                  h--;
  
              if (6 * h < 1)
                  return m1 + (m2 - m1) * 6 * h;
              else if (2 * h < 1)
                  return m2;
              else if (3 * h < 2)
                  return m1 + (m2 - m1) * (2 / 3 - h) * 6;
              else
                  return m1;
          }
  
          var processStyleCache = {};
  
          function processStyle(styleString) {
              if (styleString in processStyleCache) {
                  return processStyleCache[styleString];
              }
  
              var str, alpha = 1;
  
              styleString = String(styleString);
              if (styleString.charAt(0) == '#') {
                  str = styleString;
              } else if (/^rgb/.test(styleString)) {
                  var parts = getRgbHslContent(styleString);
                  var str = '#', n;
                  for (var i = 0; i < 3; i++) {
                      if (parts[i].indexOf('%') != -1) {
                          n = Math.floor(percent(parts[i]) * 255);
                      } else {
                          n = +parts[i];
                      }
                      str += decToHex[clamp(n, 0, 255)];
                  }
                  alpha = +parts[3];
              } else if (/^hsl/.test(styleString)) {
                  var parts = getRgbHslContent(styleString);
                  str = hslToRgb(parts);
                  alpha = parts[3];
              } else {
                  str = colorData[styleString] || styleString;
              }
              return processStyleCache[styleString] = {color: str, alpha: alpha};
          }
  
          var DEFAULT_STYLE = {
              style: 'normal',
              variant: 'normal',
              weight: 'normal',
              size: 10,
              family: 'sans-serif'
          };
  
          // Internal text style cache
          var fontStyleCache = {};
  
          function processFontStyle(styleString) {
              if (fontStyleCache[styleString]) {
                  return fontStyleCache[styleString];
              }
  
              var el = document.createElement('div');
              var style = el.style;
              try {
                  style.font = styleString;
              } catch (ex) {
                  // Ignore failures to set to invalid font.
              }
  
              return fontStyleCache[styleString] = {
                  style: style.fontStyle || DEFAULT_STYLE.style,
                  variant: style.fontVariant || DEFAULT_STYLE.variant,
                  weight: style.fontWeight || DEFAULT_STYLE.weight,
                  size: style.fontSize || DEFAULT_STYLE.size,
                  family: style.fontFamily || DEFAULT_STYLE.family
              };
          }
  
          function getComputedStyle(style, element) {
              var computedStyle = {};
  
              for (var p in style) {
                  computedStyle[p] = style[p];
              }
  
              // Compute the size
              var canvasFontSize = parseFloat(element.currentStyle.fontSize),
                  fontSize = parseFloat(style.size);
  
              if (typeof style.size == 'number') {
                  computedStyle.size = style.size;
              } else if (style.size.indexOf('px') != -1) {
                  computedStyle.size = fontSize;
              } else if (style.size.indexOf('em') != -1) {
                  computedStyle.size = canvasFontSize * fontSize;
              } else if (style.size.indexOf('%') != -1) {
                  computedStyle.size = (canvasFontSize / 100) * fontSize;
              } else if (style.size.indexOf('pt') != -1) {
                  computedStyle.size = fontSize / .75;
              } else {
                  computedStyle.size = canvasFontSize;
              }
  
              // Different scaling between normal text and VML text. This was found using
              // trial and error to get the same size as non VML text.
              computedStyle.size *= 0.981;
  
              return computedStyle;
          }
  
          function buildStyle(style) {
              return style.style + ' ' + style.variant + ' ' + style.weight + ' ' +
                  style.size + 'px ' + style.family;
          }
  
          var lineCapMap = {
              'butt': 'flat',
              'round': 'round'
          };
  
          function processLineCap(lineCap) {
              return lineCapMap[lineCap] || 'square';
          }
  
          /**
           * This class implements CanvasRenderingContext2D interface as described by
           * the WHATWG.
           * @param {HTMLElement} canvasElement The element that the 2D context should
           * be associated with
           */
          function CanvasRenderingContext2D_(canvasElement) {
              this.m_ = createMatrixIdentity();
  
              this.mStack_ = [];
              this.aStack_ = [];
              this.currentPath_ = [];
  
              // Canvas context properties
              this.strokeStyle = '#000';
              this.fillStyle = '#000';
  
              this.lineWidth = 1;
              this.lineJoin = 'miter';
              this.lineCap = 'butt';
              this.miterLimit = Z * 1;
              this.globalAlpha = 1;
              this.font = '10px sans-serif';
              this.textAlign = 'left';
              this.textBaseline = 'alphabetic';
              this.canvas = canvasElement;
  
              var cssText = 'width:' + canvasElement.clientWidth + 'px;height:' +
                  canvasElement.clientHeight + 'px;overflow:hidden;position:absolute';
              var el = canvasElement.ownerDocument.createElement('div');
              el.style.cssText = cssText;
              canvasElement.appendChild(el);
  
              var overlayEl = el.cloneNode(false);
              // Use a non transparent background.
              overlayEl.style.backgroundColor = 'red';
              overlayEl.style.filter = 'alpha(opacity=0)';
              canvasElement.appendChild(overlayEl);
  
              this.element_ = el;
              this.arcScaleX_ = 1;
              this.arcScaleY_ = 1;
              this.lineScale_ = 1;
          }
  
          var contextPrototype = CanvasRenderingContext2D_.prototype;
          contextPrototype.clearRect = function () {
              if (this.textMeasureEl_) {
                  this.textMeasureEl_.removeNode(true);
                  this.textMeasureEl_ = null;
              }
              this.element_.innerHTML = '';
          };
  
          contextPrototype.beginPath = function () {
              // TODO: Branch current matrix so that save/restore has no effect
              //       as per safari docs.
              this.currentPath_ = [];
          };
  
          contextPrototype.moveTo = function (aX, aY) {
              var p = getCoords(this, aX, aY);
              this.currentPath_.push({type: 'moveTo', x: p.x, y: p.y});
              this.currentX_ = p.x;
              this.currentY_ = p.y;
          };
  
          contextPrototype.lineTo = function (aX, aY) {
              var p = getCoords(this, aX, aY);
              this.currentPath_.push({type: 'lineTo', x: p.x, y: p.y});
  
              this.currentX_ = p.x;
              this.currentY_ = p.y;
          };
  
          contextPrototype.bezierCurveTo = function (aCP1x, aCP1y,
                                                     aCP2x, aCP2y,
                                                     aX, aY) {
              var p = getCoords(this, aX, aY);
              var cp1 = getCoords(this, aCP1x, aCP1y);
              var cp2 = getCoords(this, aCP2x, aCP2y);
              bezierCurveTo(this, cp1, cp2, p);
          };
  
          // Helper function that takes the already fixed cordinates.
          function bezierCurveTo(self, cp1, cp2, p) {
              self.currentPath_.push({
                  type: 'bezierCurveTo',
                  cp1x: cp1.x,
                  cp1y: cp1.y,
                  cp2x: cp2.x,
                  cp2y: cp2.y,
                  x: p.x,
                  y: p.y
              });
              self.currentX_ = p.x;
              self.currentY_ = p.y;
          }
  
          contextPrototype.quadraticCurveTo = function (aCPx, aCPy, aX, aY) {
              // the following is lifted almost directly from
              // http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes
  
              var cp = getCoords(this, aCPx, aCPy);
              var p = getCoords(this, aX, aY);
  
              var cp1 = {
                  x: this.currentX_ + 2.0 / 3.0 * (cp.x - this.currentX_),
                  y: this.currentY_ + 2.0 / 3.0 * (cp.y - this.currentY_)
              };
              var cp2 = {
                  x: cp1.x + (p.x - this.currentX_) / 3.0,
                  y: cp1.y + (p.y - this.currentY_) / 3.0
              };
  
              bezierCurveTo(this, cp1, cp2, p);
          };
  
          contextPrototype.arc = function (aX, aY, aRadius,
                                           aStartAngle, aEndAngle, aClockwise) {
              aRadius *= Z;
              var arcType = aClockwise ? 'at' : 'wa';
  
              var xStart = aX + mc(aStartAngle) * aRadius - Z2;
              var yStart = aY + ms(aStartAngle) * aRadius - Z2;
  
              var xEnd = aX + mc(aEndAngle) * aRadius - Z2;
              var yEnd = aY + ms(aEndAngle) * aRadius - Z2;
  
              // IE won't render arches drawn counter clockwise if xStart == xEnd.
              if (xStart == xEnd && !aClockwise) {
                  xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use something
                                   // that can be represented in binary
              }
  
              var p = getCoords(this, aX, aY);
              var pStart = getCoords(this, xStart, yStart);
              var pEnd = getCoords(this, xEnd, yEnd);
  
              this.currentPath_.push({
                  type: arcType,
                  x: p.x,
                  y: p.y,
                  radius: aRadius,
                  xStart: pStart.x,
                  yStart: pStart.y,
                  xEnd: pEnd.x,
                  yEnd: pEnd.y
              });
  
          };
  
          contextPrototype.rect = function (aX, aY, aWidth, aHeight) {
              this.moveTo(aX, aY);
              this.lineTo(aX + aWidth, aY);
              this.lineTo(aX + aWidth, aY + aHeight);
              this.lineTo(aX, aY + aHeight);
              this.closePath();
          };
  
          contextPrototype.strokeRect = function (aX, aY, aWidth, aHeight) {
              var oldPath = this.currentPath_;
              this.beginPath();
  
              this.moveTo(aX, aY);
              this.lineTo(aX + aWidth, aY);
              this.lineTo(aX + aWidth, aY + aHeight);
              this.lineTo(aX, aY + aHeight);
              this.closePath();
              this.stroke();
  
              this.currentPath_ = oldPath;
          };
  
          contextPrototype.fillRect = function (aX, aY, aWidth, aHeight) {
              var oldPath = this.currentPath_;
              this.beginPath();
  
              this.moveTo(aX, aY);
              this.lineTo(aX + aWidth, aY);
              this.lineTo(aX + aWidth, aY + aHeight);
              this.lineTo(aX, aY + aHeight);
              this.closePath();
              this.fill();
  
              this.currentPath_ = oldPath;
          };
  
          contextPrototype.createLinearGradient = function (aX0, aY0, aX1, aY1) {
              var gradient = new CanvasGradient_('gradient');
              gradient.x0_ = aX0;
              gradient.y0_ = aY0;
              gradient.x1_ = aX1;
              gradient.y1_ = aY1;
              return gradient;
          };
  
          contextPrototype.createRadialGradient = function (aX0, aY0, aR0,
                                                            aX1, aY1, aR1) {
              var gradient = new CanvasGradient_('gradientradial');
              gradient.x0_ = aX0;
              gradient.y0_ = aY0;
              gradient.r0_ = aR0;
              gradient.x1_ = aX1;
              gradient.y1_ = aY1;
              gradient.r1_ = aR1;
              return gradient;
          };
  
          contextPrototype.drawImage = function (image, var_args) {
              var dx, dy, dw, dh, sx, sy, sw, sh;
  
              // to find the original width we overide the width and height
              var oldRuntimeWidth = image.runtimeStyle.width;
              var oldRuntimeHeight = image.runtimeStyle.height;
              image.runtimeStyle.width = 'auto';
              image.runtimeStyle.height = 'auto';
  
              // get the original size
              var w = image.width;
              var h = image.height;
  
              // and remove overides
              image.runtimeStyle.width = oldRuntimeWidth;
              image.runtimeStyle.height = oldRuntimeHeight;
  
              if (arguments.length == 3) {
                  dx = arguments[1];
                  dy = arguments[2];
                  sx = sy = 0;
                  sw = dw = w;
                  sh = dh = h;
              } else if (arguments.length == 5) {
                  dx = arguments[1];
                  dy = arguments[2];
                  dw = arguments[3];
                  dh = arguments[4];
                  sx = sy = 0;
                  sw = w;
                  sh = h;
              } else if (arguments.length == 9) {
                  sx = arguments[1];
                  sy = arguments[2];
                  sw = arguments[3];
                  sh = arguments[4];
                  dx = arguments[5];
                  dy = arguments[6];
                  dw = arguments[7];
                  dh = arguments[8];
              } else {
                  throw Error('Invalid number of arguments');
              }
  
              var d = getCoords(this, dx, dy);
  
              var w2 = sw / 2;
              var h2 = sh / 2;
  
              var vmlStr = [];
  
              var W = 10;
              var H = 10;
  
              // For some reason that I've now forgotten, using divs didn't work
              vmlStr.push(' <g_vml_:group',
                  ' coordsize="', Z * W, ',', Z * H, '"',
                  ' coordorigin="0,0"',
                  ' style="width:', W, 'px;height:', H, 'px;position:absolute;');
  
              // If filters are necessary (rotation exists), create them
              // filters are bog-slow, so only create them if abbsolutely necessary
              // The following check doesn't account for skews (which don't exist
              // in the canvas spec (yet) anyway.
  
              if (this.m_[0][0] != 1 || this.m_[0][1] ||
                  this.m_[1][1] != 1 || this.m_[1][0]) {
                  var filter = [];
  
                  // Note the 12/21 reversal
                  filter.push('M11=', this.m_[0][0], ',',
                      'M12=', this.m_[1][0], ',',
                      'M21=', this.m_[0][1], ',',
                      'M22=', this.m_[1][1], ',',
                      'Dx=', mr(d.x / Z), ',',
                      'Dy=', mr(d.y / Z), '');
  
                  // Bounding box calculation (need to minimize displayed area so that
                  // filters don't waste time on unused pixels.
                  var max = d;
                  var c2 = getCoords(this, dx + dw, dy);
                  var c3 = getCoords(this, dx, dy + dh);
                  var c4 = getCoords(this, dx + dw, dy + dh);
  
                  max.x = m.max(max.x, c2.x, c3.x, c4.x);
                  max.y = m.max(max.y, c2.y, c3.y, c4.y);
  
                  vmlStr.push('padding:0 ', mr(max.x / Z), 'px ', mr(max.y / Z),
                      'px 0;filter:progid:DXImageTransform.Microsoft.Matrix(',
                      filter.join(''), ", sizingmethod='clip');");
  
              } else {
                  vmlStr.push('top:', mr(d.y / Z), 'px;left:', mr(d.x / Z), 'px;');
              }
  
              vmlStr.push(' ">',
                  '<g_vml_:image src="', image.src, '"',
                  ' style="width:', Z * dw, 'px;',
                  ' height:', Z * dh, 'px"',
                  ' cropleft="', sx / w, '"',
                  ' croptop="', sy / h, '"',
                  ' cropright="', (w - sx - sw) / w, '"',
                  ' cropbottom="', (h - sy - sh) / h, '"',
                  ' />',
                  '</g_vml_:group>');
  
              this.element_.insertAdjacentHTML('BeforeEnd', vmlStr.join(''));
          };
  
          contextPrototype.stroke = function (aFill) {
              var W = 10;
              var H = 10;
              // Divide the shape into chunks if it's too long because IE has a limit
              // somewhere for how long a VML shape can be. This simple division does
              // not work with fills, only strokes, unfortunately.
              var chunkSize = 5000;
  
              var min = {x: null, y: null};
              var max = {x: null, y: null};
  
              for (var j = 0; j < this.currentPath_.length; j += chunkSize) {
                  var lineStr = [];
                  var lineOpen = false;
  
                  lineStr.push('<g_vml_:shape',
                      ' filled="', !!aFill, '"',
                      ' style="position:absolute;width:', W, 'px;height:', H, 'px;"',
                      ' coordorigin="0,0"',
                      ' coordsize="', Z * W, ',', Z * H, '"',
                      ' stroked="', !aFill, '"',
                      ' path="');
  
                  var newSeq = false;
  
                  for (var i = j; i < Math.min(j + chunkSize, this.currentPath_.length); i++) {
                      if (i % chunkSize == 0 && i > 0) { // move into position for next chunk
                          lineStr.push(' m ', mr(this.currentPath_[i - 1].x), ',', mr(this.currentPath_[i - 1].y));
                      }
  
                      var p = this.currentPath_[i];
                      var c;
  
                      switch (p.type) {
                          case 'moveTo':
                              c = p;
                              lineStr.push(' m ', mr(p.x), ',', mr(p.y));
                              break;
                          case 'lineTo':
                              lineStr.push(' l ', mr(p.x), ',', mr(p.y));
                              break;
                          case 'close':
                              lineStr.push(' x ');
                              p = null;
                              break;
                          case 'bezierCurveTo':
                              lineStr.push(' c ',
                                  mr(p.cp1x), ',', mr(p.cp1y), ',',
                                  mr(p.cp2x), ',', mr(p.cp2y), ',',
                                  mr(p.x), ',', mr(p.y));
                              break;
                          case 'at':
                          case 'wa':
                              lineStr.push(' ', p.type, ' ',
                                  mr(p.x - this.arcScaleX_ * p.radius), ',',
                                  mr(p.y - this.arcScaleY_ * p.radius), ' ',
                                  mr(p.x + this.arcScaleX_ * p.radius), ',',
                                  mr(p.y + this.arcScaleY_ * p.radius), ' ',
                                  mr(p.xStart), ',', mr(p.yStart), ' ',
                                  mr(p.xEnd), ',', mr(p.yEnd));
                              break;
                      }
  
  
                      // TODO: Following is broken for curves due to
                      //       move to proper paths.
  
                      // Figure out dimensions so we can do gradient fills
                      // properly
                      if (p) {
                          if (min.x == null || p.x < min.x) {
                              min.x = p.x;
                          }
                          if (max.x == null || p.x > max.x) {
                              max.x = p.x;
                          }
                          if (min.y == null || p.y < min.y) {
                              min.y = p.y;
                          }
                          if (max.y == null || p.y > max.y) {
                              max.y = p.y;
                          }
                      }
                  }
                  lineStr.push(' ">');
  
                  if (!aFill) {
                      appendStroke(this, lineStr);
                  } else {
                      appendFill(this, lineStr, min, max);
                  }
  
                  lineStr.push('</g_vml_:shape>');
  
                  this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));
              }
          };
  
          function appendStroke(ctx, lineStr) {
              var a = processStyle(ctx.strokeStyle);
              var color = a.color;
              var opacity = a.alpha * ctx.globalAlpha;
              var lineWidth = ctx.lineScale_ * ctx.lineWidth;
  
              // VML cannot correctly render a line if the width is less than 1px.
              // In that case, we dilute the color to make the line look thinner.
              if (lineWidth < 1) {
                  opacity *= lineWidth;
              }
  
              lineStr.push(
                  '<g_vml_:stroke',
                  ' opacity="', opacity, '"',
                  ' joinstyle="', ctx.lineJoin, '"',
                  ' miterlimit="', ctx.miterLimit, '"',
                  ' endcap="', processLineCap(ctx.lineCap), '"',
                  ' weight="', lineWidth, 'px"',
                  ' color="', color, '" />'
              );
          }
  
          function appendFill(ctx, lineStr, min, max) {
              var fillStyle = ctx.fillStyle;
              var arcScaleX = ctx.arcScaleX_;
              var arcScaleY = ctx.arcScaleY_;
              var width = max.x - min.x;
              var height = max.y - min.y;
              if (fillStyle instanceof CanvasGradient_) {
                  // TODO: Gradients transformed with the transformation matrix.
                  var angle = 0;
                  var focus = {x: 0, y: 0};
  
                  // additional offset
                  var shift = 0;
                  // scale factor for offset
                  var expansion = 1;
  
                  if (fillStyle.type_ == 'gradient') {
                      var x0 = fillStyle.x0_ / arcScaleX;
                      var y0 = fillStyle.y0_ / arcScaleY;
                      var x1 = fillStyle.x1_ / arcScaleX;
                      var y1 = fillStyle.y1_ / arcScaleY;
                      var p0 = getCoords(ctx, x0, y0);
                      var p1 = getCoords(ctx, x1, y1);
                      var dx = p1.x - p0.x;
                      var dy = p1.y - p0.y;
                      angle = Math.atan2(dx, dy) * 180 / Math.PI;
  
                      // The angle should be a non-negative number.
                      if (angle < 0) {
                          angle += 360;
                      }
  
                      // Very small angles produce an unexpected result because they are
                      // converted to a scientific notation string.
                      if (angle < 1e-6) {
                          angle = 0;
                      }
                  } else {
                      var p0 = getCoords(ctx, fillStyle.x0_, fillStyle.y0_);
                      focus = {
                          x: (p0.x - min.x) / width,
                          y: (p0.y - min.y) / height
                      };
  
                      width /= arcScaleX * Z;
                      height /= arcScaleY * Z;
                      var dimension = m.max(width, height);
                      shift = 2 * fillStyle.r0_ / dimension;
                      expansion = 2 * fillStyle.r1_ / dimension - shift;
                  }
  
                  // We need to sort the color stops in ascending order by offset,
                  // otherwise IE won't interpret it correctly.
                  var stops = fillStyle.colors_;
                  stops.sort(function (cs1, cs2) {
                      return cs1.offset - cs2.offset;
                  });
  
                  var length = stops.length;
                  var color1 = stops[0].color;
                  var color2 = stops[length - 1].color;
                  var opacity1 = stops[0].alpha * ctx.globalAlpha;
                  var opacity2 = stops[length - 1].alpha * ctx.globalAlpha;
  
                  var colors = [];
                  for (var i = 0; i < length; i++) {
                      var stop = stops[i];
                      colors.push(stop.offset * expansion + shift + ' ' + stop.color);
                  }
  
                  // When colors attribute is used, the meanings of opacity and o:opacity2
                  // are reversed.
                  lineStr.push('<g_vml_:fill type="', fillStyle.type_, '"',
                      ' method="none" focus="100%"',
                      ' color="', color1, '"',
                      ' color2="', color2, '"',
                      ' colors="', colors.join(','), '"',
                      ' opacity="', opacity2, '"',
                      ' g_o_:opacity2="', opacity1, '"',
                      ' angle="', angle, '"',
                      ' focusposition="', focus.x, ',', focus.y, '" />');
              } else if (fillStyle instanceof CanvasPattern_) {
                  if (width && height) {
                      var deltaLeft = -min.x;
                      var deltaTop = -min.y;
                      lineStr.push('<g_vml_:fill',
                          ' position="',
                          deltaLeft / width * arcScaleX * arcScaleX, ',',
                          deltaTop / height * arcScaleY * arcScaleY, '"',
                          ' type="tile"',
                          // TODO: Figure out the correct size to fit the scale.
                          //' size="', w, 'px ', h, 'px"',
                          ' src="', fillStyle.src_, '" />');
                  }
              } else {
                  var a = processStyle(ctx.fillStyle);
                  var color = a.color;
                  var opacity = a.alpha * ctx.globalAlpha;
                  lineStr.push('<g_vml_:fill color="', color, '" opacity="', opacity,
                      '" />');
              }
          }
  
          contextPrototype.fill = function () {
              this.stroke(true);
          };
  
          contextPrototype.closePath = function () {
              this.currentPath_.push({type: 'close'});
          };
  
          function getCoords(ctx, aX, aY) {
              var m = ctx.m_;
              return {
                  x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,
                  y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2
              };
          };
  
          contextPrototype.save = function () {
              var o = {};
              copyState(this, o);
              this.aStack_.push(o);
              this.mStack_.push(this.m_);
              this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
          };
  
          contextPrototype.restore = function () {
              if (this.aStack_.length) {
                  copyState(this.aStack_.pop(), this);
                  this.m_ = this.mStack_.pop();
              }
          };
  
          function matrixIsFinite(m) {
              return isFinite(m[0][0]) && isFinite(m[0][1]) &&
                  isFinite(m[1][0]) && isFinite(m[1][1]) &&
                  isFinite(m[2][0]) && isFinite(m[2][1]);
          }
  
          function setM(ctx, m, updateLineScale) {
              if (!matrixIsFinite(m)) {
                  return;
              }
              ctx.m_ = m;
  
              if (updateLineScale) {
                  // Get the line scale.
                  // Determinant of this.m_ means how much the area is enlarged by the
                  // transformation. So its square root can be used as a scale factor
                  // for width.
                  var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];
                  ctx.lineScale_ = sqrt(abs(det));
              }
          }
  
          contextPrototype.translate = function (aX, aY) {
              var m1 = [
                  [1, 0, 0],
                  [0, 1, 0],
                  [aX, aY, 1]
              ];
  
              setM(this, matrixMultiply(m1, this.m_), false);
          };
  
          contextPrototype.rotate = function (aRot) {
              var c = mc(aRot);
              var s = ms(aRot);
  
              var m1 = [
                  [c, s, 0],
                  [-s, c, 0],
                  [0, 0, 1]
              ];
  
              setM(this, matrixMultiply(m1, this.m_), false);
          };
  
          contextPrototype.scale = function (aX, aY) {
              this.arcScaleX_ *= aX;
              this.arcScaleY_ *= aY;
              var m1 = [
                  [aX, 0, 0],
                  [0, aY, 0],
                  [0, 0, 1]
              ];
  
              setM(this, matrixMultiply(m1, this.m_), true);
          };
  
          contextPrototype.transform = function (m11, m12, m21, m22, dx, dy) {
              var m1 = [
                  [m11, m12, 0],
                  [m21, m22, 0],
                  [dx, dy, 1]
              ];
  
              setM(this, matrixMultiply(m1, this.m_), true);
          };
  
          contextPrototype.setTransform = function (m11, m12, m21, m22, dx, dy) {
              var m = [
                  [m11, m12, 0],
                  [m21, m22, 0],
                  [dx, dy, 1]
              ];
  
              setM(this, m, true);
          };
  
          /**
           * The text drawing function.
           * The maxWidth argument isn't taken in account, since no browser supports
           * it yet.
           */
          contextPrototype.drawText_ = function (text, x, y, maxWidth, stroke) {
              var m = this.m_,
                  delta = 1000,
                  left = 0,
                  right = delta,
                  offset = {x: 0, y: 0},
                  lineStr = [];
  
              var fontStyle = getComputedStyle(processFontStyle(this.font),
                  this.element_);
  
              var fontStyleString = buildStyle(fontStyle);
  
              var elementStyle = this.element_.currentStyle;
              var textAlign = this.textAlign.toLowerCase();
              switch (textAlign) {
                  case 'left':
                  case 'center':
                  case 'right':
                      break;
                  case 'end':
                      textAlign = elementStyle.direction == 'ltr' ? 'right' : 'left';
                      break;
                  case 'start':
                      textAlign = elementStyle.direction == 'rtl' ? 'right' : 'left';
                      break;
                  default:
                      textAlign = 'left';
              }
  
              // 1.75 is an arbitrary number, as there is no info about the text baseline
              switch (this.textBaseline) {
                  case 'hanging':
                  case 'top':
                      offset.y = fontStyle.size / 1.75;
                      break;
                  case 'middle':
                      break;
                  default:
                  case null:
                  case 'alphabetic':
                  case 'ideographic':
                  case 'bottom':
                      offset.y = -fontStyle.size / 2.25;
                      break;
              }
  
              switch (textAlign) {
                  case 'right':
                      left = delta;
                      right = 0.05;
                      break;
                  case 'center':
                      left = right = delta / 2;
                      break;
              }
  
              var d = getCoords(this, x + offset.x, y + offset.y);
  
              lineStr.push('<g_vml_:line from="', -left, ' 0" to="', right, ' 0.05" ',
                  ' coordsize="100 100" coordorigin="0 0"',
                  ' filled="', !stroke, '" stroked="', !!stroke,
                  '" style="position:absolute;width:1px;height:1px;">');
  
              if (stroke) {
                  appendStroke(this, lineStr);
              } else {
                  // TODO: Fix the min and max params.
                  appendFill(this, lineStr, {x: -left, y: 0},
                      {x: right, y: fontStyle.size});
              }
  
              var skewM = m[0][0].toFixed(3) + ',' + m[1][0].toFixed(3) + ',' +
                  m[0][1].toFixed(3) + ',' + m[1][1].toFixed(3) + ',0,0';
  
              var skewOffset = mr(d.x / Z) + ',' + mr(d.y / Z);
  
              lineStr.push('<g_vml_:skew on="t" matrix="', skewM, '" ',
                  ' offset="', skewOffset, '" origin="', left, ' 0" />',
                  '<g_vml_:path textpathok="true" />',
                  '<g_vml_:textpath on="true" string="',
                  encodeHtmlAttribute(text),
                  '" style="v-text-align:', textAlign,
                  ';font:', encodeHtmlAttribute(fontStyleString),
                  '" /></g_vml_:line>');
  
              this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));
          };
  
          contextPrototype.fillText = function (text, x, y, maxWidth) {
              this.drawText_(text, x, y, maxWidth, false);
          };
  
          contextPrototype.strokeText = function (text, x, y, maxWidth) {
              this.drawText_(text, x, y, maxWidth, true);
          };
  
          contextPrototype.measureText = function (text) {
              if (!this.textMeasureEl_) {
                  var s = '<span style="position:absolute;' +
                      'top:-20000px;left:0;padding:0;margin:0;border:none;' +
                      'white-space:pre;"></span>';
                  this.element_.insertAdjacentHTML('beforeEnd', s);
                  this.textMeasureEl_ = this.element_.lastChild;
              }
              var doc = this.element_.ownerDocument;
              this.textMeasureEl_.innerHTML = '';
              this.textMeasureEl_.style.font = this.font;
              // Don't use innerHTML or innerText because they allow markup/whitespace.
              this.textMeasureEl_.appendChild(doc.createTextNode(text));
              return {width: this.textMeasureEl_.offsetWidth};
          };
  
          /******** STUBS ********/
          contextPrototype.clip = function () {
              // TODO: Implement
          };
  
          contextPrototype.arcTo = function () {
              // TODO: Implement
          };
  
          contextPrototype.createPattern = function (image, repetition) {
              return new CanvasPattern_(image, repetition);
          };
  
          // Gradient / Pattern Stubs
          function CanvasGradient_(aType) {
              this.type_ = aType;
              this.x0_ = 0;
              this.y0_ = 0;
              this.r0_ = 0;
              this.x1_ = 0;
              this.y1_ = 0;
              this.r1_ = 0;
              this.colors_ = [];
          }
  
          CanvasGradient_.prototype.addColorStop = function (aOffset, aColor) {
              aColor = processStyle(aColor);
              this.colors_.push({
                  offset: aOffset,
                  color: aColor.color,
                  alpha: aColor.alpha
              });
          };
  
          function CanvasPattern_(image, repetition) {
              assertImageIsValid(image);
              switch (repetition) {
                  case 'repeat':
                  case null:
                  case '':
                      this.repetition_ = 'repeat';
                      break
                  case 'repeat-x':
                  case 'repeat-y':
                  case 'no-repeat':
                      this.repetition_ = repetition;
                      break;
                  default:
                      throwException('SYNTAX_ERR');
              }
  
              this.src_ = image.src;
              this.width_ = image.width;
              this.height_ = image.height;
          }
  
          function throwException(s) {
              throw new DOMException_(s);
          }
  
          function assertImageIsValid(img) {
              if (!img || img.nodeType != 1 || img.tagName != 'IMG') {
                  throwException('TYPE_MISMATCH_ERR');
              }
              if (img.readyState != 'complete') {
                  throwException('INVALID_STATE_ERR');
              }
          }
  
          function DOMException_(s) {
              this.code = this[s];
              this.message = s + ': DOM Exception ' + this.code;
          }
  
          var p = DOMException_.prototype = new Error;
          p.INDEX_SIZE_ERR = 1;
          p.DOMSTRING_SIZE_ERR = 2;
          p.HIERARCHY_REQUEST_ERR = 3;
          p.WRONG_DOCUMENT_ERR = 4;
          p.INVALID_CHARACTER_ERR = 5;
          p.NO_DATA_ALLOWED_ERR = 6;
          p.NO_MODIFICATION_ALLOWED_ERR = 7;
          p.NOT_FOUND_ERR = 8;
          p.NOT_SUPPORTED_ERR = 9;
          p.INUSE_ATTRIBUTE_ERR = 10;
          p.INVALID_STATE_ERR = 11;
          p.SYNTAX_ERR = 12;
          p.INVALID_MODIFICATION_ERR = 13;
          p.NAMESPACE_ERR = 14;
          p.INVALID_ACCESS_ERR = 15;
          p.VALIDATION_ERR = 16;
          p.TYPE_MISMATCH_ERR = 17;
  
          // set up externs
          G_vmlCanvasManager = G_vmlCanvasManager_;
          CanvasRenderingContext2D = CanvasRenderingContext2D_;
          CanvasGradient = CanvasGradient_;
          CanvasPattern = CanvasPattern_;
          DOMException = DOMException_;
      })();
  
  } // if
  