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// 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