#

API Docs for: 3.10.3
Show: Inherited Protected Private Deprecated

# File: graphics/js/CanvasDrawing.js

    var IMPLEMENTATION = "canvas",
        SHAPE = "shape",
    	SPLITPATHPATTERN = /[a-z][^a-z]*/ig,
        SPLITARGSPATTERN = /[\-]?[0-9]*[0-9|\.][0-9]*/g,
        DOCUMENT = Y.config.doc,
        Y_LANG = Y.Lang,
        AttributeLite = Y.AttributeLite,
    	CanvasShape,
    	CanvasPath,
    	CanvasRect,
        CanvasEllipse,
    	CanvasCircle,
        CanvasPieSlice,
        Y_DOM = Y.DOM,
        Y_Color = Y.Color,
        PARSE_INT = parseInt,
        PARSE_FLOAT = parseFloat,
        IS_NUMBER = Y_LANG.isNumber,
        RE = RegExp,
        TORGB = Y_Color.toRGB,
        TOHEX = Y_Color.toHex,
        _getClassName = Y.ClassNameManager.getClassName;

    /**
     * <a href="http://www.w3.org/TR/html5/the-canvas-element.html">Canvas</a> implementation of the <a href="Drawing.html">`Drawing`</a> class.
     * `CanvasDrawing` is not intended to be used directly. Instead, use the <a href="Drawing.html">`Drawing`</a> class.
     * If the browser lacks <a href="http://www.w3.org/TR/SVG/">SVG</a> capabilities but has
     * <a href="http://www.w3.org/TR/html5/the-canvas-element.html">Canvas</a> capabilities, the <a href="Drawing.html">`Drawing`</a>
     * class will point to the `CanvasDrawing` class.
     *
     * @module graphics
     * @class CanvasDrawing
     * @constructor
     */
    function CanvasDrawing()
    {
    }

    CanvasDrawing.prototype = {
        /**
         * Maps path to methods
         *
         * @property _pathSymbolToMethod
         * @type Object
         * @private
         */
        _pathSymbolToMethod: {
            M: "moveTo",
            m: "relativeMoveTo",
            L: "lineTo",
            l: "relativeLineTo",
            C: "curveTo",
            c: "relativeCurveTo",
            Q: "quadraticCurveTo",
            q: "relativeQuadraticCurveTo",
            z: "closePath",
            Z: "closePath"
        },

        /**
         * Current x position of the drawing.
         *
         * @property _currentX
         * @type Number
         * @private
         */
        _currentX: 0,

        /**
         * Current y position of the drqwing.
         *
         * @property _currentY
         * @type Number
         * @private
         */
        _currentY: 0,

        /**
         * Parses hex color string and alpha value to rgba
         *
         * @method _toRGBA
         * @param {Object} val Color value to parse. Can be hex string, rgb or name.
         * @param {Number} alpha Numeric value between 0 and 1 representing the alpha level.
         * @private
         */
        _toRGBA: function(val, alpha) {
            alpha = (alpha !== undefined) ? alpha : 1;
            if (!Y_Color.re_RGB.test(val)) {
                val = TOHEX(val);
            }

            if(Y_Color.re_hex.exec(val)) {
                val = 'rgba(' + [
                    PARSE_INT(RE.$1, 16),
                    PARSE_INT(RE.$2, 16),
                    PARSE_INT(RE.$3, 16)
                ].join(',') + ',' + alpha + ')';
            }
            return val;
        },

        /**
         * Converts color to rgb format
         *
         * @method _toRGB
         * @param val Color value to convert.
         * @private
         */
        _toRGB: function(val) {
            return TORGB(val);
        },

        /**
         * Sets the size of the graphics object.
         *
         * @method setSize
         * @param w {Number} width to set for the instance.
         * @param h {Number} height to set for the instance.
         * @private
         */
    	setSize: function(w, h) {
            if(this.get("autoSize"))
            {
                if(w > this.node.getAttribute("width"))
                {
                    this.node.style.width = w + "px";
                    this.node.setAttribute("width", w);
                }
                if(h > this.node.getAttribute("height"))
                {
                    this.node.style.height = h + "px";
                    this.node.setAttribute("height", h);
                }
            }
        },

    	/**
         * Tracks coordinates. Used to calculate the start point of dashed lines.
         *
         * @method _updateCoords
         * @param {Number} x x-coordinate
         * @param {Number} y y-coordinate
    	 * @private
    	 */
        _updateCoords: function(x, y)
        {
            this._xcoords.push(x);
            this._ycoords.push(y);
            this._currentX = x;
            this._currentY = y;
        },

    	/**
         * Clears the coordinate arrays. Called at the end of a drawing operation.
    	 *
         * @method _clearAndUpdateCoords
         * @private
    	 */
        _clearAndUpdateCoords: function()
        {
            var x = this._xcoords.pop() || 0,
                y = this._ycoords.pop() || 0;
            this._updateCoords(x, y);
        },

    	/**
         * Moves the shape's dom node.
         *
         * @method _updateNodePosition
    	 * @private
    	 */
        _updateNodePosition: function()
        {
            var node = this.get("node"),
                x = this.get("x"),
                y = this.get("y");
            node.style.position = "absolute";
            node.style.left = (x + this._left) + "px";
            node.style.top = (y + this._top) + "px";
        },

        /**
         * Queues up a method to be executed when a shape redraws.
         *
         * @method _updateDrawingQueue
         * @param {Array} val An array containing data that can be parsed into a method and arguments. The value at zero-index
         * of the array is a string reference of the drawing method that will be called. All subsequent indices are argument for
         * that method. For example, `lineTo(10, 100)` would be structured as:
         * `["lineTo", 10, 100]`.
         * @private
         */
        _updateDrawingQueue: function(val)
        {
            this._methods.push(val);
        },

        /**
         * Draws a line segment from the current drawing position to the specified x and y coordinates.
         *
         * @method lineTo
         * @param {Number} point1 x-coordinate for the end point.
         * @param {Number} point2 y-coordinate for the end point.
         * @chainable
         */
        lineTo: function()
        {
            this._lineTo.apply(this, [Y.Array(arguments), false]);
            return this;
        },

        /**
         * Draws a line segment from the current drawing position to the relative x and y coordinates.
         *
         * @method lineTo
         * @param {Number} point1 x-coordinate for the end point.
         * @param {Number} point2 y-coordinate for the end point.
         * @chainable
         */
        relativeLineTo: function()
        {
            this._lineTo.apply(this, [Y.Array(arguments), true]);
            return this;
        },

        /**
         * Implements lineTo methods.
         *
         * @method _lineTo
         * @param {Array} args The arguments to be used.
         * @param {Boolean} relative Indicates whether or not to use relative coordinates.
         * @private
         */
        _lineTo: function(args, relative)
        {
            var point1 = args[0],
                i,
                len,
                x,
                y,
                wt = this._stroke && this._strokeWeight ? this._strokeWeight : 0,
                relativeX = relative ? parseFloat(this._currentX) : 0,
                relativeY = relative ? parseFloat(this._currentY) : 0;
            if(!this._lineToMethods)
            {
                this._lineToMethods = [];
            }
            len = args.length - 1;
            if (typeof point1 === 'string' || typeof point1 === 'number') {
                for (i = 0; i < len; i = i + 2) {
                    x = parseFloat(args[i]);
                    y = parseFloat(args[i + 1]);
                    x = x + relativeX;
                    y = y + relativeY;
                    this._updateDrawingQueue(["lineTo", x, y]);
                    this._trackSize(x - wt, y - wt);
                    this._trackSize(x + wt, y + wt);
                    this._updateCoords(x, y);
                }
            }
            else
            {
                for (i = 0; i < len; i = i + 1)
                {
                    x = parseFloat(args[i][0]);
                    y = parseFloat(args[i][1]);
                    this._updateDrawingQueue(["lineTo", x, y]);
                    this._lineToMethods[this._lineToMethods.length] = this._methods[this._methods.length - 1];
                    this._trackSize(x - wt, y - wt);
                    this._trackSize(x + wt, y + wt);
                    this._updateCoords(x, y);
                }
            }
            this._drawingComplete = false;
            return this;
        },

        /**
         * Moves the current drawing position to specified x and y coordinates.
         *
         * @method moveTo
         * @param {Number} x x-coordinate for the end point.
         * @param {Number} y y-coordinate for the end point.
         * @chainable
         */
        moveTo: function()
        {
            this._moveTo.apply(this, [Y.Array(arguments), false]);
            return this;
        },

        /**
         * Moves the current drawing position relative to specified x and y coordinates.
         *
         * @method relativeMoveTo
         * @param {Number} x x-coordinate for the end point.
         * @param {Number} y y-coordinate for the end point.
         * @chainable
         */
        relativeMoveTo: function()
        {
            this._moveTo.apply(this, [Y.Array(arguments), true]);
            return this;
        },

        /**
         * Implements moveTo methods.
         *
         * @method _moveTo
         * @param {Array} args The arguments to be used.
         * @param {Boolean} relative Indicates whether or not to use relative coordinates.
         * @private
         */
        _moveTo: function(args, relative) {
            var wt = this._stroke && this._strokeWeight ? this._strokeWeight : 0,
                relativeX = relative ? parseFloat(this._currentX) : 0,
                relativeY = relative ? parseFloat(this._currentY) : 0,
                x = parseFloat(args[0]) + relativeX,
                y = parseFloat(args[1]) + relativeY;
            this._updateDrawingQueue(["moveTo", x, y]);
            this._trackSize(x - wt, y - wt);
            this._trackSize(x + wt, y + wt);
            this._updateCoords(x, y);
            this._drawingComplete = false;
            return this;
        },

        /**
         * Draws a bezier curve.
         *
         * @method curveTo
         * @param {Number} cp1x x-coordinate for the first control point.
         * @param {Number} cp1y y-coordinate for the first control point.
         * @param {Number} cp2x x-coordinate for the second control point.
         * @param {Number} cp2y y-coordinate for the second control point.
         * @param {Number} x x-coordinate for the end point.
         * @param {Number} y y-coordinate for the end point.
         * @chainable
         */
        curveTo: function() {
            this._curveTo.apply(this, [Y.Array(arguments), false]);
            return this;
        },

        /**
         * Draws a bezier curve relative to the current coordinates.
         *
         * @method curveTo
         * @param {Number} cp1x x-coordinate for the first control point.
         * @param {Number} cp1y y-coordinate for the first control point.
         * @param {Number} cp2x x-coordinate for the second control point.
         * @param {Number} cp2y y-coordinate for the second control point.
         * @param {Number} x x-coordinate for the end point.
         * @param {Number} y y-coordinate for the end point.
         * @chainable
         */
        relativeCurveTo: function() {
            this._curveTo.apply(this, [Y.Array(arguments), true]);
            return this;
        },

        /**
         * Implements curveTo methods.
         *
         * @method _curveTo
         * @param {Array} args The arguments to be used.
         * @param {Boolean} relative Indicates whether or not to use relative coordinates.
         * @private
         */
        _curveTo: function(args, relative) {
            var w,
                h,
                cp1x,
                cp1y,
                cp2x,
                cp2y,
                x,
                y,
                pts,
                right,
                left,
                bottom,
                top,
                i,
                len,
                relativeX = relative ? parseFloat(this._currentX) : 0,
                relativeY = relative ? parseFloat(this._currentY) : 0;
            len = args.length - 5;
            for(i = 0; i < len; i = i + 6)
            {
                cp1x = parseFloat(args[i]) + relativeX;
                cp1y = parseFloat(args[i + 1]) + relativeY;
                cp2x = parseFloat(args[i + 2]) + relativeX;
                cp2y = parseFloat(args[i + 3]) + relativeY;
                x = parseFloat(args[i + 4]) + relativeX;
                y = parseFloat(args[i + 5]) + relativeY;
                this._updateDrawingQueue(["bezierCurveTo", cp1x, cp1y, cp2x, cp2y, x, y]);
                this._drawingComplete = false;
                right = Math.max(x, Math.max(cp1x, cp2x));
                bottom = Math.max(y, Math.max(cp1y, cp2y));
                left = Math.min(x, Math.min(cp1x, cp2x));
                top = Math.min(y, Math.min(cp1y, cp2y));
                w = Math.abs(right - left);
                h = Math.abs(bottom - top);
                pts = [[this._currentX, this._currentY] , [cp1x, cp1y], [cp2x, cp2y], [x, y]];
                this._setCurveBoundingBox(pts, w, h);
                this._currentX = x;
                this._currentY = y;
            }
        },

        /**
         * Draws a quadratic bezier curve.
         *
         * @method quadraticCurveTo
         * @param {Number} cpx x-coordinate for the control point.
         * @param {Number} cpy y-coordinate for the control point.
         * @param {Number} x x-coordinate for the end point.
         * @param {Number} y y-coordinate for the end point.
         * @chainable
         */
        quadraticCurveTo: function() {
            this._quadraticCurveTo.apply(this, [Y.Array(arguments), false]);
            return this;
        },

        /**
         * Draws a quadratic bezier curve relative to the current position.
         *
         * @method relativeQuadraticCurveTo
         * @param {Number} cpx x-coordinate for the control point.
         * @param {Number} cpy y-coordinate for the control point.
         * @param {Number} x x-coordinate for the end point.
         * @param {Number} y y-coordinate for the end point.
         * @chainable
         */
        relativeQuadraticCurveTo: function() {
            this._quadraticCurveTo.apply(this, [Y.Array(arguments), true]);
            return this;
        },

        /**
         * Implements quadraticCurveTo methods.
         *
         * @method _quadraticCurveTo
         * @param {Array} args The arguments to be used.
         * @param {Boolean} relative Indicates whether or not to use relative coordinates.
         * @private
         */
        _quadraticCurveTo: function(args, relative) {
            var cpx,
                cpy,
                x,
                y,
                w,
                h,
                pts,
                right,
                left,
                bottom,
                top,
                i,
                len = args.length - 3,
                relativeX = relative ? parseFloat(this._currentX) : 0,
                relativeY = relative ? parseFloat(this._currentY) : 0;
            for(i = 0; i < len; i = i + 4)
            {
                cpx = parseFloat(args[i]) + relativeX;
                cpy = parseFloat(args[i + 1]) + relativeY;
                x = parseFloat(args[i + 2]) + relativeX;
                y = parseFloat(args[i + 3]) + relativeY;
                this._drawingComplete = false;
                right = Math.max(x, cpx);
                bottom = Math.max(y, cpy);
                left = Math.min(x, cpx);
                top = Math.min(y, cpy);
                w = Math.abs(right - left);
                h = Math.abs(bottom - top);
                pts = [[this._currentX, this._currentY] , [cpx, cpy], [x, y]];
                this._setCurveBoundingBox(pts, w, h);
                this._updateDrawingQueue(["quadraticCurveTo", cpx, cpy, x, y]);
                this._updateCoords(x, y);
            }
            return this;
        },

        /**
         * Draws a circle. Used internally by `CanvasCircle` class.
         *
         * @method drawCircle
         * @param {Number} x y-coordinate
         * @param {Number} y x-coordinate
         * @param {Number} r radius
         * @chainable
         * @protected
         */
    	drawCircle: function(x, y, radius) {
            var startAngle = 0,
                endAngle = 2 * Math.PI,
                wt = this._stroke && this._strokeWeight ? this._strokeWeight : 0,
                circum = radius * 2;
                circum += wt;
            this._drawingComplete = false;
            this._trackSize(x + circum, y + circum);
            this._trackSize(x - wt, y - wt);
            this._updateCoords(x, y);
            this._updateDrawingQueue(["arc", x + radius, y + radius, radius, startAngle, endAngle, false]);
            return this;
        },

        /**
         * Draws a diamond.
         *
         * @method drawDiamond
         * @param {Number} x y-coordinate
         * @param {Number} y x-coordinate
         * @param {Number} width width
         * @param {Number} height height
         * @chainable
         * @protected
         */
        drawDiamond: function(x, y, width, height)
        {
            var midWidth = width * 0.5,
                midHeight = height * 0.5;
            this.moveTo(x + midWidth, y);
            this.lineTo(x + width, y + midHeight);
            this.lineTo(x + midWidth, y + height);
            this.lineTo(x, y + midHeight);
            this.lineTo(x + midWidth, y);
            return this;
        },

        /**
         * Draws an ellipse. Used internally by `CanvasEllipse` class.
         *
         * @method drawEllipse
         * @param {Number} x x-coordinate
         * @param {Number} y y-coordinate
         * @param {Number} w width
         * @param {Number} h height
         * @chainable
         * @protected
         */
    	drawEllipse: function(x, y, w, h) {
            var l = 8,
                theta = -(45/180) * Math.PI,
                angle = 0,
                angleMid,
                radius = w/2,
                yRadius = h/2,
                i,
                centerX = x + radius,
                centerY = y + yRadius,
                ax, ay, bx, by, cx, cy,
                wt = this._stroke && this._strokeWeight ? this._strokeWeight : 0;

            ax = centerX + Math.cos(0) * radius;
            ay = centerY + Math.sin(0) * yRadius;
            this.moveTo(ax, ay);
            for(i = 0; i < l; i++)
            {
                angle += theta;
                angleMid = angle - (theta / 2);
                bx = centerX + Math.cos(angle) * radius;
                by = centerY + Math.sin(angle) * yRadius;
                cx = centerX + Math.cos(angleMid) * (radius / Math.cos(theta / 2));
                cy = centerY + Math.sin(angleMid) * (yRadius / Math.cos(theta / 2));
                this._updateDrawingQueue(["quadraticCurveTo", cx, cy, bx, by]);
            }
            this._trackSize(x + w + wt, y + h + wt);
            this._trackSize(x - wt, y - wt);
            this._updateCoords(x, y);
            return this;
        },

        /**
         * Draws a rectangle.
         *
         * @method drawRect
         * @param {Number} x x-coordinate
         * @param {Number} y y-coordinate
         * @param {Number} w width
         * @param {Number} h height
         * @chainable
         */
        drawRect: function(x, y, w, h) {
            this._drawingComplete = false;
            this.moveTo(x, y);
            this.lineTo(x + w, y);
            this.lineTo(x + w, y + h);
            this.lineTo(x, y + h);
            this.lineTo(x, y);
            return this;
        },

        /**
         * Draws a rectangle with rounded corners.
         *
         * @method drawRect
         * @param {Number} x x-coordinate
         * @param {Number} y y-coordinate
         * @param {Number} w width
         * @param {Number} h height
         * @param {Number} ew width of the ellipse used to draw the rounded corners
         * @param {Number} eh height of the ellipse used to draw the rounded corners
         * @chainable
         */
        drawRoundRect: function(x, y, w, h, ew, eh) {
            this._drawingComplete = false;
            this.moveTo( x, y + eh);
            this.lineTo(x, y + h - eh);
            this.quadraticCurveTo(x, y + h, x + ew, y + h);
            this.lineTo(x + w - ew, y + h);
            this.quadraticCurveTo(x + w, y + h, x + w, y + h - eh);
            this.lineTo(x + w, y + eh);
            this.quadraticCurveTo(x + w, y, x + w - ew, y);
            this.lineTo(x + ew, y);
            this.quadraticCurveTo(x, y, x, y + eh);
            return this;
        },

        /**
         * Draws a wedge.
         *
         * @method drawWedge
         * @param {Number} x x-coordinate of the wedge's center point
         * @param {Number} y y-coordinate of the wedge's center point
         * @param {Number} startAngle starting angle in degrees
         * @param {Number} arc sweep of the wedge. Negative values draw clockwise.
         * @param {Number} radius radius of wedge. If [optional] yRadius is defined, then radius is the x radius.
         * @param {Number} yRadius [optional] y radius for wedge.
         * @chainable
         * @private
         */
        drawWedge: function(x, y, startAngle, arc, radius, yRadius)
        {
            var wt = this._stroke && this._strokeWeight ? this._strokeWeight : 0,
                segs,
                segAngle,
                theta,
                angle,
                angleMid,
                ax,
                ay,
                bx,
                by,
                cx,
                cy,
                i = 0;
            yRadius = yRadius || radius;

            this._drawingComplete = false;
            // move to x,y position
            this._updateDrawingQueue(["moveTo", x, y]);

            yRadius = yRadius || radius;

            // limit sweep to reasonable numbers
            if(Math.abs(arc) > 360)
            {
                arc = 360;
            }

            // First we calculate how many segments are needed
            // for a smooth arc.
            segs = Math.ceil(Math.abs(arc) / 45);

            // Now calculate the sweep of each segment.
            segAngle = arc / segs;

            // The math requires radians rather than degrees. To convert from degrees
            // use the formula (degrees/180)*Math.PI to get radians.
            theta = -(segAngle / 180) * Math.PI;

            // convert angle startAngle to radians
            angle = (startAngle / 180) * Math.PI;

            // draw the curve in segments no larger than 45 degrees.
            if(segs > 0)
            {
                // draw a line from the center to the start of the curve
                ax = x + Math.cos(startAngle / 180 * Math.PI) * radius;
                ay = y + Math.sin(startAngle / 180 * Math.PI) * yRadius;
                this.lineTo(ax, ay);
                // Loop for drawing curve segments
                for(i = 0; i < segs; ++i)
                {
                    angle += theta;
                    angleMid = angle - (theta / 2);
                    bx = x + Math.cos(angle) * radius;
                    by = y + Math.sin(angle) * yRadius;
                    cx = x + Math.cos(angleMid) * (radius / Math.cos(theta / 2));
                    cy = y + Math.sin(angleMid) * (yRadius / Math.cos(theta / 2));
                    this._updateDrawingQueue(["quadraticCurveTo", cx, cy, bx, by]);
                }
                // close the wedge by drawing a line to the center
                this._updateDrawingQueue(["lineTo", x, y]);
            }
            this._trackSize(-wt , -wt);
            this._trackSize((radius * 2) + wt, (radius * 2) + wt);
            return this;
        },

        /**
         * Completes a drawing operation.
         *
         * @method end
         * @chainable
         */
        end: function() {
            this._closePath();
            return this;
        },

        /**
         * Ends a fill and stroke
         *
         * @method closePath
         * @chainable
         */
        closePath: function()
        {
            this._updateDrawingQueue(["closePath"]);
            this._updateDrawingQueue(["beginPath"]);
            return this;
        },

    	/**
    	 * Clears the graphics object.
    	 *
    	 * @method clear
         * @chainable
    	 */
        clear: function() {
    		this._initProps();
            if(this.node)
            {
                this._context.clearRect(0, 0, this.node.width, this.node.height);
            }
            return this;
    	},

        /**
         * Returns a linear gradient fill
         *
         * @method _getLinearGradient
         * @return CanvasGradient
         * @private
         */
        _getLinearGradient: function() {
            var isNumber = Y.Lang.isNumber,
                fill = this.get("fill"),
                stops = fill.stops,
                opacity,
                color,
                stop,
                i,
                len = stops.length,
                gradient,
                x = 0,
                y = 0,
                w = this.get("width"),
                h = this.get("height"),
                r = fill.rotation || 0,
                x1, x2, y1, y2,
                cx = x + w/2,
                cy = y + h/2,
                offset,
                radCon = Math.PI/180,
                tanRadians = parseFloat(parseFloat(Math.tan(r * radCon)).toFixed(8));
            if(Math.abs(tanRadians) * w/2 >= h/2)
            {
                if(r < 180)
                {
                    y1 = y;
                    y2 = y + h;
                }
                else
                {
                    y1 = y + h;
                    y2 = y;
                }
                x1 = cx - ((cy - y1)/tanRadians);
                x2 = cx - ((cy - y2)/tanRadians);
            }
            else
            {
                if(r > 90 && r < 270)
                {
                    x1 = x + w;
                    x2 = x;
                }
                else
                {
                    x1 = x;
                    x2 = x + w;
                }
                y1 = ((tanRadians * (cx - x1)) - cy) * -1;
                y2 = ((tanRadians * (cx - x2)) - cy) * -1;
            }
            gradient = this._context.createLinearGradient(x1, y1, x2, y2);
            for(i = 0; i < len; ++i)
            {
                stop = stops[i];
                opacity = stop.opacity;
                color = stop.color;
                offset = stop.offset;
                if(isNumber(opacity))
                {
                    opacity = Math.max(0, Math.min(1, opacity));
                    color = this._toRGBA(color, opacity);
                }
                else
                {
                    color = TORGB(color);
                }
                offset = stop.offset || i/(len - 1);
                gradient.addColorStop(offset, color);
            }
            return gradient;
        },

        /**
         * Returns a radial gradient fill
         *
         * @method _getRadialGradient
         * @return CanvasGradient
         * @private
         */
        _getRadialGradient: function() {
            var isNumber = Y.Lang.isNumber,
                fill = this.get("fill"),
                r = fill.r,
                fx = fill.fx,
                fy = fill.fy,
                stops = fill.stops,
                opacity,
                color,
                stop,
                i,
                len = stops.length,
                gradient,
                x = 0,
                y = 0,
                w = this.get("width"),
                h = this.get("height"),
                x1, x2, y1, y2, r2,
                xc, yc, xn, yn, d,
                offset,
                ratio,
                stopMultiplier;
            xc = x + w/2;
            yc = y + h/2;
            x1 = w * fx;
            y1 = h * fy;
            x2 = x + w/2;
            y2 = y + h/2;
            r2 = w * r;
            d = Math.sqrt( Math.pow(Math.abs(xc - x1), 2) + Math.pow(Math.abs(yc - y1), 2) );
            if(d >= r2)
            {
                ratio = d/r2;
                //hack. gradient won't show if it is exactly on the edge of the arc
                if(ratio === 1)
                {
                    ratio = 1.01;
                }
                xn = (x1 - xc)/ratio;
                yn = (y1 - yc)/ratio;
                xn = xn > 0 ? Math.floor(xn) : Math.ceil(xn);
                yn = yn > 0 ? Math.floor(yn) : Math.ceil(yn);
                x1 = xc + xn;
                y1 = yc + yn;
            }

            //If the gradient radius is greater than the circle's, adjusting the radius stretches the gradient properly.
            //If the gradient radius is less than the circle's, adjusting the radius of the gradient will not work.
            //Instead, adjust the color stops to reflect the smaller radius.
            if(r >= 0.5)
            {
                gradient = this._context.createRadialGradient(x1, y1, r, x2, y2, r * w);
                stopMultiplier = 1;
            }
            else
            {
                gradient = this._context.createRadialGradient(x1, y1, r, x2, y2, w/2);
                stopMultiplier = r * 2;
            }
            for(i = 0; i < len; ++i)
            {
                stop = stops[i];
                opacity = stop.opacity;
                color = stop.color;
                offset = stop.offset;
                if(isNumber(opacity))
                {
                    opacity = Math.max(0, Math.min(1, opacity));
                    color = this._toRGBA(color, opacity);
                }
                else
                {
                    color = TORGB(color);
                }
                offset = stop.offset || i/(len - 1);
                offset *= stopMultiplier;
                if(offset <= 1)
                {
                    gradient.addColorStop(offset, color);
                }
            }
            return gradient;
        },

        /**
         * Clears all values
         *
         * @method _initProps
         * @private
         */
        _initProps: function() {
            this._methods = [];
            this._lineToMethods = [];
            this._xcoords = [0];
    		this._ycoords = [0];
    		this._width = 0;
            this._height = 0;
            this._left = 0;
            this._top = 0;
            this._right = 0;
            this._bottom = 0;
            this._currentX = 0;
            this._currentY = 0;
        },

        /**
         * Indicates a drawing has completed.
         *
         * @property _drawingComplete
         * @type Boolean
         * @private
         */
        _drawingComplete: false,

        /**
         * Creates canvas element
         *
         * @method _createGraphic
         * @return HTMLCanvasElement
         * @private
         */
        _createGraphic: function() {
            var graphic = Y.config.doc.createElement('canvas');
            return graphic;
        },

        /**
         * Returns the points on a curve
         *
         * @method getBezierData
         * @param Array points Array containing the begin, end and control points of a curve.
         * @param Number t The value for incrementing the next set of points.
         * @return Array
         * @private
         */
        getBezierData: function(points, t) {
            var n = points.length,
                tmp = [],
                i,
                j;

            for (i = 0; i < n; ++i){
                tmp[i] = [points[i][0], points[i][1]]; // save input
            }

            for (j = 1; j < n; ++j) {
                for (i = 0; i < n - j; ++i) {
                    tmp[i][0] = (1 - t) * tmp[i][0] + t * tmp[parseInt(i + 1, 10)][0];
                    tmp[i][1] = (1 - t) * tmp[i][1] + t * tmp[parseInt(i + 1, 10)][1];
                }
            }
            return [ tmp[0][0], tmp[0][1] ];
        },

        /**
         * Calculates the bounding box for a curve
         *
         * @method _setCurveBoundingBox
         * @param Array pts Array containing points for start, end and control points of a curve.
         * @param Number w Width used to calculate the number of points to describe the curve.
         * @param Number h Height used to calculate the number of points to describe the curve.
         * @private
         */
        _setCurveBoundingBox: function(pts, w, h)
        {
            var i = 0,
                left = this._currentX,
                right = left,
                top = this._currentY,
                bottom = top,
                len = Math.round(Math.sqrt((w * w) + (h * h))),
                t = 1/len,
                wt = this._stroke && this._strokeWeight ? this._strokeWeight : 0,
                xy;
            for(i = 0; i < len; ++i)
            {
                xy = this.getBezierData(pts, t * i);
                left = isNaN(left) ? xy[0] : Math.min(xy[0], left);
                right = isNaN(right) ? xy[0] : Math.max(xy[0], right);
                top = isNaN(top) ? xy[1] : Math.min(xy[1], top);
                bottom = isNaN(bottom) ? xy[1] : Math.max(xy[1], bottom);
            }
            left = Math.round(left * 10)/10;
            right = Math.round(right * 10)/10;
            top = Math.round(top * 10)/10;
            bottom = Math.round(bottom * 10)/10;
            this._trackSize(right + wt, bottom + wt);
            this._trackSize(left - wt, top - wt);
        },

        /**
         * Updates the size of the graphics object
         *
         * @method _trackSize
         * @param {Number} w width
         * @param {Number} h height
         * @private
         */
        _trackSize: function(w, h) {
            if (w > this._right) {
                this._right = w;
            }
            if(w < this._left)
            {
                this._left = w;
            }
            if (h < this._top)
            {
                this._top = h;
            }
            if (h > this._bottom)
            {
                this._bottom = h;
            }
            this._width = this._right - this._left;
            this._height = this._bottom - this._top;
        }
    };
    Y.CanvasDrawing = CanvasDrawing;