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YUI.add('series-curve-util', function (Y, NAME) {
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/**
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 * Provides functionality for drawing curves in a series.
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 *
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 * @module charts
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 * @submodule series-curve-util
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 */
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/**
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 * Utility class used for calculating curve points.
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 *
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 * @class CurveUtil
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 * @constructor
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 * @submodule series-curve-util
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 */
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function CurveUtil()
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{
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}
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CurveUtil.prototype = {
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    /**
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     * Creates an array of start, end and control points for splines.
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     *
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     * @method getCurveControlPoints
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     * @param {Array} xcoords Collection of x-coordinates used for calculate the curves
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     * @param {Array} ycoords Collection of y-coordinates used for calculate the curves
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     * @return Object
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     * @protected
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     */
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    getCurveControlPoints: function(xcoords, ycoords)
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    {
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		var outpoints = [],
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            i = 1,
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            l = xcoords.length - 1,
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            xvals = [],
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            yvals = [];
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		// Too few points, need at least two
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		if (l < 1)
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        {
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			return null;
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		}
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        outpoints[0] = {
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            startx: xcoords[0],
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            starty: ycoords[0],
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            endx: xcoords[1],
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            endy: ycoords[1]
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        };
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		// Special case, the Bezier should be a straight line
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        if (l === 1)
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        {
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			outpoints[0].ctrlx1 = (2.0*xcoords[0] + xcoords[1])/3.0;
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			outpoints[0].ctrly2 = (2.0*ycoords[0] + ycoords[1])/3.0;
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			outpoints[0].ctrlx2 = 2.0*outpoints[0].ctrlx1 - xcoords[0];
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            outpoints[0].ctrly2 = 2.0*outpoints[0].ctrly1 - ycoords[0];
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            return outpoints;
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		}
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		for (; i < l; ++i)
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        {
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			outpoints.push({
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                startx: Math.round(xcoords[i]),
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                starty: Math.round(ycoords[i]),
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                endx: Math.round(xcoords[i+1]),
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                endy: Math.round(ycoords[i+1])
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            });
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			xvals[i] = 4.0 * xcoords[i] + 2*xcoords[i+1];
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			yvals[i] = 4.0*ycoords[i] + 2*ycoords[i+1];
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		}
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		xvals[0] = xcoords[0] + (2.0 * xcoords[1]);
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		xvals[l-1] = (8.0 * xcoords[l-1] + xcoords[l]) / 2.0;
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		xvals = this.getControlPoints(xvals.concat());
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        yvals[0] = ycoords[0] + (2.0 * ycoords[1]);
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		yvals[l-1] = (8.0 * ycoords[l-1] + ycoords[l]) / 2.0;
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		yvals = this.getControlPoints(yvals.concat());
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        for (i = 0; i < l; ++i)
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        {
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			outpoints[i].ctrlx1 = Math.round(xvals[i]);
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            outpoints[i].ctrly1 = Math.round(yvals[i]);
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			if (i < l-1)
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            {
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				outpoints[i].ctrlx2 = Math.round(2*xcoords[i+1] - xvals[i+1]);
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                outpoints[i].ctrly2 = Math.round(2*ycoords[i+1] - yvals[i+1]);
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			}
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			else
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            {
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				outpoints[i].ctrlx2 = Math.round((xcoords[l] + xvals[l-1])/2);
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                outpoints[i].ctrly2 = Math.round((ycoords[l] + yvals[l-1])/2);
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			}
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		}
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		return outpoints;
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	},
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    /**
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     * Gets the control points for the curve.
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     *
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     * @method getControlPoints
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     * @param {Array} vals Collection of values coords used to generate control points.
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     * @return Array
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     * @private
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     */
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	getControlPoints: function(vals)
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    {
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		var l = vals.length,
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            x = [],
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            tmp = [],
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            b = 2.0,
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            i = 1;
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		x[0] = vals[0] / b;
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		for (; i < l; ++i)
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        {
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			tmp[i] = 1/b;
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			b = (i < l-1 ? 4.0 : 3.5) - tmp[i];
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			x[i] = (vals[i] - x[i-1]) / b;
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		}
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		for (i = 1; i < l; ++i)
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        {
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			x[l-i-1] -= tmp[l-i] * x[l-i];
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		}
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		return x;
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	}
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};
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Y.CurveUtil = CurveUtil;
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}, '3.18.1');