@amcharts/amcharts5/.internal/core/render/MonotoneYTension.js

amCharts 5

/**
 * @ignore
 */
export class MonotoneYTension {
    constructor(context, tension) {
        this._line = 0;
        this._point = 0;
        this._x0 = 0;
        this._x1 = 0;
        this._y0 = 0;
        this._y1 = 0;
        this._t0 = 0;
        this._tension = 0;
        this._context = context;
        this._tension = tension;
    }
    areaStart() {
        this._line = 0;
    }
    areaEnd() {
        this._line = NaN;
    }
    lineStart() {
        this._x0 = this._x1 =
            this._y0 = this._y1 =
                this._t0 = NaN;
        this._point = 0;
    }
    lineEnd() {
        switch (this._point) {
            case 2:
                this._context.lineTo(this._x1, this._y1);
                break;
            case 3:
                point(this, this._t0, slope2(this, this._t0));
                break;
        }
        if (this._line || (this._line !== 0 && this._point === 1))
            this._context.closePath();
        this._line = 1 - this._line;
    }
    point(x, y) {
        [x, y] = [y, x];
        let t1 = NaN;
        x = +x, y = +y;
        if (x === this._x1 && y === this._y1)
            return; // Ignore coincident points.
        switch (this._point) {
            case 0:
                this._point = 1;
                this._line ? this._context.lineTo(y, x) : this._context.moveTo(y, x);
                break;
            case 1:
                this._point = 2;
                break;
            case 2:
                this._point = 3;
                point(this, slope2(this, t1 = slope3(this, x, y)), t1);
                break;
            default:
                point(this, this._t0, t1 = slope3(this, x, y));
                break;
        }
        this._x0 = this._x1, this._x1 = x;
        this._y0 = this._y1, this._y1 = y;
        this._t0 = t1;
    }
}
/**
 * @ignore
 */
export function curveMonotoneYTension(tension) {
    function monotoneYTension(context) {
        return new MonotoneYTension(context, tension);
    }
    monotoneYTension.tension = function (tension) {
        return curveMonotoneYTension(+tension);
    };
    return monotoneYTension;
}
/**
 * @ignore
 */
function sign(x) {
    return x < 0 ? -1 : 1;
}
/**
 * @ignore
 */
function slope3(that, x2, y2) {
    let h0 = (that._x1 - that._x0);
    let h1 = (x2 - that._x1);
    let s0 = (that._y1 - that._y0) / (h0 || h1 < 0 && -0);
    let s1 = (y2 - that._y1) / (h1 || h0 < 0 && -0);
    let p = (s0 * h1 + s1 * h0) / (h0 + h1);
    return (sign(s0) + sign(s1)) * Math.min(Math.abs(s0), Math.abs(s1), 0.5 * Math.abs(p)) || 0;
}
/**
 * @ignore
 */
function slope2(that, t) {
    let h = that._x1 - that._x0;
    return h ? (3 * (that._y1 - that._y0) / h - t) / 2 : t;
}
/**
 * @ignore
 */
function point(that, t0, t1) {
    let x0 = that._x0, y0 = that._y0, x1 = that._x1, y1 = that._y1, dx = (x1 - x0) / 1.5 * (1 - that._tension);
    that._context.bezierCurveTo(y0 + dx * t0, x0 + dx, y1 - dx * t1, x1 - dx, y1, x1);
}
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