source: node_modules/d3-shape/src/curve/bump.js@ e4c61dd

import pointRadial from "../pointRadial.js";

class Bump {
  constructor(context, x) {
    this._context = context;
    this._x = x;
  }
  areaStart() {
    this._line = 0;
  }
  areaEnd() {
    this._line = NaN;
  }
  lineStart() {
    this._point = 0;
  }
  lineEnd() {
    if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath();
    this._line = 1 - this._line;
  }
  point(x, y) {
    x = +x, y = +y;
    switch (this._point) {
      case 0: {
        this._point = 1;
        if (this._line) this._context.lineTo(x, y);
        else this._context.moveTo(x, y);
        break;
      }
      case 1: this._point = 2; // falls through
      default: {
        if (this._x) this._context.bezierCurveTo(this._x0 = (this._x0 + x) / 2, this._y0, this._x0, y, x, y);
        else this._context.bezierCurveTo(this._x0, this._y0 = (this._y0 + y) / 2, x, this._y0, x, y);
        break;
      }
    }
    this._x0 = x, this._y0 = y;
  }
}

class BumpRadial {
  constructor(context) {
    this._context = context;
  }
  lineStart() {
    this._point = 0;
  }
  lineEnd() {}
  point(x, y) {
    x = +x, y = +y;
    if (this._point === 0) {
      this._point = 1;
    } else {
      const p0 = pointRadial(this._x0, this._y0);
      const p1 = pointRadial(this._x0, this._y0 = (this._y0 + y) / 2);
      const p2 = pointRadial(x, this._y0);
      const p3 = pointRadial(x, y);
      this._context.moveTo(...p0);
      this._context.bezierCurveTo(...p1, ...p2, ...p3);
    }
    this._x0 = x, this._y0 = y;
  }
}

export function bumpX(context) {
  return new Bump(context, true);
}

export function bumpY(context) {
  return new Bump(context, false);
}

export function bumpRadial(context) {
  return new BumpRadial(context);
}