chartjs-chart-geo/build/index.cjs

Chart.js module for charting maps

/**
 * chartjs-chart-geo
 * https://github.com/sgratzl/chartjs-chart-geo
 *
 * Copyright (c) 2019-2023 Samuel Gratzl <sam@sgratzl.com>
 */

'use strict';

var chart_js = require('chart.js');
var helpers = require('chart.js/helpers');
var topojsonClient = require('topojson-client');

function _interopNamespaceDefault(e) {
  var n = Object.create(null);
  if (e) {
    Object.keys(e).forEach(function (k) {
      if (k !== 'default') {
        var d = Object.getOwnPropertyDescriptor(e, k);
        Object.defineProperty(n, k, d.get ? d : {
          enumerable: true,
          get: function () { return e[k]; }
        });
      }
    });
  }
  n.default = e;
  return Object.freeze(n);
}

var topojsonClient__namespace = /*#__PURE__*/_interopNamespaceDefault(topojsonClient);

// https://github.com/python/cpython/blob/a74eea238f5baba15797e2e8b570d153bc8690a7/Modules/mathmodule.c#L1423
class Adder {
  constructor() {
    this._partials = new Float64Array(32);
    this._n = 0;
  }
  add(x) {
    const p = this._partials;
    let i = 0;
    for (let j = 0; j < this._n && j < 32; j++) {
      const y = p[j],
        hi = x + y,
        lo = Math.abs(x) < Math.abs(y) ? x - (hi - y) : y - (hi - x);
      if (lo) p[i++] = lo;
      x = hi;
    }
    p[i] = x;
    this._n = i + 1;
    return this;
  }
  valueOf() {
    const p = this._partials;
    let n = this._n, x, y, lo, hi = 0;
    if (n > 0) {
      hi = p[--n];
      while (n > 0) {
        x = hi;
        y = p[--n];
        hi = x + y;
        lo = y - (hi - x);
        if (lo) break;
      }
      if (n > 0 && ((lo < 0 && p[n - 1] < 0) || (lo > 0 && p[n - 1] > 0))) {
        y = lo * 2;
        x = hi + y;
        if (y == x - hi) hi = x;
      }
    }
    return hi;
  }
}

function* flatten(arrays) {
  for (const array of arrays) {
    yield* array;
  }
}

function merge(arrays) {
  return Array.from(flatten(arrays));
}

function range(start, stop, step) {
  start = +start, stop = +stop, step = (n = arguments.length) < 2 ? (stop = start, start = 0, 1) : n < 3 ? 1 : +step;

  var i = -1,
      n = Math.max(0, Math.ceil((stop - start) / step)) | 0,
      range = new Array(n);

  while (++i < n) {
    range[i] = start + i * step;
  }

  return range;
}

var epsilon = 1e-6;
var epsilon2 = 1e-12;
var pi = Math.PI;
var halfPi = pi / 2;
var quarterPi = pi / 4;
var tau = pi * 2;

var degrees$1 = 180 / pi;
var radians$1 = pi / 180;

var abs = Math.abs;
var atan = Math.atan;
var atan2 = Math.atan2;
var cos = Math.cos;
var ceil = Math.ceil;
var exp = Math.exp;
var log = Math.log;
var pow = Math.pow;
var sin = Math.sin;
var sign = Math.sign || function(x) { return x > 0 ? 1 : x < 0 ? -1 : 0; };
var sqrt = Math.sqrt;
var tan = Math.tan;

function acos(x) {
  return x > 1 ? 0 : x < -1 ? pi : Math.acos(x);
}

function asin(x) {
  return x > 1 ? halfPi : x < -1 ? -halfPi : Math.asin(x);
}

function noop() {}

function streamGeometry(geometry, stream) {
  if (geometry && streamGeometryType.hasOwnProperty(geometry.type)) {
    streamGeometryType[geometry.type](geometry, stream);
  }
}

var streamObjectType = {
  Feature: function(object, stream) {
    streamGeometry(object.geometry, stream);
  },
  FeatureCollection: function(object, stream) {
    var features = object.features, i = -1, n = features.length;
    while (++i < n) streamGeometry(features[i].geometry, stream);
  }
};

var streamGeometryType = {
  Sphere: function(object, stream) {
    stream.sphere();
  },
  Point: function(object, stream) {
    object = object.coordinates;
    stream.point(object[0], object[1], object[2]);
  },
  MultiPoint: function(object, stream) {
    var coordinates = object.coordinates, i = -1, n = coordinates.length;
    while (++i < n) object = coordinates[i], stream.point(object[0], object[1], object[2]);
  },
  LineString: function(object, stream) {
    streamLine(object.coordinates, stream, 0);
  },
  MultiLineString: function(object, stream) {
    var coordinates = object.coordinates, i = -1, n = coordinates.length;
    while (++i < n) streamLine(coordinates[i], stream, 0);
  },
  Polygon: function(object, stream) {
    streamPolygon(object.coordinates, stream);
  },
  MultiPolygon: function(object, stream) {
    var coordinates = object.coordinates, i = -1, n = coordinates.length;
    while (++i < n) streamPolygon(coordinates[i], stream);
  },
  GeometryCollection: function(object, stream) {
    var geometries = object.geometries, i = -1, n = geometries.length;
    while (++i < n) streamGeometry(geometries[i], stream);
  }
};

function streamLine(coordinates, stream, closed) {
  var i = -1, n = coordinates.length - closed, coordinate;
  stream.lineStart();
  while (++i < n) coordinate = coordinates[i], stream.point(coordinate[0], coordinate[1], coordinate[2]);
  stream.lineEnd();
}

function streamPolygon(coordinates, stream) {
  var i = -1, n = coordinates.length;
  stream.polygonStart();
  while (++i < n) streamLine(coordinates[i], stream, 1);
  stream.polygonEnd();
}

function geoStream(object, stream) {
  if (object && streamObjectType.hasOwnProperty(object.type)) {
    streamObjectType[object.type](object, stream);
  } else {
    streamGeometry(object, stream);
  }
}

function spherical(cartesian) {
  return [atan2(cartesian[1], cartesian[0]), asin(cartesian[2])];
}

function cartesian(spherical) {
  var lambda = spherical[0], phi = spherical[1], cosPhi = cos(phi);
  return [cosPhi * cos(lambda), cosPhi * sin(lambda), sin(phi)];
}

function cartesianDot(a, b) {
  return a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
}

function cartesianCross(a, b) {
  return [a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0]];
}

// TODO return a
function cartesianAddInPlace(a, b) {
  a[0] += b[0], a[1] += b[1], a[2] += b[2];
}

function cartesianScale(vector, k) {
  return [vector[0] * k, vector[1] * k, vector[2] * k];
}

// TODO return d
function cartesianNormalizeInPlace(d) {
  var l = sqrt(d[0] * d[0] + d[1] * d[1] + d[2] * d[2]);
  d[0] /= l, d[1] /= l, d[2] /= l;
}

function compose(a, b) {

  function compose(x, y) {
    return x = a(x, y), b(x[0], x[1]);
  }

  if (a.invert && b.invert) compose.invert = function(x, y) {
    return x = b.invert(x, y), x && a.invert(x[0], x[1]);
  };

  return compose;
}

function rotationIdentity(lambda, phi) {
  if (abs(lambda) > pi) lambda -= Math.round(lambda / tau) * tau;
  return [lambda, phi];
}

rotationIdentity.invert = rotationIdentity;

function rotateRadians(deltaLambda, deltaPhi, deltaGamma) {
  return (deltaLambda %= tau) ? (deltaPhi || deltaGamma ? compose(rotationLambda(deltaLambda), rotationPhiGamma(deltaPhi, deltaGamma))
    : rotationLambda(deltaLambda))
    : (deltaPhi || deltaGamma ? rotationPhiGamma(deltaPhi, deltaGamma)
    : rotationIdentity);
}

function forwardRotationLambda(deltaLambda) {
  return function(lambda, phi) {
    lambda += deltaLambda;
    if (abs(lambda) > pi) lambda -= Math.round(lambda / tau) * tau;
    return [lambda, phi];
  };
}

function rotationLambda(deltaLambda) {
  var rotation = forwardRotationLambda(deltaLambda);
  rotation.invert = forwardRotationLambda(-deltaLambda);
  return rotation;
}

function rotationPhiGamma(deltaPhi, deltaGamma) {
  var cosDeltaPhi = cos(deltaPhi),
      sinDeltaPhi = sin(deltaPhi),
      cosDeltaGamma = cos(deltaGamma),
      sinDeltaGamma = sin(deltaGamma);

  function rotation(lambda, phi) {
    var cosPhi = cos(phi),
        x = cos(lambda) * cosPhi,
        y = sin(lambda) * cosPhi,
        z = sin(phi),
        k = z * cosDeltaPhi + x * sinDeltaPhi;
    return [
      atan2(y * cosDeltaGamma - k * sinDeltaGamma, x * cosDeltaPhi - z * sinDeltaPhi),
      asin(k * cosDeltaGamma + y * sinDeltaGamma)
    ];
  }

  rotation.invert = function(lambda, phi) {
    var cosPhi = cos(phi),
        x = cos(lambda) * cosPhi,
        y = sin(lambda) * cosPhi,
        z = sin(phi),
        k = z * cosDeltaGamma - y * sinDeltaGamma;
    return [
      atan2(y * cosDeltaGamma + z * sinDeltaGamma, x * cosDeltaPhi + k * sinDeltaPhi),
      asin(k * cosDeltaPhi - x * sinDeltaPhi)
    ];
  };

  return rotation;
}

function rotation(rotate) {
  rotate = rotateRadians(rotate[0] * radians$1, rotate[1] * radians$1, rotate.length > 2 ? rotate[2] * radians$1 : 0);

  function forward(coordinates) {
    coordinates = rotate(coordinates[0] * radians$1, coordinates[1] * radians$1);
    return coordinates[0] *= degrees$1, coordinates[1] *= degrees$1, coordinates;
  }

  forward.invert = function(coordinates) {
    coordinates = rotate.invert(coordinates[0] * radians$1, coordinates[1] * radians$1);
    return coordinates[0] *= degrees$1, coordinates[1] *= degrees$1, coordinates;
  };

  return forward;
}

// Generates a circle centered at [0°, 0°], with a given radius and precision.
function circleStream(stream, radius, delta, direction, t0, t1) {
  if (!delta) return;
  var cosRadius = cos(radius),
      sinRadius = sin(radius),
      step = direction * delta;
  if (t0 == null) {
    t0 = radius + direction * tau;
    t1 = radius - step / 2;
  } else {
    t0 = circleRadius(cosRadius, t0);
    t1 = circleRadius(cosRadius, t1);
    if (direction > 0 ? t0 < t1 : t0 > t1) t0 += direction * tau;
  }
  for (var point, t = t0; direction > 0 ? t > t1 : t < t1; t -= step) {
    point = spherical([cosRadius, -sinRadius * cos(t), -sinRadius * sin(t)]);
    stream.point(point[0], point[1]);
  }
}

// Returns the signed angle of a cartesian point relative to [cosRadius, 0, 0].
function circleRadius(cosRadius, point) {
  point = cartesian(point), point[0] -= cosRadius;
  cartesianNormalizeInPlace(point);
  var radius = acos(-point[1]);
  return ((-point[2] < 0 ? -radius : radius) + tau - epsilon) % tau;
}

function clipBuffer() {
  var lines = [],
      line;
  return {
    point: function(x, y, m) {
      line.push([x, y, m]);
    },
    lineStart: function() {
      lines.push(line = []);
    },
    lineEnd: noop,
    rejoin: function() {
      if (lines.length > 1) lines.push(lines.pop().concat(lines.shift()));
    },
    result: function() {
      var result = lines;
      lines = [];
      line = null;
      return result;
    }
  };
}

function pointEqual(a, b) {
  return abs(a[0] - b[0]) < epsilon && abs(a[1] - b[1]) < epsilon;
}

function Intersection(point, points, other, entry) {
  this.x = point;
  this.z = points;
  this.o = other; // another intersection
  this.e = entry; // is an entry?
  this.v = false; // visited
  this.n = this.p = null; // next & previous
}

// A generalized polygon clipping algorithm: given a polygon that has been cut
// into its visible line segments, and rejoins the segments by interpolating
// along the clip edge.
function clipRejoin(segments, compareIntersection, startInside, interpolate, stream) {
  var subject = [],
      clip = [],
      i,
      n;

  segments.forEach(function(segment) {
    if ((n = segment.length - 1) <= 0) return;
    var n, p0 = segment[0], p1 = segment[n], x;

    if (pointEqual(p0, p1)) {
      if (!p0[2] && !p1[2]) {
        stream.lineStart();
        for (i = 0; i < n; ++i) stream.point((p0 = segment[i])[0], p0[1]);
        stream.lineEnd();
        return;
      }
      // handle degenerate cases by moving the point
      p1[0] += 2 * epsilon;
    }

    subject.push(x = new Intersection(p0, segment, null, true));
    clip.push(x.o = new Intersection(p0, null, x, false));
    subject.push(x = new Intersection(p1, segment, null, false));
    clip.push(x.o = new Intersection(p1, null, x, true));
  });

  if (!subject.length) return;

  clip.sort(compareIntersection);
  link(subject);
  link(clip);

  for (i = 0, n = clip.length; i < n; ++i) {
    clip[i].e = startInside = !startInside;
  }

  var start = subject[0],
      points,
      point;

  while (1) {
    // Find first unvisited intersection.
    var current = start,
        isSubject = true;
    while (current.v) if ((current = current.n) === start) return;
    points = current.z;
    stream.lineStart();
    do {
      current.v = current.o.v = true;
      if (current.e) {
        if (isSubject) {
          for (i = 0, n = points.length; i < n; ++i) stream.point((point = points[i])[0], point[1]);
        } else {
          interpolate(current.x, current.n.x, 1, stream);
        }
        current = current.n;
      } else {
        if (isSubject) {
          points = current.p.z;
          for (i = points.length - 1; i >= 0; --i) stream.point((point = points[i])[0], point[1]);
        } else {
          interpolate(current.x, current.p.x, -1, stream);
        }
        current = current.p;
      }
      current = current.o;
      points = current.z;
      isSubject = !isSubject;
    } while (!current.v);
    stream.lineEnd();
  }
}

function link(array) {
  if (!(n = array.length)) return;
  var n,
      i = 0,
      a = array[0],
      b;
  while (++i < n) {
    a.n = b = array[i];
    b.p = a;
    a = b;
  }
  a.n = b = array[0];
  b.p = a;
}

function longitude(point) {
  return abs(point[0]) <= pi ? point[0] : sign(point[0]) * ((abs(point[0]) + pi) % tau - pi);
}

function polygonContains(polygon, point) {
  var lambda = longitude(point),
      phi = point[1],
      sinPhi = sin(phi),
      normal = [sin(lambda), -cos(lambda), 0],
      angle = 0,
      winding = 0;

  var sum = new Adder();

  if (sinPhi === 1) phi = halfPi + epsilon;
  else if (sinPhi === -1) phi = -halfPi - epsilon;

  for (var i = 0, n = polygon.length; i < n; ++i) {
    if (!(m = (ring = polygon[i]).length)) continue;
    var ring,
        m,
        point0 = ring[m - 1],
        lambda0 = longitude(point0),
        phi0 = point0[1] / 2 + quarterPi,
        sinPhi0 = sin(phi0),
        cosPhi0 = cos(phi0);

    for (var j = 0; j < m; ++j, lambda0 = lambda1, sinPhi0 = sinPhi1, cosPhi0 = cosPhi1, point0 = point1) {
      var point1 = ring[j],
          lambda1 = longitude(point1),
          phi1 = point1[1] / 2 + quarterPi,
          sinPhi1 = sin(phi1),
          cosPhi1 = cos(phi1),
          delta = lambda1 - lambda0,
          sign = delta >= 0 ? 1 : -1,
          absDelta = sign * delta,
          antimeridian = absDelta > pi,
          k = sinPhi0 * sinPhi1;

      sum.add(atan2(k * sign * sin(absDelta), cosPhi0 * cosPhi1 + k * cos(absDelta)));
      angle += antimeridian ? delta + sign * tau : delta;

      // Are the longitudes either side of the point’s meridian (lambda),
      // and are the latitudes smaller than the parallel (phi)?
      if (antimeridian ^ lambda0 >= lambda ^ lambda1 >= lambda) {
        var arc = cartesianCross(cartesian(point0), cartesian(point1));
        cartesianNormalizeInPlace(arc);
        var intersection = cartesianCross(normal, arc);
        cartesianNormalizeInPlace(intersection);
        var phiArc = (antimeridian ^ delta >= 0 ? -1 : 1) * asin(intersection[2]);
        if (phi > phiArc || phi === phiArc && (arc[0] || arc[1])) {
          winding += antimeridian ^ delta >= 0 ? 1 : -1;
        }
      }
    }
  }

  // First, determine whether the South pole is inside or outside:
  //
  // It is inside if:
  // * the polygon winds around it in a clockwise direction.
  // * the polygon does not (cumulatively) wind around it, but has a negative
  //   (counter-clockwise) area.
  //
  // Second, count the (signed) number of times a segment crosses a lambda
  // from the point to the South pole.  If it is zero, then the point is the
  // same side as the South pole.

  return (angle < -epsilon || angle < epsilon && sum < -epsilon2) ^ (winding & 1);
}

function clip(pointVisible, clipLine, interpolate, start) {
  return function(sink) {
    var line = clipLine(sink),
        ringBuffer = clipBuffer(),
        ringSink = clipLine(ringBuffer),
        polygonStarted = false,
        polygon,
        segments,
        ring;

    var clip = {
      point: point,
      lineStart: lineStart,
      lineEnd: lineEnd,
      polygonStart: function() {
        clip.point = pointRing;
        clip.lineStart = ringStart;
        clip.lineEnd = ringEnd;
        segments = [];
        polygon = [];
      },
      polygonEnd: function() {
        clip.point = point;
        clip.lineStart = lineStart;
        clip.lineEnd = lineEnd;
        segments = merge(segments);
        var startInside = polygonContains(polygon, start);
        if (segments.length) {
          if (!polygonStarted) sink.polygonStart(), polygonStarted = true;
          clipRejoin(segments, compareIntersection, startInside, interpolate, sink);
        } else if (startInside) {
          if (!polygonStarted) sink.polygonStart(), polygonStarted = true;
          sink.lineStart();
          interpolate(null, null, 1, sink);
          sink.lineEnd();
        }
        if (polygonStarted) sink.polygonEnd(), polygonStarted = false;
        segments = polygon = null;
      },
      sphere: function() {
        sink.polygonStart();
        sink.lineStart();
        interpolate(null, null, 1, sink);
        sink.lineEnd();
        sink.polygonEnd();
      }
    };

    function point(lambda, phi) {
      if (pointVisible(lambda, phi)) sink.point(lambda, phi);
    }

    function pointLine(lambda, phi) {
      line.point(lambda, phi);
    }

    function lineStart() {
      clip.point = pointLine;
      line.lineStart();
    }

    function lineEnd() {
      clip.point = point;
      line.lineEnd();
    }

    function pointRing(lambda, phi) {
      ring.push([lambda, phi]);
      ringSink.point(lambda, phi);
    }

    function ringStart() {
      ringSink.lineStart();
      ring = [];
    }

    function ringEnd() {
      pointRing(ring[0][0], ring[0][1]);
      ringSink.lineEnd();

      var clean = ringSink.clean(),
          ringSegments = ringBuffer.result(),
          i, n = ringSegments.length, m,
          segment,
          point;

      ring.pop();
      polygon.push(ring);
      ring = null;

      if (!n) return;

      // No intersections.
      if (clean & 1) {
        segment = ringSegments[0];
        if ((m = segment.length - 1) > 0) {
          if (!polygonStarted) sink.polygonStart(), polygonStarted = true;
          sink.lineStart();
          for (i = 0; i < m; ++i) sink.point((point = segment[i])[0], point[1]);
          sink.lineEnd();
        }
        return;
      }

      // Rejoin connected segments.
      // TODO reuse ringBuffer.rejoin()?
      if (n > 1 && clean & 2) ringSegments.push(ringSegments.pop().concat(ringSegments.shift()));

      segments.push(ringSegments.filter(validSegment));
    }

    return clip;
  };
}

function validSegment(segment) {
  return segment.length > 1;
}

// Intersections are sorted along the clip edge. For both antimeridian cutting
// and circle clipping, the same comparison is used.
function compareIntersection(a, b) {
  return ((a = a.x)[0] < 0 ? a[1] - halfPi - epsilon : halfPi - a[1])
       - ((b = b.x)[0] < 0 ? b[1] - halfPi - epsilon : halfPi - b[1]);
}

var clipAntimeridian = clip(
  function() { return true; },
  clipAntimeridianLine,
  clipAntimeridianInterpolate,
  [-pi, -halfPi]
);

// Takes a line and cuts into visible segments. Return values: 0 - there were
// intersections or the line was empty; 1 - no intersections; 2 - there were
// intersections, and the first and last segments should be rejoined.
function clipAntimeridianLine(stream) {
  var lambda0 = NaN,
      phi0 = NaN,
      sign0 = NaN,
      clean; // no intersections

  return {
    lineStart: function() {
      stream.lineStart();
      clean = 1;
    },
    point: function(lambda1, phi1) {
      var sign1 = lambda1 > 0 ? pi : -pi,
          delta = abs(lambda1 - lambda0);
      if (abs(delta - pi) < epsilon) { // line crosses a pole
        stream.point(lambda0, phi0 = (phi0 + phi1) / 2 > 0 ? halfPi : -halfPi);
        stream.point(sign0, phi0);
        stream.lineEnd();
        stream.lineStart();
        stream.point(sign1, phi0);
        stream.point(lambda1, phi0);
        clean = 0;
      } else if (sign0 !== sign1 && delta >= pi) { // line crosses antimeridian
        if (abs(lambda0 - sign0) < epsilon) lambda0 -= sign0 * epsilon; // handle degeneracies
        if (abs(lambda1 - sign1) < epsilon) lambda1 -= sign1 * epsilon;
        phi0 = clipAntimeridianIntersect(lambda0, phi0, lambda1, phi1);
        stream.point(sign0, phi0);
        stream.lineEnd();
        stream.lineStart();
        stream.point(sign1, phi0);
        clean = 0;
      }
      stream.point(lambda0 = lambda1, phi0 = phi1);
      sign0 = sign1;
    },
    lineEnd: function() {
      stream.lineEnd();
      lambda0 = phi0 = NaN;
    },
    clean: function() {
      return 2 - clean; // if intersections, rejoin first and last segments
    }
  };
}

function clipAntimeridianIntersect(lambda0, phi0, lambda1, phi1) {
  var cosPhi0,
      cosPhi1,
      sinLambda0Lambda1 = sin(lambda0 - lambda1);
  return abs(sinLambda0Lambda1) > epsilon
      ? atan((sin(phi0) * (cosPhi1 = cos(phi1)) * sin(lambda1)
          - sin(phi1) * (cosPhi0 = cos(phi0)) * sin(lambda0))
          / (cosPhi0 * cosPhi1 * sinLambda0Lambda1))
      : (phi0 + phi1) / 2;
}

function clipAntimeridianInterpolate(from, to, direction, stream) {
  var phi;
  if (from == null) {
    phi = direction * halfPi;
    stream.point(-pi, phi);
    stream.point(0, phi);
    stream.point(pi, phi);
    stream.point(pi, 0);
    stream.point(pi, -phi);
    stream.point(0, -phi);
    stream.point(-pi, -phi);
    stream.point(-pi, 0);
    stream.point(-pi, phi);
  } else if (abs(from[0] - to[0]) > epsilon) {
    var lambda = from[0] < to[0] ? pi : -pi;
    phi = direction * lambda / 2;
    stream.point(-lambda, phi);
    stream.point(0, phi);
    stream.point(lambda, phi);
  } else {
    stream.point(to[0], to[1]);
  }
}

function clipCircle(radius) {
  var cr = cos(radius),
      delta = 2 * radians$1,
      smallRadius = cr > 0,
      notHemisphere = abs(cr) > epsilon; // TODO optimise for this common case

  function interpolate(from, to, direction, stream) {
    circleStream(stream, radius, delta, direction, from, to);
  }

  function visible(lambda, phi) {
    return cos(lambda) * cos(phi) > cr;
  }

  // Takes a line and cuts into visible segments. Return values used for polygon
  // clipping: 0 - there were intersections or the line was empty; 1 - no
  // intersections 2 - there were intersections, and the first and last segments
  // should be rejoined.
  function clipLine(stream) {
    var point0, // previous point
        c0, // code for previous point
        v0, // visibility of previous point
        v00, // visibility of first point
        clean; // no intersections
    return {
      lineStart: function() {
        v00 = v0 = false;
        clean = 1;
      },
      point: function(lambda, phi) {
        var point1 = [lambda, phi],
            point2,
            v = visible(lambda, phi),
            c = smallRadius
              ? v ? 0 : code(lambda, phi)
              : v ? code(lambda + (lambda < 0 ? pi : -pi), phi) : 0;
        if (!point0 && (v00 = v0 = v)) stream.lineStart();
        if (v !== v0) {
          point2 = intersect(point0, point1);
          if (!point2 || pointEqual(point0, point2) || pointEqual(point1, point2))
            point1[2] = 1;
        }
        if (v !== v0) {
          clean = 0;
          if (v) {
            // outside going in
            stream.lineStart();
            point2 = intersect(point1, point0);
            stream.point(point2[0], point2[1]);
          } else {
            // inside going out
            point2 = intersect(point0, point1);
            stream.point(point2[0], point2[1], 2);
            stream.lineEnd();
          }
          point0 = point2;
        } else if (notHemisphere && point0 && smallRadius ^ v) {
          var t;
          // If the codes for two points are different, or are both zero,
          // and there this segment intersects with the small circle.
          if (!(c & c0) && (t = intersect(point1, point0, true))) {
            clean = 0;
            if (smallRadius) {
              stream.lineStart();
              stream.point(t[0][0], t[0][1]);
              stream.point(t[1][0], t[1][1]);
              stream.lineEnd();
            } else {
              stream.point(t[1][0], t[1][1]);
              stream.lineEnd();
              stream.lineStart();
              stream.point(t[0][0], t[0][1], 3);
            }
          }
        }
        if (v && (!point0 || !pointEqual(point0, point1))) {
          stream.point(point1[0], point1[1]);
        }
        point0 = point1, v0 = v, c0 = c;
      },
      lineEnd: function() {
        if (v0) stream.lineEnd();
        point0 = null;
      },
      // Rejoin first and last segments if there were intersections and the first
      // and last points were visible.
      clean: function() {
        return clean | ((v00 && v0) << 1);
      }
    };
  }

  // Intersects the great circle between a and b with the clip circle.
  function intersect(a, b, two) {
    var pa = cartesian(a),
        pb = cartesian(b);

    // We have two planes, n1.p = d1 and n2.p = d2.
    // Find intersection line p(t) = c1 n1 + c2 n2 + t (n1 ⨯ n2).
    var n1 = [1, 0, 0], // normal
        n2 = cartesianCross(pa, pb),
        n2n2 = cartesianDot(n2, n2),
        n1n2 = n2[0], // cartesianDot(n1, n2),
        determinant = n2n2 - n1n2 * n1n2;

    // Two polar points.
    if (!determinant) return !two && a;

    var c1 =  cr * n2n2 / determinant,
        c2 = -cr * n1n2 / determinant,
        n1xn2 = cartesianCross(n1, n2),
        A = cartesianScale(n1, c1),
        B = cartesianScale(n2, c2);
    cartesianAddInPlace(A, B);

    // Solve |p(t)|^2 = 1.
    var u = n1xn2,
        w = cartesianDot(A, u),
        uu = cartesianDot(u, u),
        t2 = w * w - uu * (cartesianDot(A, A) - 1);

    if (t2 < 0) return;

    var t = sqrt(t2),
        q = cartesianScale(u, (-w - t) / uu);
    cartesianAddInPlace(q, A);
    q = spherical(q);

    if (!two) return q;

    // Two intersection points.
    var lambda0 = a[0],
        lambda1 = b[0],
        phi0 = a[1],
        phi1 = b[1],
        z;

    if (lambda1 < lambda0) z = lambda0, lambda0 = lambda1, lambda1 = z;

    var delta = lambda1 - lambda0,
        polar = abs(delta - pi) < epsilon,
        meridian = polar || delta < epsilon;

    if (!polar && phi1 < phi0) z = phi0, phi0 = phi1, phi1 = z;

    // Check that the first point is between a and b.
    if (meridian
        ? polar
          ? phi0 + phi1 > 0 ^ q[1] < (abs(q[0] - lambda0) < epsilon ? phi0 : phi1)
          : phi0 <= q[1] && q[1] <= phi1
        : delta > pi ^ (lambda0 <= q[0] && q[0] <= lambda1)) {
      var q1 = cartesianScale(u, (-w + t) / uu);
      cartesianAddInPlace(q1, A);
      return [q, spherical(q1)];
    }
  }

  // Generates a 4-bit vector representing the location of a point relative to
  // the small circle's bounding box.
  function code(lambda, phi) {
    var r = smallRadius ? radius : pi - radius,
        code = 0;
    if (lambda < -r) code |= 1; // left
    else if (lambda > r) code |= 2; // right
    if (phi < -r) code |= 4; // below
    else if (phi > r) code |= 8; // above
    return code;
  }

  return clip(visible, clipLine, interpolate, smallRadius ? [0, -radius] : [-pi, radius - pi]);
}

function clipLine(a, b, x0, y0, x1, y1) {
  var ax = a[0],
      ay = a[1],
      bx = b[0],
      by = b[1],
      t0 = 0,
      t1 = 1,
      dx = bx - ax,
      dy = by - ay,
      r;

  r = x0 - ax;
  if (!dx && r > 0) return;
  r /= dx;
  if (dx < 0) {
    if (r < t0) return;
    if (r < t1) t1 = r;
  } else if (dx > 0) {
    if (r > t1) return;
    if (r > t0) t0 = r;
  }

  r = x1 - ax;
  if (!dx && r < 0) return;
  r /= dx;
  if (dx < 0) {
    if (r > t1) return;
    if (r > t0) t0 = r;
  } else if (dx > 0) {
    if (r < t0) return;
    if (r < t1) t1 = r;
  }

  r = y0 - ay;
  if (!dy && r > 0) return;
  r /= dy;
  if (dy < 0) {
    if (r < t0) return;
    if (r < t1) t1 = r;
  } else if (dy > 0) {
    if (r > t1) return;
    if (r > t0) t0 = r;
  }

  r = y1 - ay;
  if (!dy && r < 0) return;
  r /= dy;
  if (dy < 0) {
    if (r > t1) return;
    if (r > t0) t0 = r;
  } else if (dy > 0) {
    if (r < t0) return;
    if (r < t1) t1 = r;
  }

  if (t0 > 0) a[0] = ax + t0 * dx, a[1] = ay + t0 * dy;
  if (t1 < 1) b[0] = ax + t1 * dx, b[1] = ay + t1 * dy;
  return true;
}

var clipMax = 1e9, clipMin = -clipMax;

// TODO Use d3-polygon’s polygonContains here for the ring check?
// TODO Eliminate duplicate buffering in clipBuffer and polygon.push?

function clipRectangle(x0, y0, x1, y1) {

  function visible(x, y) {
    return x0 <= x && x <= x1 && y0 <= y && y <= y1;
  }

  function interpolate(from, to, direction, stream) {
    var a = 0, a1 = 0;
    if (from == null
        || (a = corner(from, direction)) !== (a1 = corner(to, direction))
        || comparePoint(from, to) < 0 ^ direction > 0) {
      do stream.point(a === 0 || a === 3 ? x0 : x1, a > 1 ? y1 : y0);
      while ((a = (a + direction + 4) % 4) !== a1);
    } else {
      stream.point(to[0], to[1]);
    }
  }

  function corner(p, direction) {
    return abs(p[0] - x0) < epsilon ? direction > 0 ? 0 : 3
        : abs(p[0] - x1) < epsilon ? direction > 0 ? 2 : 1
        : abs(p[1] - y0) < epsilon ? direction > 0 ? 1 : 0
        : direction > 0 ? 3 : 2; // abs(p[1] - y1) < epsilon
  }

  function compareIntersection(a, b) {
    return comparePoint(a.x, b.x);
  }

  function comparePoint(a, b) {
    var ca = corner(a, 1),
        cb = corner(b, 1);
    return ca !== cb ? ca - cb
        : ca === 0 ? b[1] - a[1]
        : ca === 1 ? a[0] - b[0]
        : ca === 2 ? a[1] - b[1]
        : b[0] - a[0];
  }

  return function(stream) {
    var activeStream = stream,
        bufferStream = clipBuffer(),
        segments,
        polygon,
        ring,
        x__, y__, v__, // first point
        x_, y_, v_, // previous point
        first,
        clean;

    var clipStream = {
      point: point,
      lineStart: lineStart,
      lineEnd: lineEnd,
      polygonStart: polygonStart,
      polygonEnd: polygonEnd
    };

    function point(x, y) {
      if (visible(x, y)) activeStream.point(x, y);
    }

    function polygonInside() {
      var winding = 0;

      for (var i = 0, n = polygon.length; i < n; ++i) {
        for (var ring = polygon[i], j = 1, m = ring.length, point = ring[0], a0, a1, b0 = point[0], b1 = point[1]; j < m; ++j) {
          a0 = b0, a1 = b1, point = ring[j], b0 = point[0], b1 = point[1];
          if (a1 <= y1) { if (b1 > y1 && (b0 - a0) * (y1 - a1) > (b1 - a1) * (x0 - a0)) ++winding; }
          else { if (b1 <= y1 && (b0 - a0) * (y1 - a1) < (b1 - a1) * (x0 - a0)) --winding; }
        }
      }

      return winding;
    }

    // Buffer geometry within a polygon and then clip it en masse.
    function polygonStart() {
      activeStream = bufferStream, segments = [], polygon = [], clean = true;
    }

    function polygonEnd() {
      var startInside = polygonInside(),
          cleanInside = clean && startInside,
          visible = (segments = merge(segments)).length;
      if (cleanInside || visible) {
        stream.polygonStart();
        if (cleanInside) {
          stream.lineStart();
          interpolate(null, null, 1, stream);
          stream.lineEnd();
        }
        if (visible) {
          clipRejoin(segments, compareIntersection, startInside, interpolate, stream);
        }
        stream.polygonEnd();
      }
      activeStream = stream, segments = polygon = ring = null;
    }

    function lineStart() {
      clipStream.point = linePoint;
      if (polygon) polygon.push(ring = []);
      first = true;
      v_ = false;
      x_ = y_ = NaN;
    }

    // TODO rather than special-case polygons, simply handle them separately.
    // Ideally, coincident intersection points should be jittered to avoid
    // clipping issues.
    function lineEnd() {
      if (segments) {
        linePoint(x__, y__);
        if (v__ && v_) bufferStream.rejoin();
        segments.push(bufferStream.result());
      }
      clipStream.point = point;
      if (v_) activeStream.lineEnd();
    }

    function linePoint(x, y) {
      var v = visible(x, y);
      if (polygon) ring.push([x, y]);
      if (first) {
        x__ = x, y__ = y, v__ = v;
        first = false;
        if (v) {
          activeStream.lineStart();
          activeStream.point(x, y);
        }
      } else {
        if (v && v_) activeStream.point(x, y);
        else {
          var a = [x_ = Math.max(clipMin, Math.min(clipMax, x_)), y_ = Math.max(clipMin, Math.min(clipMax, y_))],
              b = [x = Math.max(clipMin, Math.min(clipMax, x)), y = Math.max(clipMin, Math.min(clipMax, y))];
          if (clipLine(a, b, x0, y0, x1, y1)) {
            if (!v_) {
              activeStream.lineStart();
              activeStream.point(a[0], a[1]);
            }
            activeStream.point(b[0], b[1]);
            if (!v) activeStream.lineEnd();
            clean = false;
          } else if (v) {
            activeStream.lineStart();
            activeStream.point(x, y);
            clean = false;
          }
        }
      }
      x_ = x, y_ = y, v_ = v;
    }

    return clipStream;
  };
}

var lengthSum$1,
    lambda0,
    sinPhi0,
    cosPhi0;

var lengthStream$1 = {
  sphere: noop,
  point: noop,
  lineStart: lengthLineStart,
  lineEnd: noop,
  polygonStart: noop,
  polygonEnd: noop
};

function lengthLineStart() {
  lengthStream$1.point = lengthPointFirst$1;
  lengthStream$1.lineEnd = lengthLineEnd;
}

function lengthLineEnd() {
  lengthStream$1.point = lengthStream$1.lineEnd = noop;
}

function lengthPointFirst$1(lambda, phi) {
  lambda *= radians$1, phi *= radians$1;
  lambda0 = lambda, sinPhi0 = sin(phi), cosPhi0 = cos(phi);
  lengthStream$1.point = lengthPoint$1;
}

function lengthPoint$1(lambda, phi) {
  lambda *= radians$1, phi *= radians$1;
  var sinPhi = sin(phi),
      cosPhi = cos(phi),
      delta = abs(lambda - lambda0),
      cosDelta = cos(delta),
      sinDelta = sin(delta),
      x = cosPhi * sinDelta,
      y = cosPhi0 * sinPhi - sinPhi0 * cosPhi * cosDelta,
      z = sinPhi0 * sinPhi + cosPhi0 * cosPhi * cosDelta;
  lengthSum$1.add(atan2(sqrt(x * x + y * y), z));
  lambda0 = lambda, sinPhi0 = sinPhi, cosPhi0 = cosPhi;
}

function length(object) {
  lengthSum$1 = new Adder();
  geoStream(object, lengthStream$1);
  return +lengthSum$1;
}

var coordinates = [null, null],
    object = {type: "LineString", coordinates: coordinates};

function distance(a, b) {
  coordinates[0] = a;
  coordinates[1] = b;
  return length(object);
}

var containsObjectType = {
  Feature: function(object, point) {
    return containsGeometry(object.geometry, point);
  },
  FeatureCollection: function(object, point) {
    var features = object.features, i = -1, n = features.length;
    while (++i < n) if (containsGeometry(features[i].geometry, point)) return true;
    return false;
  }
};

var containsGeometryType = {
  Sphere: function() {
    return true;
  },
  Point: function(object, point) {
    return containsPoint(object.coordinates, point);
  },
  MultiPoint: function(object, point) {
    var coordinates = object.coordinates, i = -1, n = coordinates.length;
    while (++i < n) if (containsPoint(coordinates[i], point)) return true;
    return false;
  },
  LineString: function(object, point) {
    return containsLine(object.coordinates, point);
  },
  MultiLineString: function(object, point) {
    var coordinates = object.coordinates, i = -1, n = coordinates.length;
    while (++i < n) if (containsLine(coordinates[i], point)) return true;
    return false;
  },
  Polygon: function(object, point) {
    return containsPolygon(object.coordinates, point);
  },
  MultiPolygon: function(object, point) {
    var coordinates = object.coordinates, i = -1, n = coordinates.length;
    while (++i < n) if (containsPolygon(coordinates[i], point)) return true;
    return false;
  },
  GeometryCollection: function(object, point) {
    var geometries = object.geometries, i = -1, n = geometries.length;
    while (++i < n) if (containsGeometry(geometries[i], point)) return true;
    return false;
  }
};

function containsGeometry(geometry, point) {
  return geometry && containsGeometryType.hasOwnProperty(geometry.type)
      ? containsGeometryType[geometry.type](geometry, point)
      : false;
}

function containsPoint(coordinates, point) {
  return distance(coordinates, point) === 0;
}

function containsLine(coordinates, point) {
  var ao, bo, ab;
  for (var i = 0, n = coordinates.length; i < n; i++) {
    bo = distance(coordinates[i], point);
    if (bo === 0) return true;
    if (i > 0) {
      ab = distance(coordinates[i], coordinates[i - 1]);
      if (
        ab > 0 &&
        ao <= ab &&
        bo <= ab &&
        (ao + bo - ab) * (1 - Math.pow((ao - bo) / ab, 2)) < epsilon2 * ab
      )
        return true;
    }
    ao = bo;
  }
  return false;
}

function containsPolygon(coordinates, point) {
  return !!polygonContains(coordinates.map(ringRadians), pointRadians(point));
}

function ringRadians(ring) {
  return ring = ring.map(pointRadians), ring.pop(), ring;
}

function pointRadians(point) {
  return [point[0] * radians$1, point[1] * radians$1];
}

function geoContains(object, point) {
  return (object && containsObjectType.hasOwnProperty(object.type)
      ? containsObjectType[object.type]
      : containsGeometry)(object, point);
}

function graticuleX(y0, y1, dy) {
  var y = range(y0, y1 - epsilon, dy).concat(y1);
  return function(x) { return y.map(function(y) { return [x, y]; }); };
}

function graticuleY(x0, x1, dx) {
  var x = range(x0, x1 - epsilon, dx).concat(x1);
  return function(y) { return x.map(function(x) { return [x, y]; }); };
}

function graticule() {
  var x1, x0, X1, X0,
      y1, y0, Y1, Y0,
      dx = 10, dy = dx, DX = 90, DY = 360,
      x, y, X, Y,
      precision = 2.5;

  function graticule() {
    return {type: "MultiLineString", coordinates: lines()};
  }

  function lines() {
    return range(ceil(X0 / DX) * DX, X1, DX).map(X)
        .concat(range(ceil(Y0 / DY) * DY, Y1, DY).map(Y))
        .concat(range(ceil(x0 / dx) * dx, x1, dx).filter(function(x) { return abs(x % DX) > epsilon; }).map(x))
        .concat(range(ceil(y0 / dy) * dy, y1, dy).filter(function(y) { return abs(y % DY) > epsilon; }).map(y));
  }

  graticule.lines = function() {
    return lines().map(function(coordinates) { return {type: "LineString", coordinates: coordinates}; });
  };

  graticule.outline = function() {
    return {
      type: "Polygon",
      coordinates: [
        X(X0).concat(
        Y(Y1).slice(1),
        X(X1).reverse().slice(1),
        Y(Y0).reverse().slice(1))
      ]
    };
  };

  graticule.extent = function(_) {
    if (!arguments.length) return graticule.extentMinor();
    return graticule.extentMajor(_).extentMinor(_);
  };

  graticule.extentMajor = function(_) {
    if (!arguments.length) return [[X0, Y0], [X1, Y1]];
    X0 = +_[0][0], X1 = +_[1][0];
    Y0 = +_[0][1], Y1 = +_[1][1];
    if (X0 > X1) _ = X0, X0 = X1, X1 = _;
    if (Y0 > Y1) _ = Y0, Y0 = Y1, Y1 = _;
    return graticule.precision(precision);
  };

  graticule.extentMinor = function(_) {
    if (!arguments.length) return [[x0, y0], [x1, y1]];
    x0 = +_[0][0], x1 = +_[1][0];
    y0 = +_[0][1], y1 = +_[1][1];
    if (x0 > x1) _ = x0, x0 = x1, x1 = _;
    if (y0 > y1) _ = y0, y0 = y1, y1 = _;
    return graticule.precision(precision);
  };

  graticule.step = function(_) {
    if (!arguments.length) return graticule.stepMinor();
    return graticule.stepMajor(_).stepMinor(_);
  };

  graticule.stepMajor = function(_) {
    if (!arguments.length) return [DX, DY];
    DX = +_[0], DY = +_[1];
    return graticule;
  };

  graticule.stepMinor = function(_) {
    if (!arguments.length) return [dx, dy];
    dx = +_[0], dy = +_[1];
    return graticule;
  };

  graticule.precision = function(_) {
    if (!arguments.length) return precision;
    precision = +_;
    x = graticuleX(y0, y1, 90);
    y = graticuleY(x0, x1, precision);
    X = graticuleX(Y0, Y1, 90);
    Y = graticuleY(X0, X1, precision);
    return graticule;
  };

  return graticule
      .extentMajor([[-180, -90 + epsilon], [180, 90 - epsilon]])
      .extentMinor([[-180, -80 - epsilon], [180, 80 + epsilon]]);
}

function graticule10() {
  return graticule()();
}

var identity = x => x;

var areaSum = new Adder(),
    areaRingSum = new Adder(),
    x00$2,
    y00$2,
    x0$3,
    y0$3;

var areaStream = {
  point: noop,
  lineStart: noop,
  lineEnd: noop,
  polygonStart: function() {
    areaStream.lineStart = areaRingStart;
    areaStream.lineEnd = areaRingEnd;
  },
  polygonEnd: function() {
    areaStream.lineStart = areaStream.lineEnd = areaStream.point = noop;
    areaSum.add(abs(areaRingSum));
    areaRingSum = new Adder();
  },
  result: function() {
    var area = areaSum / 2;
    areaSum = new Adder();
    return area;
  }
};

function areaRingStart() {
  areaStream.point = areaPointFirst;
}

function areaPointFirst(x, y) {
  areaStream.point = areaPoint;
  x00$2 = x0$3 = x, y00$2 = y0$3 = y;
}

function areaPoint(x, y) {
  areaRingSum.add(y0$3 * x - x0$3 * y);
  x0$3 = x, y0$3 = y;
}

function areaRingEnd() {
  areaPoint(x00$2, y00$2);
}

var x0$2 = Infinity,
    y0$2 = x0$2,
    x1 = -x0$2,
    y1 = x1;

var boundsStream = {
  point: boundsPoint,
  lineStart: noop,
  lineEnd: noop,
  polygonStart: noop,
  polygonEnd: noop,
  result: function() {
    var bounds = [[x0$2, y0$2], [x1, y1]];
    x1 = y1 = -(y0$2 = x0$2 = Infinity);
    return bounds;
  }
};

function boundsPoint(x, y) {
  if (x < x0$2) x0$2 = x;
  if (x > x1) x1 = x;
  if (y < y0$2) y0$2 = y;
  if (y > y1) y1 = y;
}

// TODO Enforce positive area for exterior, negative area for interior?

var X0 = 0,
    Y0 = 0,
    Z0 = 0,
    X1 = 0,
    Y1 = 0,
    Z1 = 0,
    X2 = 0,
    Y2 = 0,
    Z2 = 0,
    x00$1,
    y00$1,
    x0$1,
    y0$1;

var centroidStream = {
  point: centroidPoint,
  lineStart: centroidLineStart,
  lineEnd: centroidLineEnd,
  polygonStart: function() {
    centroidStream.lineStart = centroidRingStart;
    centroidStream.lineEnd = centroidRingEnd;
  },
  polygonEnd: function() {
    centroidStream.point = centroidPoint;
    centroidStream.lineStart = centroidLineStart;
    centroidStream.lineEnd = centroidLineEnd;
  },
  result: function() {
    var centroid = Z2 ? [X2 / Z2, Y2 / Z2]
        : Z1 ? [X1 / Z1, Y1 / Z1]
        : Z0 ? [X0 / Z0, Y0 / Z0]
        : [NaN, NaN];
    X0 = Y0 = Z0 =
    X1 = Y1 = Z1 =
    X2 = Y2 = Z2 = 0;
    return centroid;
  }
};

function centroidPoint(x, y) {
  X0 += x;
  Y0 += y;
  ++Z0;
}

function centroidLineStart() {
  centroidStream.point = centroidPointFirstLine;
}

function centroidPointFirstLine(x, y) {
  centroidStream.point = centroidPointLine;
  centroidPoint(x0$1 = x, y0$1 = y);
}

function centroidPointLine(x, y) {
  var dx = x - x0$1, dy = y - y0$1, z = sqrt(dx * dx + dy * dy);
  X1 += z * (x0$1 + x) / 2;
  Y1 += z * (y0$1 + y) / 2;
  Z1 += z;
  centroidPoint(x0$1 = x, y0$1 = y);
}

function centroidLineEnd() {
  centroidStream.point = centroidPoint;
}

function centroidRingStart() {
  centroidStream.point = centroidPointFirstRing;
}

function centroidRingEnd() {
  centroidPointRing(x00$1, y00$1);
}

function centroidPointFirstRing(x, y) {
  centroidStream.point = centroidPointRing;
  centroidPoint(x00$1 = x0$1 = x, y00$1 = y0$1 = y);
}

function centroidPointRing(x, y) {
  var dx = x - x0$1,
      dy = y - y0$1,
      z = sqrt(dx * dx + dy * dy);

  X1 += z * (x0$1 + x) / 2;
  Y1 += z * (y0$1 + y) / 2;
  Z1 += z;

  z = y0$1 * x - x0$1 * y;
  X2 += z * (x0$1 + x);
  Y2 += z * (y0$1 + y);
  Z2 += z * 3;
  centroidPoint(x0$1 = x, y0$1 = y);
}

function PathContext(context) {
  this._context = context;
}

PathContext.prototype = {
  _radius: 4.5,
  pointRadius: function(_) {
    return this._radius = _, this;
  },
  polygonStart: function() {
    this._line = 0;
  },
  polygonEnd: function() {
    this._line = NaN;
  },
  lineStart: function() {
    this._point = 0;
  },
  lineEnd: function() {
    if (this._line === 0) this._context.closePath();
    this._point = NaN;
  },
  point: function(x, y) {
    switch (this._point) {
      case 0: {
        this._context.moveTo(x, y);
        this._point = 1;
        break;
      }
      case 1: {
        this._context.lineTo(x, y);
        break;
      }
      default: {
        this._context.moveTo(x + this._radius, y);
        this._context.arc(x, y, this._radius, 0, tau);
        break;
      }
    }
  },
  result: noop
};

var lengthSum = new Adder(),
    lengthRing,
    x00,
    y00,
    x0,
    y0;

var lengthStream = {
  point: noop,
  lineStart: function() {
    lengthStream.point = lengthPointFirst;
  },
  lineEnd: function() {
    if (lengthRing) lengthPoint(x00, y00);
    lengthStream.point = noop;
  },
  polygonStart: function() {
    lengthRing = true;
  },
  polygonEnd: function() {
    lengthRing = null;
  },
  result: function() {
    var length = +lengthSum;
    lengthSum = new Adder();
    return length;
  }
};

function lengthPointFirst(x, y) {
  lengthStream.point = lengthPoint;
  x00 = x0 = x, y00 = y0 = y;
}

function lengthPoint(x, y) {
  x0 -= x, y0 -= y;
  lengthSum.add(sqrt(x0 * x0 + y0 * y0));
  x0 = x, y0 = y;
}

// Simple caching for constant-radius points.
let cacheDigits, cacheAppend, cacheRadius, cacheCircle;

class PathString {
  constructor(digits) {
    this._append = digits == null ? append : appendRound(digits);
    this._radius = 4.5;
    this._ = "";
  }
  pointRadius(_) {
    this._radius = +_;
    return this;
  }
  polygonStart() {
    this._line = 0;
  }
  polygonEnd() {
    this._line = NaN;
  }
  lineStart() {
    this._point = 0;
  }
  lineEnd() {
    if (this._line === 0) this._ += "Z";
    this._point = NaN;
  }
  point(x, y) {
    switch (this._point) {
      case 0: {
        this._append`M${x},${y}`;
        this._point = 1;
        break;
      }
      case 1: {
        this._append`L${x},${y}`;
        break;
      }
      default: {
        this._append`M${x},${y}`;
        if (this._radius !== cacheRadius || this._append !== cacheAppend) {
          const r = this._radius;
          const s = this._;
          this._ = ""; // stash the old string so we can cache the circle path fragment
          this._append`m0,${r}a${r},${r} 0 1,1 0,${-2 * r}a${r},${r} 0 1,1 0,${2 * r}z`;
          cacheRadius = r;
          cacheAppend = this._append;
          cacheCircle = this._;
          this._ = s;
        }
        this._ += cacheCircle;
        break;
      }
    }
  }
  result() {
    const result = this._;
    this._ = "";
    return result.length ? result : null;
  }
}

function append(strings) {
  let i = 1;
  this._ += strings[0];
  for (const j = strings.length; i < j; ++i) {
    this._ += arguments[i] + strings[i];
  }
}

function appendRound(digits) {
  const d = Math.floor(digits);
  if (!(d >= 0)) throw new RangeError(`invalid digits: ${digits}`);
  if (d > 15) return append;
  if (d !== cacheDigits) {
    const k = 10 ** d;
    cacheDigits = d;
    cacheAppend = function append(strings) {
      let i = 1;
      this._ += strings[0];
      for (const j = strings.length; i < j; ++i) {
        this._ += Math.round(arguments[i] * k) / k + strings[i];
      }
    };
  }
  return cacheAppend;
}

function geoPath(projection, context) {
  let digits = 3,
      pointRadius = 4.5,
      projectionStream,
      contextStream;

  function path(object) {
    if (object) {
      if (typeof pointRadius === "function") contextStream.pointRadius(+pointRadius.apply(this, arguments));
      geoStream(object, projectionStream(contextStream));
    }
    return contextStream.result();
  }

  path.area = function(object) {
    geoStream(object, projectionStream(areaStream));
    return areaStream.result();
  };

  path.measure = function(object) {
    geoStream(object, projectionStream(lengthStream));
    return lengthStream.result();
  };

  path.bounds = function(object) {
    geoStream(object, projectionStream(boundsStream));
    return boundsStream.result();
  };

  path.centroid = function(object) {
    geoStream(object, projectionStream(centroidStream));
    return centroidStream.result();
  };

  path.projection = function(_) {
    if (!arguments.length) return projection;
    projectionStream = _ == null ? (projection = null, identity) : (projection = _).stream;
    return path;
  };

  path.context = function(_) {
    if (!arguments.length) return context;
    contextStream = _ == null ? (context = null, new PathString(digits)) : new PathContext(context = _);
    if (typeof pointRadius !== "function") contextStream.pointRadius(pointRadius);
    return path;
  };

  path.pointRadius = function(_) {
    if (!arguments.length) return pointRadius;
    pointRadius = typeof _ === "function" ? _ : (contextStream.pointRadius(+_), +_);
    return path;
  };

  path.digits = function(_) {
    if (!arguments.length) return digits;
    if (_ == null) digits = null;
    else {
      const d = Math.floor(_);
      if (!(d >= 0)) throw new RangeError(`invalid digits: ${_}`);
      digits = d;
    }
    if (context === null) contextStream = new PathString(digits);
    return path;
  };

  return path.projection(projection).digits(digits).context(context);
}

function transformer(methods) {
  return function(stream) {
    var s = new TransformStream;
    for (var key in methods) s[key] = methods[key];
    s.stream = stream;
    return s;
  };
}

function TransformStream() {}

TransformStream.prototype = {
  constructor: TransformStream,
  point: function(x, y) { this.stream.point(x, y); },
  sphere: function() { this.stream.sphere(); },
  lineStart: function() { this.stream.lineStart(); },
  lineEnd: function() { this.stream.lineEnd(); },
  polygonStart: function() { this.stream.polygonStart(); },
  polygonEnd: function() { this.stream.polygonEnd(); }
};

function fit(projection, fitBounds, object) {
  var clip = projection.clipExtent && projection.cl