source: node_modules/d3-geo/src/projection/index.js@ e4c61dd

import clipAntimeridian from "../clip/antimeridian.js";
import clipCircle from "../clip/circle.js";
import clipRectangle from "../clip/rectangle.js";
import compose from "../compose.js";
import identity from "../identity.js";
import {cos, degrees, radians, sin, sqrt} from "../math.js";
import {rotateRadians} from "../rotation.js";
import {transformer} from "../transform.js";
import {fitExtent, fitSize, fitWidth, fitHeight} from "./fit.js";
import resample from "./resample.js";

var transformRadians = transformer({
  point: function(x, y) {
    this.stream.point(x * radians, y * radians);
  }
});

function transformRotate(rotate) {
  return transformer({
    point: function(x, y) {
      var r = rotate(x, y);
      return this.stream.point(r[0], r[1]);
    }
  });
}

function scaleTranslate(k, dx, dy, sx, sy) {
  function transform(x, y) {
    x *= sx; y *= sy;
    return [dx + k * x, dy - k * y];
  }
  transform.invert = function(x, y) {
    return [(x - dx) / k * sx, (dy - y) / k * sy];
  };
  return transform;
}

function scaleTranslateRotate(k, dx, dy, sx, sy, alpha) {
  if (!alpha) return scaleTranslate(k, dx, dy, sx, sy);
  var cosAlpha = cos(alpha),
      sinAlpha = sin(alpha),
      a = cosAlpha * k,
      b = sinAlpha * k,
      ai = cosAlpha / k,
      bi = sinAlpha / k,
      ci = (sinAlpha * dy - cosAlpha * dx) / k,
      fi = (sinAlpha * dx + cosAlpha * dy) / k;
  function transform(x, y) {
    x *= sx; y *= sy;
    return [a * x - b * y + dx, dy - b * x - a * y];
  }
  transform.invert = function(x, y) {
    return [sx * (ai * x - bi * y + ci), sy * (fi - bi * x - ai * y)];
  };
  return transform;
}

export default function projection(project) {
  return projectionMutator(function() { return project; })();
}

export function projectionMutator(projectAt) {
  var project,
      k = 150, // scale
      x = 480, y = 250, // translate
      lambda = 0, phi = 0, // center
      deltaLambda = 0, deltaPhi = 0, deltaGamma = 0, rotate, // pre-rotate
      alpha = 0, // post-rotate angle
      sx = 1, // reflectX
      sy = 1, // reflectX
      theta = null, preclip = clipAntimeridian, // pre-clip angle
      x0 = null, y0, x1, y1, postclip = identity, // post-clip extent
      delta2 = 0.5, // precision
      projectResample,
      projectTransform,
      projectRotateTransform,
      cache,
      cacheStream;

  function projection(point) {
    return projectRotateTransform(point[0] * radians, point[1] * radians);
  }

  function invert(point) {
    point = projectRotateTransform.invert(point[0], point[1]);
    return point && [point[0] * degrees, point[1] * degrees];
  }

  projection.stream = function(stream) {
    return cache && cacheStream === stream ? cache : cache = transformRadians(transformRotate(rotate)(preclip(projectResample(postclip(cacheStream = stream)))));
  };

  projection.preclip = function(_) {
    return arguments.length ? (preclip = _, theta = undefined, reset()) : preclip;
  };

  projection.postclip = function(_) {
    return arguments.length ? (postclip = _, x0 = y0 = x1 = y1 = null, reset()) : postclip;
  };

  projection.clipAngle = function(_) {
    return arguments.length ? (preclip = +_ ? clipCircle(theta = _ * radians) : (theta = null, clipAntimeridian), reset()) : theta * degrees;
  };

  projection.clipExtent = function(_) {
    return arguments.length ? (postclip = _ == null ? (x0 = y0 = x1 = y1 = null, identity) : clipRectangle(x0 = +_[0][0], y0 = +_[0][1], x1 = +_[1][0], y1 = +_[1][1]), reset()) : x0 == null ? null : [[x0, y0], [x1, y1]];
  };

  projection.scale = function(_) {
    return arguments.length ? (k = +_, recenter()) : k;
  };

  projection.translate = function(_) {
    return arguments.length ? (x = +_[0], y = +_[1], recenter()) : [x, y];
  };

  projection.center = function(_) {
    return arguments.length ? (lambda = _[0] % 360 * radians, phi = _[1] % 360 * radians, recenter()) : [lambda * degrees, phi * degrees];
  };

  projection.rotate = function(_) {
    return arguments.length ? (deltaLambda = _[0] % 360 * radians, deltaPhi = _[1] % 360 * radians, deltaGamma = _.length > 2 ? _[2] % 360 * radians : 0, recenter()) : [deltaLambda * degrees, deltaPhi * degrees, deltaGamma * degrees];
  };

  projection.angle = function(_) {
    return arguments.length ? (alpha = _ % 360 * radians, recenter()) : alpha * degrees;
  };

  projection.reflectX = function(_) {
    return arguments.length ? (sx = _ ? -1 : 1, recenter()) : sx < 0;
  };

  projection.reflectY = function(_) {
    return arguments.length ? (sy = _ ? -1 : 1, recenter()) : sy < 0;
  };

  projection.precision = function(_) {
    return arguments.length ? (projectResample = resample(projectTransform, delta2 = _ * _), reset()) : sqrt(delta2);
  };

  projection.fitExtent = function(extent, object) {
    return fitExtent(projection, extent, object);
  };

  projection.fitSize = function(size, object) {
    return fitSize(projection, size, object);
  };

  projection.fitWidth = function(width, object) {
    return fitWidth(projection, width, object);
  };

  projection.fitHeight = function(height, object) {
    return fitHeight(projection, height, object);
  };

  function recenter() {
    var center = scaleTranslateRotate(k, 0, 0, sx, sy, alpha).apply(null, project(lambda, phi)),
        transform = scaleTranslateRotate(k, x - center[0], y - center[1], sx, sy, alpha);
    rotate = rotateRadians(deltaLambda, deltaPhi, deltaGamma);
    projectTransform = compose(project, transform);
    projectRotateTransform = compose(rotate, projectTransform);
    projectResample = resample(projectTransform, delta2);
    return reset();
  }

  function reset() {
    cache = cacheStream = null;
    return projection;
  }

  return function() {
    project = projectAt.apply(this, arguments);
    projection.invert = project.invert && invert;
    return recenter();
  };
}