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import {epsilon} from "../math.js";
import albers from "./albers.js";
import conicEqualArea from "./conicEqualArea.js";
import {fitExtent, fitSize, fitWidth, fitHeight} from "./fit.js";
// The projections must have mutually exclusive clip regions on the sphere,
// as this will avoid emitting interleaving lines and polygons.
function multiplex(streams) {
var n = streams.length;
return {
point: function(x, y) { var i = -1; while (++i < n) streams[i].point(x, y); },
sphere: function() { var i = -1; while (++i < n) streams[i].sphere(); },
lineStart: function() { var i = -1; while (++i < n) streams[i].lineStart(); },
lineEnd: function() { var i = -1; while (++i < n) streams[i].lineEnd(); },
polygonStart: function() { var i = -1; while (++i < n) streams[i].polygonStart(); },
polygonEnd: function() { var i = -1; while (++i < n) streams[i].polygonEnd(); }
};
}
// A composite projection for the United States, configured by default for
// 960×500. The projection also works quite well at 960×600 if you change the
// scale to 1285 and adjust the translate accordingly. The set of standard
// parallels for each region comes from USGS, which is published here:
// http://egsc.usgs.gov/isb/pubs/MapProjections/projections.html#albers
export default function() {
var cache,
cacheStream,
lower48 = albers(), lower48Point,
alaska = conicEqualArea().rotate([154, 0]).center([-2, 58.5]).parallels([55, 65]), alaskaPoint, // EPSG:3338
hawaii = conicEqualArea().rotate([157, 0]).center([-3, 19.9]).parallels([8, 18]), hawaiiPoint, // ESRI:102007
point, pointStream = {point: function(x, y) { point = [x, y]; }};
function albersUsa(coordinates) {
var x = coordinates[0], y = coordinates[1];
return point = null,
(lower48Point.point(x, y), point)
|| (alaskaPoint.point(x, y), point)
|| (hawaiiPoint.point(x, y), point);
}
albersUsa.invert = function(coordinates) {
var k = lower48.scale(),
t = lower48.translate(),
x = (coordinates[0] - t[0]) / k,
y = (coordinates[1] - t[1]) / k;
return (y >= 0.120 && y < 0.234 && x >= -0.425 && x < -0.214 ? alaska
: y >= 0.166 && y < 0.234 && x >= -0.214 && x < -0.115 ? hawaii
: lower48).invert(coordinates);
};
albersUsa.stream = function(stream) {
return cache && cacheStream === stream ? cache : cache = multiplex([lower48.stream(cacheStream = stream), alaska.stream(stream), hawaii.stream(stream)]);
};
albersUsa.precision = function(_) {
if (!arguments.length) return lower48.precision();
lower48.precision(_), alaska.precision(_), hawaii.precision(_);
return reset();
};
albersUsa.scale = function(_) {
if (!arguments.length) return lower48.scale();
lower48.scale(_), alaska.scale(_ * 0.35), hawaii.scale(_);
return albersUsa.translate(lower48.translate());
};
albersUsa.translate = function(_) {
if (!arguments.length) return lower48.translate();
var k = lower48.scale(), x = +_[0], y = +_[1];
lower48Point = lower48
.translate(_)
.clipExtent([[x - 0.455 * k, y - 0.238 * k], [x + 0.455 * k, y + 0.238 * k]])
.stream(pointStream);
alaskaPoint = alaska
.translate([x - 0.307 * k, y + 0.201 * k])
.clipExtent([[x - 0.425 * k + epsilon, y + 0.120 * k + epsilon], [x - 0.214 * k - epsilon, y + 0.234 * k - epsilon]])
.stream(pointStream);
hawaiiPoint = hawaii
.translate([x - 0.205 * k, y + 0.212 * k])
.clipExtent([[x - 0.214 * k + epsilon, y + 0.166 * k + epsilon], [x - 0.115 * k - epsilon, y + 0.234 * k - epsilon]])
.stream(pointStream);
return reset();
};
albersUsa.fitExtent = function(extent, object) {
return fitExtent(albersUsa, extent, object);
};
albersUsa.fitSize = function(size, object) {
return fitSize(albersUsa, size, object);
};
albersUsa.fitWidth = function(width, object) {
return fitWidth(albersUsa, width, object);
};
albersUsa.fitHeight = function(height, object) {
return fitHeight(albersUsa, height, object);
};
function reset() {
cache = cacheStream = null;
return albersUsa;
}
return albersUsa.scale(1070);
}
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