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import {Adder} from "d3-array";
import {abs} from "../math.js";
import noop from "../noop.js";
var areaSum = new Adder(),
areaRingSum = new Adder(),
x00,
y00,
x0,
y0;
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 = x0 = x, y00 = y0 = y;
}
function areaPoint(x, y) {
areaRingSum.add(y0 * x - x0 * y);
x0 = x, y0 = y;
}
function areaRingEnd() {
areaPoint(x00, y00);
}
export default areaStream;