en/builder/src/zrender3/contain/polygon.js

import windingLine from './windingLine';
var EPSILON = 1e-8;

function isAroundEqual(a, b) {
  return Math.abs(a - b) < EPSILON;
}

export function contain(points, x, y) {
  var w = 0;
  var p = points[0];

  if (!p) {
    return false;
  }

  for (var i = 1; i < points.length; i++) {
    var p2 = points[i];
    w += windingLine(p[0], p[1], p2[0], p2[1], x, y);
    p = p2;
  } // Close polygon


  var p0 = points[0];

  if (!isAroundEqual(p[0], p0[0]) || !isAroundEqual(p[1], p0[1])) {
    w += windingLine(p[0], p[1], p0[0], p0[1], x, y);
  }

  return w !== 0;
}