判断经纬度是否在某个区域内

通过经纬度信息，判断某点是否在某个区域内

代码

/**
 * 处理区域轮廓点数据
 * path : [ [ lon,lat ] ]
 */
export function preceedPointInArea(lng, lat, points) {
  const polygon = [];
  for (const point of points) {
    if (point.length == 2) {
      point["lng"] = parseFloat(point[0]);
      point["lat"] = parseFloat(point[1]);
      polygon.push(point);
    }
  }
  return isPointInPolygon(polygon, lng, lat);
}

/**
 * 判断点是否在某个区域
 */
export function isPointInPolygon(polygon, lng, lat) {
  const numberOfPoints = polygon.length;
  const polygonLats = [];
  const polygonLngs = [];
  for (let i = 0; i < numberOfPoints; i++) {
    polygonLats.push(polygon[i]["lat"]);
    polygonLngs.push(polygon[i]["lng"]);
  }
  let polygonContainsPoint = false;
  for (
    let node = 0, altNode = numberOfPoints - 1;
    node < numberOfPoints;
    altNode = node++
  ) {
    if (
      polygonLngs[node] > lng != polygonLngs[altNode] > lng &&
      lat <
        ((polygonLats[altNode] - polygonLats[node]) *
          (lng - polygonLngs[node])) /
          (polygonLngs[altNode] - polygonLngs[node]) +
          polygonLats[node]
    ) {
      polygonContainsPoint = !polygonContainsPoint;
    }
  }
  return polygonContainsPoint;
}

使用

 import { preceedPointInArea } from "./utli.js";
 const path = [
 	[ 120,25 ],
 	[ 130,25 ],
 	[ 130,20 ],
 	[ 120,20 ]
 ];
 console.log(preceedPointInArea(121.5654, 24.033, path)); // true