server-position/app/service/transform_position.js

'use strict';
const { CrudService } = require('naf-framework-mongoose-free/lib/service');
const { BusinessError, ErrorCode } = require('naf-core').Error;
const _ = require('lodash');
const assert = require('assert');

//
class Transform_positionService extends CrudService {
  constructor(ctx) {
    super(ctx, 'transform_position');
    this.a = 6378245.0;
    this.ee = 0.00669342162296594323;
  }

  transform(wgLat, wgLon) {
    if (this.outOfChina(wgLat, wgLon)) {
      return [ wgLat, wgLon ];
    }
    let dLat = this.transformLat(wgLon - 105.0, wgLat - 35.0);
    let dLon = this.transformLon(wgLon - 105.0, wgLat - 35.0);
    const radLat = (wgLat / 180.0) * Math.PI;
    let magic = Math.sin(radLat);
    magic = 1 - this.ee * magic * magic;
    const sqrtMagic = Math.sqrt(magic);
    dLat = (dLat * 180.0) / (((this.a * (1 - this.ee)) / (magic * sqrtMagic)) * Math.PI);
    dLon = (dLon * 180.0) / ((this.a / sqrtMagic) * Math.cos(radLat) * Math.PI);
    const mgLat = wgLat + dLat;
    const mgLon = wgLon + dLon;

    return [ mgLat, mgLon ];
  }

  outOfChina(lat, lon) {
    if (lon < 72.004 || lon > 137.8347) return true;
    if (lat < 0.8293 || lat > 55.8271) return true;
    return false;
  }

  transformLat(x, y) {
    let ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
    ret += ((20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0) / 3.0;
    ret += ((20.0 * Math.sin(y * Math.PI) + 40.0 * Math.sin((y / 3.0) * Math.PI)) * 2.0) / 3.0;
    ret += ((160.0 * Math.sin((y / 12.0) * Math.PI) + 320 * Math.sin((y * Math.PI) / 30.0)) * 2.0) / 3.0;
    return ret;
  }
  transformLon(x, y) {
    let ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
    ret += ((20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0) / 3.0;
    ret += ((20.0 * Math.sin(x * Math.PI) + 40.0 * Math.sin((x / 3.0) * Math.PI)) * 2.0) / 3.0;
    ret += ((150.0 * Math.sin((x / 12.0) * Math.PI) + 300.0 * Math.sin((x / 30.0) * Math.PI)) * 2.0) / 3.0;
    return ret;
  }
}

module.exports = Transform_positionService;