根据经纬度计算地图的缩放级别和中心点

本功能适用腾讯地图，百度地图，高德地图设置地图缩放级别和中心点

1.points是经纬度集合

2.centerW是中点的lat

3.centerJ是中点的lng

4.zoom是地图的锁房级别

 getCenterPoint(points) {
      //通过经纬度获取中心位置和缩放级别
      var maxJ = points[0].lng;
      var minJ = points[0].lng;
      var maxW = points[0].lat;
      var minW = points[0].lat;
      var res;
      for (var i = points.length - 1; i >= 0; i--) {
        res = points[i];
        if (res.lng > maxJ) maxJ = res.lng;
        if (res.lng < minJ) minJ = res.lng;
        if (res.lat > maxW) maxW = res.lat;
        if (res.lat < minW) minW = res.lat;
      }
      if (maxJ == minJ && maxW == minW) return [maxJ, maxW, 9];
      var diff = maxJ - minJ;
      if (diff < maxW - minW) diff = maxW - minW;
      diff = parseInt(10000 * diff) / 10000;
      var centerJ = minJ * 1000000 + (1000000 * (maxJ - minJ)) / 2;
      var centerW = minW * 1000000 + (1000000 * (maxW - minW)) / 2;
      var zoom = this.getRoom(diff);
      console.log(centerJ / 1000000, centerW / 1000000, zoom);
      return [centerJ / 1000000, centerW / 1000000, zoom];
 },
 getRoom(diff) {
      var room = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14);
      var diffArr = new Array(360,180,90,45,22,11,5,2.5,1.25, 0.6,0.3,0.15,0.07,0.03,0);
      for (var i = 0; i < diffArr.length; i++) {
        if (diff - diffArr[i] >= 0) {
          return room[i];
        }
      }
      return 14;
 },
 
 
 
//使用方法
 var center = new tMap.LatLng(
    this.getCenterPoint(this.lineList)[1],
    this.getCenterPoint(this.lineList)[0]
);
//定义map变量，调用 TMap.Map() 构造函数创建地图
var map = new tMap.Map(document.getElementById("map"), {
    center: center, //设置地图中心点坐标
    zoom: this.getCenterPoint(this.lineList)[2], //设置地图缩放级别
});