在谷歌地图api中移动一个圆圈

Question

好的,所以我正在学习谷歌地图API,我正试图根据长和拉特(谷歌地图如何与蓝点一起工作)获得实时移动点

不,除非我弄错了,看起来我必须绘制自己的圆圈并更新它的位置.

问题是我无法让圆圈得到更新.

这是我的代码:

var citymap = {};
citymap['chicago'] = {
  center: new google.maps.LatLng(41.878113, -87.629798),
  population: 2842518
};

var cityCircle;

function initialize() {
  // Create the map.
  var mapOptions = {
    zoom: 4,
    center: new google.maps.LatLng(37.09024, -95.712891),
    mapTypeId: google.maps.MapTypeId.TERRAIN
  };

  var map = new google.maps.Map(document.getElementById('map-canvas'),
      mapOptions);

  // Construct the circle for each value in citymap.
  // Note: We scale the population by a factor of 20.
  for (var city in citymap) {
    var populationOptions = {
      strokeColor: '#fff',
      strokeOpacity: 0.8,
      strokeWeight: 2,
      fillColor: '#fff',
      map: map,
      center: citymap[city].center,
      radius: 50000,

    };
    // Add the circle for this city to the map.
    cityCircle = new google.maps.Circle(populationOptions);
    var a=0;
    window.setInterval(function(){
        var p = populationOptions.center;
        var g = p.lat()+500;
        var m = p.lng()+500;    
        cityCircle.setCenter(new google.maps.LatLng(g,m));
        cityCircle.setRadius(a+=10);
    }, 50);
  }
}

我真的很惊讶谷歌的api不只是暴露那个蓝色标记,你可以在需要时移动它.

Answer 1

您的更新功能不正确.任何有效的纬度+ 500都将不在地图上.更合理的数字是0.1度.另外,您应该使用cityCircle.getCenter()来代替populationOptions.center.

// Add the circle for this city to the map.
cityCircle = new google.maps.Circle(populationOptions);
var a=50000;
window.setInterval(function(){
    var p = cityCircle.getCenter();
    var g = p.lat()+0.1;
    var m = p.lng()+0.1;    
    cityCircle.setCenter(new google.maps.LatLng(g,m));
    cityCircle.setRadius(a+=10);
}, 500);

工作实例