javascript - 从坐标数组中，我如何决定将 map 居中？

Question

假设我正在使用以下位置的 JSON:

var beaches = [
  ['Bondi Beach', -33.890542, 151.274856, 4],
  ['Coogee Beach', -33.923036, 151.259052, 5],
  ['Cronulla Beach', -34.028249, 151.157507, 3],
  ['Manly Beach', -33.80010128657071, 151.28747820854187, 2],
  ['Maroubra Beach', -33.950198, 151.259302, 1]
];

我在 Google map 上绘制这些，我想大致以中间的那个为中心。

Google map API 中是否有执行此操作的函数？还是我必须自己算出平均值？

我已经编写了一个函数，我可以将 JSON 和缩放级别传递给:

function initialize_map(places, zoom) {

    // use first coordinates in the json to initiate the map
    var place_lat_lng = new google.maps.LatLng(places[0][1],places[0][2]);

    var mapOptions = {
          zoom: zoom,
          center: place_lat_lng,
          mapTypeId: google.maps.MapTypeId.ROADMAP
        };

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

    var marker, i; 

    // loop through all the places to get markers
    for (var i=0;i<places.length;i++)
    { 
        var place = places[i];

         marker = new google.maps.Marker({
            position: new google.maps.LatLng(place[1], place[2]),
            map: map,
            animation: google.maps.Animation.DROP
        });
        // add the marker
        marker.setMap(map);            
    }   
}   

此功能有效，但它不会居中，并且标记会在 View 之外。

您将如何使 View 居中并使所有标记都可见？

Answer 1

Google Maps API v3 contains a method for displaying a set of markers :

fitBounds(bounds:LatLngBounds) - None - Sets the viewport to contain the given bounds.

将所有标记添加到 google.maps.LatLngBounds 对象，然后在 map 对象上调用该方法。像这样:

function initialize_map(places, zoom) {
     var bounds = new google.maps.LatLngBounds(); // empty bounds object

    // use first coordinates in the json to initiate the map
    var place_lat_lng = new google.maps.LatLng(places[0][1],places[0][2]);

    var mapOptions = {
          zoom: zoom,
          center: place_lat_lng,
          mapTypeId: google.maps.MapTypeId.ROADMAP
        };

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

    var marker, i; 

    // loop through all the places to get markers
    for (var i=0;i<places.length;i++)
    { 
        var place = places[i];

         marker = new google.maps.Marker({
            position: new google.maps.LatLng(place[1], place[2]),
            map: map,
            animation: google.maps.Animation.DROP
        });
        // add the marker
        marker.setMap(map);            
        bounds.extend(marker.getPosition()); // add the marker to the bounds

    }   

    map.fitBounds(bounds); // show all the markers.
}