javascript - Google maps v3 API - 计算给定中心坐标和距离的边界

Question

所以，我看到了this solution关于如何计算给定中心和缩放的边界，但我正在尝试计算给定中心坐标和以英里为单位的距离的边界。

我该怎么做？

Answer 1

使用computeOffset计算中心以东和以西一定距离的点。将这两点添加到 google.maps.LatLngBounds并在该边界上调用 map.fitBounds。

proof of concept fiddle

代码片段:

// This example requires the Geometry library. Include the libraries=geometry
// parameter when you first load the API. For example:
// <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry">
function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 4,
    center: {lat: 37.04831, lng: -95.297565}
  });
  var distance = 10000; // 10 km
  var bounds = new google.maps.LatLngBounds();
  var east = google.maps.geometry.spherical.computeOffset(map.getCenter(), distance, 90);
  bounds.extend(east);
  var west = google.maps.geometry.spherical.computeOffset(map.getCenter(), distance, 270);
  bounds.extend(west);
  map.fitBounds(bounds);
  var polyline = new google.maps.Polyline({
    path: [east, west],
    map: map
  });
  var lineLength = google.maps.geometry.spherical.computeLength(polyline.getPath());
  var infowindow = new google.maps.InfoWindow();
  infowindow.setContent("line length is "+(lineLength/1000).toFixed(2)+" km");
  infowindow.setPosition(map.getCenter());
  infowindow.open(map);
}

/* Always set the map height explicitly to define the size of the div
 * element that contains the map. */
#map {
  height: 100%;
}

/* Optional: Makes the sample page fill the window. */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

<div id="map"></div>
<!-- Replace the value of the key parameter with your own API key. -->
<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&libraries=geometry&callback=initMap"
        async defer></script>