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激活 Google Maps JavaScript API

为帮助您起步,我们将引导您在 Google Developers Console 中先完成几项任务:

  1. 创建或选择项目
  2. 激活 Google Maps JavaScript API 及相关服务
  3. 创建相应密钥
继续

Navigation functions (heading)

This example demonstrates computing the heading between two coordinates using the Geometry library. Drag the markers on the map to see the origin, destination and heading change accordingly.

Read the documentation or view this example full screen.

// 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">

var marker1, marker2;
var poly, geodesicPoly;

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 4,
    center: {lat: 34, lng: -40.605}
  });

  map.controls[google.maps.ControlPosition.TOP_CENTER].push(
      document.getElementById('info'));

  marker1 = new google.maps.Marker({
    map: map,
    draggable: true,
    position: {lat: 40.714, lng: -74.006}
  });

  marker2 = new google.maps.Marker({
    map: map,
    draggable: true,
    position: {lat: 48.857, lng: 2.352}
  });

  var bounds = new google.maps.LatLngBounds(
      marker1.getPosition(), marker2.getPosition());
  map.fitBounds(bounds);

  google.maps.event.addListener(marker1, 'position_changed', update);
  google.maps.event.addListener(marker2, 'position_changed', update);

  poly = new google.maps.Polyline({
    strokeColor: '#FF0000',
    strokeOpacity: 1.0,
    strokeWeight: 3,
    map: map,
  });

  geodesicPoly = new google.maps.Polyline({
    strokeColor: '#CC0099',
    strokeOpacity: 1.0,
    strokeWeight: 3,
    geodesic: true,
    map: map
  });

  update();
}

function update() {
  var path = [marker1.getPosition(), marker2.getPosition()];
  poly.setPath(path);
  geodesicPoly.setPath(path);
  var heading = google.maps.geometry.spherical.computeHeading(path[0], path[1]);
  document.getElementById('heading').value = heading;
  document.getElementById('origin').value = path[0].toString();
  document.getElementById('destination').value = path[1].toString();
}
<div id="map"></div>
<div id="floating-panel">
  Origin: <input type="text" readonly id="origin">
  Destination: <input type="text" readonly id="destination"><br>
  Heading: <input type="text" readonly id="heading"> degrees
</div>
/* 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;
}
#floating-panel {
  position: absolute;
  top: 10px;
  left: 25%;
  z-index: 5;
  background-color: #fff;
  padding: 5px;
  border: 1px solid #999;
  text-align: center;
  font-family: 'Roboto','sans-serif';
  line-height: 30px;
  padding-left: 10px;
}
<!-- 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>

自己试一试

悬停在代码块右上角以复制代码或在 JSFiddle 中打开。

<!DOCTYPE html>
<html>
  <head>
    <title>Navigation functions (heading)</title>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <style>
      /* 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;
      }
      #floating-panel {
        position: absolute;
        top: 10px;
        left: 25%;
        z-index: 5;
        background-color: #fff;
        padding: 5px;
        border: 1px solid #999;
        text-align: center;
        font-family: 'Roboto','sans-serif';
        line-height: 30px;
        padding-left: 10px;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
    <div id="floating-panel">
      Origin: <input type="text" readonly id="origin">
      Destination: <input type="text" readonly id="destination"><br>
      Heading: <input type="text" readonly id="heading"> degrees
    </div>
    <script>
      // 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">

      var marker1, marker2;
      var poly, geodesicPoly;

      function initMap() {
        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 4,
          center: {lat: 34, lng: -40.605}
        });

        map.controls[google.maps.ControlPosition.TOP_CENTER].push(
            document.getElementById('info'));

        marker1 = new google.maps.Marker({
          map: map,
          draggable: true,
          position: {lat: 40.714, lng: -74.006}
        });

        marker2 = new google.maps.Marker({
          map: map,
          draggable: true,
          position: {lat: 48.857, lng: 2.352}
        });

        var bounds = new google.maps.LatLngBounds(
            marker1.getPosition(), marker2.getPosition());
        map.fitBounds(bounds);

        google.maps.event.addListener(marker1, 'position_changed', update);
        google.maps.event.addListener(marker2, 'position_changed', update);

        poly = new google.maps.Polyline({
          strokeColor: '#FF0000',
          strokeOpacity: 1.0,
          strokeWeight: 3,
          map: map,
        });

        geodesicPoly = new google.maps.Polyline({
          strokeColor: '#CC0099',
          strokeOpacity: 1.0,
          strokeWeight: 3,
          geodesic: true,
          map: map
        });

        update();
      }

      function update() {
        var path = [marker1.getPosition(), marker2.getPosition()];
        poly.setPath(path);
        geodesicPoly.setPath(path);
        var heading = google.maps.geometry.spherical.computeHeading(path[0], path[1]);
        document.getElementById('heading').value = heading;
        document.getElementById('origin').value = path[0].toString();
        document.getElementById('destination').value = path[1].toString();
      }
    </script>
    <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry&callback=initMap"
        async defer></script>
  </body>
</html>

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Google Maps JavaScript API
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