我正在开发一个带有Google Maps API v3的网页。我目前有一个功能地图和搜索栏。我需要能够在地图上的某个 KML 文件上显示从搜索地址到最近地标的距离。我该怎么做?
以下是页面的代码:
<script type="text/javascript">
var geocoder;
var map;
var marker;
var layers = [];
function initialize() {
geocoder = new google.maps.Geocoder ();
var latlng = new google.maps.LatLng (41, -73.4);
var myOptions = {
zoom: 7,
center: latlng,
mapTypeId: google.maps.MapTypeId.ROADMAP
}
map = new google.maps.Map(document.getElementById("map_canvas"),
myOptions);
marker = new google.maps.Marker({map:map});
layers[0] = new google.maps.KmlLayer('http://dl.dropbox.com/u/80233620/South-and-North-County-Trailway.kml',
{preserveViewport: true});
layers[1] = new google.maps.KmlLayer('http://www.nyc.gov/html/dot/downloads/misc/cityracks.kml',
{preserveViewport: true});
layers[2] = new google.maps.KmlLayer('http://dl.dropbox.com/u/80233620/NWS%20Radar%20Images.kmz',
{preserveViewport: true});
for (var i = 0; i < layers.length; i++) {
layers[i].setMap(map);
}
}
function codeAddress () {
var address = document.getElementById ("address").value;
geocoder.geocode ( { 'address': address}, function(results, status) {
if (status == google.maps.GeocoderStatus.OK) {
map.setCenter(results [0].geometry.location);
marker.setPosition(results [0].geometry.location);
map.setZoom(14);
}
else {
alert("Geocode was not successful for the following reason: " + status);
}
});
}
function toggleLayer(i) {
if(layers[i].getMap() === null) {
layers[i].setMap(map);
}
else {
layers[i].setMap(null);}
}
</script>
您无法像这样访问 KML 图层中的数据
https://developers.google.com/maps/documentation/javascript/layers#KMLLayers
由于 KML 可能包含大量要素,因此您可能无法访问 直接来自 KmlLayer 对象的要素数据。相反,作为功能 显示,它们被渲染为看起来像可点击的地图 API 覆盖。
相反,您可以手动处理 XML 并添加标记,然后使用几何库和computeDistanceBetween()
来获取距离。 我通常将距离乘以某个数字来解释转弯(距离公式得到直线距离)。我相信大约1.2
是最准确的。