在Windows 8应用中，经常需要实现从一个地点到另一个地点的路线绘制功能。本文将介绍如何使用Bing地图的REST服务来实现这一功能。首先，需要了解Bing地图的REST服务以及如何使用C#/XAML来调用这些服务。
在实现之前，需要确保已经安装了Bing地图SDK，并且拥有使用这些服务的密钥。可以通过CodeProject的文章了解Bing地图的基本操作，然后添加Bing地图REST服务.NET库。需要注意的是，Bing地图在某些地区可能不受支持，可以通过特定链接检查支持情况。如果不支持，地图上将显示一个带有红色叉号的圆圈。为了设置支持的区域，需要设置HomeRegion属性，否则它将使用Windows 8用户的区域。
接下来，将创建一个线程来异步获取响应。线程将获取REST服务的URL，该URL可以包含两个位置的坐标或地标作为参数，并返回一个JSON字符串。将使用DataContractJsonSerializer类来序列化JSON响应。
private async Task GetResponse(Uri uri) {
System.Net.Http.HttpClient client = new System.Net.Http.HttpClient();
var response = await client.GetAsync(uri);
using (var stream = await response.Content.ReadAsStreamAsync()) {
DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(Response));
return ser.ReadObject(stream) as Response;
}
}
private async void btnGiveDirections_Click(object sender, RoutedEventArgs e) {
try {
tbError.Text = string.Empty;
if (rdCoord.IsChecked == true) {
URL = "http://dev.virtualearth.net/REST/V1/Routes/Driving?o=json&wp.0=" + txtFromCoord.Text + "&wp.1=" + txtToCoord.Text + "&optmz=distance&rpo=Points&key=" + MyMap.Credentials;
} else {
URL = "http://dev.virtualearth.net/REST/V1/Routes/Driving?o=json&wp.0=" + txtFromLocation.Text + "&wp.1=" + txtToLocation.Text + "&optmz=distance&rpo=Points&key=" + MyMap.Credentials;
}
Uri geocodeRequest = new Uri(URL);
BingMapsRESTService.Response r = await GetResponse(geocodeRequest);
geolocator = new Geolocator();
MyPushPin = new Pushpin();
FromLatitude = ((BingMapsRESTService.Route)(r.ResourceSets[0].Resources[0])).RoutePath.Line.Coordinates[0][0];
FromLongitude = ((BingMapsRESTService.Route)(r.ResourceSets[0].Resources[0])).RoutePath.Line.Coordinates[0][1];
location = new Location(FromLatitude, FromLongitude);
MapLayer.SetPosition(MyPushPin, location);
MyMap.Children.Add(MyPushPin);
MyMap.SetView(location, 15.0f);
MapPolyline routeLine = new MapPolyline();
routeLine.Locations = new LocationCollection();
routeLine.Color = Windows.UI.Colors.Blue;
routeLine.Width = 5.0;
int bound = ((BingMapsRESTService.Route)(r.ResourceSets[0].Resources[0])).RoutePath.Line.Coordinates.GetUpperBound(0);
for (int i = 0; i < bound; i++) {
routeLine.Locations.Add(new Location {
Latitude = ((BingMapsRESTService.Route)(r.ResourceSets[0].Resources[0])).RoutePath.Line.Coordinates[i][0],
Longitude = ((BingMapsRESTService.Route)(r.ResourceSets[0].Resources[0])).RoutePath.Line.Coordinates[i][1]
});
}
MapShapeLayer shapeLayer = new MapShapeLayer();
shapeLayer.Shapes.Add(routeLine);
MyMap.ShapeLayers.Add(shapeLayer);
} catch (Exception) {
tbError.Text = "Error Occured !!! Please Try Again";
}
}