Bing Maps开发扩展三：Bing Maps中渲染ESRI SHP空间数据

Bing Maps作为通用性开发平台，无论是Silverlight还是JavaScript版本的API，都能够实现渲染其他厂商的相关地图数据，本文以实现渲染ESRI SHP格式地图数据为例，详细介绍如何在Bing Map Silverlight Control上实现Esri SHP地图数据的渲染呈现。由于BMSC不具备相应的数据读取API，需要借助第三方开源组件完成SHP收的读取，数据通过发布WCF服务提供给客户端使用。

一、开源组件

1、NetTopologySuite --地址：http://code.google.com/p/nettopologysuite/

2、GeoAPI --GeoAPI是开源项目SharpMap的一部分。

二、ESRI SHP数据读取并发布WCF服务

使用上面的开源组件API读取ESRI SHP地图数据，将里面的空间数据全部提取出来转化为WKT格式的数据通过服务发布给客户端调用即可。

1 /// <summary>
2 /// 读取指定路径的SHP文件并返回空间对象集合
3 /// </summary>
4 /// <param name="shapepath">SHP文件路径</param>
5 /// <returns>空间对象集合</returns>
6 private IGeometryCollection ReadShape(string shapepath)
7 {
8     //判断文件是否存在
9     if (!File.Exists(shapepath))
10         throw new ArgumentException("文件 " + shapepath + " 未找到!");
11
12     //读取SHP文件的空间数据返回空间对象集合
13     ShapefileReader reader = new ShapefileReader(shapepath);
14     IGeometryCollection geometries = reader.ReadAll();
15     return geometries;
16 }

使用WCF对外发布服务接口，Silverlight客户端即可非常方便的调用接口获取到数据。

1 /// <summary>
2 /// 读取SHP地图数据并发布WCF服务
3 /// </summary>
4 /// <returns>返回空间对象的WKT</returns>
5 public List<string> GetShapeDate()
6 {
7     string shpPath = "D:\\BingMapDemo.DataService\\App_Data\\大区界线_polyline.shp";
8     IGeometryCollection collection = ReadShape(shpPath);
9
10     List<string> result = new List<string>();
11     foreach (IGeometry item in collection.Geometries)
12     {
13         //存储WKT格式空间数据
14         result.Add(item.AsText());
15     }
16     return result;
17 }

三、坐标转换

因使用GeoAPI的空间对象（IGeometry）存储的空间数据格式不能完全与Bing Map Silverlight Control中的空间坐标对象完全兼容，客户端获取到数据后必须将GeoAPI的Coordinate对象转化为Bing Map Silverlight Control的Location，以兼容坐标数据的使用。

1 public static class CoordinateConvertor
2 {
3     public static ICoordinate Convert(Location location)
4     {
5         return new Coordinate {Y = location.Latitude, X = location.Longitude};
6     }
7
8     public static Location ConvertBack(ICoordinate location)
9     {
10         return new Location {Latitude = location.Y, Longitude = location.X};
11     }
12
13     public static LocationCollection CoordinatesToLocationCollection(ICoordinate[] coordinates)
14     {
15         var locations = new LocationCollection();
16         foreach (var coordinate in coordinates)
17         {
18             locations.Add(ConvertBack(coordinate));
19         }
20         return locations;
21     }
22
23     public static ICoordinate[] LocationCollectionToCoordinates(LocationCollection locations)
24     {
25         var coordinates = new Coordinate[locations.Count];
26         for (var x = 0; x < locations.Count;x++ )
27         {
28             coordinates[x] = (Coordinate)Convert(locations[x]);
29         }
30         return (ICoordinate[])coordinates;
31     }
32
33     public static LocationCollection LocationRectToLocationCollection(LocationRect locationRect)
34     {
35         var locations = new LocationCollection
36                             {
37                                 locationRect.Northwest,
38                                 locationRect.Southwest,
39                                 locationRect.Southeast,
40                                 locationRect.Northeast,
41                                 locationRect.Northwest
42                             };
43         return locations;
44     }
45 }

四、渲染SHP空间数据

SHP文件中的空间数据通过WCF以WK的格式发布到客户端，客户端通过读取WKT为GeoAPI的空间对象，然后通过坐标转换将坐标转化为Bing Map Silverlight Control所兼容的坐标数据格式，数据在客户端以多边形的方式进行渲染呈现。

1 private void ShpMapReader()
2 {
3     GeometryServiceClient service = new GeometryServiceClient();
4     service.GetShapeDateCompleted += service_GetShapeDateCompleted;
5     service.GetShapeDateAsync();
6 }
7
8 private void service_GetShapeDateCompleted(object sender, GetShapeDateCompletedEventArgs e)
9 {
10     if (e.Error == null)
11     {
12         ObservableCollection<string> result = e.Result;
13         WKTReader reader = null;
14         foreach (var item in result)
15         {
16             reader = new WKTReader();
17             //读取WKT到空间对象
18             IGeometry geometry = reader.Read(item);
19             if (geometry == null) continue;
20             //边界
21             MapPolygon line = new MapPolygon();
22             //转换坐标
23             line.Locations = CoordinateConvertor.CoordinatesToLocationCollection(geometry.Coordinates);
24             line.Fill = new SolidColorBrush(Colors.Gray);
25             line.BorderBrush = new SolidColorBrush(Colors.Green);
26             line.BorderThickness = new Thickness(2);
27             line.MouseEnter += new MouseEventHandler(line_MouseEnter);
28             line.MouseLeave += new MouseEventHandler(line_MouseLeave);
29             this.mlayer.Children.Add(line);
30         }
31     }
32 }

Bing Maps中渲染ESRI SHP空间数据的实现非常简单，掌握了应用开源组件对数据进行读取就OK，以下是运行的效果图。

五、相关资源：

[1]、SharpMap:http://sharpmap.codeplex.com

[2]、NetTopologySuite:http://code.google.com/p/nettopologysuite

[3]、WKT：http://www.opengis.org/techno/specs.htm