原文:

      在做水利、气象、土地等行业中，若能使用到Google的地形图那是再合适不过了，下面就介绍如何在ArcGIS API for Silverlight中加载Google地

形图。先上一个图，初步制作，待后续继续改进

 

 

       ArcGIS API for Silverlight 中的ArcGISTiledMapServiceLayer图层，继承自TiledMapServiceLayer。如果想实现自己的缓存地图图

 

层，继承它并重载GetTileUrl方法就可以了。

ArcGIS API for Silverlight 内部会计算当前访问的缩放等级level，切片二维编号row，

 

col。这些参数暴露给GetTileUrl方法，在这个方法里面设置访问google静态地图的Url地址。

 

1、在Silverlight项目中新建一个文件夹，并添加一个名为GoogleTopographicLayer.cs文件，内容如下：

 

using System;using System.Net;using System.Windows;using System.Windows.Controls;using System.Windows.Documents;using System.Windows.Ink;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Animation;using System.Windows.Shapes;using ESRI.ArcGIS.Client;using ESRI.ArcGIS.Client.Geometry;namespace GoogleMap.CommonClass{    public class GoogleTopographicLayer: TiledMapServiceLayer    {        private const double cornerCoordinate = 20037508.3427892;        private string _baseURL = "t@128"; //google地形图        public override void Initialize()        {            ESRI.ArcGIS.Client.Projection.WebMercator mercator = new ESRI.ArcGIS.Client.Projection.WebMercator();            this.FullExtent = new ESRI.ArcGIS.Client.Geometry.Envelope(-20037508.3427892, -20037508.3427892, 20037508.3427892, 20037508.3427892)            {                SpatialReference = new SpatialReference(102100)            };            //图层的空间坐标系            this.SpatialReference = new SpatialReference(102100);            // 建立切片信息，每个切片大小256*256px，共16级.            this.TileInfo = new TileInfo()            {                Height = 256,                Width = 256,                Origin = new MapPoint(-cornerCoordinate, cornerCoordinate) { SpatialReference = new ESRI.ArcGIS.Client.Geometry.SpatialReference(102100) },                Lods = new Lod[16]            };            //为每级建立方案，每一级是前一级别的一半.            double resolution = cornerCoordinate * 2 / 256;            for (int i = 0; i < TileInfo.Lods.Length; i++)            {                TileInfo.Lods[i] = new Lod() { Resolution = resolution };                resolution /= 2;            }            // 调用初始化函数            base.Initialize();        }        public override string GetTileUrl(int level, int row, int col)        {            string url = "http://mt" + (col % 4) + ".google.cn/vt/lyrs=" + _baseURL + "&v=w2.114&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level + "&s=Galil";            if (_baseURL == "s@92")            {                 url = "http://mt" + (col % 4) + ".google.cn/vt/lyrs=" + _baseURL + "&v=w2.114&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level + "&s=Galil"; //加载Google遥感图            }            if (_baseURL == "t@128")            {                url = "http://mt" + (col % 4) + ".google.cn/vt/lyrs=" + _baseURL + ",r@169000000&v=w2.114&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level + "&s=Galil";//加载Google地形图             }            if (_baseURL == "m@161000000")            {                url = "http://mt" + (col % 4) + ".google.cn/vt/lyrs=" + _baseURL + "&v=w2.114&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level + "&s=Galil"; //加载Google街道图            }            return string.Format(url);            //调用加载初始的Google街道地图            //string baseUrl = "http://mt2.google.cn/vt/v=w2.116&hl=zh-CN&gl=cn&x={0}&y={1}&z={2}&s=G";            //return string.Format(baseUrl, col, row, level);        }    }}//以上显示的Google地图类型，有三种，根据需要，可以修改变量_baseURL的初始值即可。

 2、Silverlight项目中的MainPage.xaml文件内容如下：

 

 

3、Silverlight项目中的MainPage.xaml.cs文件内容如下：

 

using System;using System.Collections.Generic;using System.Linq;using System.Net;using System.Windows;using System.Windows.Controls;using System.Windows.Documents;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Animation;using System.Windows.Shapes;using TestDZX.CommonClass;using ESRI.ArcGIS.Client.Geometry;using ESRI.ArcGIS.Client;namespace GoogleMap{    public partial class MainPage: UserControl    {        ESRI.ArcGIS.Client.Projection.WebMercator mercator = new ESRI.ArcGIS.Client.Projection.WebMercator();        public MainPage()        {            InitializeComponent();        }        private void UserControl_Loaded(object sender, RoutedEventArgs e)        {            GoogleTopographicLayerlayer = new GoogleTopographicLayer();            myMap.Layers.Add(layer);        }    }}

4、完成以上步骤后，运行，可以看见Google地形图了，just try it，have fun！

 

5、补充：这里使用的是墨卡托坐标，而我们经常使用的是经纬度坐标，这就需要做转换，下面提供一个类，WKIDConvert.cs，内容

如下：

 

using System;using System.Net;using System.Windows;using System.Windows.Controls;using System.Windows.Documents;using System.Windows.Ink;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Animation;using System.Windows.Shapes;using ESRI.ArcGIS.Client.Geometry;namespace GoogleMap.CommonClass{    public static class WKIDConvert    {        //经纬度转墨卡托        public static MapPoint lonlat2mercator(MapPoint lonlat)        {            MapPoint mercator = new MapPoint();            double X = lonlat.X * 20037508.34 / 180;            double Y = Math.Log(Math.Tan((90 + lonlat.Y) * Math.PI / 360)) / (Math.PI / 180);            Y = Y * 20037508.34 / 180;            mercator.X = X;            mercator.Y = Y;            return mercator;        }        //墨卡托转经纬度        public static MapPoint mercator2lonlat(MapPoint mercator)        {            MapPoint lonlat = new MapPoint();            double X = mercator.X / 20037508.34 * 180;            double Y = mercator.Y / 20037508.34 * 180;            Y = 180 / Math.PI * (2 * Math.Atan(Math.Exp(Y * Math.PI / 180)) - Math.PI / 2);            lonlat.X = X;            lonlat.Y = Y;            return lonlat;        }    }}

然后我们如果要定位到某个城市的话，比如黄山市，其Extent为：117.647738815324,29.4704217183843,118.446182957997,30.4124245048916

 

我们这里为MainPage.xaml.cs中添加一行代码即可定位到黄山市范围

private void UserControl_Loaded(object sender, RoutedEventArgs e)

{         

            GoogleTopographicLayer   layer = new GoogleTopographicLayer();

            myMap.Layers.Add(layer);

            myMap.Extent = new Envelope(WKIDConvert.lonlat2mercator(new MapPoint(117.647738815324, 29.4704217183843)), WKIDConvert.lonlat2mercator(new MapPoint(118.446182957997, 30.4124245048916)));

}

 

6、再次补充：在之前的Google地形图上叠加自定义ArcMap地图，可以是动态图也可以是静态图，只要加上发布的地图，即可显示，在MainPage.xaml.cs中添加如下几行代码即可。

private void UserControl_Loaded(object sender, RoutedEventArgs e)

{

            //叠加Google地形图瓦片

            GoogleTopographicLayer layer = new GoogleTopographicLayer();

            myMap.Layers.Add(layer);

            layer.Opacity = 1;

            //加载动态图

            ESRI.ArcGIS.Client.ArcGISDynamicMapServiceLayer dLayer = new ESRI.ArcGIS.Client.ArcGISDynamicMapServiceLayer();

            myMap.Layers.LayersInitialized += (evtsender, args) =>

            {

                myMap.ZoomTo(dLayer.InitialExtent);

            };

            dLayer.Url = "";

            myMap.Layers.Add(dLayer);

            dLayer.Opacity = 1;

            myMap.Extent = new Envelope(WKIDConvert.lonlat2mercator(new MapPoint(117.647738815324, 29.4704217183843)), WKIDConvert.lonlat2mercator(new MapPoint(118.446182957997, 30.4124245048916)));

}

 

效果图如下，这里只是做了黄山市的市界边线，主要作用就是在Google地形图上明显看出黄山市的范围：

 

 

 

 

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