原文:ArcGIS API for Silverlight中加载Google地形图（瓦片图）
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 = "[email protected]"; //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 == "[email protected]")
{
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 == "[email protected]")
{
url = "http://mt" + (col % 4) + ".google.cn/vt/lyrs=" + _baseURL + ",[email protected]&v=w2.114&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level + "&s=Galil";//加载Google地形图
}
if (_baseURL == "[email protected]")
{
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：
<UserControl x:Class="GoogleMap.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:esri="http://schemas.esri.com/arcgis/client/2009"
xmlns:controlsToolkit="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Toolkit"
xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
xmlns:layer="clr-namespace:GoogleMap.CommonClass"
d:DesignHeight="300" d:DesignWidth="400" Loaded="UserControl_Loaded">
<Grid x:Name="LayoutRoot" Background="White">
<esri:Map x:Name="myMap" IsLogoVisible="False" ZoomDuration="0:00:02" PanDuration="0:00:02">
</esri:Map>
</Grid>
</UserControl>
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 = "http://localhost/arcgis/rest/services/HS/MapServer/";
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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