GMap.Net中使用高德地图

GMap.Net是.Net下一个地图控件，可以基于Http协议加载各个公司的地图，如Google，Bing，ArcGIS的，主要原理是通过解析各个公司的地图服务的URL，传入相应的参数得到对应的切片底图（Tiled map），如一个高德地图的GMapProvider的实现如下：

using System;
using GMap.NET;
using GMap.NET.MapProviders;
using GMap.NET.Projections;

namespace GMapProvidersExt
{
public abstract class AMapProviderBase : GMapProvider
{
public AMapProviderBase()
{
MaxZoom = null;
RefererUrl = "http://www.amap.com/";
//Copyright = string.Format("©{0} 高德 Corporation, ©{0} NAVTEQ, ©{0} Image courtesy of NASA", DateTime.Today.Year);
}

public override PureProjection Projection
{
get { return MercatorProjection.Instance; }
}

GMapProvider[] overlays;
public override GMapProvider[] Overlays
{
get
{
if (overlays == null)
{
overlays = new GMapProvider[] { this };
}
return overlays;
}
}
}

public class AMapProvider : AMapProviderBase
{
public static readonly AMapProvider Instance;

readonly Guid id = new Guid("EF3DD303-3F74-4938-BF40-232D0595EE88");
public override Guid Id
{
get { return id; }
}

readonly string name = "AMap";
public override string Name
{
get
{
return name;
}
}

static AMapProvider()
{
Instance = new AMapProvider();
}

public override PureImage GetTileImage(GPoint pos, int zoom)
{
try
{
string url = MakeTileImageUrl(pos, zoom, LanguageStr);
return GetTileImageUsingHttp(url);
}
catch (Exception ex)
{
return null;
}
}

string MakeTileImageUrl(GPoint pos, int zoom, string language)
{
var num = (pos.X + pos.Y) % 4 + 1;
//string url = string.Format(UrlFormat, num, pos.X, pos.Y, zoom);
string url = string.Format(UrlFormat, pos.X, pos.Y, zoom);
return url;
}

//static readonly string UrlFormat = "http://webrd04.is.autonavi.com/appmaptile?x={0}&y={1}&z={2}&lang=zh_cn&size=1&scale=1&style=7";
static readonly string UrlFormat = "http://webrd01.is.autonavi.com/appmaptile?lang=zh_cn&size=1&scale=1&style=7&x={0}&y={1}&z={2}";
}
}

如下为高德地图的显示：



通过类似的办法，可以实现加载Google、腾讯的地图，百度的地图也可以加载，但是因为百度采用自己的加偏算法（BD-09），导致加载的地图显示偏差大，当在不同的地图间切换时，无法正确显示。

引自：http://www.cnblogs.com/luxiaoxun/p/3802559.html