Senparc.Weixin.MP SDK 微信公众平台开发教程（十三）：地图相关接口说明

　　为了方便大家开发LBS应用，SDK对常用计算公式，以及百度和谷歌的地图接口做了封装。

常用计算：

　　用于计算2个坐标点之间的直线距离：Senparc.Weixin.MP.Helpers.Distance(double n1, double e1, double n2, double e2)

根据距离获取维度差：Senparc.Weixin.MP.Helpers.GetLatitudeDifference(double km)

根据距离获取经度差：Senparc.Weixin.MP.Helpers.GetLongitudeDifference(double km)

百度API类：Senparc.Weixin.MP.Helpers.BaiduMapHelper

生成百度静态地图URL：BaiduMapHelper.GetBaiduStaticMap(double lng, double lat, int scale, int zoom, IList<BaiduMarkers> markersList, int width = 400, int height = 300)

最后生成的地址如下：

http://maps.googleapis.com/maps/api/staticmap?center=&zoom=13&size=640x640&maptype=roadmap&format=jpg&sensor=false&language=zh&&markers=color:red%7Clabel:O%7C31.285774,120.59761&markers=color:blue%7Clabel:T%7C31.289774,120.59791

生成的URL可以直接放到<img>中，或者直接赋值在ResponseMessageNews的Article.PicUrl。

对应的GoogleMap API，SDK中做了一致的操作体验。

GoogleMap API类：Senparc.Weixin.MP.Helpers.GoogleMapHelper

生成百度静态地图URL：GoogleMapHelper.GetGoogleStaticMap(int scale, IList<GoogleMapMarkers> markersList, string size = "640x640")

生成的地址如下：

http://maps.googleapis.com/maps/api/staticmap?center=&zoom=&size=640x640&maptype=roadmap&format=jpg&sensor=false&language=zh&&markers=color:red%7Clabel:O%7C31.285774,120.59761&markers=color:blue%7Clabel:T%7C31.289774,120.59791

　　结合SDk，我们可以在用户发送位置消息过来的时候，使用地图接口做一些功能，例如我们在MessageHandler的OnLocationRequest实践中对消息进行处理：

/// <summary>
   /// 处理位置请求
   /// </summary>
   /// <param name="requestMessage"></param>
   /// <returns></returns>
   public override IResponseMessageBase OnLocationRequest(RequestMessageLocation requestMessage)
   {
       var responseMessage = ResponseMessageBase.CreateFromRequestMessage<ResponseMessageNews>(requestMessage);
 
       var markersList = new List<GoogleMapMarkers>();
       markersList.Add(new GoogleMapMarkers()
       {
           X = requestMessage.Location_X,
           Y = requestMessage.Location_Y,
           Color = "red",
           Label = "S",
           Size = GoogleMapMarkerSize.Default,
       });
       var mapSize = "480x600";
       var mapUrl = GoogleMapHelper.GetGoogleStaticMap(19 /*requestMessage.Scale*//*微信和GoogleMap的Scale不一致，这里建议使用固定值*/,
                                                       markersList, mapSize);
       responseMessage.Articles.Add(new Article()
       {
           Description = string.Format("您刚才发送了地理位置信息。Location_X：{0}，Location_Y：{1}，Scale：{2}，标签：{3}",
                         requestMessage.Location_X, requestMessage.Location_Y,
                         requestMessage.Scale, requestMessage.Label),
           PicUrl = mapUrl,
           Title = "定位地点周边地图",
           Url = mapUrl
       });
       responseMessage.Articles.Add(new Article()
       {
           Title = "微信公众平台SDK 官网链接",
           Description = "Senparc.Weixin.MK SDK地址",
           PicUrl = "http://weixin.senparc.com/images/logo.jpg",
           Url = "http://weixin.senparc.com"
       });            return responseMessage;<br> }