GMap.NET.Core/GMap.NET.Projections/MercatorProjection.cs

这里只显示每个文件的开头 60 行。登录后可以解锁完整代码。

微信扫码关注公众号，代码整理好后第一时间通知你。

namespace GMap.NET.Projections
{
   using System;

   /// <summary>
   /// The Mercator projection
   /// PROJCS["World_Mercator",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Mercator"],PARAMETER["False_Easting",0],PARAMETER["False_Northing",0],PARAMETER["Central_Meridian",0],PARAMETER["standard_parallel_1",0],UNIT["Meter",1]]
   /// </summary>
   public class MercatorProjection : PureProjection
   {
      public static readonly MercatorProjection Instance = new MercatorProjection();

      static readonly double MinLatitude = -85.05112878;
      static readonly double MaxLatitude = 85.05112878;
      static readonly double MinLongitude = -180;
      static readonly double MaxLongitude = 180;

      readonly GSize tileSize = new GSize(256, 256);
      public override GSize TileSize
      {
         get
         {
            return tileSize;
         }
      }

      public override double Axis
      {
         get
         {
            return 6378137;
         }
      }

      public override double Flattening
      {
         get
         {
            return (1.0 / 298.257223563);
         }
      }

      public override GPoint FromLatLngToPixel(double lat, double lng, int zoom)
      {
         GPoint ret = GPoint.Empty;

         lat = Clip(lat, MinLatitude, MaxLatitude);
         lng = Clip(lng, MinLongitude, MaxLongitude);

         double x = (lng + 180) / 360;
         double sinLatitude = Math.Sin(lat * Math.PI / 180);
         double y = 0.5 - Math.Log((1 + sinLatitude) / (1 - sinLatitude)) / (4 * Math.PI);

         GSize s = GetTileMatrixSizePixel(zoom);
         long mapSizeX = s.Width;
         long mapSizeY = s.Height;

         ret.X = (int)Clip(x * mapSizeX + 0.5, 0, mapSizeX - 1);
         ret.Y = (int)Clip(y * mapSizeY + 0.5, 0, mapSizeY - 1);