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| 2287 | - | 1 | |
| 2 | namespace GMap.NET.Projections |
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| 3 | { |
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| 4 | using System; |
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| 5 | |||
| 6 | /// <summary> |
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| 7 | /// The Mercator projection |
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| 8 | /// 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]] |
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| 9 | /// </summary> |
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| 10 | public class MercatorProjection : PureProjection |
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| 11 | { |
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| 12 | public static readonly MercatorProjection Instance = new MercatorProjection(); |
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| 13 | |||
| 14 | static readonly double MinLatitude = -85.05112878; |
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| 15 | static readonly double MaxLatitude = 85.05112878; |
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| 16 | static readonly double MinLongitude = -180; |
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| 17 | static readonly double MaxLongitude = 180; |
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| 18 | |||
| 19 | public override RectLatLng Bounds |
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| 20 | { |
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| 21 | get |
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| 22 | { |
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| 23 | return RectLatLng.FromLTRB(MinLongitude, MaxLatitude, MaxLongitude, MinLatitude); |
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| 24 | } |
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| 25 | } |
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| 26 | |||
| 27 | readonly GSize tileSize = new GSize(256, 256); |
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| 28 | public override GSize TileSize |
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| 29 | { |
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| 30 | get |
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| 31 | { |
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| 32 | return tileSize; |
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| 33 | } |
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| 34 | } |
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| 35 | |||
| 36 | public override double Axis |
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| 37 | { |
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| 38 | get |
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| 39 | { |
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| 40 | return 6378137; |
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| 41 | } |
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| 42 | } |
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| 43 | |||
| 44 | public override double Flattening |
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| 45 | { |
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| 46 | get |
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| 47 | { |
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| 48 | return (1.0 / 298.257223563); |
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| 49 | } |
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| 50 | } |
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| 51 | |||
| 52 | public override GPoint FromLatLngToPixel(double lat, double lng, int zoom) |
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| 53 | { |
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| 54 | GPoint ret = GPoint.Empty; |
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| 55 | |||
| 56 | lat = Clip(lat, MinLatitude, MaxLatitude); |
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| 57 | lng = Clip(lng, MinLongitude, MaxLongitude); |
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| 58 | |||
| 59 | double x = (lng + 180) / 360; |
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| 60 | double sinLatitude = Math.Sin(lat * Math.PI / 180); |
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| 61 | double y = 0.5 - Math.Log((1 + sinLatitude) / (1 - sinLatitude)) / (4 * Math.PI); |
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| 62 | |||
| 63 | GSize s = GetTileMatrixSizePixel(zoom); |
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| 64 | long mapSizeX = s.Width; |
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| 65 | long mapSizeY = s.Height; |
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| 66 | |||
| 67 | ret.X = (long)Clip(x * mapSizeX + 0.5, 0, mapSizeX - 1); |
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| 68 | ret.Y = (long)Clip(y * mapSizeY + 0.5, 0, mapSizeY - 1); |
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| 69 | |||
| 70 | return ret; |
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| 71 | } |
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| 72 | |||
| 73 | public override PointLatLng FromPixelToLatLng(long x, long y, int zoom) |
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| 74 | { |
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| 75 | PointLatLng ret = PointLatLng.Empty; |
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| 76 | |||
| 77 | GSize s = GetTileMatrixSizePixel(zoom); |
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| 78 | double mapSizeX = s.Width; |
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| 79 | double mapSizeY = s.Height; |
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| 80 | |||
| 81 | double xx = (Clip(x, 0, mapSizeX - 1) / mapSizeX) - 0.5; |
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| 82 | double yy = 0.5 - (Clip(y, 0, mapSizeY - 1) / mapSizeY); |
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| 83 | |||
| 84 | ret.Lat = 90 - 360 * Math.Atan(Math.Exp(-yy * 2 * Math.PI)) / Math.PI; |
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| 85 | ret.Lng = 360 * xx; |
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| 86 | |||
| 87 | return ret; |
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| 88 | } |
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| 89 | |||
| 90 | public override GSize GetTileMatrixMinXY(int zoom) |
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| 91 | { |
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| 92 | return new GSize(0, 0); |
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| 93 | } |
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| 94 | |||
| 95 | public override GSize GetTileMatrixMaxXY(int zoom) |
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| 96 | { |
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| 97 | long xy = (1 << zoom); |
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| 98 | return new GSize(xy - 1, xy - 1); |
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| 99 | } |
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| 100 | } |
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| 101 | } |