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https://github.com/ClemensFischer/XAML-Map-Control.git
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50 lines
2 KiB
C#
50 lines
2 KiB
C#
// XAML Map Control - https://github.com/ClemensFischer/XAML-Map-Control
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// © 2019 Clemens Fischer
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// Licensed under the Microsoft Public License (Ms-PL)
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using System;
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#if !WINDOWS_UWP
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using System.Windows;
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#endif
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namespace MapControl.Projections
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{
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/// <summary>
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/// Elliptical Mercator Projection implemented by setting the WKT property of a GeoApiProjection.
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/// See "Map Projections - A Working Manual" (https://pubs.usgs.gov/pp/1395/report.pdf), p.44-45.
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/// </summary>
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public class WorldMercatorProjection : GeoApiProjection
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{
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public WorldMercatorProjection()
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{
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WKT = "PROJCS[\"WGS 84 / World Mercator\"," +
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"GEOGCS[\"WGS 84\"," +
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"DATUM[\"WGS_1984\"," +
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"SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]]," +
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"AUTHORITY[\"EPSG\",\"6326\"]]," +
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"PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]]," +
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"UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]]," +
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"AUTHORITY[\"EPSG\",\"4326\"]]," +
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"PROJECTION[\"Mercator_1SP\"]," +
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"PARAMETER[\"latitude_of_origin\",0]," +
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"PARAMETER[\"central_meridian\",0]," +
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"PARAMETER[\"scale_factor\",1]," +
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"PARAMETER[\"false_easting\",0]," +
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"PARAMETER[\"false_northing\",0]," +
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"UNIT[\"metre\",1,AUTHORITY[\"EPSG\",\"9001\"]]," +
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"AXIS[\"Easting\",EAST]," +
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"AXIS[\"Northing\",NORTH]," +
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"AUTHORITY[\"EPSG\",\"3395\"]]";
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}
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public override Vector GetMapScale(Location location)
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{
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var lat = location.Latitude * Math.PI / 180d;
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var eSinLat = Wgs84Eccentricity * Math.Sin(lat);
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var k = Math.Sqrt(1d - eSinLat * eSinLat) / Math.Cos(lat); // p.44 (7-8)
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return new Vector(ViewportScale * k, ViewportScale * k);
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}
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}
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}
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