Version 4.10.0: Updated target framework versions. Cleanup of TypeConverters, ImageLoader, MBTileSource.

MapControl/Shared/BoundingBox.cs

@@ -10,7 +10,10 @@ namespace MapControl
     /// <summary>
     /// A geographic bounding box with south and north latitude and west and east longitude values in degrees.
     /// </summary>
-    public partial class BoundingBox
+#if !WINDOWS_UWP
+    [System.ComponentModel.TypeConverter(typeof(BoundingBoxConverter))]
+#endif
+    public class BoundingBox
     {
         private double south;
         private double west;

MapControl/Shared/ImageLoader.cs

@@ -0,0 +1,69 @@
+// XAML Map Control - https://github.com/ClemensFischer/XAML-Map-Control
+// © 2018 Clemens Fischer
+// Licensed under the Microsoft Public License (Ms-PL)
+
+using System;
+using System.Diagnostics;
+using System.Threading.Tasks;
+#if WINDOWS_UWP
+using Windows.Web.Http;
+using Windows.UI.Xaml.Media;
+using Windows.UI.Xaml.Media.Imaging;
+#else
+using System.Net.Http;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+#endif
+
+namespace MapControl
+{
+    public static partial class ImageLoader
+    {
+        /// <summary>
+        /// The HttpClient instance used when image data is downloaded from a web resource.
+        /// </summary>
+        public static HttpClient HttpClient { get; set; } = new HttpClient();
+
+        public static async Task<ImageSource> LoadImageAsync(Uri uri, bool isTileImage)
+        {
+            ImageSource imageSource = null;
+
+            if (!uri.IsAbsoluteUri || uri.Scheme == "file")
+            {
+                imageSource = await LoadLocalImageAsync(uri);
+            }
+            else if (uri.Scheme == "http")
+            {
+                imageSource = await LoadHttpImageAsync(uri, isTileImage);
+            }
+            else
+            {
+                imageSource = new BitmapImage(uri);
+            }
+
+            return imageSource;
+        }
+
+        public static async Task<ImageSource> LoadHttpImageAsync(Uri uri, bool isTileImage)
+        {
+            ImageSource imageSource = null;
+
+            using (var response = await HttpClient.GetAsync(uri))
+            {
+                if (!response.IsSuccessStatusCode)
+                {
+                    Debug.WriteLine("ImageLoader: {0}: {1} {2}", uri, (int)response.StatusCode, response.ReasonPhrase);
+                }
+                else if (!isTileImage || IsTileAvailable(response.Headers))
+                {
+                    using (var stream = await GetResponseStreamAsync(response.Content))
+                    {
+                        imageSource = await CreateImageSourceAsync(stream);
+                    }
+                }
+
+                return imageSource;
+            }
+        }
+    }
+}

MapControl/Shared/Location.cs

@@ -10,7 +10,10 @@ namespace MapControl
     /// <summary>
     /// A geographic location with latitude and longitude values in degrees.
     /// </summary>
-    public partial class Location : IEquatable<Location>
+#if !WINDOWS_UWP
+    [System.ComponentModel.TypeConverter(typeof(LocationConverter))]
+#endif
+    public class Location : IEquatable<Location>
     {
         private double latitude;
         private double longitude;

MapControl/Shared/LocationCollection.cs

@@ -11,7 +11,10 @@ namespace MapControl
     /// <summary>
     /// A collection of Locations with support for parsing.
     /// </summary>
-    public partial class LocationCollection : List<Location>
+#if !WINDOWS_UWP
+    [System.ComponentModel.TypeConverter(typeof(LocationCollectionConverter))]
+#endif
+    public class LocationCollection : List<Location>
     {
         public LocationCollection()
         {

MapControl/Shared/LocationEx.cs

@@ -7,6 +7,9 @@ using System.Linq;
 
 namespace MapControl
 {
+    /// <summary>
+    /// Provides helper methods for geodetic calculations on a sphere.
+    /// </summary>
     public static class LocationEx
     {
         /// <summary>
@@ -18,9 +21,48 @@ namespace MapControl
             var lon1 = location1.Longitude * Math.PI / 180d;
             var lat2 = location2.Latitude * Math.PI / 180d;
             var lon2 = location2.Longitude * Math.PI / 180d;
-            var cosS12 = Math.Sin(lat1) * Math.Sin(lat2) + Math.Cos(lat1) * Math.Cos(lat2) * Math.Cos(lon2 - lon1);
+            var sinLat1 = Math.Sin(lat1);
+            var cosLat1 = Math.Cos(lat1);
+            var sinLat2 = Math.Sin(lat2);
+            var cosLat2 = Math.Cos(lat2);
+            var cosLon12 = Math.Cos(lon2 - lon1);
+            var cosS12 = sinLat1 * sinLat2 + cosLat1 * cosLat2 * cosLon12;
+            var s12 = 0d;
 
-            return earthRadius * Math.Acos(Math.Min(Math.Max(cosS12, -1d), 1d));
+            if (Math.Abs(cosS12) < 0.99999999)
+            {
+                s12 = Math.Acos(Math.Min(Math.Max(cosS12, -1d), 1d));
+            }
+            else
+            {
+                var sinLon12 = Math.Sin(lon2 - lon1);
+                var a = cosLat1 * sinLat2 - sinLat1 * cosLat2 * cosLon12;
+                var b = cosLat2 * sinLon12;
+                s12 = Math.Atan2(Math.Sqrt(a * a + b * b), cosS12);
+            }
+
+            return earthRadius * s12;
+        }
+
+        /// <summary>
+        /// see https://en.wikipedia.org/wiki/Great-circle_navigation
+        /// </summary>
+        public static Location GreatCircleLocation(this Location location, double azimuth, double distance, double earthRadius = MapProjection.Wgs84EquatorialRadius)
+        {
+            var s12 = distance / earthRadius;
+            var az1 = azimuth * Math.PI / 180d;
+            var lat1 = location.Latitude * Math.PI / 180d;
+            var lon1 = location.Longitude * Math.PI / 180d;
+            var sinS12 = Math.Sin(s12);
+            var cosS12 = Math.Cos(s12);
+            var sinAz1 = Math.Sin(az1);
+            var cosAz1 = Math.Cos(az1);
+            var sinLat1 = Math.Sin(lat1);
+            var cosLat1 = Math.Cos(lat1);
+            var lat2 = Math.Asin(sinLat1 * cosS12 + cosLat1 * sinS12 * cosAz1);
+            var lon2 = lon1 + Math.Atan2(sinS12 * sinAz1, (cosLat1 * cosS12 - sinLat1 * sinS12 * cosAz1));
+
+            return new Location(lat2 / Math.PI * 180d, lon2 / Math.PI * 180d);
         }
 
         public static LocationCollection CalculateMeridianLocations(this Location location, double latitude2, double resolution = 1d)

MapControl/Shared/MapTileLayer.cs

@@ -344,9 +344,11 @@ namespace MapControl
                 var maxZoomLevel = Math.Min(TileGrid.ZoomLevel, MaxZoomLevel);
                 var minZoomLevel = MinZoomLevel;
 
-                if (minZoomLevel < maxZoomLevel && parentMap.MapLayer != this) // load lower tiles only in a base layer
+                if (minZoomLevel < maxZoomLevel &&
+                    parentMap.MapLayer != this &&
+                    parentMap.Children.Cast<UIElement>().FirstOrDefault() != this)
                 {
-                    minZoomLevel = maxZoomLevel;
+                    minZoomLevel = maxZoomLevel; // do not load lower level tiles if this is note a "base" layer
                 }
 
                 for (var z = minZoomLevel; z <= maxZoomLevel; z++)

MapControl/Shared/TileSource.cs

@@ -9,6 +9,7 @@ using System.Threading.Tasks;
 #if WINDOWS_UWP
 using Windows.UI.Xaml.Media;
 #else
+using System.ComponentModel;
 using System.Windows.Media;
 #endif
 
@@ -17,7 +18,10 @@ namespace MapControl
     /// <summary>
     /// Provides the download Uri or ImageSource of map tiles.
     /// </summary>
-    public partial class TileSource
+#if !WINDOWS_UWP
+    [TypeConverter(typeof(TileSourceConverter))]
+#endif
+    public class TileSource
     {
         private Func<int, int, int, string> getUri;
         private string uriFormat;