Fix HttpTileMapImageProvider to use BaseStorageFolder

Author: BobLd

OxyPlot.Core.Cartography/Axes/LatitudeWebMercatorAxis.cs

@@ -1,7 +1,7 @@
 namespace OxyPlot.Axes
 {
     /// <summary>
-    /// Represents an axis with Web Mercator latitude scale.
+    /// Represents an axis with Web Mercator latitude scale (Y axis).
     /// <para>
     /// Web Mercator, Google Web Mercator, Spherical Mercator, WGS 84 Web Mercator or WGS 84/Pseudo-Mercator
     /// is a variant of the Mercator map projection and is the de facto standard for Web mapping applications.
@@ -22,6 +22,9 @@ public class LatitudeWebMercatorAxis : Axis
 
         /// <summary>
         /// Initializes a new instance of the <see cref="LatitudeWebMercatorAxis"/> class.
+        /// <para>
+        /// Represents an axis with Web Mercator latitude scale (Y axis).
+        /// </para>
         /// </summary>
         public LatitudeWebMercatorAxis()
         {

OxyPlot.Core.Cartography/Axes/LongitudeAxis.cs

@@ -1,13 +1,21 @@
 namespace OxyPlot.Axes
 {
     /// <summary>
-    /// Represents an axis with longitude scale.
-    /// https://en.wikipedia.org/wiki/Web_Mercator_projection
+    /// Represents an axis with longitude scale (X axis).
+    /// <para>
+    /// <see href="https://en.wikipedia.org/wiki/Web_Mercator_projection"/>
+    /// </para>
     /// </summary>
     public class LongitudeAxis : LinearAxis
     {
         private const double _maxDefaultValue = 180;
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="LongitudeAxis"/> class.
+        /// <para>
+        /// Represents an axis with longitude scale (X axis).
+        /// </para>
+        /// </summary>
         public LongitudeAxis() : base()
         {
             this.FilterMinValue = -_maxDefaultValue;

OxyPlot.Core.Cartography/Data/HttpTileMapImageProvider.cs

@@ -114,7 +114,7 @@ public string Url
             {
                 _url = value;
                 var uri = new Uri(_url);
-                _fullStoragePath = CartographyHelper.GetStoragePathFromUri(uri);
+                _fullStoragePath = Path.Combine(BaseStorageFolder, CartographyHelper.GetStoragePathFromUri(uri));
             }
         }
 

SimpleDemo/ViewModels/MapViewModel.cs

@@ -6,6 +6,7 @@
 using OxyPlot.Axes;
 using OxyPlot.Data;
 using OxyPlot.Legends;
+using OxyPlot.Series;
 using ReactiveUI;
 using System;
 using System.IO;
@@ -68,28 +69,35 @@ private PlotModel CreateMapPlotView()
 
             var tileMapImageProvider = new HttpTileMapImageProvider(SynchronizationContext.Current)
             {
+                //Url = "https://www.metoffice.gov.uk/public/tiles/map/{Z}/{Y}/{X}.png",
                 Url = "http://tile.openstreetmap.org/{Z}/{X}/{Y}.png",
                 //Url = "https://server.arcgisonline.com/arcgis/rest/services/World_Imagery/MapServer/tile/{Z}/{Y}/{X}", // https://developers.arcgis.com/documentation/mapping-apis-and-services/data-hosting/services/image-tile-service/
                 //Url = "https://maptiles.finncdn.no/tileService/1.0.3/norortho/{Z}/{X}/{Y}.png",
                 //Url = "https://maptiles.finncdn.no/tileService/1.0.3/normap/{Z}/{X}/{Y}.png",
 
                 MaxNumberOfDownloads = 2,
                 UserAgent = "OxyPlot.Cartography",
-                ImageConverter = new Func<byte[], byte[]>(input =>
+                ImageConverter = new Func<byte[], byte[]>(bytes =>
                 {
-                    // Only convert if file format is Jpeg
                     // https://github.com/oxyplot/oxyplot/blob/205e968870c292ecaeab2cb9e7f34904897126cb/Source/OxyPlot/Imaging/OxyImage.cs#L221
-                    if (input.Length >= 2 && input[0] == 0xFF && input[1] == 0xD8)
+                    if (bytes.Length >= 2 && bytes[0] == 0x42 && bytes[1] == 0x4D)
+                    {
+                        return bytes; // Bmp
+                    }
+
+                    if (bytes.Length >= 4 && bytes[0] == 0x89 && bytes[1] == 0x50 && bytes[2] == 0x4E && bytes[3] == 0x47)
                     {
-                        using (var msInput = new MemoryStream(input))
-                        using (var msOutput = new MemoryStream())
-                        {
-                            var bitmap = Bitmap.DecodeToWidth(msInput, 256);
-                            bitmap.Save(msOutput);
-                            return msOutput.ToArray();
-                        }
+                        return bytes; //Png
+                    }
+
+                    using (var msInput = new MemoryStream(bytes))
+                    using (var msOutput = new MemoryStream())
+                    {
+                        var bitmap = Bitmap.DecodeToWidth(msInput, 256);
+                        bitmap.Save(msOutput);
+                        return msOutput.ToArray();
                     }
-                    return input;
+                    return bytes;
                 })
             };