WMTS tile handling

MapControl/Shared/TileCollection.cs

@@ -0,0 +1,35 @@
+// XAML Map Control - https://github.com/ClemensFischer/XAML-Map-Control
+// © 2022 Clemens Fischer
+// Licensed under the Microsoft Public License (Ms-PL)
+
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MapControl
+{
+    public class TileCollection : List<Tile>
+    {
+        /// <summary>
+        /// Get a matching Tile from a TileCollection or create a new one.
+        /// </summary>
+        public Tile GetTile(int zoomLevel, int x, int y, int columnCount)
+        {
+            var tile = this.FirstOrDefault(t => t.ZoomLevel == zoomLevel && t.X == x && t.Y == y);
+
+            if (tile == null)
+            {
+                tile = new Tile(zoomLevel, x, y, columnCount);
+
+                var equivalentTile = this.FirstOrDefault(
+                    t => t.IsLoaded && t.ZoomLevel == tile.ZoomLevel && t.Column == tile.Column && t.Row == tile.Row);
+
+                if (equivalentTile != null)
+                {
+                    tile.SetImageSource(equivalentTile.Image.Source, false); // no opacity animation
+                }
+            }
+
+            return tile;
+        }
+    }
+}