Version 4: Upgrade to VS 2017

MapControl/UWP/MapPanel.UWP.cs

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+// XAML Map Control - https://github.com/ClemensFischer/XAML-Map-Control
+// © 2017 Clemens Fischer
+// Licensed under the Microsoft Public License (Ms-PL)
+
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Media;
+
+namespace MapControl
+{
+    public partial class MapPanel
+    {
+        public static readonly DependencyProperty ParentMapProperty = DependencyProperty.RegisterAttached(
+            "ParentMap", typeof(MapBase), typeof(MapPanel), new PropertyMetadata(null, ParentMapPropertyChanged));
+
+        public MapPanel()
+        {
+            if (this is MapBase)
+            {
+                SetValue(ParentMapProperty, this);
+            }
+            else
+            {
+                AddParentMapHandlers(this);
+            }
+        }
+
+        /// <summary>
+        /// Helper method to work around missing property value inheritance in Silverlight and Windows Runtime.
+        /// Adds Loaded and Unloaded event handlers to the specified FrameworkElement, which set and clear the
+        /// value of the MapPanel.ParentMap attached property.
+        /// </summary>
+        public static void AddParentMapHandlers(FrameworkElement element)
+        {
+            element.Loaded += (s, e) => GetParentMap(element);
+            element.Unloaded += (s, e) => element.ClearValue(ParentMapProperty);
+        }
+
+        public static MapBase GetParentMap(UIElement element)
+        {
+            var parentMap = (MapBase)element.GetValue(ParentMapProperty);
+
+            if (parentMap == null && (parentMap = FindParentMap(element)) != null)
+            {
+                element.SetValue(ParentMapProperty, parentMap);
+            }
+
+            return parentMap;
+        }
+
+        private static MapBase FindParentMap(UIElement element)
+        {
+            MapBase parentMap = null;
+            var parentElement = VisualTreeHelper.GetParent(element) as UIElement;
+
+            if (parentElement != null)
+            {
+                parentMap = parentElement as MapBase;
+
+                if (parentMap == null)
+                {
+                    parentMap = GetParentMap(parentElement);
+                }
+            }
+
+            return parentMap;
+        }
+    }
+}