From e8b29be79e5391dea7383ff69d9712ade7ca100d Mon Sep 17 00:00:00 2001
From: ClemensF <fischer.clemens@gmail.com>
Date: Sat, 29 Sep 2012 15:03:59 +0200
Subject: [PATCH] Set AffectsRender flag on MapPanel.ViewportPosition property,
 fixed Map.ZoomMap method.

---
 MapControl/Map.cs      | 8 +++++++-
 MapControl/MapPanel.cs | 6 ++----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/MapControl/Map.cs b/MapControl/Map.cs
index edbba0ba..03c7f87f 100644
--- a/MapControl/Map.cs
+++ b/MapControl/Map.cs
@@ -405,6 +405,7 @@ namespace MapControl
                 UpdateTransform();
             }
 
+            ResetTransformOrigin();
             TranslateMap(translation);
         }
 
@@ -414,8 +415,13 @@ namespace MapControl
         /// </summary>
         public void ZoomMap(Point origin, double zoomLevel)
         {
-            SetTransformOrigin(origin);
+            double targetZoomLebel = TargetZoomLevel;
             TargetZoomLevel = zoomLevel;
+
+            if (TargetZoomLevel != targetZoomLebel) // TargetZoomLevel might be coerced
+            {
+                SetTransformOrigin(origin);
+            }
         }
 
         /// <summary>
diff --git a/MapControl/MapPanel.cs b/MapControl/MapPanel.cs
index 03a3c564..0beba283 100644
--- a/MapControl/MapPanel.cs
+++ b/MapControl/MapPanel.cs
@@ -22,7 +22,7 @@ namespace MapControl
 
         private static readonly DependencyPropertyKey ViewportPositionPropertyKey = DependencyProperty.RegisterAttachedReadOnly(
             "ViewportPosition", typeof(Point?), typeof(MapPanel),
-            new FrameworkPropertyMetadata(ViewportPositionPropertyChanged));
+            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.AffectsRender, ViewportPositionPropertyChanged));
 
         public static readonly DependencyProperty ViewportPositionProperty = ViewportPositionPropertyKey.DependencyProperty;
 
@@ -93,15 +93,13 @@ namespace MapControl
 
         protected virtual void OnViewportChanged()
         {
-            Map parentMap = ParentMap;
-
             foreach (UIElement element in InternalChildren)
             {
                 Location location = GetLocation(element);
 
                 if (location != null)
                 {
-                    SetViewportPosition(element, parentMap, location);
+                    SetViewportPosition(element, ParentMap, location);
                 }
             }
         }