Fixed an issue with SimpleEdgeRouting start and end points. It was using the upper left of the controls instead of the center, which resulted in an increase in undesirable routing outcomes. (#65)

GraphX.PCL.Logic/Algorithms/EdgeRouting/SimpleER/SimpleEdgeRouting.cs

@@ -62,10 +62,12 @@ namespace GraphX.PCL.Logic.Algorithms.EdgeRouting
             //bad edge data check
             if (ctrl.Source.ID == -1 || ctrl.Target.ID == -1)
                 throw new GX_InvalidDataException("SimpleEdgeRouting() -> You must assign unique ID for each vertex to use SimpleER algo!");
-            if (ctrl.Source.ID == ctrl.Target.ID || !VertexPositions.ContainsKey(ctrl.Target)) return;
+            if (ctrl.Source.ID == ctrl.Target.ID || !VertexSizes.ContainsKey(ctrl.Source) || !VertexSizes.ContainsKey(ctrl.Target)) return;
 
-            var startPoint = VertexPositions[ctrl.Source];// new Point(GraphAreaBase.GetX(ctrl.Source), GraphAreaBase.GetY(ctrl.Source));
-            var endPoint = VertexPositions[ctrl.Target];// new Point(GraphAreaBase.GetX(ctrl.Target), GraphAreaBase.GetY(ctrl.Target));
+			var ss = VertexSizes[ctrl.Source];
+			var es = VertexSizes[ctrl.Target];
+            var startPoint = new Point(ss.X + ss.Width * 0.5, ss.Y + ss.Height * 0.5);
+            var endPoint = new Point(es.X + es.Width * 0.5, es.Y + es.Height * 0.5);
 
 			if (startPoint == endPoint) return;