Add polygon shape

StructureHelperCommon/Models/Shapes/Logics/IPolygonCalculator.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows.Shapes;
+
+namespace StructureHelperCommon.Models.Shapes
+{
+    public interface IPolygonCalculator
+    {
+        double GetPerimeter(IPolygonShape polygon);
+        double GetArea(IPolygonShape polygon);
+        bool ContainsPoint(IPolygonShape polygon, IPoint2D point);
+    }
+
+}