Add import of polygon from dxf

StructureHelperCommon/Models/Shapes/Logics/ArcFlatteningOption.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace StructureHelperCommon.Models.Shapes
+{
+    public enum ArcFlatteningMode
+    {
+        ByAngleStep,
+        BySegmentCount,
+        ByMaxSegmentLength,
+        Combined
+    }
+
+    public class ArcFlatteningOption : IArcFlatteningOption
+    {
+        public ArcFlatteningMode Mode { get; set; } = ArcFlatteningMode.Combined;
+        public double AngleStepRadians { get; set; } = Math.PI / 8; // 22.5°
+        public int SegmentCount { get; set; } = 2;
+        public double MaxSegmentLength { get; set; } = 0.05; // (m)
+    }
+}