feat: resolve per-entity color and line type from DXF imports

Add LineTypeName to Layer and propagate resolved color/line-type
through all DXF entity conversions (Arc, Circle, Line, Spline,
Polyline, LwPolyline, Ellipse). Entities that inherit ByLayer
properties now correctly resolve to their layer's values.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

OpenNest.Core/Geometry/Layer.cs

@@ -21,6 +21,8 @@ namespace OpenNest.Geometry
 
         public Color Color { get; set; }
 
+        public string LineTypeName { get; set; }
+
         public override string ToString()
         {
             return Name;

OpenNest/IO/Extensions.cs

@@ -22,33 +22,39 @@ namespace OpenNest.IO
 
         public static Geometry.Arc ToOpenNest(this ACadSharp.Entities.Arc arc)
         {
-            return new Geometry.Arc(
+            var result = new Geometry.Arc(
                 arc.Center.X, arc.Center.Y, arc.Radius,
                 arc.StartAngle,
                 arc.EndAngle)
                 {
                     Layer = arc.Layer.ToOpenNest()
                 };
+            result.ApplyDxfProperties(arc);
+            return result;
         }
 
         public static Geometry.Circle ToOpenNest(this ACadSharp.Entities.Circle circle)
         {
-            return new Geometry.Circle(
+            var result = new Geometry.Circle(
                 circle.Center.X, circle.Center.Y,
                 circle.Radius)
                 {
                     Layer = circle.Layer.ToOpenNest()
                 };
+            result.ApplyDxfProperties(circle);
+            return result;
         }
 
         public static Geometry.Line ToOpenNest(this ACadSharp.Entities.Line line)
         {
-            return new Geometry.Line(
+            var result = new Geometry.Line(
                 line.StartPoint.X, line.StartPoint.Y,
                 line.EndPoint.X, line.EndPoint.Y)
                 {
                     Layer = line.Layer.ToOpenNest()
                 };
+            result.ApplyDxfProperties(line);
+            return result;
         }
 
         public static List<Geometry.Line> ToOpenNest(this Spline spline)
@@ -59,21 +65,28 @@ namespace OpenNest.IO
             if (pts.Count == 0)
                 return lines;
 
+            var layer = spline.Layer.ToOpenNest();
+            var color = spline.ResolveColor();
+            var lineTypeName = spline.ResolveLineTypeName();
             var lastPoint = pts[0].ToOpenNest();
 
             for (var i = 1; i < pts.Count; i++)
             {
                 var nextPoint = pts[i].ToOpenNest();
 
-                lines.Add(new Geometry.Line(
+                lines.Add(new Geometry.Line(lastPoint, nextPoint)
-                    lastPoint,
+                {
-                    nextPoint) { Layer = spline.Layer.ToOpenNest() });
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
 
                 lastPoint = nextPoint;
             }
 
             if (spline.IsClosed)
-                lines.Add(new Geometry.Line(lastPoint, pts[0].ToOpenNest()) { Layer = spline.Layer.ToOpenNest() });
+                lines.Add(new Geometry.Line(lastPoint, pts[0].ToOpenNest())
+                {
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
 
             return lines;
         }
@@ -85,15 +98,19 @@ namespace OpenNest.IO
             if (polyline.Vertices.Count == 0)
                 return lines;
 
+            var layer = polyline.Layer.ToOpenNest();
+            var color = polyline.ResolveColor();
+            var lineTypeName = polyline.ResolveLineTypeName();
             var lastPoint = polyline.Vertices[0].Location.ToOpenNest();
 
             for (var i = 1; i < polyline.Vertices.Count; i++)
             {
                 var nextPoint = polyline.Vertices[i].Location.ToOpenNest();
 
-                lines.Add(new Geometry.Line(
+                lines.Add(new Geometry.Line(lastPoint, nextPoint)
-                    lastPoint,
+                {
-                    nextPoint) { Layer = polyline.Layer.ToOpenNest() });
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
 
                 lastPoint = nextPoint;
             }
@@ -101,7 +118,10 @@ namespace OpenNest.IO
             var isClosed = (polyline.Flags & PolylineFlags.ClosedPolylineOrClosedPolygonMeshInM) != 0;
 
             if (isClosed)
-                lines.Add(new Geometry.Line(lastPoint, polyline.Vertices[0].Location.ToOpenNest()) { Layer = polyline.Layer.ToOpenNest() });
+                lines.Add(new Geometry.Line(lastPoint, polyline.Vertices[0].Location.ToOpenNest())
+                {
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
 
             return lines;
         }
@@ -113,15 +133,19 @@ namespace OpenNest.IO
             if (polyline.Vertices.Count == 0)
                 return lines;
 
+            var layer = polyline.Layer.ToOpenNest();
+            var color = polyline.ResolveColor();
+            var lineTypeName = polyline.ResolveLineTypeName();
             var lastPoint = polyline.Vertices[0].ToOpenNest();
 
             for (var i = 1; i < polyline.Vertices.Count; i++)
             {
                 var nextPoint = polyline.Vertices[i].ToOpenNest();
 
-                lines.Add(new Geometry.Line(
+                lines.Add(new Geometry.Line(lastPoint, nextPoint)
-                    lastPoint,
+                {
-                    nextPoint) { Layer = polyline.Layer.ToOpenNest() });
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
 
                 lastPoint = nextPoint;
             }
@@ -129,7 +153,10 @@ namespace OpenNest.IO
             var isClosed = (polyline.Flags & LwPolylineFlags.Closed) != 0;
 
             if (isClosed)
-                lines.Add(new Geometry.Line(lastPoint, polyline.Vertices[0].ToOpenNest()) { Layer = polyline.Layer.ToOpenNest() });
+                lines.Add(new Geometry.Line(lastPoint, polyline.Vertices[0].ToOpenNest())
+                {
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
 
             return lines;
         }
@@ -170,10 +197,15 @@ namespace OpenNest.IO
             }
 
             var layer = ellipse.Layer.ToOpenNest();
+            var color = ellipse.ResolveColor();
+            var lineTypeName = ellipse.ResolveLineTypeName();
 
             for (var i = 0; i < points.Count - 1; i++)
             {
-                lines.Add(new Geometry.Line(points[i], points[i + 1]) { Layer = layer });
+                lines.Add(new Geometry.Line(points[i], points[i + 1])
+                {
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
             }
 
             // Close the ellipse if it's a full ellipse
@@ -181,7 +213,10 @@ namespace OpenNest.IO
             {
                 var first = lines.First();
                 var last = lines.Last();
-                lines.Add(new Geometry.Line(last.EndPoint, first.StartPoint) { Layer = layer });
+                lines.Add(new Geometry.Line(last.EndPoint, first.StartPoint)
+                {
+                    Layer = layer, Color = color, LineTypeName = lineTypeName
+                });
             }
 
             return lines;
@@ -192,10 +227,37 @@ namespace OpenNest.IO
             return new Geometry.Layer(layer.Name)
             {
                 Color = Color.FromArgb(layer.Color.R, layer.Color.G, layer.Color.B),
-                IsVisible = layer.IsOn
+                IsVisible = layer.IsOn,
+                LineTypeName = layer.LineType?.Name
             };
         }
 
+        public static Color ResolveColor(this ACadSharp.Entities.Entity entity)
+        {
+            var color = entity.Color;
+
+            if (color.IsByLayer)
+                color = entity.Layer.Color;
+
+            return Color.FromArgb(color.R, color.G, color.B);
+        }
+
+        public static string ResolveLineTypeName(this ACadSharp.Entities.Entity entity)
+        {
+            var lt = entity.LineType;
+
+            if (lt == null || string.Equals(lt.Name, "ByLayer", System.StringComparison.OrdinalIgnoreCase))
+                return entity.Layer.LineType?.Name ?? "Continuous";
+
+            return lt.Name;
+        }
+
+        public static void ApplyDxfProperties(this Geometry.Entity target, ACadSharp.Entities.Entity source)
+        {
+            target.Color = source.ResolveColor();
+            target.LineTypeName = source.ResolveLineTypeName();
+        }
+
         public static Vector ToOpenNest(this LwPolyline.Vertex v)
         {
             return new Vector(v.Location.X, v.Location.Y);