feat: add SplitDxfWriter for split DXF output with bend data

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

OpenNest.IO/SplitDxfWriter.cs

@@ -0,0 +1,177 @@
+using ACadSharp;
+using ACadSharp.Entities;
+using ACadSharp.IO;
+using ACadSharp.Tables;
+using CSMath;
+using OpenNest.Bending;
+using OpenNest.Converters;
+using OpenNest.Geometry;
+using System.Collections.Generic;
+using System.IO;
+
+// Disambiguate Entity — both ACadSharp.Entities and OpenNest.Geometry define it
+using GeoEntity = OpenNest.Geometry.Entity;
+
+namespace OpenNest.IO
+{
+    public class SplitDxfWriter
+    {
+        private const double DefaultEtchLength = 1.0;
+
+        public double EtchLength { get; set; } = DefaultEtchLength;
+
+        public void Write(string path, Drawing drawing)
+        {
+            var doc = new CadDocument();
+
+            var cutLayer = new ACadSharp.Tables.Layer("CUT") { Color = new Color(7) };
+            var bendLayer = new ACadSharp.Tables.Layer("BEND") { Color = new Color(2) };
+            var etchLayer = new ACadSharp.Tables.Layer("ETCH") { Color = new Color(3) };
+            doc.Layers.Add(cutLayer);
+            doc.Layers.Add(bendLayer);
+            doc.Layers.Add(etchLayer);
+
+            var centerLineType = new LineType("CENTERX2");
+            doc.LineTypes.Add(centerLineType);
+
+            WriteProgramEntities(doc, drawing.Program, cutLayer);
+
+            if (drawing.Bends != null)
+            {
+                foreach (var bend in drawing.Bends)
+                {
+                    WriteBendLine(doc, bend, bendLayer, centerLineType);
+                    WriteEtchLines(doc, bend, etchLayer);
+                }
+            }
+
+            using var stream = File.Create(path);
+            using var writer = new DxfWriter(stream, doc, false);
+            writer.Write();
+        }
+
+        private static void WriteProgramEntities(CadDocument doc, CNC.Program program, ACadSharp.Tables.Layer layer)
+        {
+            var geometry = ConvertProgram.ToGeometry(program);
+            WriteGeometryEntities(doc, geometry, layer);
+        }
+
+        private static void WriteGeometryEntities(CadDocument doc, List<GeoEntity> geometry, ACadSharp.Tables.Layer layer)
+        {
+            foreach (var entity in geometry)
+            {
+                // Skip rapid moves
+                if (entity.Layer == SpecialLayers.Rapid)
+                    continue;
+
+                switch (entity)
+                {
+                    case OpenNest.Geometry.Line line:
+                        doc.Entities.Add(new ACadSharp.Entities.Line
+                        {
+                            StartPoint = new XYZ(line.StartPoint.X, line.StartPoint.Y, 0),
+                            EndPoint = new XYZ(line.EndPoint.X, line.EndPoint.Y, 0),
+                            Layer = layer
+                        });
+                        break;
+
+                    case OpenNest.Geometry.Arc arc:
+                        var startAngle = arc.StartAngle;
+                        var endAngle = arc.EndAngle;
+                        if (arc.IsReversed)
+                            OpenNest.Math.Generic.Swap(ref startAngle, ref endAngle);
+
+                        doc.Entities.Add(new ACadSharp.Entities.Arc
+                        {
+                            Center = new XYZ(arc.Center.X, arc.Center.Y, 0),
+                            Radius = arc.Radius,
+                            StartAngle = startAngle,
+                            EndAngle = endAngle,
+                            Layer = layer
+                        });
+                        break;
+
+                    case OpenNest.Geometry.Circle circle:
+                        doc.Entities.Add(new ACadSharp.Entities.Circle
+                        {
+                            Center = new XYZ(circle.Center.X, circle.Center.Y, 0),
+                            Radius = circle.Radius,
+                            Layer = layer
+                        });
+                        break;
+
+                    case OpenNest.Geometry.Shape shape:
+                        WriteGeometryEntities(doc, shape.Entities, layer);
+                        break;
+                }
+            }
+        }
+
+        private static void WriteBendLine(CadDocument doc, Bend bend, ACadSharp.Tables.Layer layer, LineType lineType)
+        {
+            var line = new ACadSharp.Entities.Line
+            {
+                StartPoint = new XYZ(bend.StartPoint.X, bend.StartPoint.Y, 0),
+                EndPoint = new XYZ(bend.EndPoint.X, bend.EndPoint.Y, 0),
+                Layer = layer,
+                LineType = lineType
+            };
+            doc.Entities.Add(line);
+
+            if (!string.IsNullOrEmpty(bend.NoteText))
+            {
+                var midX = (bend.StartPoint.X + bend.EndPoint.X) / 2;
+                var midY = (bend.StartPoint.Y + bend.EndPoint.Y) / 2;
+
+                var mtext = new MText
+                {
+                    InsertPoint = new XYZ(midX, midY + 0.5, 0),
+                    Value = bend.NoteText,
+                    Height = 0.1,
+                    Layer = layer
+                };
+                doc.Entities.Add(mtext);
+            }
+        }
+
+        private void WriteEtchLines(CadDocument doc, Bend bend, ACadSharp.Tables.Layer layer)
+        {
+            if (bend.Direction != BendDirection.Up)
+                return;
+
+            var start = bend.StartPoint;
+            var end = bend.EndPoint;
+            var length = bend.Length;
+
+            if (length < EtchLength * 3.0)
+            {
+                doc.Entities.Add(new ACadSharp.Entities.Line
+                {
+                    StartPoint = new XYZ(start.X, start.Y, 0),
+                    EndPoint = new XYZ(end.X, end.Y, 0),
+                    Layer = layer
+                });
+            }
+            else
+            {
+                var angle = start.AngleTo(end);
+                var dx = System.Math.Cos(angle) * EtchLength;
+                var dy = System.Math.Sin(angle) * EtchLength;
+
+                doc.Entities.Add(new ACadSharp.Entities.Line
+                {
+                    StartPoint = new XYZ(start.X, start.Y, 0),
+                    EndPoint = new XYZ(start.X + dx, start.Y + dy, 0),
+                    Layer = layer
+                });
+
+                doc.Entities.Add(new ACadSharp.Entities.Line
+                {
+                    StartPoint = new XYZ(end.X, end.Y, 0),
+                    EndPoint = new XYZ(end.X - dx, end.Y - dy, 0),
+                    Layer = layer
+                });
+            }
+        }
+    }
+}

OpenNest/Forms/CadConverterForm.cs

@@ -249,17 +249,19 @@ namespace OpenNest.Forms
             var index = fileList.SelectedIndex;
             var newItems = new List<string>();
 
+            var splitWriter = new SplitDxfWriter();
+
             for (var i = 0; i < form.ResultDrawings.Count; i++)
             {
+                var splitDrawing = form.ResultDrawings[i];
+
+                // Assign bends from the source item — spatial filtering is a future enhancement
+                splitDrawing.Bends.AddRange(item.Bends);
+
                 var splitName = $"{baseName}_split{i + 1}.dxf";
                 var splitPath = GetUniquePath(Path.Combine(writableDir, splitName));
 
-                // TODO: Use SplitDxfWriter when implemented
+                splitWriter.Write(splitPath, splitDrawing);
-                // For now, export via DxfExporter
-                var exporter = new DxfExporter();
-                using var stream = new FileStream(splitPath, FileMode.Create);
-                exporter.ExportProgram(form.ResultDrawings[i].Program, stream);
-
                 newItems.Add(splitPath);
             }