feat: render lead-in/lead-out codes in yellow, skip suppressed codes

Add GetGraphicsPaths/AddProgramSplit to GraphicsHelper that builds separate
GraphicsPath objects for cut vs lead-in/lead-out codes, skipping suppressed
codes. Update LayoutPart to use split paths when HasManualLeadIns is set,
drawing lead-in geometry in yellow regardless of selection state.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest/GraphicsHelper.cs

@@ -85,6 +85,74 @@ namespace OpenNest
             return img;
         }
 
+        public static void GetGraphicsPaths(this Program pgm, Vector origin,
+            out GraphicsPath cutPath, out GraphicsPath leadPath)
+        {
+            cutPath = new GraphicsPath();
+            leadPath = new GraphicsPath();
+            var curpos = origin;
+
+            AddProgramSplit(cutPath, leadPath, pgm, pgm.Mode, ref curpos);
+        }
+
+        private static void AddProgramSplit(GraphicsPath cutPath, GraphicsPath leadPath,
+            Program pgm, Mode mode, ref Vector curpos)
+        {
+            mode = pgm.Mode;
+
+            for (var i = 0; i < pgm.Length; ++i)
+            {
+                var code = pgm[i];
+
+                switch (code.Type)
+                {
+                    case CodeType.ArcMove:
+                        var arc = (ArcMove)code;
+                        if (arc.Suppressed)
+                        {
+                            var endpt = arc.EndPoint;
+                            if (mode == Mode.Incremental) endpt += curpos;
+                            curpos = endpt;
+                            break;
+                        }
+                        var arcPath = (arc.Layer == LayerType.Leadin || arc.Layer == LayerType.Leadout)
+                            ? leadPath : cutPath;
+                        AddArc(arcPath, arc, mode, ref curpos);
+                        break;
+
+                    case CodeType.LinearMove:
+                        var line = (LinearMove)code;
+                        if (line.Suppressed)
+                        {
+                            var endpt = line.EndPoint;
+                            if (mode == Mode.Incremental) endpt += curpos;
+                            curpos = endpt;
+                            break;
+                        }
+                        var linePath = (line.Layer == LayerType.Leadin || line.Layer == LayerType.Leadout)
+                            ? leadPath : cutPath;
+                        AddLine(linePath, line, mode, ref curpos);
+                        break;
+
+                    case CodeType.RapidMove:
+                        AddLine(cutPath, (RapidMove)code, mode, ref curpos);
+                        break;
+
+                    case CodeType.SubProgramCall:
+                        var tmpmode = mode;
+                        var subpgm = (SubProgramCall)code;
+                        if (subpgm.Program != null)
+                        {
+                            cutPath.StartFigure();
+                            leadPath.StartFigure();
+                            AddProgramSplit(cutPath, leadPath, subpgm.Program, mode, ref curpos);
+                        }
+                        mode = tmpmode;
+                        break;
+                }
+            }
+        }
+
         private static void AddArc(GraphicsPath path, ArcMove arc, Mode mode, ref Vector curpos)
         {
             var endpt = arc.EndPoint;

OpenNest/LayoutPart.cs

@@ -15,6 +15,7 @@ namespace OpenNest
         private static Color selectedColor;
         private static Pen selectedPen;
         private static Brush selectedBrush;
+        private static Pen leadInPen;
 
         private Color color;
         private Brush brush;
@@ -34,6 +35,7 @@ namespace OpenNest
         {
             programIdFont = new Font(SystemFonts.DefaultFont, FontStyle.Bold | FontStyle.Underline);
             SelectedColor = Color.FromArgb(90, 150, 200, 255);
+            leadInPen = new Pen(Color.Yellow, 1.5f);
         }
 
         private LayoutPart(Part part)
@@ -52,6 +54,8 @@ namespace OpenNest
 
         public GraphicsPath Path { get; private set; }
 
+        public GraphicsPath LeadInPath { get; private set; }
+
         public Color Color
         {
             get { return color; }
@@ -83,6 +87,9 @@ namespace OpenNest
                 g.FillPath(brush, Path);
                 g.DrawPath(pen, Path);
             }
+
+            if (LeadInPath != null)
+                g.DrawPath(leadInPen, LeadInPath);
         }
 
         public void Draw(Graphics g, string id)
@@ -98,6 +105,9 @@ namespace OpenNest
                 g.DrawPath(pen, Path);
             }
 
+            if (LeadInPath != null)
+                g.DrawPath(leadInPen, LeadInPath);
+
             using var sf = new StringFormat
             {
                 Alignment = StringAlignment.Center,
@@ -138,8 +148,22 @@ namespace OpenNest
 
         public void Update(DrawControl plateView)
         {
-            Path = GraphicsHelper.GetGraphicsPath(BasePart.Program, BasePart.Location);
+            if (BasePart.HasManualLeadIns)
-            Path.Transform(plateView.Matrix);
+            {
+                BasePart.Program.GetGraphicsPaths(BasePart.Location, out var cutPath, out var leadPath);
+                cutPath.Transform(plateView.Matrix);
+                leadPath.Transform(plateView.Matrix);
+                Path = cutPath;
+                LeadInPath?.Dispose();
+                LeadInPath = leadPath;
+            }
+            else
+            {
+                Path = GraphicsHelper.GetGraphicsPath(BasePart.Program, BasePart.Location);
+                Path.Transform(plateView.Matrix);
+                LeadInPath?.Dispose();
+                LeadInPath = null;
+            }
 
             _labelPoint ??= ComputeLabelPoint();
             var rotatedLabel = _labelPoint.Value.Rotate(BasePart.Rotation);