refactor: simplify CutOff methods and fix ActionCutOff issues

- Extract MakePoint/AxisBounds/CrossAxisBounds helpers in CutOff to
  eliminate repeated axis-dependent branching
- Simplify BuildProgram loop from 4 code paths to 2
- Use static EmptyExclusions to avoid per-part list allocations
- Fix double event subscription in ActionCutOff constructor
- Dispose debounce timer in DisconnectEvents
- Remove redundant BuildPerimeterCache call in OnMouseDown
- Extract TotalCutLength test helper, remove duplicate test

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

OpenNest.Core/CutOff.cs

@@ -104,29 +104,17 @@ namespace OpenNest
             return segments;
         }
 
+        private static readonly List<(double Start, double End)> EmptyExclusions = new();
+
         private List<(double Start, double End)> GetPartExclusions(
             Part part, Entity perimeter, double cutPosition, double lineStart, double lineEnd, double clearance)
         {
             var bb = part.BoundingBox;
-            double partMin, partMax, partStart, partEnd;
+            var (partMin, partMax) = AxisBounds(bb, clearance);
-
+            var (partStart, partEnd) = CrossAxisBounds(bb, clearance);
-            if (Axis == CutOffAxis.Vertical)
-            {
-                partMin = bb.X - clearance;
-                partMax = bb.X + bb.Width + clearance;
-                partStart = bb.Y - clearance;
-                partEnd = bb.Y + bb.Length + clearance;
-            }
-            else
-            {
-                partMin = bb.Y - clearance;
-                partMax = bb.Y + bb.Length + clearance;
-                partStart = bb.X - clearance;
-                partEnd = bb.X + bb.Width + clearance;
-            }
 
             if (cutPosition < partMin || cutPosition > partMax)
-                return new List<(double Start, double End)>();
+                return EmptyExclusions;
 
             if (perimeter != null)
             {
@@ -141,19 +129,7 @@ namespace OpenNest
         private List<(double Start, double End)> IntersectPerimeter(
             Entity perimeter, double cutPosition, double lineStart, double lineEnd, double clearance)
         {
-            Vector p1, p2;
+            var cutLine = new Line(MakePoint(cutPosition, lineStart), MakePoint(cutPosition, lineEnd));
-            if (Axis == CutOffAxis.Vertical)
-            {
-                p1 = new Vector(cutPosition, lineStart);
-                p2 = new Vector(cutPosition, lineEnd);
-            }
-            else
-            {
-                p1 = new Vector(lineStart, cutPosition);
-                p2 = new Vector(lineEnd, cutPosition);
-            }
-
-            var cutLine = new Line(p1, p2);
 
             if (!perimeter.Intersects(cutLine, out var pts) || pts.Count < 2)
                 return null;
@@ -173,6 +149,21 @@ namespace OpenNest
             return result;
         }
 
+        private Vector MakePoint(double cutCoord, double lineCoord) =>
+            Axis == CutOffAxis.Vertical
+                ? new Vector(cutCoord, lineCoord)
+                : new Vector(lineCoord, cutCoord);
+
+        private (double Min, double Max) AxisBounds(Box bb, double clearance) =>
+            Axis == CutOffAxis.Vertical
+                ? (bb.X - clearance, bb.X + bb.Width + clearance)
+                : (bb.Y - clearance, bb.Y + bb.Length + clearance);
+
+        private (double Start, double End) CrossAxisBounds(Box bb, double clearance) =>
+            Axis == CutOffAxis.Vertical
+                ? (bb.Y - clearance, bb.Y + bb.Length + clearance)
+                : (bb.X - clearance, bb.X + bb.Width + clearance);
+
         private Program BuildProgram(List<(double Start, double End)> segments, CutOffSettings settings)
         {
             var program = new Program();
@@ -180,39 +171,18 @@ namespace OpenNest
             if (segments.Count == 0)
                 return program;
 
-            if (settings.CutDirection == CutDirection.TowardOrigin)
+            var toward = settings.CutDirection == CutDirection.TowardOrigin;
-                segments = segments.OrderByDescending(s => s.Start).ToList();
+            segments = toward
-            else
+                ? segments.OrderByDescending(s => s.Start).ToList()
-                segments = segments.OrderBy(s => s.Start).ToList();
+                : segments.OrderBy(s => s.Start).ToList();
+
+            var cutPos = Axis == CutOffAxis.Vertical ? Position.X : Position.Y;
 
             foreach (var seg in segments)
             {
-                double startVal, endVal;
+                var (from, to) = toward ? (seg.End, seg.Start) : (seg.Start, seg.End);
-                if (settings.CutDirection == CutDirection.TowardOrigin)
+                program.Codes.Add(new RapidMove(MakePoint(cutPos, from)));
-                {
+                program.Codes.Add(new LinearMove(MakePoint(cutPos, to)));
-                    startVal = seg.End;
-                    endVal = seg.Start;
-                }
-                else
-                {
-                    startVal = seg.Start;
-                    endVal = seg.End;
-                }
-
-                Vector startPt, endPt;
-                if (Axis == CutOffAxis.Vertical)
-                {
-                    startPt = new Vector(Position.X, startVal);
-                    endPt = new Vector(Position.X, endVal);
-                }
-                else
-                {
-                    startPt = new Vector(startVal, Position.Y);
-                    endPt = new Vector(endVal, Position.Y);
-                }
-
-                program.Codes.Add(new RapidMove(startPt));
-                program.Codes.Add(new LinearMove(endPt));
             }
 
             return program;

OpenNest.Tests/CutOffGeometryTests.cs

@@ -9,6 +9,22 @@ public class CutOffGeometryTests
 {
     private static readonly CutOffSettings ZeroClearance = new() { PartClearance = 0.0 };
 
+    private static double TotalCutLength(Program program, CutOffAxis axis = CutOffAxis.Vertical)
+    {
+        var total = 0.0;
+        for (var i = 0; i < program.Codes.Count - 1; i += 2)
+        {
+            if (program.Codes[i] is RapidMove rapid &&
+                program.Codes[i + 1] is LinearMove linear)
+            {
+                total += axis == CutOffAxis.Vertical
+                    ? System.Math.Abs(rapid.EndPoint.Y - linear.EndPoint.Y)
+                    : System.Math.Abs(rapid.EndPoint.X - linear.EndPoint.X);
+            }
+        }
+        return total;
+    }
+
     private static Program MakeSquare(double size)
     {
         var pgm = new Program();
@@ -95,20 +111,8 @@ public class CutOffGeometryTests
         // The circle chord at X=2 from center (10,0) is much shorter than 20.
         // With geometry, we get a tighter exclusion, so the segments should
         // cover more of the plate than with BB.
-        var segments = cutoff.Drawing.Program.Codes.OfType<LinearMove>().ToList();
-        Assert.True(segments.Count >= 1);
-
         // Total cut length should be greater than 80 (BB would give 100-20=80)
-        var totalCutLength = 0.0;
+        var totalCutLength = TotalCutLength(cutoff.Drawing.Program);
-        for (var i = 0; i < cutoff.Drawing.Program.Codes.Count - 1; i += 2)
-        {
-            if (cutoff.Drawing.Program.Codes[i] is RapidMove rapid &&
-                cutoff.Drawing.Program.Codes[i + 1] is LinearMove linear)
-            {
-                totalCutLength += System.Math.Abs(rapid.EndPoint.Y - linear.EndPoint.Y);
-            }
-        }
-
         Assert.True(totalCutLength > 80, $"Geometry should give more cut length than BB. Got {totalCutLength:F2}");
     }
 
@@ -129,18 +133,9 @@ public class CutOffGeometryTests
         var cutoff = new CutOff(new Vector(5, 0), CutOffAxis.Vertical);
         cutoff.Regenerate(plate, ZeroClearance, cache);
 
-        var totalCutLength = 0.0;
-        for (var i = 0; i < cutoff.Drawing.Program.Codes.Count - 1; i += 2)
-        {
-            if (cutoff.Drawing.Program.Codes[i] is RapidMove rapid &&
-                cutoff.Drawing.Program.Codes[i + 1] is LinearMove linear)
-            {
-                totalCutLength += System.Math.Abs(rapid.EndPoint.Y - linear.EndPoint.Y);
-            }
-        }
-
         // BB would exclude full 20 → cut length = 80.
         // Geometry excludes only 10 → cut length = 90.
+        var totalCutLength = TotalCutLength(cutoff.Drawing.Program);
         Assert.True(totalCutLength > 85, $"Diamond geometry should give more cut than BB. Got {totalCutLength:F2}");
     }
 
@@ -161,18 +156,9 @@ public class CutOffGeometryTests
         var cutoff = new CutOff(new Vector(20, 0), CutOffAxis.Vertical);
         cutoff.Regenerate(plate, ZeroClearance, cache);
 
-        var totalCutLength = 0.0;
-        for (var i = 0; i < cutoff.Drawing.Program.Codes.Count - 1; i += 2)
-        {
-            if (cutoff.Drawing.Program.Codes[i] is RapidMove rapid &&
-                cutoff.Drawing.Program.Codes[i + 1] is LinearMove linear)
-            {
-                totalCutLength += System.Math.Abs(rapid.EndPoint.Y - linear.EndPoint.Y);
-            }
-        }
-
         // BB would exclude [10,40] = 30 → cut = 70.
         // Geometry excludes [10,30] = 20 → cut = 80.
+        var totalCutLength = TotalCutLength(cutoff.Drawing.Program);
         Assert.True(totalCutLength > 75, $"Triangle geometry should give more cut than BB. Got {totalCutLength:F2}");
     }
 
@@ -208,18 +194,9 @@ public class CutOffGeometryTests
         var cutoff = new CutOff(new Vector(0, 2), CutOffAxis.Horizontal);
         cutoff.Regenerate(plate, ZeroClearance, cache);
 
-        var totalCutLength = 0.0;
-        for (var i = 0; i < cutoff.Drawing.Program.Codes.Count - 1; i += 2)
-        {
-            if (cutoff.Drawing.Program.Codes[i] is RapidMove rapid &&
-                cutoff.Drawing.Program.Codes[i + 1] is LinearMove linear)
-            {
-                totalCutLength += System.Math.Abs(rapid.EndPoint.X - linear.EndPoint.X);
-            }
-        }
-
         // BB would exclude X=[0,20] → cut = 80.
         // Circle chord at Y=2 is much shorter → cut > 80.
+        var totalCutLength = TotalCutLength(cutoff.Drawing.Program, CutOffAxis.Horizontal);
         Assert.True(totalCutLength > 80, $"Circle horizontal cut should use geometry. Got {totalCutLength:F2}");
     }
 
@@ -338,25 +315,6 @@ public class CutOffGeometryTests
         Assert.Single(cache);
     }
 
-    [Fact]
-    public void PlatePerimeterCache_OpenContourUsesConvexHull()
-    {
-        var pgm = new Program();
-        pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
-        pgm.Codes.Add(new LinearMove(new Vector(10, 0)));
-        pgm.Codes.Add(new LinearMove(new Vector(10, 10)));
-
-        var plate = new Plate(100, 100);
-        plate.Parts.Add(new Part(new Drawing("open", pgm)));
-
-        var cache = Plate.BuildPerimeterCache(plate);
-        Assert.Single(cache);
-
-        var part = plate.Parts[0];
-        Assert.True(cache.ContainsKey(part));
-        Assert.NotNull(cache[part]);
-    }
-
     [Fact]
     public void RegenerateCutOffs_UsesGeometryExclusions()
     {
@@ -373,17 +331,8 @@ public class CutOffGeometryTests
 
         // Find the materialized cut-off part
         var cutPart = plate.Parts.First(p => p.BaseDrawing.IsCutOff);
-        var totalCutLength = 0.0;
-        for (var i = 0; i < cutPart.BaseDrawing.Program.Codes.Count - 1; i += 2)
-        {
-            if (cutPart.BaseDrawing.Program.Codes[i] is RapidMove rapid &&
-                cutPart.BaseDrawing.Program.Codes[i + 1] is LinearMove linear)
-            {
-                totalCutLength += System.Math.Abs(rapid.EndPoint.Y - linear.EndPoint.Y);
-            }
-        }
-
         // BB would give 80 (100 - 20). Geometry should give more.
+        var totalCutLength = TotalCutLength(cutPart.BaseDrawing.Program);
         Assert.True(totalCutLength > 80, $"RegenerateCutOffs should use geometry. Got {totalCutLength:F2}");
     }
 

OpenNest/Actions/ActionCutOff.cs

@@ -23,14 +23,9 @@ namespace OpenNest.Actions
             : base(plateView)
         {
             settings = plateView.CutOffSettings;
-            perimeterCache = Plate.BuildPerimeterCache(plateView.Plate);
             debounceTimer = new Timer { Interval = 16 };
             debounceTimer.Tick += OnDebounce;
-
+            ConnectEvents();
-            plateView.MouseMove += OnMouseMove;
-            plateView.MouseDown += OnMouseDown;
-            plateView.KeyDown += OnKeyDown;
-            plateView.Paint += OnPaint;
         }
 
         public override void ConnectEvents()
@@ -46,6 +41,7 @@ namespace OpenNest.Actions
         public override void DisconnectEvents()
         {
             debounceTimer.Stop();
+            debounceTimer.Dispose();
             plateView.MouseMove -= OnMouseMove;
             plateView.MouseDown -= OnMouseDown;
             plateView.KeyDown -= OnKeyDown;
@@ -90,7 +86,6 @@ namespace OpenNest.Actions
 
             plateView.Plate.CutOffs.Add(cutoff);
             plateView.Plate.RegenerateCutOffs(settings);
-            perimeterCache = Plate.BuildPerimeterCache(plateView.Plate);
             plateView.Invalidate();
         }