From 14b7c1cf32935ba9a407171643b310e8f7a01170 Mon Sep 17 00:00:00 2001
From: AJ Isaacs <ajisaacs27@gmail.com>
Date: Mon, 20 Apr 2026 09:13:37 -0400
Subject: [PATCH] feat(core): store Source.Angle; recompute when Program
 changes

---
 OpenNest.Core/Drawing.cs                     | 22 +++++++-
 OpenNest.Tests/Engine/CanonicalAngleTests.cs | 57 ++++++++++++++++++++
 2 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/OpenNest.Core/Drawing.cs b/OpenNest.Core/Drawing.cs
index 080569f..d266f7c 100644
--- a/OpenNest.Core/Drawing.cs
+++ b/OpenNest.Core/Drawing.cs
@@ -54,9 +54,9 @@ namespace OpenNest
             Id = Interlocked.Increment(ref nextId);
             Name = name;
             Material = new Material();
-            Program = pgm;
             Constraints = new NestConstraints();
             Source = new SourceInfo();
+            Program = pgm;
         }
 
         public int Id { get; }
@@ -78,9 +78,29 @@ namespace OpenNest
             {
                 program = value;
                 UpdateArea();
+                RecomputeCanonicalAngle();
             }
         }
 
+        /// <summary>
+        /// Recomputes and stores the canonical angle from the current Program.
+        /// Callers that mutate Program in place (rather than reassigning it) must invoke this explicitly.
+        /// Cut-off drawings are left with Angle=0.
+        /// </summary>
+        public void RecomputeCanonicalAngle()
+        {
+            if (Source == null)
+                Source = new SourceInfo();
+
+            if (program == null || IsCutOff)
+            {
+                Source.Angle = 0.0;
+                return;
+            }
+
+            Source.Angle = CanonicalAngle.Compute(this);
+        }
+
         public Color Color { get; set; }
 
         public bool IsCutOff { get; set; }
diff --git a/OpenNest.Tests/Engine/CanonicalAngleTests.cs b/OpenNest.Tests/Engine/CanonicalAngleTests.cs
index 3b23e98..d570c54 100644
--- a/OpenNest.Tests/Engine/CanonicalAngleTests.cs
+++ b/OpenNest.Tests/Engine/CanonicalAngleTests.cs
@@ -97,3 +97,60 @@ public class CanonicalAngleTests
         Assert.Equal(0.0, CanonicalAngle.Compute(d), precision: 6);
     }
 }
+
+public class DrawingCanonicalAngleWiringTests
+{
+    private static OpenNest.CNC.Program RotatedRectProgram(double w, double h, double theta)
+    {
+        var pgm = new OpenNest.CNC.Program();
+        pgm.Codes.Add(new RapidMove(new Vector(0, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, 0)));
+        pgm.Codes.Add(new LinearMove(new Vector(w, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, h)));
+        pgm.Codes.Add(new LinearMove(new Vector(0, 0)));
+        if (!OpenNest.Math.Tolerance.IsEqualTo(theta, 0))
+            pgm.Rotate(theta, pgm.BoundingBox().Center);
+        return pgm;
+    }
+
+    [Fact]
+    public void Constructor_ComputesAngleOnProgramAssignment()
+    {
+        var pgm = RotatedRectProgram(100, 50, 0.5);
+        var d = new Drawing("r", pgm);
+        Assert.InRange(d.Source.Angle, -0.52, -0.48);
+    }
+
+    [Fact]
+    public void SetProgram_RecomputesAngle()
+    {
+        var d = new Drawing("r", RotatedRectProgram(100, 50, 0.0));
+        Assert.Equal(0.0, d.Source.Angle, precision: 6);
+
+        d.Program = RotatedRectProgram(100, 50, 0.5);
+        Assert.InRange(d.Source.Angle, -0.52, -0.48);
+    }
+
+    [Fact]
+    public void IsCutOff_SkipsAngleComputation()
+    {
+        var d = new Drawing("cut", RotatedRectProgram(100, 50, 0.5)) { IsCutOff = true };
+        // Re-assign after flag is set so the setter observes IsCutOff.
+        d.Program = RotatedRectProgram(100, 50, 0.5);
+        Assert.Equal(0.0, d.Source.Angle, precision: 6);
+    }
+
+    [Fact]
+    public void RecomputeCanonicalAngle_UpdatesAfterMutation()
+    {
+        var d = new Drawing("r", RotatedRectProgram(100, 50, 0.0));
+        Assert.Equal(0.0, d.Source.Angle, precision: 6);
+
+        // Mutate in-place (doesn't trigger setter).
+        d.Program.Rotate(0.5, d.Program.BoundingBox().Center);
+        Assert.Equal(0.0, d.Source.Angle, precision: 6); // still stale
+
+        d.RecomputeCanonicalAngle();
+        Assert.InRange(d.Source.Angle, -0.52, -0.48);
+    }
+}