From 062eb55250db1f081f718650952a1ca22a6c860a Mon Sep 17 00:00:00 2001
From: Doug Walker <doug.walker@autodesk.com>
Date: Thu, 19 Mar 2026 17:43:00 -0400
Subject: [PATCH] Fix bug in hue curve python binding

Signed-off-by: Doug Walker <doug.walker@autodesk.com>
---
 .../fileformats/ctf/CTFReaderHelper.cpp       |  4 ++--
 src/bindings/python/PyGradingData.cpp         |  3 +++
 tests/python/GradingDataTest.py               | 23 +++++++++++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/OpenColorIO/fileformats/ctf/CTFReaderHelper.cpp b/src/OpenColorIO/fileformats/ctf/CTFReaderHelper.cpp
index f8ecd7eb6e..00ef9ac01b 100644
--- a/src/OpenColorIO/fileformats/ctf/CTFReaderHelper.cpp
+++ b/src/OpenColorIO/fileformats/ctf/CTFReaderHelper.cpp
@@ -862,11 +862,11 @@ void CTFReaderDescElt::start(const char **  atttributes )
     m_language = {};
 
     const char ** attr = atttributes;
-    while (*attr)
+    while (attr && *attr)
     {
         if (0 == Platform::Strcasecmp(ATTR_LANGUAGE, *attr))
         {
-            if (!attr || !(attr + 1))
+            if (!(attr + 1) || !*(attr + 1))
             {
                 throwMessage("Attribute 'language' does not have a value.");
             }
diff --git a/src/bindings/python/PyGradingData.cpp b/src/bindings/python/PyGradingData.cpp
index a1a093d7b3..c34179cf4e 100644
--- a/src/bindings/python/PyGradingData.cpp
+++ b/src/bindings/python/PyGradingData.cpp
@@ -21,11 +21,14 @@ using GradingControlPointIterator = PyIterator<GradingBSplineCurveRcPtr, IT_CONT
 
 void CopyGradingBSpline(GradingBSplineCurveRcPtr to, const ConstGradingBSplineCurveRcPtr from)
 {
+    to->setSplineType(from->getSplineType());
+
     const size_t numPt = from->getNumControlPoints();
     to->setNumControlPoints(numPt);
     for (size_t pt = 0; pt < numPt; ++pt)
     {
         to->getControlPoint(pt) = from->getControlPoint(pt);
+        to->setSlope(pt, from->getSlope(pt));
     }
 }
 
diff --git a/tests/python/GradingDataTest.py b/tests/python/GradingDataTest.py
index 39cd8ba5cc..34abd89fff 100644
--- a/tests/python/GradingDataTest.py
+++ b/tests/python/GradingDataTest.py
@@ -368,6 +368,29 @@ def test_huecurve(self):
         assertEqualBSpline(self, hcrv.lum_sat, ls)
         self.assertEqual(hcrv.lum_sat, ls)
 
+        # Check that setting the hue curve preserves the spline type.
+        hcrv.hue_sat = ls
+        ls2 = hcrv.hue_sat
+        # Spline type is now different than what hue_sat normally uses (PERIODIC_1_B_SPLINE).
+        self.assertEqual(ls2.getSplineType(), OCIO.HORIZONTAL1_B_SPLINE)
+        self.assertEqual(hcrv.hue_sat, ls)
+        self.assertEqual(ls2, ls)
+
+        # Check that setting the hue curve preserves the slopes.
+        self.assertEqual(ls.slopesAreDefault(), True)
+        slopes = ls.getSlopes()
+        slopes[1] = 0.5
+        ls.setSlopes(slopes)
+        self.assertEqual(ls.slopesAreDefault(), False)
+        hcrv.hue_sat = ls
+        ls2 = hcrv.hue_sat
+        self.assertEqual(ls2.slopesAreDefault(), False)
+        slopes2 = ls2.getSlopes()
+        self.assertEqual(slopes2[1], 0.5)
+        self.assertEqual(slopes2, slopes)
+        self.assertEqual(hcrv.hue_sat, ls)
+        self.assertEqual(ls2, ls)
+
     def test_rgbmsw(self):
         """
         Test the GradingRGBMSW struct.