From 4fc794327cd2b2f0875ddab105b5da51b66da48a Mon Sep 17 00:00:00 2001
From: Fan Gong <gongfan99@hotmail.com>
Date: Thu, 1 Jan 2026 13:42:42 -0500
Subject: [PATCH] fix: Color class corrected to use sRGB 	modified:  
 src/build123d/geometry.py 	modified:  
 tests/test_direct_api/test_color.py

---
 src/build123d/geometry.py           | 22 ++++++++++++----------
 tests/test_direct_api/test_color.py |  6 ++++--
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/src/build123d/geometry.py b/src/build123d/geometry.py
index 3e3807f..ad04b0d 100644
--- a/src/build123d/geometry.py
+++ b/src/build123d/geometry.py
@@ -41,7 +41,7 @@ import json
 import logging
 import warnings
 from collections.abc import Callable, Iterable, Sequence
-from math import degrees, isclose, log10, pi, radians, prod
+from math import degrees, isclose, log10, pi, prod, radians
 from typing import TYPE_CHECKING, Any, TypeAlias, overload
 
 import numpy as np
@@ -72,7 +72,7 @@ from OCP.gp import (
 
 # properties used to store mass calculation result
 from OCP.GProp import GProp_GProps
-from OCP.Quantity import Quantity_Color, Quantity_ColorRGBA
+from OCP.Quantity import Quantity_Color, Quantity_ColorRGBA, Quantity_TypeOfColor
 from OCP.TopAbs import TopAbs_ShapeEnum
 from OCP.TopLoc import TopLoc_Location
 from OCP.TopoDS import TopoDS, TopoDS_Edge, TopoDS_Face, TopoDS_Shape, TopoDS_Vertex
@@ -1200,7 +1200,7 @@ class Color:
 
     @overload
     def __init__(self, red: float, green: float, blue: float, alpha: float = 1.0):
-        """Color from RGBA and Alpha values
+        """Color from sRGB and Alpha values
 
         Args:
             red (float): 0.0 <= red <= 1.0
@@ -1312,7 +1312,10 @@ class Color:
                 raise TypeError(f"Unsupported color definition: {color_format}")
 
         if not self.wrapped:
-            self.wrapped = Quantity_ColorRGBA(red, green, blue, alpha)
+            the_color = Quantity_Color(
+                red, green, blue, Quantity_TypeOfColor.Quantity_TOC_sRGB
+            )
+            self.wrapped = Quantity_ColorRGBA(the_color, alpha)
 
     def __iter__(self):
         """Initialize to beginning"""
@@ -1321,14 +1324,14 @@ class Color:
 
     def __next__(self):
         """return the next value"""
-        rgb = self.wrapped.GetRGB()
-        rgb_tuple = (rgb.Red(), rgb.Green(), rgb.Blue(), self.wrapped.Alpha())
+        r, g, b = self.wrapped.GetRGB().Values(Quantity_TypeOfColor.Quantity_TOC_sRGB)
+        rgb_tuple = (r, g, b, self.wrapped.Alpha())
 
         if self.iter_index > 3:
             raise StopIteration
         value = rgb_tuple[self.iter_index]
         self.iter_index += 1
-        return value
+        return round(value, 7)
 
     def __copy__(self) -> Color:
         """Return copy of self"""
@@ -1340,10 +1343,9 @@ class Color:
 
     def __str__(self) -> str:
         """Generate string"""
-        rgb = self.wrapped.GetRGB()
-        rgb = (rgb.Red(), rgb.Green(), rgb.Blue())
+        rgb = self.wrapped.GetRGB().Values(Quantity_TypeOfColor.Quantity_TOC_sRGB)
         try:
-            name = webcolors.rgb_to_name([int(c * 255) for c in rgb])
+            name = webcolors.rgb_to_name([round(c * 255) for c in rgb])
             qualifier = "is"
         except ValueError:
             # This still uses OCCT X11 colors instead of css3
diff --git a/tests/test_direct_api/test_color.py b/tests/test_direct_api/test_color.py
index 9e50a8a..bcf46fa 100644
--- a/tests/test_direct_api/test_color.py
+++ b/tests/test_direct_api/test_color.py
@@ -29,10 +29,11 @@ license:
 import colorsys
 import copy
 import math
+
 import numpy as np
 import pytest
-
 from OCP.Quantity import Quantity_ColorRGBA
+
 from build123d.geometry import Color
 
 
@@ -250,7 +251,7 @@ def test_str_repr_is():
 
 def test_str_repr_near():
     c = Color(1, 0.5, 0)
-    assert str(c) == "Color: (1.0, 0.5, 0.0, 1.0) near 'DARKGOLDENROD1'"
+    assert str(c) == "Color: (1.0, 0.5, 0.0, 1.0) near 'DARKORANGE1'"
     assert repr(c) == "Color(1.0, 0.5, 0.0, 1.0)"
 
 
@@ -319,3 +320,4 @@ class TestColorCategoricalSet:
         for c in colors:
             (_, _, _, a) = tuple(c)
             assert math.isclose(a, 1.0, rel_tol=1e-6)
+            assert math.isclose(a, 1.0, rel_tol=1e-6)