From de14265ba710ece1fd9c6ec4916acb2981334df4 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@freecad.org>
Date: Thu, 14 Aug 2025 18:31:41 +0200
Subject: [PATCH] Part: Check for straight splines or Bezier curves

Straight splines or Bezier curves can be considered as line segments and thus can be used to measure e.g. angles.

This fixes https://github.com/FreeCAD/FreeCAD/issues/22878
---
 src/Mod/Part/App/MeasureClient.cpp | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/src/Mod/Part/App/MeasureClient.cpp b/src/Mod/Part/App/MeasureClient.cpp
index 5d1a937496..42b53d40d8 100644
--- a/src/Mod/Part/App/MeasureClient.cpp
+++ b/src/Mod/Part/App/MeasureClient.cpp
@@ -36,6 +36,8 @@
 #include <BRepGProp.hxx>
 #include <BRepAdaptor_Curve.hxx>
 #include <BRepAdaptor_Surface.hxx>
+#include <Geom_BezierCurve.hxx>
+#include <Geom_BSplineCurve.hxx>
 #include <TopExp.hxx>
 #include <GProp_GProps.hxx>
 #include <ShapeAnalysis_Edge.hxx>
@@ -127,6 +129,13 @@ TopoDS_Shape getLocatedShape(const App::SubObjectT& subject, Base::Matrix4D* mat
 
 App::MeasureElementType PartMeasureTypeCb(App::DocumentObject* ob, const char* subName)
 {
+    auto isStraightBezierCurve = [](Handle(Geom_BezierCurve) curve) {
+        return curve->NbPoles() == 2;
+    };
+    auto isStraightBSplineCurve = [](Handle(Geom_BSplineCurve) curve) {
+        return curve->NbPoles() == 2;
+    };
+
     TopoDS_Shape shape = Part::Feature::getShape(ob,
                                                     Part::ShapeOption::NeedSubElement
                                                   | Part::ShapeOption::ResolveLink
@@ -153,10 +162,18 @@ App::MeasureElementType PartMeasureTypeCb(App::DocumentObject* ob, const char* s
                     return ob->isDerivedFrom<Part::Datum>() ? App::MeasureElementType::LINE
                                                             : App::MeasureElementType::LINESEGMENT;
                 }
-                case GeomAbs_Circle: { return App::MeasureElementType::CIRCLE; }
-                case GeomAbs_BezierCurve:
+                case GeomAbs_Circle: {
+                    return App::MeasureElementType::CIRCLE;
+                }
+                case GeomAbs_BezierCurve: {
+                    return isStraightBezierCurve(curve.Bezier())
+                               ? App::MeasureElementType::LINESEGMENT
+                               : App::MeasureElementType::CURVE;
+                }
                 case GeomAbs_BSplineCurve: {
-                    return App::MeasureElementType::CURVE;
+                    return isStraightBSplineCurve(curve.BSpline())
+                               ? App::MeasureElementType::LINESEGMENT
+                               : App::MeasureElementType::CURVE;
                 }
                 default: { return App::MeasureElementType::INVALID; }
             }