From 8d7622b4a91d22b78d9839228b219867a60be4e2 Mon Sep 17 00:00:00 2001
From: Abdullah Tahiri <abdullah.tahiri.yo@gmail.com>
Date: Fri, 11 May 2018 11:06:50 +0200
Subject: [PATCH] Sketcher: error message when trying to increase the degree of
 not-a-bspline fixes #3471

---
 .../Sketcher/Gui/CommandSketcherBSpline.cpp   | 33 ++++++++++++++-----
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/src/Mod/Sketcher/Gui/CommandSketcherBSpline.cpp b/src/Mod/Sketcher/Gui/CommandSketcherBSpline.cpp
index b59f11b743..763d9905ce 100644
--- a/src/Mod/Sketcher/Gui/CommandSketcherBSpline.cpp
+++ b/src/Mod/Sketcher/Gui/CommandSketcherBSpline.cpp
@@ -452,6 +452,8 @@ void CmdSketcherIncreaseDegree::activated(int iMsg)
     Sketcher::SketchObject* Obj = static_cast<Sketcher::SketchObject*>(selection[0].getObject());
 
     openCommand("Increase degree");
+    
+    bool ignored=false;
 
     for (unsigned int i=0; i<SubNames.size(); i++ ) {
         // only handle edges
@@ -459,18 +461,31 @@ void CmdSketcherIncreaseDegree::activated(int iMsg)
 
             int GeoId = std::atoi(SubNames[i].substr(4,4000).c_str()) - 1;
 
-            Gui::Command::doCommand(
-                Doc,"App.ActiveDocument.%s.increaseBSplineDegree(%d) ",
-                                    selection[0].getFeatName(),GeoId);
-            
-            // add new control points
-            Gui::Command::doCommand(Gui::Command::Doc,
-                                    "App.ActiveDocument.%s.exposeInternalGeometry(%d)",
-                                    selection[0].getFeatName(),
-                                    GeoId);
+            const Part::Geometry * geo = Obj->getGeometry(GeoId);
+
+            if (geo->getTypeId() == Part::GeomBSplineCurve::getClassTypeId()) {
+
+                Gui::Command::doCommand(
+                    Doc,"App.ActiveDocument.%s.increaseBSplineDegree(%d) ",
+                                        selection[0].getFeatName(),GeoId);
+
+                // add new control points
+                Gui::Command::doCommand(Gui::Command::Doc,
+                                        "App.ActiveDocument.%s.exposeInternalGeometry(%d)",
+                                        selection[0].getFeatName(),
+                                        GeoId);
+            }
+            else {
+                ignored=true;
+            }
         }
     }
 
+    if(ignored) {
+        QMessageBox::warning(Gui::getMainWindow(), QObject::tr("Wrong selection"),
+                             QObject::tr("At least one of the selected objects was not a B-Spline and was ignored."));
+    }
+
     commitCommand();
 
     tryAutoRecomputeIfNotSolve(Obj);