commit f2b872ba4dc509622bda2d86ce42e2464d40832b
Author: Christoph Moench-Tegeder <cmt@burggraben.net>
Date:   Mon Mar 24 01:03:53 2025 +0100

    attempt to fix building with libspnav

diff --git cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake
index e9aa47fd6e..826c510ef0 100644
--- cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake
+++ cMake/FreeCAD_Helpers/InitializeFreeCADBuildOptions.cmake
@@ -142,6 +142,7 @@ macro(InitializeFreeCADBuildOptions)
     option(BUILD_CLOUD "Build the FreeCAD cloud module" OFF)
     option(ENABLE_DEVELOPER_TESTS "Build the FreeCAD unit tests suit" ON)
 
+    option(FREECAD_SPNAV_SUPPORT "Enable libspnav support" OFF)
     if(MSVC)
         set(FREECAD_3DCONNEXION_SUPPORT "NavLib" CACHE STRING "Select version of the 3Dconnexion device integration")
         set_property(CACHE FREECAD_3DCONNEXION_SUPPORT PROPERTY STRINGS "NavLib" "Raw input")
diff --git src/Gui/CMakeLists.txt src/Gui/CMakeLists.txt
index 642f58568f..52cc393875 100644
--- src/Gui/CMakeLists.txt
+++ src/Gui/CMakeLists.txt
@@ -133,7 +133,8 @@ if(${Qt5WinExtras_FOUND})
     )
 endif()
 
-IF(SPNAV_FOUND)
+IF(FREECAD_SPNAV_SUPPORT AND SPNAV_FOUND)
+    add_definitions(-D_USE_3DCONNEXION_SDK)
     if(SPNAV_USE_X11)
         add_definitions(-DSPNAV_USE_X11)
         if (FREECAD_QT_MAJOR_VERSION EQUAL 5 AND UNIX AND NOT APPLE)
@@ -175,7 +176,11 @@ IF(SPNAV_FOUND)
     list(APPEND FreeCADGui_LIBS
         ${SPNAV_LIBRARIES}
     )
-ENDIF(SPNAV_FOUND)
+ENDIF(FREECAD_SPNAV_SUPPORT AND SPNAV_FOUND)
+
+IF(FREECAD_SPNAV_SUPPORT AND NOT SPNAV_FOUND)
+    MESSAGE(FATAL_ERROR "libspnav support requested but libspnav not found")
+ENDIF(FREECAD_SPNAV_SUPPORT AND NOT SPNAV_FOUND)
 
 IF(OCULUS_FOUND)
     add_definitions(-DOCULUS_FOUND)
diff --git src/Gui/GuiApplicationNativeEventAware.cpp src/Gui/GuiApplicationNativeEventAware.cpp
index ba41901472..c0cf3c7666 100644
--- src/Gui/GuiApplicationNativeEventAware.cpp
+++ src/Gui/GuiApplicationNativeEventAware.cpp
@@ -33,7 +33,7 @@
 
 
 #if defined(_USE_3DCONNEXION_SDK) || defined(SPNAV_FOUND)
-#if defined(Q_OS_LINUX)
+#if defined(Q_OS_LINUX) || defined(Q_OS_FREEBSD)
   #if defined(SPNAV_USE_X11)
     #include "3Dconnexion/GuiNativeEventLinuxX11.h"
   #else
@@ -59,7 +59,15 @@ Gui::GUIApplicationNativeEventAware::~GUIApplicationNativeEventAware() = default
 void Gui::GUIApplicationNativeEventAware::initSpaceball(QMainWindow *window)
 {
 #if defined(_USE_3DCONNEXION_SDK) || defined(SPNAV_FOUND)
+# if defined(USE_3DCONNEXION_NAVLIB)
+    ParameterGrp::handle hViewGrp = App::GetApplication().GetParameterGroupByPath(
+        "User parameter:BaseApp/Preferences/View");
+    if (nativeEvent && hViewGrp->GetBool("LegacySpaceMouseDevices", false)) {
+        nativeEvent->initSpaceball(window);
+    }
+# else
     nativeEvent->initSpaceball(window);
+# endif
 #else
     Q_UNUSED(window);
 #endif
diff --git src/Gui/View3DInventorViewer.cpp src/Gui/View3DInventorViewer.cpp
index 694f834583..d32c2486b5 100644
--- src/Gui/View3DInventorViewer.cpp
+++ src/Gui/View3DInventorViewer.cpp
@@ -555,7 +555,15 @@ void View3DInventorViewer::init()
     //filter a few qt events
     viewerEventFilter = new ViewerEventFilter;
     installEventFilter(viewerEventFilter);
+#if defined(USE_3DCONNEXION_NAVLIB)
+    ParameterGrp::handle hViewGrp = App::GetApplication().GetParameterGroupByPath(
+        "User parameter:BaseApp/Preferences/View");
+    if (hViewGrp->GetBool("LegacySpaceMouseDevices", false)) {
+        getEventFilter()->registerInputDevice(new SpaceNavigatorDevice);
+    }
+#else
     getEventFilter()->registerInputDevice(new SpaceNavigatorDevice);
+#endif
     getEventFilter()->registerInputDevice(new GesturesDevice(this));
 
     try{