SoShapeScale: Fix SoShapeScale does not take DPI scaling into account

src/Gui/CMakeLists.txt

@@ -1066,6 +1066,7 @@ SET(Inventor_CPP_SRCS
     SoFCSelectionAction.cpp
     SoFCVectorizeSVGAction.cpp
     SoFCVectorizeU3DAction.cpp
+    SoDevicePixelRatioElement.cpp
     SoTextLabel.cpp
     SoDatumLabel.cpp
     SoTouchEvents.cpp
@@ -1097,6 +1098,7 @@ SET(Inventor_SRCS
     SoFCSelectionAction.h
     SoFCVectorizeSVGAction.h
     SoFCVectorizeU3DAction.h
+    SoDevicePixelRatioElement.h
     SoTextLabel.h
     SoDatumLabel.h
     SoTouchEvents.h

src/Gui/Inventor/SoAxisCrossKit.cpp

@@ -51,11 +51,10 @@
 #endif
 
 #include "SoAxisCrossKit.h"
-
+#include "SoDevicePixelRatioElement.h"
 
 using namespace Gui;
 
-
 SO_KIT_SOURCE(SoShapeScale)
 
 //  Constructor.
@@ -101,6 +100,9 @@ SoShapeScale::GLRender(SoGLRenderAction * action)
         float nsize = this->scaleFactor.getValue() / float(vp.getViewportSizePixels()[0]);
         SoModelMatrixElement::get(state).multVecMatrix(center, center); // world coords
         float sf = vv.getWorldToScreenScale(center, nsize);
+
+        sf *= SoDevicePixelRatioElement::get(state);
+
         SbVec3f v(sf, sf, sf);
         if (scale->scaleFactor.getValue() != v){
             scale->scaleFactor = v;

src/Gui/SoDevicePixelRatioElement.cpp

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+ /****************************************************************************
+  *                                                                          *
+  *   Copyright (c) 2024 Pierre-Louis Boyer <development@ondsel.com>         *
+  *                                                                          *
+  *   This file is part of FreeCAD.                                          *
+  *                                                                          *
+  *   FreeCAD is free software: you can redistribute it and/or modify it     *
+  *   under the terms of the GNU Lesser General Public License as            *
+  *   published by the Free Software Foundation, either version 2.1 of the   *
+  *   License, or (at your option) any later version.                        *
+  *                                                                          *
+  *   FreeCAD is distributed in the hope that it will be useful, but         *
+  *   WITHOUT ANY WARRANTY; without even the implied warranty of             *
+  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU       *
+  *   Lesser General Public License for more details.                        *
+  *                                                                          *
+  *   You should have received a copy of the GNU Lesser General Public       *
+  *   License along with FreeCAD. If not, see                                *
+  *   <https://www.gnu.org/licenses/>.                                       *
+  *                                                                          *
+  ***************************************************************************/
+
+
+#include "PreCompiled.h"
+
+#ifndef _PreComp_
+#include <Inventor/actions/SoGLRenderAction.h>
+# include <Inventor/misc/SoState.h>
+#endif
+
+#include "SoDevicePixelRatioElement.h"
+
+SO_ELEMENT_SOURCE(SoDevicePixelRatioElement);
+
+void SoDevicePixelRatioElement::initClass() {
+    SO_ELEMENT_INIT_CLASS(SoDevicePixelRatioElement, SoFloatElement);
+    // Ensure the element is enabled for GLRenderAction
+    SO_ENABLE(SoGLRenderAction, SoDevicePixelRatioElement);
+}
+
+void SoDevicePixelRatioElement::init(SoState* state) {
+    SoFloatElement::init(state);
+    data = 1.0f; // Default to a device pixel ratio of 1.0
+}
+
+void SoDevicePixelRatioElement::set(SoState* state, float dpr) {
+    SoFloatElement::set(classStackIndex, state, dpr);
+}
+
+float SoDevicePixelRatioElement::get(SoState* state) {
+    return SoFloatElement::get(classStackIndex, state);
+}
+
+SoDevicePixelRatioElement::~SoDevicePixelRatioElement() {}

src/Gui/SoDevicePixelRatioElement.h

@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+ /****************************************************************************
+  *                                                                          *
+  *   Copyright (c) 2024 Pierre-Louis Boyer <development@ondsel.com>         *
+  *                                                                          *
+  *   This file is part of FreeCAD.                                          *
+  *                                                                          *
+  *   FreeCAD is free software: you can redistribute it and/or modify it     *
+  *   under the terms of the GNU Lesser General Public License as            *
+  *   published by the Free Software Foundation, either version 2.1 of the   *
+  *   License, or (at your option) any later version.                        *
+  *                                                                          *
+  *   FreeCAD is distributed in the hope that it will be useful, but         *
+  *   WITHOUT ANY WARRANTY; without even the implied warranty of             *
+  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU       *
+  *   Lesser General Public License for more details.                        *
+  *                                                                          *
+  *   You should have received a copy of the GNU Lesser General Public       *
+  *   License along with FreeCAD. If not, see                                *
+  *   <https://www.gnu.org/licenses/>.                                       *
+  *                                                                          *
+  ***************************************************************************/
+
+#ifndef SO_DEVICE_PIXEL_RATIO_ELEMENT_H
+#define SO_DEVICE_PIXEL_RATIO_ELEMENT_H
+
+#include <Inventor/elements/SoFloatElement.h>
+
+class SoState;
+
+class SoDevicePixelRatioElement : public SoFloatElement {
+    SO_ELEMENT_HEADER(SoDevicePixelRatioElement);
+
+public:
+    // Initializes the class
+    static void initClass();
+
+    // Initializes the element
+    virtual void init(SoState* state) override;
+
+    // Sets the device pixel ratio
+    static void set(SoState* state, float dpr);
+
+    // Retrieves the device pixel ratio
+    static float get(SoState* state);
+
+protected:
+    virtual ~SoDevicePixelRatioElement();
+};
+
+#endif // SO_DEVICE_PIXEL_RATIO_ELEMENT_H

src/Gui/SoFCDB.cpp

@@ -53,6 +53,7 @@
 #include "GestureNavigationStyle.h"
 #include "NavigationStyle.h"
 #include "SelectionObject.h"
+#include "SoDevicePixelRatioElement.h"
 #include "SoFCColorBar.h"
 #include "SoFCColorGradient.h"
 #include "SoFCColorLegend.h"
@@ -94,6 +95,7 @@ SbBool Gui::SoFCDB::isInitialized()
 void Gui::SoFCDB::init()
 {
     SoInteraction                   ::init();
+    SoDevicePixelRatioElement       ::initClass();
     SoGLRenderActionElement         ::initClass();
     SoFCInteractiveElement          ::initClass();
     SoGLWidgetElement               ::initClass();

src/Gui/View3DInventorViewer.cpp

@@ -107,6 +107,7 @@
 #include "NaviCube.h"
 #include "NavigationStyle.h"
 #include "Selection.h"
+#include "SoDevicePixelRatioElement.h"
 #include "SoFCDB.h"
 #include "SoFCInteractiveElement.h"
 #include "SoFCOffscreenRenderer.h"
@@ -2360,6 +2361,7 @@ void View3DInventorViewer::renderScene()
     // Render our scenegraph with the image.
     SoGLRenderAction* glra = this->getSoRenderManager()->getGLRenderAction();
     SoState* state = glra->getState();
+    SoDevicePixelRatioElement::set(state, devicePixelRatio());
     SoGLWidgetElement::set(state, qobject_cast<QtGLWidget*>(this->getGLWidget()));
     SoGLRenderActionElement::set(state, glra);
     SoGLVBOActivatedElement::set(state, this->vboEnabled);