Gui: add SoColorBarLabel as workaround for a Coin3D bug

src/Gui/SoFCColorGradient.cpp

@@ -35,6 +35,7 @@
 #endif
 
 #include "SoFCColorGradient.h"
+#include "SoTextLabel.h"
 #include "DlgSettingsColorGradientImp.h"
 #include "MainWindow.h"
 #include "MDIView.h"
@@ -98,7 +99,7 @@ void SoFCColorGradient::setMarkerLabel(const SoMFString& label)
         for (int i = 0; i < num; i++) {
             SoTransform* trans = new SoTransform;
             SoBaseColor* color = new SoBaseColor;
-            SoText2    * text2 = new SoText2;
+            SoText2    * text2 = new SoColorBarLabel;
 
             trans->translation.setValue(0, -fStep, 0);
             color->rgb.setValue(0, 0, 0);

src/Gui/SoFCDB.cpp

@@ -124,6 +124,7 @@ void Gui::SoFCDB::init()
     SoVRMLAction                    ::initClass();
     SoSkipBoundingGroup             ::initClass();
     SoTextLabel                     ::initClass();
+    SoColorBarLabel                 ::initClass();
     SoStringLabel                   ::initClass();
     SoFrameLabel                    ::initClass();
     TranslateManip                  ::initClass();

src/Gui/SoTextLabel.cpp

@@ -298,6 +298,33 @@ void SoTextLabel::GLRender(SoGLRenderAction *action)
 
 // ------------------------------------------------------
 
+SO_NODE_SOURCE(SoColorBarLabel)
+
+void SoColorBarLabel::initClass()
+{
+    SO_NODE_INIT_CLASS(SoColorBarLabel, SoText2, "Text2");
+}
+
+SoColorBarLabel::SoColorBarLabel()
+{
+    SO_NODE_CONSTRUCTOR(SoColorBarLabel);
+}
+
+void SoColorBarLabel::computeBBox(SoAction * action, SbBox3f & box, SbVec3f & center)
+{
+    inherited::computeBBox(action, box, center);
+    if (!box.hasVolume()) {
+        SbViewVolume vv = SoViewVolumeElement::get(action->getState());
+        // workaround for https://github.com/coin3d/coin/issues/417:
+        // extend by 2 percent
+        vv.scaleWidth(1.02f);
+        SoViewVolumeElement::set(action->getState(), this, vv);
+        inherited::computeBBox(action, box, center);
+    }
+}
+
+// ------------------------------------------------------
+
 SO_NODE_SOURCE(SoStringLabel)
 
 void SoStringLabel::initClass()

src/Gui/SoTextLabel.h

@@ -32,6 +32,7 @@
 #include <Inventor/manips/SoTransformManip.h>
 #include <Inventor/nodes/SoImage.h>
 #include <Inventor/nodes/SoText2.h>
+#include <FCGlobal.h>
 
 
 namespace Gui {
@@ -54,10 +55,27 @@ public:
     SoSFFloat frameSize;
 
 protected:
-    virtual ~SoTextLabel() {};
+    virtual ~SoTextLabel() {}
     virtual void GLRender(SoGLRenderAction *action);
 };
 
+/**
+ * A text label for the color bar.
+ * @author Werner Mayer
+ */
+class GuiExport SoColorBarLabel : public SoText2 {
+    typedef SoText2 inherited;
+
+    SO_NODE_HEADER(SoColorBarLabel);
+
+public:
+    static void initClass();
+    SoColorBarLabel();
+
+protected:
+    void computeBBox(SoAction * action, SbBox3f & box, SbVec3f & center) override;
+};
+
 class GuiExport SoStringLabel : public SoNode {
     typedef SoNode inherited;