Materials: Change display of Quantity values

The default display type of quantity objects is fixed point resulting
in insufficient accuracy when changing unit systems, or when the values
are small. This fix changes the default format from 'Fixed' to the more
apt 'Default' format. This allows the displayed values to scale as
appropriate.

Fixes #18149

src/App/PropertyUnits.cpp

@@ -48,7 +48,9 @@ TYPESYSTEM_SOURCE(App::PropertyQuantity, App::PropertyFloat)
 
 Base::Quantity PropertyQuantity::getQuantityValue() const
 {
-    return Quantity(_dValue, _Unit);
+    Quantity quantity(_dValue, _Unit);
+    quantity.setFormat(_Format);
+    return quantity;
 }
 
 const char* PropertyQuantity::getEditorName() const
@@ -129,7 +131,9 @@ void PropertyQuantity::setPathValue(const ObjectIdentifier& /*path*/, const boos
 
 const boost::any PropertyQuantity::getPathValue(const ObjectIdentifier& /*path*/) const
 {
-    return Quantity(_dValue, _Unit);
+    Quantity quantity(_dValue, _Unit);
+    quantity.setFormat(_Format);
+    return quantity;
 }
 
 //**************************************************************************

src/App/PropertyUnits.h

@@ -73,6 +73,15 @@ public:
         return PropertyFloat::getValue();
     }
 
+    const Base::QuantityFormat& getFormat() const
+    {
+        return _Format;
+    }
+    void setFormat(const Base::QuantityFormat& fmt)
+    {
+        _Format = fmt;
+    }
+
     void setPathValue(const App::ObjectIdentifier& path, const boost::any& value) override;
     const boost::any getPathValue(const App::ObjectIdentifier& path) const override;
 
@@ -89,6 +98,7 @@ public:
 protected:
     Base::Quantity createQuantityFromPy(PyObject* value);
     Base::Unit _Unit;
+    Base::QuantityFormat _Format;
 };
 
 /** Float with Unit property