display hue chroma lumaref on mask curves - dispaly 1:1 in some expanders - thanks to Pandagrapher

rtgui/curveeditor.cc

@@ -247,6 +247,7 @@ CurveEditor::CurveEditor (Glib::ustring text, CurveEditorGroup* ceGroup, CurveEd
 {
 
     bgHistValid = false;
+    locallabRef = 0.0;    
     remoteDrag = false;
     selected = DCT_Linear;
     bottomBarCP = nullptr;
@@ -321,6 +322,19 @@ void CurveEditor::updateBackgroundHistogram(const LUTu& hist)
     subGroup->updateBackgroundHistogram(this);
 }
 
+/*
+ * Update Locallab reference value displayed in the background
+ */
+void CurveEditor::updateLocallabBackground(double ref)
+{
+    // Copy Locallab reference value in the curve editor cache
+    locallabRef = ref;
+
+     // Then call the curve editor group to eventually update the histogram
+    subGroup->updateLocallabBackground(this);
+}
+
+
 // Open up the curve if it has modifications and it's not already opened
 // Returns: true if curve was non linear and opened
 bool CurveEditor::openIfNonlinear()