Update background with luma and chroma ref for L C curves Color and Light

rtgui/mydiagonalcurve.cc

@@ -39,7 +39,9 @@ MyDiagonalCurve::MyDiagonalCurve () :
     ugpX(0.0),
     ugpY(0.0),
     activeParam(-1),
-    bghistvalid(false)
+    bghistvalid(false),
+    locallabRef(0.0)
+
 {
 
     grab_point = -1;
@@ -129,6 +131,36 @@ std::vector<double> MyDiagonalCurve::get_vector (int veclen)
     return vector;
 }
 
+void MyDiagonalCurve::updateLocallabBackground(double ref)
+{
+    locallabRef = ref;
+
+     mcih->pending++;
+
+     idle_register.add(
+        [this]() -> bool
+        {
+            if (mcih->destroyed) {
+                if (mcih->pending == 1) {
+                    delete mcih;
+                } else {
+                    --mcih->pending;
+                }
+
+                 return false;
+            }
+
+             mcih->clearPixmap();
+            mcih->myCurve->queue_draw();
+
+             --mcih->pending;
+
+             return false;
+        }
+    );
+}
+
+
 void MyDiagonalCurve::get_LUT (LUTf &lut)
 {
 
@@ -260,6 +292,20 @@ void MyDiagonalCurve::draw (int handle)
 
     cr->set_line_width (1.0 * s);
 
+    // Draw Locallab reference value in the background
+    if (locallabRef > 0.0) {
+        cr->set_line_width(1.0);
+        cr->move_to(double(graphX + 1), double(graphY - 1));
+        c = style->get_color(state);
+        cr->set_source_rgba(c.get_red(), c.get_green(), c.get_blue(), 0.2);
+        cr->line_to(double(graphX + 1), double(graphY - 1) -  double(graphH - 2));
+        cr->line_to(double(graphX) + 1.5 + locallabRef*double(graphW -2), double(graphY - 1) - double(graphH - 2));
+        cr->line_to(double(graphX) + 1.5 + locallabRef*double(graphW -2), double(graphY - 1));
+        cr->close_path();
+        cr->fill();
+        cr->stroke();
+    }
+
     // draw the left colored bar
     if (leftBar) {
         // first the background