Solved missing reference marker issues

This commit fixes the issues described by in3otd
(Qucs#407 (comment))

The fix consist on updating the ActiveMarkers map in the paint() event
so as to know if the reference marker has been removed or if its name
has changed. In these cases, the marker pointing to that reference is
set to be a convenitional marker.

In the same line, if the user activates the delta mode for the reference
marker, those markers pointing to that reference are converted into
conventional markers

qucs/qucs/diagrams/diagram.cpp

@@ -153,6 +153,21 @@ qDebug() << "----------------------------";
    foreach(Graph *pg, Graphs)
     foreach(Marker *pm, pg->Markers)
     {
+      IDref = pm->getReferenceMarkerID();
+      if (!ActiveMarkers.contains(IDref))
+      {//If the reference marker was removed or its name has changed, the marker pointing to that reference must be a conventional marker
+        pm->setReferenceMarkerID("");
+        pm->setMarkerMode(0);
+      }
+      else
+      {//The reference marker exists, then check if delta mode is activated
+        RefData = ActiveMarkers[IDref];//Reference marker data. The 5th field shows if delta mode is activated
+        if (RefData[5] == 1)
+        {//If the reference marker is already a delta marker, the current marker must be a conventional marker
+          pm->setReferenceMarkerID("");
+          pm->setMarkerMode(0);
+        }
+      }
       pm->setMarkersMap(ActiveMarkers);
       pm->paint(p, cx, cy);
     }

qucs/qucs/diagrams/marker.cpp

@@ -121,6 +121,11 @@ void Marker::setReferenceMarkerID(QString ref)
    ReferenceMarkerID=ref;
 }
 
+QString Marker::getReferenceMarkerID()
+{
+   return ReferenceMarkerID;
+}
+
 
 // This function returns the marker values. Its main use is to provide data to the Diagram object so
 // as to build a map with the data of all the active markers.

qucs/qucs/diagrams/marker.h

@@ -79,6 +79,7 @@ class Marker : public Element {
   Graph const *pGraph;   // the corresponding graph
 
   void setReferenceMarkerID(QString);
+  QString getReferenceMarkerID();
   void setMarkersMap(QMap<QString, std::vector<double>>);
 
   QMap<QString, std::vector<double>> getMarkersMap();