Added pen labels to interactive marker. For ravel #512.

Modulo arithmetic when acessing pen style incorrectly uses the fixed paletteSz rather than palette.size(). For ravel #553.

include/plot.h

@@ -224,8 +224,11 @@ namespace ecolab
 
   protected: // only protected because of TCL_obj problems
     /// default formatter suitable for plots of numeric data
-    static std::string defaultFormatter(double,double);
-    using Formatter=std::function<std::string(double,double)>;
+    /// @param label - pen label
+    /// @param x x coordinate of point to be labelled
+    /// @param y y coordinate of point to be labelled
+    static std::string defaultFormatter(const string& label,double x,double y);
+    using Formatter=std::function<std::string(const string&,double,double)>;
     /// if \a (x,y) within ([0,1],[0,1]), then paint a value box corresponding to closest curve
     /// @param tolerance - how close in user relative coordinates the mouse needs to be to a data point
     /// @param formatter - produce text label given (x,y) values 

src/plot.cc

@@ -892,7 +892,7 @@ namespace ecolab
         for (size_t i=0; i<x.size(); ++i)
           {
             if (x[i].empty()) continue;
-            const LineStyle& ls=palette[i%paletteSz];
+            const LineStyle& ls=palette[i%palette.size()];
 
             // transform y coordinates (handles RHS being a different scale)
             XFY xfy=aff;
@@ -1034,7 +1034,7 @@ namespace ecolab
           }
         auto my=xfy(mouseY);
         // put a marker where the found location is (mouse can be slightly different)
-        const LineStyle& ls=palette[mousePen%paletteSz];
+        const LineStyle& ls=palette[mousePen%palette.size()];
         cairo_set_source_rgba(cairo, ls.colour.r, ls.colour.g, ls.colour.b, 0.5*ls.colour.a);
         {
           cairo::CairoSave cs(cairo);
@@ -1274,11 +1274,11 @@ namespace ecolab
       throw error("exporting to %s failed",filename.c_str());
   }
 
-  string Plot::defaultFormatter(double x, double y)
+  string Plot::defaultFormatter(const string& label, double x, double y)
   {
     ostringstream r;
     r.precision(3);
-    r<<"("<<x<<","<<y<<")";
+    r<<label<<":("<<x<<","<<y<<")";
     return r.str();
   }
 
@@ -1316,6 +1316,7 @@ namespace ecolab
 
     double xp=std::numeric_limits<double>::max(), yp=xp;
     double mind=std::numeric_limits<double>::max();
+    string penLabel;
     assert(x.size()==y.size());
     for (size_t pen=0; pen<x.size(); ++pen)
       {
@@ -1333,14 +1334,15 @@ namespace ecolab
               {
                 xp=x[pen][i];
                 yp=y[pen][i];
+                penLabel=penTextLabel[pen];
                 mousePen=pen;
                 mind=d;
               }
           }
       }
     string valueString1;
     if (xp<maxx)
-      valueString1=formatter(xp,yp);
+      valueString1=formatter(penLabel,xp,yp);
     if (valueString1!=valueString)
       {
         valueString=valueString1;