customcolor.h

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// Author: Timur Pocheptsov, 14/1/2014.
 
#ifndef CUSTOMCOLOR_INCLUDED
#define CUSTOMCOLOR_INCLUDED
 
#include <algorithm>
 
#include "TError.h"
#include "Rtypes.h"
#include "TROOT.h"
 
namespace ROOT {
namespace CocoaTutorials {
 
//___________________________________________________________
inline Color_t FindFreeCustomColorIndex(Color_t start = 1000)
{
   if (!gROOT) {
      // AH??? WHAT??? Should never happen! :)
      ::Error("FindFreeCustomColorIndex", "gROOT is null");
      return -1;
   }
   // Some (probably stupid) assumption about the TColor -
   // I'm trying to find some 'free' index in the range [1000, 10000).
   for (Color_t i = std::max(start, Color_t(1000)), e = 10000; i < e; ++i)
      if (!gROOT->GetColor(i))
         return i;
 
   ::Error("FindFreeCustomColorIndex", "no index found");
 
   return -1;
}
 
//
// Ho-ho-ho! Say good-bye to CINT and hello CLING ... and good old templates!!!
//___________________________________________________________
template <unsigned N>
inline unsigned FindFreeCustomColorIndices(Color_t (&indices)[N])
{
   // All or none.
   Color_t tmp[N] = {};
   tmp[0] = FindFreeCustomColorIndex();
   if (tmp[0] == -1) // Not found.
      return 0;
 
   unsigned nFound = 1;
   for (; nFound < N; ++nFound) {
      tmp[nFound] = FindFreeCustomColorIndex(tmp[nFound - 1] + 1); // the next free color index.
      if (tmp[nFound] == -1)
         break;
   }
 
   if (nFound == N)
      std::copy(tmp, tmp + N, indices);
 
   return nFound;
}
 
} // namespace CocoaTutorials
} // namespace ROOT
 
#endif