#include"TROOT.h"
#include"TFile.h"
#include"TH1.h"
#include"TCanvas.h"
#include"TSpectrum.h"

void background(const char *fname = "AF11225_5_20_20_day5_7200_12042016.root",
                const char *bname = "h1")
{
  if ((!fname) || (!(fname[0]))) return; // just a precaution
  if ((!bname) || (!(bname[0]))) return; // just a precaution
  
  TFile *f = TFile::Open(fname, "READ");
  if ((!f) || (f->IsZombie())) { delete f; return; } // just a precaution
  
  TH1F *back;
  f->GetObject(bname, back);
  if (!back) { delete f; return; } // just a precaution
  
  TCanvas *Background =
    (TCanvas *)gROOT->GetListOfCanvases()->FindObject("Background");
  if (Background) Background->Clear();
  else Background =
         new TCanvas("Background",
                     "Estimation of background with increasing window",
                     10, 10, 1000, 700);
  
  back->Draw();
  
  Int_t nbins = back->GetNbinsX();
#if ROOT_VERSION_CODE >= ROOT_VERSION(6,00,00)
  Double_t *source = new Double_t[nbins]; // ROOT 6
#else
  Float_t *source = new Float_t[nbins]; // ROOT 5
#endif
  Int_t i;
  for (i = 0; i < nbins; i++) source[i] = back->GetBinContent(i + 1);
  
  TSpectrum *s = new TSpectrum();
  s->Background(source, nbins, 6,
                TSpectrum::kBackIncreasingWindow, TSpectrum::kBackOrder2,
                kFALSE, TSpectrum::kBackSmoothing3, kFALSE);
  
  TH1F *d = new TH1F("d", "", nbins,
                     back->GetXaxis()->GetXmin(),
                     back->GetXaxis()->GetXmax());
  d->SetDirectory(gROOT); // (gROOT) ... or ... (0)
  for (i = 0; i < nbins; i++) d->SetBinContent(i + 1, source[i]);
  d->SetLineColor(kRed);
  d->Draw("SAME L");
  
  delete[] source; // no longer needed
}