//2D gaussian function
Double_t Gaus2D(Double_t *x, Double_t *par) {
  Double_t r1 = Double_t((x[0]-par[1])/par[2]);
  Double_t r2 = Double_t((x[1]-par[3])/par[4]);
  return par[0]*TMath::Exp(-0.5*(r1*r1+(par[5]*r1*r2)+r2*r2));
}

//Draw circle with holes
TCanvas *circle_with_holes(){
  TCanvas *c1 = new TCanvas("c1", "c1", 500, 500);
  c1->cd();

  //define 2D gaussian function
  TF2* fgaus2d = new TF2("gaussian_fill", &Plotters::Gaus2D, -3, 3, -3, 3, 6);
  fgaus2d->SetParameters(1.,0,1,0,1,0);
  fgaus2d->SetParNames("norm","xmean","xsigma","ymean","ysigma","orientation");

  //fill random gaussian histogram
  TH2D* hist = new TH2D("hist","2D gaussian",100,-2,2,100,-2,2);
  hist->FillRandom("gaussian_fill", 100000);
  hist->Draw("colz");

  TEllipse *circle = new TEllipse(0.5, 0.5, 0.4);
  circle->SetLineWidth(6);
  circle->SetFillStyle(1001); //solid
  circle->SetFillColor(kGray);
  circle->Draw("Lf");

  TEllipse *hole1 = new TEllipse(0.4, 0.4, 0.1);
  hole1->SetLineWidth(6);
  hole1->SetFillStyle(0); //hollow
  hole1->Draw("L");

  TEllipse *hole2 = new TEllipse(0.6, 0.6, 0.1);
  hole2->SetLineWidth(6);
  hole2->SetFillStyle(0); //hollow
  hole2->Draw("L");

  return c1;
}