#include <TROOT.h>
#include <TSystem.h>
#include <TStyle.h>
#include <TCanvas.h>
#include <TH1F.h>

void CanvasPartition(TCanvas *C,const Int_t Nx = 2,const Int_t Ny = 2)
{
  if(!C) return;

  // Margins
  Float_t lMargin = 0.15;
  Float_t rMargin = 0.05;
  Float_t bMargin = 0.15;
  Float_t tMargin = 0.05;
    
  // Setup Pad layout:
  Float_t vSpacing = 0.0; 
  Float_t vStep  = (1.- bMargin - tMargin - (Ny-1) * vSpacing) / Ny;

  Float_t hSpacing = 0.0; 
  Float_t hStep  = (1.- lMargin - rMargin - (Nx-1) * hSpacing) / Nx;
    
  Float_t vposd = 0.0;
  Float_t vposu = 0.0;
  Float_t vmard = 0.0;
  Float_t vmaru = 0.0;
  Float_t vfactor = 0.0;

  Float_t hposl = 0.0;
  Float_t hposr = 0.0;
  Float_t hmarl = 0.0;
  Float_t hmarr = 0.0;
  Float_t hfactor = 0.0;

  for(Int_t i=0;i<Nx;i++) {

    if(i==0) {
      hposl = 0.0;
      hposr = lMargin + hStep;
      hfactor = hposr-hposl;  
      hmarl = lMargin / hfactor;
      hmarr = 0.0;
    } else if(i == Nx-1) {
      hposl = hposr + hSpacing;
      hposr = hposl + hStep + rMargin;
      hfactor = hposr-hposl;   
      hmarl = 0.0;
      hmarr = rMargin / (hposr-hposl);
    } else {
      hposl = hposr + hSpacing;
      hposr = hposl + hStep; 
      hfactor = hposr-hposl;
      hmarl = 0.0;
      hmarr = 0.0;
    }        
    
    for(Int_t j=0;j<Ny;j++) {
      
      if(j==0) {
	vposd = 0.0;
	vposu = bMargin + vStep;
	vfactor = vposu-vposd;  
	vmard = bMargin / vfactor;
	vmaru = 0.0;
      } else if(j == Ny-1) {
	vposd = vposu + vSpacing;
	vposu = vposd + vStep + tMargin;
	vfactor = vposu-vposd;   
	vmard = 0.0;
	vmaru = tMargin / (vposu-vposd);
      } else {
	vposd = vposu + vSpacing;
	vposu = vposd + vStep; 
	vfactor = vposu-vposd;
	vmard = 0.0;
	vmaru = 0.0;
      }    
         
      C->cd(0);
      
      //      cout << Form(" %i  %i : (%.2f,%.2f,%.2f,%.2f)",i,j,hposl,vposd,hposr,vposu) << endl;

      char name[16];
      sprintf(name,"pad_%i_%i",i,j);
      TPad *pad = (TPad*) gROOT->FindObject(name);
      if(pad) delete pad;
      pad = new TPad(name,"",hposl,vposd,hposr,vposu);
      pad->SetLeftMargin(hmarl);
      pad->SetRightMargin(hmarr);  
      pad->SetBottomMargin(vmard);
      pad->SetTopMargin(vmaru);

      pad->SetFrameBorderMode(0);
      pad->SetBorderMode(0);
      pad->SetBorderSize(0);
     
      pad->Draw();
    }
  }
  
}


void testCanvasPartition() 
{
  gStyle->SetOptStat(0);

  TCanvas *C = (TCanvas*) gROOT->FindObject("C");
  if(C) delete C;
  C = new TCanvas("C","canvas",1024,640);
  C->SetFillStyle(4000);

  const Int_t Nx =2;
  const Int_t Ny =2;

  TH1F *h = (TH1F*) gROOT->FindObject("histo");
  if(h) delete h;
  h = new TH1F("histo","",100,-5.0,5.0);
  h->FillRandom("gaus",10000);
  h->GetXaxis()->SetTitle("x axis");
  h->GetYaxis()->SetTitle("y axis");

  TPad *pad[Nx][Ny]; 
  CanvasPartition(C,Nx,Ny);  
  
  for(Int_t i=0;i<Nx;i++) {
    for(Int_t j=0;j<Ny;j++) {
      C->cd(0);
      char pname[16];
      sprintf(pname,"pad_%i_%i",i,j);
      pad[i][j] = (TPad*) gROOT->FindObject(pname);
      pad[i][j]->Draw();
      pad[i][j]->SetFillStyle(4000);
      pad[i][j]->SetFrameFillStyle(4000);
      pad[i][j]->cd();
      
      Float_t xFactor = pad[0][0]->GetAbsWNDC()/pad[i][j]->GetAbsWNDC();
      Float_t yFactor = pad[0][0]->GetAbsHNDC()/pad[i][j]->GetAbsHNDC();

      //  cout << Form(" %i  %i : (%.2f,%.2f)",i,j,xFactor,yFactor) << endl;

      char hname[16];
      sprintf(hname,"h_%i_%i",i,j);
      TH1F *hFrame = (TH1F*) h->Clone(hname);
      hFrame->Reset();

      hFrame->Draw();
      
      hFrame->GetYaxis()->SetRangeUser(0.0001,1.2*h->GetMaximum());
     
      // Format for y axis
      hFrame->GetYaxis()->CenterTitle();
      hFrame->GetYaxis()->SetNdivisions(505);

      hFrame->GetYaxis()->SetLabelSize(0.095*yFactor);
      hFrame->GetYaxis()->SetLabelOffset(0.02/yFactor);
      hFrame->GetYaxis()->SetTitleSize(0.1*yFactor);
      hFrame->GetYaxis()->SetTitleOffset(1.2/yFactor);
      hFrame->GetYaxis()->SetTickLength(0.02/yFactor);

      // Format for x axis
      hFrame->GetXaxis()->CenterTitle();
      hFrame->GetXaxis()->SetNdivisions(505);

      hFrame->GetXaxis()->SetLabelSize(0.095*xFactor);
      hFrame->GetXaxis()->SetLabelOffset(0.02/xFactor);
      hFrame->GetXaxis()->SetTitleSize(0.1*xFactor);
      hFrame->GetXaxis()->SetTitleOffset(1.2/xFactor);
      hFrame->GetXaxis()->SetTickLength(0.02/xFactor);
  
      hFrame->SetLabelFont(42,"xyz");
      hFrame->SetTitleFont(42,"xyz");
      
      h->Draw("same");
    }
  }
  
  C->cd();
  C->Print("testCanvasPartition.pdf");
  
}