#include "TH2D.h"
#include "TCanvas.h"
#include "TStyle.h"
#include "TExec.h"
#include "TPad.h"
#include "TRandom.h"
#include "TPaletteAxis.h"
#include "TList.h"
#include "TColor.h"

void BPalette()
{
  Double_t r[]    = {0., 0.0, 1.0, 1.0, 1.0};
  Double_t g[]    = {0., 0.0, 0.0, 1.0, 1.0};
  Double_t b[]    = {0., 1.0, 0.0, 0.0, 1.0};
  Double_t stop[] = {0., .25, .50, .75, 1.0};
  TColor::CreateGradientColorTable(5, stop, r, g, b, 100);
}

void GrayPalette()
{
  Double_t r[]    = {0., 1.};
  Double_t g[]    = {0., 1.};
  Double_t b[]    = {0., 1.};
  Double_t stop[] = {0., 1.};
  TColor::CreateGradientColorTable(2, stop, r, g, b, 100);
}

void GrayInvPalette()
{
  Double_t r[]    = {1., 0.};
  Double_t g[]    = {1., 0.};
  Double_t b[]    = {1., 0.};
  Double_t stop[] = {0., 1.};
  TColor::CreateGradientColorTable(2, stop, r, g, b, 100);
}

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

  TCanvas* can = new TCanvas("can", "can", 400, 600);
  can->Divide(2, 3, 1e-10, 1e-10);
  
  TH2D* hist  = new TH2D("hist", "", 100, -5, 5, 100, -5, 5);
  hist->SetContour(100);

  for(int i = 0; i < 100000; i++){
    double x = gRandom->Gaus();
    double y = gRandom->Gaus();
    hist->Fill(x, y);
  } // i

  TExec* exe[6];

  exe[0] = new TExec("ex0", "gStyle->SetPalette(0);");
  exe[1] = new TExec("ex1", "gStyle->SetPalette(1);");
  exe[2] = new TExec("ex2", "GrayPalette();");
  exe[3] = new TExec("ex3", "GrayInvPalette();");
  exe[4] = new TExec("ex4", "BPalette();");
  exe[5] = new TExec("ex5", "BPalette();");

  for(int i = 0; i < 6; i++){
    can->cd(i + 1);
    hist->Draw("axis z");
    if(i == 5){
      TPaletteAxis* palette = (TPaletteAxis*)hist->GetListOfFunctions()->FindObject("palette");
      Int_t col = palette->GetValueColor(0.);
      gPad->SetFrameFillColor(col);
    } // if
    gPad->Update();
    exe[i]->Draw();
    hist->Draw("same colz");
    gPad->Update();
  } // i
}