canvas2.C

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/// \file
/// \ingroup tutorial_graphics
/// \notebook
/// \preview Example of canvas partitioning.
/// Sometimes the Divide() method is not appropriate to divide a Canvas.
/// Because of the left and right margins, all the pads do not have the
/// same width and height. CanvasPartition does that properly. This
/// example also ensure that the axis labels and titles have the same
/// sizes and that the tick marks length is uniform.
/// In addition, XtoPad and YtoPad allow to place graphics objects like
/// text in the right place in each sub-pads.
///
/// \macro_image
/// \macro_code
///
/// \author Olivier Couet
 
void CanvasPartition(TCanvas *C,const Int_t Nx = 2,const Int_t Ny = 2,
                     Float_t lMargin = 0.15, Float_t rMargin = 0.05,
                     Float_t bMargin = 0.15, Float_t tMargin = 0.05);
double XtoPad(double x);
double YtoPad(double x);
 
void canvas2()
{
   gStyle->SetOptStat(0);
 
   auto C = (TCanvas*) gROOT->FindObject("C");
   if (C) delete C;
   C = new TCanvas("C","canvas",1024,640);
   C->SetFillStyle(4000);
 
   // Number of PADS
   const Int_t Nx = 5;
   const Int_t Ny = 5;
 
   // Margins
   Float_t lMargin = 0.12;
   Float_t rMargin = 0.05;
   Float_t bMargin = 0.15;
   Float_t tMargin = 0.05;
 
   // Canvas setup
   CanvasPartition(C,Nx,Ny,lMargin,rMargin,bMargin,tMargin);
 
   // Dummy histogram.
   auto 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];
 
   for (Int_t i = 0; i < Nx; i++) {
      for (Int_t j = 0; j < Ny; j++) {
         C->cd(0);
 
         // Get the pads previously created.
         pad[i][j] = (TPad*) C->FindObject(TString::Format("pad_%d_%d",i,j).Data());
         pad[i][j]->Draw();
         pad[i][j]->SetFillStyle(4000);
         pad[i][j]->SetFrameFillStyle(4000);
         pad[i][j]->cd();
 
         // Size factors
         Float_t xFactor = pad[0][0]->GetAbsWNDC()/pad[i][j]->GetAbsWNDC();
         Float_t yFactor = pad[0][0]->GetAbsHNDC()/pad[i][j]->GetAbsHNDC();
 
         TH1F *hFrame = (TH1F*) h->Clone(TString::Format("h_%d_%d",i,j).Data());
 
         // y axis range
         hFrame->SetMinimum(0.0001); // do not show 0
         hFrame->SetMaximum(1.2*h->GetMaximum());
 
         // Format for y axis
         hFrame->GetYaxis()->SetLabelFont(43);
         hFrame->GetYaxis()->SetLabelSize(16);
         hFrame->GetYaxis()->SetLabelOffset(0.02);
         hFrame->GetYaxis()->SetTitleFont(43);
         hFrame->GetYaxis()->SetTitleSize(16);
         hFrame->GetYaxis()->SetTitleOffset(2);
 
         hFrame->GetYaxis()->CenterTitle();
         hFrame->GetYaxis()->SetNdivisions(505);
 
         // TICKS Y Axis
         hFrame->GetYaxis()->SetTickLength(xFactor*0.04/yFactor);
 
         // Format for x axis
         hFrame->GetXaxis()->SetLabelFont(43);
         hFrame->GetXaxis()->SetLabelSize(16);
         hFrame->GetXaxis()->SetLabelOffset(0.02);
         hFrame->GetXaxis()->SetTitleFont(43);
         hFrame->GetXaxis()->SetTitleSize(16);
         hFrame->GetXaxis()->SetTitleOffset(1);
         hFrame->GetXaxis()->CenterTitle();
         hFrame->GetXaxis()->SetNdivisions(505);
 
         // TICKS X Axis
         hFrame->GetXaxis()->SetTickLength(yFactor*0.06/xFactor);
 
         // Draw cloned histogram with individual settings
         hFrame->Draw();
 
         TText text;
         text.SetTextAlign(31);
         text.SetTextFont(43);
         text.SetTextSize(10);
         text.DrawTextNDC(XtoPad(0.9), YtoPad(0.8), gPad->GetName());
      }
   }
   C->cd();
}
 
 
 
void CanvasPartition(TCanvas *C,const Int_t Nx,const Int_t Ny,
                     Float_t lMargin, Float_t rMargin,
                     Float_t bMargin, Float_t tMargin)
{
   if (!C) return;
 
   // 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,vposu,vmard,vmaru,vfactor;
   Float_t hposl,hposr,hmarl,hmarr,hfactor;
 
   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);
 
         auto name = TString::Format("pad_%d_%d",i,j);
         auto pad = (TPad*) C->FindObject(name.Data());
         if (pad) delete pad;
         pad = new TPad(name.Data(),"",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();
      }
   }
}
 
double XtoPad(double x)
{
   double xl,yl,xu,yu;
   gPad->GetPadPar(xl,yl,xu,yu);
   double pw = xu-xl;
   double lm = gPad->GetLeftMargin();
   double rm = gPad->GetRightMargin();
   double fw = pw-pw*lm-pw*rm;
   return (x*fw+pw*lm)/pw;
}
 
double YtoPad(double y)
{
   double xl,yl,xu,yu;
   gPad->GetPadPar(xl,yl,xu,yu);
   double ph = yu-yl;
   double tm = gPad->GetTopMargin();
   double bm = gPad->GetBottomMargin();
   double fh = ph-ph*bm-ph*tm;
   return (y*fh+bm*ph)/ph;
}