Writing several canvases to the same PDF file

ROOT
1

Hi,
I tried the TCanvas::Print(“file.pdf[”,“pdf”) mechanism but it seems there is a bug because, differently from the postscript case, using a PDF file an empty initial page is produced:

TCanvas *myc = new TCanvas(“myc”,"",500,600);
myc->Print(dir+“plot.pdf[”,“pdf”);
for(i=0;i<Npages;i++){
histo->Draw();
myc->Print(“file.pdf”,“pdf”);
}
myc->Print(“file.pdf]”,“pdf”);

using postscript I correctly get a file with Npages, while using PDF I get Npages+1, the first one being empty.

I’m using last ROOT versiom (5.18)

2

this one works for me:

{
   TCanvas* canvas = new TCanvas("canvas");

   TH1F* histo = new TH1F("histo","test 1",10,0.,10.);

   histo->Fill(2.);
   histo->Draw();
   canvas->Print("plots.pdf(","pdf");

   histo->Fill(4.);
   histo->Draw();
   canvas->Print("plots.pdf","pdf");

   histo->Fill(6.);
   histo->Draw();
   canvas->Print("plots.pdf","pdf");

   histo->Fill(8.);
   histo->Draw();
   canvas->Print("plots.pdf)","pdf");
}
3

yes also for me.
But if you try:

{
TCanvas* canvas = new TCanvas(“canvas”);

TH1F* histo = new TH1F(“histo”,“test 1”,10,0.,10.);

canvas->Print(“plots.pdf[”,“pdf”);
for(int i=1; i<=4; i++){
histo->Fill((float)i);
histo->Draw();
canvas->Print(“plots.pdf”,“pdf”);
}
canvas->Print(“plots.pdf]”,“pdf”);
}

you will see that the first page is empty.

4 
{
   TCanvas* canvas = new TCanvas("canvas");
   TH1F* histo = new TH1F("histo","test 1",10,0.,10.);
   for(int i=1; i<=4; i++){
      histo->Fill((float)i);
      histo->Draw();
      if (i==1) {
         canvas->Print("plots.pdf(","pdf");
      } elseif (i==4) {
         canvas->Print("plots.pdf)","pdf");
      } else {
         canvas->Print("plots.pdf","pdf");
      }
   }
}
5

sure with that code it works I know. But it was only to stress that the “[” mechanism seems not to work properly because instead of simply opening the file (without any print) it opens the file but also print the current (empty) cnavas…

6

In fact if you look at the documentation this mechanism is described for PS. It is the same pdf.

7

I see! I expected it should work also for PDF. Ok thanks a lot!