Printing pad to pdf is missing endobj in some cases

[hpekeler]

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Description

I played around with printing a canvas to pdf, using the EmbedFonts option or not. During EmbedFonts, where ghostcsript is called, it complaines about missing endobj in the pdf file. As far as i understand it is just a warning and the output still looks correct.

Still, no need for this warning. Why not just print the endobj?

Also: ghostscript option -dUseCIEColor is deprecated for gs > 9.11 One could remove this option in the print.

Changes to the ROOT code:
graf2d/postscript/src/TPDF.cxx:
Add PrintStr("endobj@"); at the end of the "/Title (Page" blocks and the "/Title (Contents" block.

graf2d/gpad/src/TPad.cxx:
remove option -dUseCIEColor from the gs system call.

After this two changes, everything is fine for me again. No more warnings. And output looks still the same.

Reproducer

ROOT macro: (Macro.cpp)

{
TCanvas *c1=new TCanvas("c1","c1");
double *a=new double[3];
a[0]=1;a[1]=2;a[2]=3;
TGraph *g=new TGraph(3,a,a);
g->Draw();
c1->Print("Test.pdf","EmbedFonts");
}

Run with: root -l -b -q Macro.cpp

ROOT version

ROOT version: 6.24/08

Installation method

yum

Operating system

CentOS7

Additional context

No response

[couet]

I ran your macro on Mac. The generated file is attached. It can be opened without problem using the Mac utility "Preview".
Test.pdf

[hpekeler]

Yes opening the pdf is fine. i just get warnings when using ghostscript to convert the pdf with EmbedFonts. These are not critical but also not needed in my opinion. One could just get rid of them by implementing the endobj lines.

Do you not get warnings during the macro from ghostscript on mac?

[couet]

I do not see any warnings with gs:

% gs Test.pdf
GPL Ghostscript 9.05 (2012-02-08)
Copyright (C) 2010 Artifex Software, Inc.  All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
Processing pages 1 through 1.
Page 1
>>showpage, press <return> to continue<<

[hpekeler]

I mean the ghostscript which is called inside of c1->Print().

[couet]

I get this:

root [0] TCanvas *c1=new TCanvas("c1","c1");
root [1] double *a=new double[3];
root [2] a[0]=1;a[1]=2;a[2]=3;
root [3] TGraph *g=new TGraph(3,a,a);
root [4] g->Draw();
root [5] c1->Print("Test.pdf","EmbedFonts");
Info in <TCanvas::Print>: EmbedFonts file Test.pdf has been created
root [6] 

[hpekeler]

Ok strange. Maybe it is due to gs version? I am using default centos7 version and i get the warnings.
GPL Ghostscript 9.25 (2018-09-13)
Copyright (C) 2018 Artifex Software, Inc. All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.

[couet]

Let me check if Ghostscript is really called in my case...

[hpekeler]

I do not see any warnings with gs:

% gs Test.pdf
GPL Ghostscript 9.05 (2012-02-08)
Copyright (C) 2010 Artifex Software, Inc.  All rights reserved.
This software comes with NO WARRANTY: see the file PUBLIC for details.
Processing pages 1 through 1.
Page 1
>>showpage, press <return> to continue<<

you version is defnitly different to mine. Maybe they changed something over the years and now these warnings apear.

[couet]

The command executed by root is:

gs -quiet -dSAFER -dNOPLATFONTS -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dUseCIEColor -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dCompatibilityLevel=1.4 -dMaxSubsetPct=100 -dSubsetFonts=true -dEmbedAllFonts=true -sOutputFile=pdf_temp.pdf -f Test.pdf

I tried on an other Mac with a more recent version of gs and I see also the error message. I am investigating.

root [5] c1->Print("Test.pdf","EmbedFonts");
Info in <TCanvas::Print>: EmbedFonts file Test.pdf has been created
GPL Ghostscript 9.55.0: 

Use of -dUseCIEColor detected!
Since the release of version 9.11 of Ghostscript we recommend you do not set
-dUseCIEColor with the pdfwrite/ps2write device family.

   **** Error: Encountered 'obj' while expecting 'endobj'.
               Treating this as a missing 'endobj', output may be incorrect.
   **** Error: Encountered 'obj' while expecting 'endobj'.
               Treating this as a missing 'endobj', output may be incorrect.
GPL Ghostscript 9.55.0: 

Use of -dUseCIEColor detected!
Since the release of version 9.11 of Ghostscript we recommend you do not set
-dUseCIEColor with the pdfwrite/ps2write device family.

root [6] 

[hpekeler]

very good. I actually linked a fix to this messages directly in the start of my bug report.

[hpekeler]

Changes to the ROOT code:
graf2d/postscript/src/TPDF.cxx:
Add PrintStr("endobj@"); at the end of the "/Title (Page" blocks and the "/Title (Contents" block.

graf2d/gpad/src/TPad.cxx:
remove option -dUseCIEColor from the gs system call.

This solves the warnings

[couet]

The PR to fix the problem is ready: #13564
Thanks for the report.

[hpekeler]

Thanks for fixing so quickly! I had a brief look at the PR and i think you missed one EndObject()
Around line 1500 in the if(fNbPage>1) condition, there is not EndObject at the end of that condition.
It wasnt before the PR and is not present in the PR if i am not mistaken.

[couet]

I'll check

[couet]

Yes you are right, with the follwing example the new mechanism I introduced shows warnings:

{

TFile f("hsimple.root","READ");

c1 = new TCanvas("c1","c1",200,10,700,500);
c2 = new TCanvas("c2","c2",200,300,700,500);

hpx->SetTitle("#alpha");
c1->cd(); hpx->Draw();
c2->cd(); hpx->Draw();

c1->Print("h1.pdf[");
c2->Print("h1.pdf", "Title:aaa");
c2->Print("h1.pdf", "Title:Verrex");
c1->Print("h1.pdf", "Title:bbb");
c1->Print("h1.pdf]");

} 

[couet]

fixed

[hpekeler]

Thanks!

[couet]

I'll commit it today. There is a few more details to check.

[couet]

The PR is now merged. Thanks for reporting this issue.

[github-actions]

Hi @couet,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖