zref: Unstable output when conditionally appending a tikz-drawn page using \ztotpages with \AtVeryEndDocument

Question

I need to append a draft page only if the total number of pages in the main document is odd.

The following works well

\documentclass{exam}
\usepackage{blindtext,tikz,ulem,atveryend,hyperref}
\usepackage[totpages,user]{zref}
\newcommand\DraftPage{%https://tex.stackexchange.com/a/263613/2288
    \clearpage
    \begingroup
    \null
    \thispagestyle{empty}%
    \begin{tikzpicture}[remember picture,overlay]
    \node at ([yshift=-2cm]current page.north) {\LARGE\textbf{\uline{Draft Page}}};
    \draw[line width=5pt]
    (current page.north west) -- (current page.south east);
    \draw[line width=5pt]
    (current page.south west) -- (current page.north east);
    \end{tikzpicture}
    \addtocounter{page}{-1}%
    \hypersetup{pageanchor=false}%
    \clearpage
    \endgroup
}
\AtVeryEndDocument{
    \ifodd\ztotpages 
    \DraftPage
    \fi
}
\begin{document}
    \blindtext[1-30]\\
    \textbf{Total number of pages is \ztotpages.}
    \DraftPage
\end{document}

until changing it to

\begin{document}
    \blindtext[1-30]\\
    \textbf{Total number of pages is \ztotpages.}
\end{document}

then I get on the second page a wrongly rendered appended draft page.

So, I have two questions:

1- How to make the command \DraftPage not affect the total number of pages detected by \ztotpages in the former working case? In other words. \ztotpages needs to be 1.

2- Why does the second case result in the wrong output? and how to fix it?

Zarko · Accepted Answer · 2020-03-01T19:41:30.910

2

Edit:

An another solution, hopefully this time more stable:

\documentclass{exam}
\usepackage{tikz,ulem,etoolbox,hyperref}
\usepackage{lipsum}
\usepackage[totpages,user]{zref}
\newcommand\DraftPage{
    \cleardoublepage                % <---
    \thispagestyle{empty}
    \ifodd\thepage\else             % <---
    \centering\LARGE\textbf{\uline{Draft Page}} % <--- 
    \begin{tikzpicture}[remember picture,overlay]
    \draw[line width=5pt]
    (current page.north west) -- (current page.south east);
    \draw[line width=5pt]
    (current page.south west) -- (current page.north east);
    \end{tikzpicture}
   \fi%                             % <---
}
\AtEndDocument{\DraftPage}          % <---

\begin{document}
    \lipsum%\lipsum\lipsum\lipsum
    \lipsum[1-3]
    \textbf{Number of pages is \ztotpages.}
\end{document}

This solution in documents with odd number of pages add \DraftPage on the end of document. This is obtained after at least two compilation of documents. I tested the solution with documents with up to five pages of text. All results was correct after two compilations.

Definition of the \DraftPage is changed. Now it contain the test if the last page is odd.
In my MWE I use lipsum instead blindtext since I'm more familiar with it.
In solution is used the etoolbox package and its document hook \AtEndDocument instead of atveryend package and its hook \AtVeryEndDocument, which to my best knowledge doesn't work as you expected (but I may be wrong).
In solution is not used \ztotpages anymore. It now serve only for show the number of documents' page.

edited Mar 01 '20 at 19:41

answered Mar 01 '20 at 00:07

Zarko

296,517

May I know why you added \mbox{}? – Diaa Mar 01 '20 at 11:37
It actually start \DraftPag page. Without it you obtain only part of image as you shown in your question. – Zarko Mar 01 '20 at 11:45
Please try this one: `\AtEndDocument{ \ifodd\ztotpages \else \DraftPage \fi}
\begin{document} \lipsum \lipsum %\lipsum[1-3] \textbf{Number of pages is \ztotpages.} \end{document}`. You will always get different output each time you compile. I only need to print a draft page only if the total number of pages is odd. I think it is a different question needed to be asked separately.
– Diaa Mar 01 '20 at 11:47
Do you compile twice? I obtain correct result. – Zarko Mar 01 '20 at 11:53
I compiled a lot of times. Each compile gets different output than the previous run. – Diaa Mar 01 '20 at 11:55
The second compilation is needed due to tikzpicture which use options remember picture,overlay. After second compilation result is stable -- always the same. I use recent MikTeX with recent packages, if this matter. – Zarko Mar 01 '20 at 12:00
This document switches between two pages document and three pages with a wrongly rendered draft page every single run. – Diaa Mar 01 '20 at 12:03
@Diaa, indeed. I will delete my answer. – Zarko Mar 01 '20 at 12:06

score 1 · Answer 2 · answered Mar 01 '20 at 13:26

1

I'd use \BeforeLastShipout.

\documentclass{exam}
\usepackage{lipsum,tikz,ulem,atveryend,hyperref}
\usepackage[totpages,user]{zref}

\BeforeClearDocument{\clearpage\DraftPage}
\newcommand{\DraftPage}{%
  \ifodd\value{page}\else
    \thispagestyle{empty}%
    \mbox{}%
    \begin{tikzpicture}[remember picture,overlay]
    \node at ([yshift=-2cm]current page.north) {\LARGE\textbf{\uline{Draft Page}}};
    \draw[line width=5pt]
    (current page.north west) -- (current page.south east);
    \draw[line width=5pt]
    (current page.south west) -- (current page.north east);
    \end{tikzpicture}%
    \addtocounter{page}{-1}%
    \hypersetup{pageanchor=false}%
    \renewcommand{\DraftPage}{}%
  \fi
}

\begin{document}

\lipsum[1-25]

\textbf{Total number of pages is \zpageref{LastPage}.}

\end{document}

If you change into \lipsum[1-30], the additional page is not shipped out.

answered Mar 01 '20 at 13:26

egreg

1,121,712

Many thanks for this stable solution. If you don't mind I would be happy to make sure I understand some stuff correctly: (1) does \ifodd\value{page}\else check the total number of pages is even so that it activates the command \DraftPage? It seems superficially to check for even number although I found it activates \DraftPage when the total number of pages is odd. (2) why does \BeforeClearDocument{\clearpage\DraftPage\clearpage\DraftPage} not work in case I want to append multiple instances of the daft page? – Diaa Mar 01 '20 at 17:52
@Diaa It's necessary to redefine \DraftPage to do nothing, otherwise it would add two pages. You wanted one, didn't you? – egreg Mar 01 '20 at 17:54
Kindly, check my previous comment after editing it. I don't quite understand how \ifodd\value{page}\else works/means. – Diaa Mar 01 '20 at 17:56
@Diaa I emit \clearpage so everything is (hopefully) shipped out. This operation steps the page counter. There are two cases: page is even means that the last shipped page was odd and you need \DraftPage; otherwise page is odd and the last shipped page was even. – egreg Mar 01 '20 at 17:59
I apologize for not having the enough knowledge to let me fully grasp your technical description. For your previous question of whether or not I need one page, my main target is to check the total number of pages, and it will fall in two cases: (1) odd number of pages print a draft page then use \includepdf{GraphPaper.pdf} then draft page then \includepdf{GraphPaper.pdf}. (2) even number of pages print a graph paper with \includepdf{GraphPaper.pdf} then draft page then \includepdf{GraphPaper.pdf}. So, I started my experimentation by trying to conditionally print the draft page. – Diaa Mar 01 '20 at 18:05
I found out that \AtEndDocument{ \ifodd\thepage\else \DraftPage \fi \includepdf{GraphPaper} \DraftPage \includepdf{GraphPaper} } does the job pretty well. I just found that \AtEndDocument behaves differently from \AtVeryEndDocument, which I don't know if it is worth asking a new question or not. – Diaa Mar 01 '20 at 18:49

zref: Unstable output when conditionally appending a tikz-drawn page using \ztotpages with \AtVeryEndDocument

2 Answers2