Add an progress bar image based on page number

Question

I would like to add a "progress bar" to each page of my report. I have 25 images named pbar1.png to pbar25.png, as shown below, to be put on slides:

pbar1.png:

pbar12.png:

pbar25.png:

Because I have exactly 25 images, but my report may have more pages (or less), I map the page number to image number using a simple linear map:

enter image description here

I can do the calculations using calc. My problem is to determine how many pages there are. I can use lastpage package or just simply add a label at the end of the pages and call \pageref{lastpagenum}, but then when I run LaTeX on the file for the first time, the reference is undefined and I get an Arithmatic overflow error (as it appears in the denominator of the fraction). I tried using \getrefbykeydefault{lastpagenum}{page}{1400} from refcount to avoid getting zero, but that didn't help. I also tried \ifstrequal, which didn't help either.

Here is the MWE. Some comments are provided in the code.

\documentclass{article}

\newcounter{imagenum}
\newcounter{dummy}

\usepackage{calc}
\usepackage{graphicx}
\usepackage{refcount}
\usepackage{fancyhdr}
\usepackage{lipsum}
\pagestyle{fancy}
\lhead{
    % 1400 below can be replaced with any number number big enough
    \setcounter{dummy}{\getrefbykeydefault{lastpagenum}{page}{1400}-1}
    % To run without error, replace \thedummy below with 3 (which is 4-1)
    \setcounter{imagenum}{(\thepage-1)*\ratio{24 cm}{\thedummy cm} +1}
    %\includegraphics{../../../_Common/ProgressBar/pbar\theimagenum.png} 
    % includegraphics above clearly won't work. So simply just print the scaled image number
    \theimagenum
    }

\begin{document}
\lipsum[1]\newpage

\lipsum[1]\newpage

\lipsum[1]\newpage

\lipsum[1]

\label{lastpagenum}
\end{document}

set last page number to, let's say, 1000 in beginning of document. — Eddy_Em, May 23 '13 at 04:40
Related Progress bar for latex-beamer and it's linked Q's and The progressbar Beamer theme — texenthusiast, May 23 '13 at 04:43
@texenthusiast, Interesting that I searched for many combinations of keywords, but missed the obvious one that would include "progress bar." — Ali Mehrizi, May 23 '13 at 05:03
hint: beamer tag search, look at first one. hence tagging/title is very important on SX — texenthusiast, May 23 '13 at 05:08
@texenthusiast, I'm having second thoughts about the beamer tag, because the solution/question is not really limited to beamer, nor does it need beamer. It can well be used for other document styles. I certainly agree with your point though. — Ali Mehrizi, May 23 '13 at 05:12

Xavier · Accepted Answer · 2013-05-23T05:07:50.343

You could simply check whether the lastpage reference (i.e. \r@lastpagenum) is defined (using the \ifdefined macro) before performing your calculations:

\makeatletter% required as some of the commands we will use contain "@" in their name
\lhead{
  % only perform the calculations if the "lastpagenum" reference is defined
  \ifdefined\r@lastpagenum%
    % 1400 below can be replaced with any number number big enough
    \setcounter{dummy}{\getrefbykeydefault{lastpagenum}{page}{1400}-1}%
    \setcounter{imagenum}{(\thepage-1)*\ratio{24 cm}{\thedummy cm} +1}%
    %\includegraphics{../../../_Common/ProgressBar/pbar\theimagenum.png} 
    \theimagenum%
  \fi%
}
\makeatother

The next step is to remove the use of the dummy counter, by getting / converting the last page reference into a number that can be used inside the calculations, using refcount's \getpagerefnumber:

\makeatletter% required as some of the commands we will use contain "@" in their name
\lhead{
  % only perform the calculations if the "lastpagenum" reference is defined
  \ifdefined\r@lastpagenum%
    \setcounter{imagenum}{(\thepage-1)*24/(\getpagerefnumber{lastpagenum}-1) +1}%
    %\includegraphics{../../../_Common/ProgressBar/pbar\theimagenum.png} 
    \theimagenum%
  \fi%
}
\makeatother

I was just doing the same (removing dummy) but you beat me to it. Just a minor modification to keep the equation correct: \setcounter{imagenum}{(\thepage-1)*24/(\getpagerefnumber{lastpagenum}-1) + 1} — Ali Mehrizi, May 23 '13 at 05:06
I'm accepting your answer. Probably one of the fastest complete accepted answers on TeX.SX! — Ali Mehrizi, May 23 '13 at 05:10
@AliMehrizi I was just refreshing the unanswered list a last time before going to bed :) — Xavier, May 23 '13 at 05:16

Add an progress bar image based on page number

1 Answers1