[Tex/LaTex] Text copied from pdf is missing spaces, or has extra ones

copy/pastenewtxpdftexspacing

When I create a pdf with pdflatexand copy text from that pdf (using Adobe Reader DC on Windows 10), some of the spaces are missing. Here's an MWE:

\documentclass{article}
\usepackage{newtxtext}
\begin{document}
    Therefore, this work ... \hspace*{\linewidth}
\end{document}

When I copy text from that pdf, this is what I get (1 being the page number):

Therefore, thiswork ...
1

Removing the \hspace*, OR removing newtxtext (or both) fixed the problem, but that's not I want, of course (as \hspace* represents some text following "this work").

I have come across Problem copying text from pdf – spaces being stripped and XeLaTeX and missing spaces in PDF text, which proposed \pdfgeninterwordspace, which is now \pdfinterwordspaceon (thanks, @egreg). So I tried that:

\documentclass{article}
\usepackage{newtxtext}
\pdfmapline{+dummy-space <dummy-space.pfb}
\pdfinterwordspaceon
\begin{document}
    Therefore, this work ... \hspace*{\linewidth}
\end{document}

(See Use pdfinterwordspaceon with pdflatex from MiKTeX on Windows if that does not compile for you.)

Now, when I copy text from that pdf, I get this:

Therefore,  this work  ... 
1

So basically, additional space has been introduced regardless of whether or not it was needed. Yes, the missing space in "thiswork" has been added, which is good; but so have three extra spaces after "Therefore,", "work", and "…", which is not good.

Is there a better solution? Am I using \pdfinterwordspaceon correctly?

Best Answer

This is at least partly a known issue with Adobe Reader. Adobe Reader fails to recognise spaces between words in certain cases (e.g. where the spacing is smaller than average) or recognises one space as multiple spaces (e.g. where the spacing is larger than average).

It is an issue in the viewer, not the file - as demonstrated by the fact that other viewers work fine - and there's not much to be done on the TeX side of things.

Related Solutions

[Tex/LaTex] How to make listings code indentation remain unchanged when copied from PDF

To prevent random spaces when copying the text from a listing, you need to use

\lstset{columns=flexible}

But you will now note that the text is not neatly aligned anymore; to solve this, you need to also use

\lstset{keepspaces=true}

This will not solve your problem with spaces disappearing at the beginning of lines when copying. The following hack will produce visible spaces and then make them invisible by coloring them in the background color:

\makeatletter
\def\lst@outputspace{{\ifx\lst@bkgcolor\empty\color{white}\else\lst@bkgcolor\fi\lst@visiblespace}}
\makeatother

This hack is not perfect, however, as the typesetted character is really a visible space, not a space (so searching the pdf for char line will not work) and some PDF readers (like Mac's preview) will copy a visible space. It works under Acrobat Reader and it's extremely pleasant to be able to quickly copy/paste code without problem (perhaps the problem can be circumvented by writing direct PDF code to tell that it's a space, I've never had the time to try). It might also not work with all typewriter fonts.

Here's the full code of your example:

\documentclass[12pt,oneside]{memoir}

\usepackage{listings}
\usepackage[T1]{fontenc}
\usepackage{xcolor}
\usepackage{textcomp}

\definecolor{codebg}{HTML}{EEEEEE}
\definecolor{codeframe}{HTML}{CCCCCC}

\lstset{language=Awk}
\lstset{backgroundcolor=\color{codebg}}
\lstset{frame=single}
\lstset{framesep=10pt}
\lstset{rulecolor=\color{codeframe}}
\lstset{upquote=true}
\lstset{basicstyle=\ttfamily}
\lstset{showstringspaces=false}

\lstset{columns=flexible}
\lstset{keepspaces=true}
\makeatletter
\def\lst@outputspace{{\ifx\lst@bkgcolor\empty\color{white}\else\lst@bkgcolor\fi\lst@visiblespace}}
\makeatother

\begin{document}

This code example prints out all users on your system:

\begin{lstlisting}[language=c]
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_LINE_LEN 1024

int main() {
    char line[MAX_LINE_LEN];
    FILE *in = fopen("/etc/passwd", "r");
    if (!in) exit(EXIT_FAILURE);

    while (fgets(line, MAX_LINE_LEN, in) != NULL) {
        char *sep = strchr(line, ':');
        if (!sep) exit(EXIT_FAILURE);
        *sep = '\0';
        printf("%s\n", line);
    }
    fclose(in);
    return EXIT_SUCCESS;
}
\end{lstlisting}

\end{document}

[Tex/LaTex] Problem copying text from pdf – spaces being stripped

The original purpose of PDF was to represent printed documents, and there was no explicit way of showing a space character. With modern developments around PDF, people are interested in things like automatic reflow for small screens and structural information for document processing or interfacing to screenreaders for people with visual impairment. Due to this, it is now possible to represent the spaces explicitly (I believe it is even a requirement for some grade of PDF/A compliance). There is a patch for pdftex here after which I believe you are supposed to add the following to your tex file:

\pdfmapline{+dummy-space <dummy-space.pfb}
\pdfgeninterwordspace

I don't know if the patch still applies (the bug tracker claims it has been replaced by a branch, probably this one), and I haven't tested it to see if it actually solves the problem.

Best Answer

Related Solutions

[Tex/LaTex] How to make listings code indentation remain unchanged when copied from PDF

[Tex/LaTex] Problem copying text from pdf – spaces being stripped

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