[Tex/LaTex] How to keep indentations in Python code copied from LaTeX PDF

indentationlistingspdfpython

I tried to include Python 3.6 code in a LaTeX PDF document which should be easily be copied to save to a file or to try the Python code.

Although,

\begin{verbatim}
for row in range(1,9):
    for col in range(1,9):
        print(int(str(row)+str(col)))
\end{verbatim}

shows nicely in the PDF but if I copy it and paste it to a text editor it looks like:

for row in range(1,9):
for col in range(1,9):
print(int(str(row)+str(col)))

The indentations which are essential for Python are gone.

I also tried the suggestion here using the listings package:

How to highlight Python syntax in LaTeX Listings \lstinputlistings command

where I can simply give the file name of an Python file
e.g.

\pythonexternal{Test.py}

And the source code will be included and colored.
But the same thing with the missing spaces at the start when copy&pasting.

If I use the option "showspaces=true"
I get the following:

for␣row␣in␣range(1,9):
␣␣␣␣for␣col␣in␣range(1,9):
␣␣␣␣␣␣␣␣print(int(str(row)+str(col)))

which is also not suitable for copy&paste. Well, I could replace all ␣ with space… not a really practicable solution.

There have been some weird hacks described in 2011 here:

How to make listings code indentation remain unchanged when copied from PDF?

Is there anything new since then…?
Any ideas how to achieve copy&paste Python code in a LaTeX PDF?
Thank you for suggestions.

Best Answer

One more solution that works well in both Acrobat Reader and Chrome, but is compatible with pdfTeX only (not XeTeX/LuaTeX):

\usepackage{transparent}
\makeatletter
\def\@xobeysp{\leavevmode\nobreak\texttransparent{0}{\char32}}
\makeatother

The \texttransparent is used to make ⎵ symbol invisible (actually, in some fonts the slot 32 is mapped onto the real space character, and this trick is not necessary, but the above code covers all cases).

Most likely, this code works because the generated file is not Unicode-based, and PDF viewer has no information about matching between code 32 and actual Unicode character, and so it copies it "as-is" as character code 32 (i.e. the space character). In favor of this hypothesis, there are failed XeTeX/LuaTeX-generated files and an attempt to set Unicode correspondence via /ActualText command (by replacing \char32 with \pdfliteral direct{/Span<</ActualText<FEFF0020>>> BDC}\char32\pdfliteral direct{EMC} in the above code).

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] How to create beamer slides with source code that can be copied

use the \defverbatim[...]\command definition:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{cmap}
\usepackage[utf8]{inputenc}
\usepackage{listings}
\lstset{breakatwhitespace,
language=C++,
columns=fullflexible,
keepspaces,
breaklines,
tabsize=3, 
showstringspaces=false,
extendedchars=true}

\begin{document}
\defverbatim[colored]\lst{%
\begin{lstlisting}[tabsize=8,basicstyle=\ttfamily]
const char *processing() const{
    somestring = "-1";
}
\end{lstlisting}
}

\begin{frame}
\lst
\end{frame}

\end{document}

it is a problem with beamer which ignores the tabs. However, the above works

Best Answer

Related Solutions

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

[Tex/LaTex] How to create beamer slides with source code that can be copied

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