6

Consider the following code taken from here to produce a fancy listing :

% PACKAGES
\documentclass[11pt,a4paper]{book}
\usepackage[top=1in, bottom=1in, left=1in, right=1in]{geometry}
\usepackage{lmodern}
\usepackage{multicol}
\usepackage{lipsum}
\usepackage{xcolor}
\usepackage{tcolorbox}
\tcbuselibrary{skins,listings}
\definecolor{nicedarkgreen}{RGB}{0,127,0}
\definecolor{nicedarkblue}{RGB}{0, 0, 102}

% LISTINGS
\newtcblisting{cpplisting}[1][]{%
  enhanced,
  arc = 0pt,
  outer arc = 0pt,
  colback = blue!5,
  colframe = nicedarkblue,
  listing only,
  fonttitle = \bfseries,
  listing options = {%
    basicstyle=\tiny\ttfamily,
    keywordstyle=\color{blue},
    language = C++,
    commentstyle=\color{nicedarkgreen},
    tabsize=2,
    morekeywords={constexpr},
    multicols = 2,
    numbers = left,
    xleftmargin = 0.5em,
    showstringspaces = false,
  },
  overlay = {%
    \fill[gray!30] 
      (interior.north west)
      rectangle 
      ([xshift = 1.25em]interior.south west);
    \fill[gray!30] 
      ([xshift = -1em]interior.north)
      rectangle 
      ([xshift = 0.25em]interior.south);
    \draw[ultra thick, nicedarkblue]
      ([xshift = -1em]interior.north) -- 
      ([xshift = -1em]interior.south); 
  }
  /utils/exec = {%
    \def\thelstnumber{%
      \texttt{\csname two@digits\endcsname{\the\value{lstnumber}}}}},
  title = {\centering\ttfamily #1}
}

% TEST
\begin{document}
\lipsum[1]
\begin{cpplisting}[An example of C++ file]
// Include
#include <iostream>

// Example
int main()
{
    std::cout<<"Hello World"<<std::endl;
    std::cout<<"This is just an example"<<std::endl;
    std::cout<<"With two columns"<<std::endl;
    return 0;
}
\end{cpplisting}
\end{document}

listing_result

With :

  • alpha : one-column text width
  • beta : first column width
  • gamma : second column width
  • mu : number column width
  • nu : distance between numbers and text
  • sigma : mu+nu
  • phi : distance between title and first line
  • psi : distance after last line

It looks great ... but the alignment is not and it causing me headaches... Instead of the current result, I want :

  • beta = gamma : same total column width (so the blue line in the middle will correspond to the middle of the page)
  • mu : to be adjusted to contains 3 digits (and when a number is three digit-long I want it to be centered on mu)
  • phi = psi : same top and bottom margin

To know exactly the logic, it would be great if all of that would be achievable programmatically using :

\newlength{...}
\setlength{...}{...}

or something similar.

How to achieve this ?

4

Here is the result after more than 3 hours of hesitations and experimentations. It produces the result I want for my particular font/size of font, but it is still experimental. Improvements to make it scaling right for different fonts/size of fonts would be greatly appreciated :

% PACKAGES
\documentclass[11pt,a4paper]{book}
\usepackage[top=1in, bottom=1in, left=1in, right=1in]{geometry}
\usepackage{lmodern}
\usepackage{multicol}
\usepackage{lipsum}
\usepackage{xcolor}
\usepackage{tcolorbox}
\usepackage{layouts}
\usepackage{calc}
\tcbuselibrary{skins,listings}
\definecolor{nicedarkgreen}{RGB}{0,127,0}
\definecolor{nicedarkblue}{RGB}{0, 0, 102}
\definecolor{lstgrey}{RGB}{217, 217, 217}
\definecolor{lstback}{RGB}{242, 242, 255}

% LISTINGS
\newlength{\zerolength}
\setlength{\zerolength}{0em}
\newlength{\tinyheight}
\setlength{\tinyheight}{\totalheightof{\tiny\ttfamily PpQq}}
\newlength{\beforetitle}
\setlength{\beforetitle}{2pt}
\newlength{\numberlength}
\setlength{\numberlength}{\widthof{\tiny\ttfamily 9999}}
\setlength{\numberlength}{0.25\numberlength}
\makeatletter
\def\three@digits#1{\ifnum#1<10 00\else\ifnum#1<100 0\fi\fi\number#1}
\makeatother
\newtcblisting{cpplisting}[1][]{%
  % Frame
  enhanced,
  arc = \zerolength,
  outer arc = \zerolength,
  % Title
  fonttitle = \ttfamily,
  toptitle = \zerolength,
  bottomtitle = \zerolength,
  titlerule = \zerolength,
  toptitle = \beforetitle,
  bottomtitle = \beforetitle,
  % Vertical alignment
  top = -0.5\tinyheight,
  bottom = 0.25\tinyheight,
  % Horizontal alignment
  left = \zerolength,
  right = 1.5\numberlength,
  colback = lstback,
  colframe = nicedarkblue,
  % Contents
  listing only,
  title = {\centering #1},
  listing options = {%
    % Language
    language = C++,
    tabsize=2, 
    basicstyle=\tiny\ttfamily,
    keywordstyle=\color{blue},
    commentstyle=\color{nicedarkgreen},
    morekeywords={constexpr},
    showstringspaces = false,
    % Alignment
    multicols = 2,
    numbers = left,
    numbersep = 2\numberlength, 
    xleftmargin = 5\numberlength,
    framesep = \zerolength,
    aboveskip = \zerolength,
    belowskip = \zerolength,
  },
  overlay = {%
    \fill[lstgrey] (interior.north west) rectangle ([xshift = 5\numberlength] interior.south west);
    \draw[ultra thick, nicedarkblue] ([xshift = \zerolength] interior.north) -- ([xshift = \zerolength] interior.south);
    \fill[lstgrey] (interior.north) rectangle ([xshift = 5\numberlength] interior.south); 
  },
  %/utils/exec = {%
  %  \def\thelstnumber{%
  %    \texttt{\csname three@digits\endcsname{\the\value{lstnumber}}}}}
}

% TEST
\begin{document}
\lipsum[1]
\begin{cpplisting}[An example of a C++ file]
// Include
#include <iostream>

// Example
int main()
{
    std::cout<<"Hello World"<<std::endl;
    std::cout<<"This is just an example"<<std::endl;
    std::cout<<"With two columns"<<std::endl;
    return 0;
}
\end{cpplisting}
\end{document}

listing_result

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