[Tex/LaTex] Code examples, like in the TikZ/PGF manual

Question

I like very much the 'side-by-side' code examples in the TikZ/PGF manual…

… and I would like to use the same thing in a manual I'm writing. I have found the source code for the codeexample environment that the TikZ/PGF manual uses for this purpose (specifically, it's located at /usr/local/texlive/2012/texmf-dist/doc/generic/pgf/macros/pgfmanual-en-macros.tex).

My (probably rather basic) question is: how can I use the same codeexample environment in my own documents? I ask because I tried compiling the example in the related question below, but the file couldn't be found.

• Automatic linking (aka code highlight) in Till Tantau's `codeexample`

Answer 1

Here, I use tcolorbox to resemble the visual appearance of the TikZ examples. The mandatory parameter of my example environment sidebyside is the width of the picture.

Update: The first two examples use an automated invisible tikzpicture environment to display only a code snippet. The third example uses and displays the tikzpicture environment deliberately.

\documentclass{article}
\usepackage[most]{tcolorbox}
\pgfdeclarelayer{background}
\pgfsetlayers{background,main}

\lstdefinestyle{example}{style=tcblatex,
  classoffset=0,
  texcsstyle=*\color{blue},%
  deletetexcs={begin,end},
  moretexcs={,%
    pgfdeclarehorizontalshading,pgfuseshading,node,
    useasboundingbox,draw}%
  classoffset=1,
  keywordstyle=\color{blue},%
  morekeywords={tikzpicture,shade,fill,draw,path,node,child,line,width,rectangle},
  classoffset=0}

\tcbset{%
  fillbackground/.style={before lower pre={%
  \tikzset{every picture/.style={execute at end picture={\begin{pgfonlayer}{background}
    \fill[yellow!25!white]
    ([xshift=-1mm,yshift=-1mm]current bounding box.south west) rectangle
    ([xshift=1mm,yshift=1mm]current bounding box.north east);
    \end{pgfonlayer}}}}}},
  explicitpicture/.style={before lower=\begin{center},after lower=\end{center},fillbackground}}

\newtcblisting{sidebyside}[2][]{%
  enhanced,frame hidden,
  top=0pt,bottom=0pt,left=0pt,right=0pt,arc=0pt,boxrule=0pt,
  colback=blue!25!white,
  listing style=example,
  sidebyside,text and listing,text outside listing,sidebyside gap=2mm,
  lefthand width=#2,tikz lower,fillbackground,
  #1}

\begin{document}

\begin{sidebyside}[before lower app={\path[] (-2,-0.5) rectangle (2,0.5);}]{4.2cm}
\pgfdeclarehorizontalshading{myshadingA}
  {1cm}{rgb(0cm)=(1,0,0); color(2cm)=(green); color(4cm)=(blue)}
\pgfuseshading{myshadingA}
\end{sidebyside}

\begin{sidebyside}{4.2cm}
\node {root}
  child {node {left}}
  child {node {right}
    child {node {child}}
    child {node {child}}
};
\end{sidebyside}

\begin{sidebyside}[explicitpicture]{4.2cm}
\begin{tikzpicture}[line width=20pt]
  \useasboundingbox (0,-1.5) rectangle (3.5,1.5);
  \draw[red] (0,0) -- (3,0);
  \draw[gray,->] (0,0) -- (3,0);
\end{tikzpicture}
\end{sidebyside}

\end{document}