[Tex/LaTex] Fancy example environment

environments

How do create a colourful example environment like the one here?

enter image description here

Best Answer

Below I present two options, both of them admitting page breaks.

A simple example using tcolorbox (admits page breaks); adjust the settings according to your needs:

enter image description here

The code:

\documentclass{article}
\usepackage{lipsum}
\usepackage[many]{tcolorbox}

\definecolor{greentitle}{RGB}{61,170,61}
\definecolor{greentitleback}{RGB}{216,233,213}

\newtcolorbox[
  auto counter,
  number within=section
]{myexample}[2][]{%
  breakable,
  enhanced,
  colback=white,
  colbacktitle=white,
  arc=0pt,
  leftrule=1pt,
  rightrule=0pt,
  toprule=0pt,
  bottomrule=0pt,
  titlerule=0pt,
  colframe=greentitleback,
  fonttitle=\normalcolor,
  overlay={
    \node[
      outer sep=0pt,
      anchor=east,
      text width=2.5cm,
      minimum height=4ex,
      fill=greentitleback,
      font=\color{greentitle}\sffamily\scshape
    ] at (title.west) {example~\thetcbcounter};
  },
  title=#2,
  #1
}
\newcommand\Solution{\par\textbf{\textsf{Solution}}\par\medskip}

\begin{document}

\section{A test section}
\begin{myexample}{Factorise $x^2-2x+1$}
\Solution
 \lipsum[4]
\end{myexample}

\end{document}

A simple example using mdframed (admits page breaks); adjust the settings according to your needs:

enter image description here

The code:

\documentclass{article}
\usepackage{chngcntr}
\usepackage[tikz]{mdframed}
\usepackage{lipsum}

\definecolor{greentitle}{RGB}{61,170,61}
\definecolor{greentitleback}{RGB}{216,233,213}

\newcounter{mdexample}
\counterwithin{mdexample}{section}

\newenvironment{myexample}[1]
  {\stepcounter{mdexample}\begin{mdframed}[
    frametitle=#1,
    frametitlefont=\normalfont,
    topline=false,
    bottomline=false,
    rightline=false,
    linecolor=greentitleback,
    linewidth=2pt,
    singleextra={
      \node[
        overlay,
        outer sep=0pt,
        anchor=north east,
        text width=2.5cm,
        minimum height=4ex,
        fill=greentitleback,
        font=\color{greentitle}\sffamily\scshape
      ] at (O|-P) {example~\themdexample};
      },
    firstextra={
      \node[
        overlay,
        outer sep=0pt,
        anchor=north east,
        text width=2.5cm,
        minimum height=4ex,
        fill=greentitleback,
        font=\color{greentitle}\sffamily\scshape
      ] at (O|-P) {example~\themdexample};
      }
    ]
  }
  {\end{mdframed}}
\newcommand\Solution{\par\textbf{\textsf{Solution}}\par\medskip}

\begin{document}

\section{A test section}
\begin{myexample}{Factorise $x^2-2x+1$}
\Solution
 \lipsum[4]
\end{myexample}

\end{document}

Related Solutions

[Tex/LaTex] LaTeX example environment

Here a simple solution with rule:

\documentclass{article}
\usepackage{xcolor}
\usepackage{ntheorem,lipsum}
\theoremseparator{:}
\newtheorem*{example}{Example}
\newtheorem*{solution}{Solution}
\newlength\outerlinewidth
\newlength\interline
\newlength\hangleft
\newenvironment{block}{%
 \trivlist\item\relax\par%
 \noindent\rlap{\hspace*{-\hangleft}\color{gray}%
   \rule{\dimexpr \hangleft+\linewidth\relax}{\outerlinewidth}%
   }%
 }{\par%
 \noindent\rlap{\hspace*{-\hangleft}\color{gray}%
   \rule{\dimexpr \hangleft+\linewidth\relax}{\outerlinewidth}
   }%
   \endtrivlist}
\newcommand*\blockline{\par\noindent%
       \begingroup\color{gray}%
       \rule{\linewidth\relax}{\interline}\endgroup\par%
}


%Set parameter:
\setlength{\outerlinewidth}{6pt} %height of the outer line
\setlength{\interline}{2pt} %height of the inter line
\setlength{\hangleft}{1cm} % left indention
\begin{document}
\begin{block}
\begin{example}[Rear clock ahead]
\lipsum[1]
\end{example}
\begin{solution}
\lipsum[2]
\end{solution}
\blockline
\begin{example}[Rear clock ahead]
\lipsum[1]
\end{example}
\begin{solution}
\lipsum[2]
\end{solution}
\end{block}
\end{document}

enter image description here

EDIT

Here a solution with mdframed

\documentclass{article}
\usepackage{microtype}
\usepackage{xcolor}
\usepackage{ntheorem,lipsum}
\usepackage[framemethod=default]{mdframed}
\usepackage{showframe}

\mdfdefinestyle{block}{%
   rightmargin=0pt,
   innerrightmargin=0pt,
   skipabove=\topskip,
   skipbelow=\topskip,
   leftline=false,
   rightline=false,
   leftmargin=-1cm,
   innerleftmargin=1cm,
   linecolor=gray,
   linewidth=6pt
}

\newmdenv[style=block,ntheorem]{block}


\theoremseparator{:}
\newtheorem*{example}{Example}
\newtheorem*{solution}{Solution}
\newlength\outerlinewidth
\newlength\interline
\newcommand*\blockline{\par\noindent%
       \begingroup\color{gray}%
       \rule{\linewidth\relax}{\interline}\endgroup\par%
}
%Set parameter:
\setlength{\interline}{2pt} %height of the inter line

\begin{document}
\begin{block}
\begin{example}[Rear clock ahead]
\lipsum[1]
\end{example}
\begin{solution}
\lipsum[2]
\end{solution}
\blockline
\begin{example}[Rear clock ahead]
\lipsum[1]
\end{example}
\begin{solution}
\lipsum[2]
\end{solution}
\end{block}
\end{document}

EDIT 2

Here a solution with mdframed in combination with etoolbox. Of course you can use the solution without using mdframed.

\documentclass{article}
\usepackage{microtype}
\usepackage{xcolor}
\usepackage{ntheorem,lipsum}
\usepackage[framemethod=default]{mdframed}
\usepackage{showframe}

\mdfdefinestyle{block}{%
   rightmargin=0pt,
   innerrightmargin=0pt,
   skipabove=\topskip,
   skipbelow=\topskip,
   leftline=false,
   rightline=false,
   leftmargin=-1cm,
   innerleftmargin=1cm,
   linecolor=gray,
   linewidth=6pt
}

\newmdenv[style=block,ntheorem]{block}


\theoremseparator{:}
\theorembodyfont{}
\newtheorem*{example}{Example}
\newtheorem*{solution}{Solution}

\newtoggle{env:example}
\newtoggle{env:solution}
\newtoggle{env:block}
\settoggle{env:solution}{false}
\settoggle{env:example}{false}
\settoggle{env:block}{false}

\BeforeBeginEnvironment{block}%
    {\settoggle{env:block}{true}
     \settoggle{env:solution}{false}
     \settoggle{env:example}{false}}

\AfterEndEnvironment{block}%
    {\settoggle{env:solution}{false}
     \settoggle{env:block}{false}
     \settoggle{env:example}{false}}

\BeforeBeginEnvironment{example}%
    {\ifboolexpr{ test {\iftoggle{env:block}}
                  and 
                  test {\iftoggle{env:example}}}%
                 {\settoggle{env:example}{true}}{}
     \iftoggle{env:example}{\blockline}{}}

\AfterEndEnvironment{example}%
    {\settoggle{env:example}{true}}

\newlength\outerlinewidth
\newlength\interline
\newcommand*\blockline{\par\noindent%
       \begingroup\color{gray}%
       \rule{\linewidth\relax}{\interline}\endgroup\par%
}
%Set parameter:
\setlength{\interline}{2pt} %height of the inter line

\begin{document}
\begin{block}
\begin{example}[Rear clock ahead]
\lipsum[1]
\end{example}
\begin{solution}
\lipsum[2]
\end{solution}
%\blockline
\begin{example}[Rear clock ahead]
\lipsum[1]
\end{example}
\begin{solution}
\lipsum[2]
\end{solution}
\end{block}
\end{document}

[Tex/LaTex] define a new Example environment

This is just a partial answer (for a complete answer, go to the last exampe). I used the thmtools package as a front-end for amsthm to define a theorem-like structure.

The use of

  \interlinepenalty 10000

in postheadhook prevents pagebreaks as requested.

\documentclass{book}
\usepackage{xcolor}
\usepackage{amsthm}
\usepackage{amssymb}
\usepackage{thmtools}
\usepackage{lipsum}

\colorlet{myred}{red!80!black}

\declaretheoremstyle[
spaceabove=\topsep, spacebelow=\topsep,
headfont=\normalfont\color{myred},
notefont=\mdseries\color{myred}, notebraces={(}{)},
bodyfont=\normalfont,
postheadspace=\newline,
headpunct=,
numberwithin=chapter,
postheadhook=\leavevmode%
  \interlinepenalty 10000%
  \vskip-1.3\baselineskip%
  \noindent{\color{myred}\rule{\textwidth}{1pt}}%
  \interlinepenalty 10000%
  \vskip0.3\baselineskip\noindent,
qed=\textcolor{myred}{$\blacksquare$}
]{mystyle}
\declaretheorem[style=mystyle]{example}

\renewcommand\theexample{\thechapter-\arabic{example}}

\begin{document}

\chapter{Test Chapter}
%\lipsum[1-3]
\begin{example}
\lipsum*[2]
\end{example}

\end{document}

enter image description here

The only thing that remains unsolved is the positioning of the end-mark when the last line in the environment belongs to a displayed math expression. Quite frankly I wouldn't know how to conditionally change the end-mark placement.

Here's another possibility using this time the mdframed package; the end-mark is provided using the \xqed macro defined in the document linked in the page Theorems in AMS-LaTeX of the AMS-FAQ.:

\documentclass{book}
\usepackage[framemethod=tikz]{mdframed}
\usepackage{amssymb}
\usepackage{lipsum}
\usepackage{etoolbox}

\newcommand{\xqed}[1]{%
  \leavevmode\unskip\penalty9999 \hbox{}\nobreak\hfill
  \quad\hbox{\ensuremath{#1}}}

\AtBeginEnvironment{example}{\stepcounter{example}}
\AtEndEnvironment{example}{\xqed{\textcolor{myred}{\blacksquare}}}

\colorlet{myred}{red!80!black}

\newmdenv[
  hidealllines=true,
  frametitle={Example~\theexample},
  frametitlerule=true,
  frametitlerulecolor=myred,
  frametitlerulewidth=2pt,
  frametitlefont=\bfseries\color{myred},
  innerleftmargin=0pt,
  innerrightmargin=0pt
]{example}

\newcounter{example}[chapter]
\renewcommand\theexample{\thechapter-\arabic{example}}

\begin{document}

\chapter{Test Chapter}
\begin{example}
\lipsum*[2]
\end{example}

\end{document}

enter image description here

Here's now a possible complete solution; instead of conditionally redefining the behaviour of the end-marks (which could be really difficult), the user can manually select the lexample environment which behaves like example, but placing the end-mark to the left:

\documentclass{book}
\usepackage[framemethod=tikz]{mdframed}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{etoolbox}

\newlength\mylen

\newcommand{\xxqed}[1]{%
  \settowidth\mylen{$#1$}%
  \vskip-2\baselineskip\hspace*{-\mylen}\llap{\hbox{\ensuremath{#1}}}%
}

\newcommand{\xqed}[1]{%
  \leavevmode\unskip\penalty9999 \hbox{}\nobreak\hfill
  \quad\hbox{\ensuremath{#1}}}

\AtBeginEnvironment{example}{\stepcounter{example}}
\AtEndEnvironment{example}{\xqed{\textcolor{myred}{\blacksquare}}}

\AtBeginEnvironment{lexample}{\stepcounter{example}}
\AtEndEnvironment{lexample}{\xxqed{\textcolor{myred}{\blacksquare}}}

\colorlet{myred}{red!80!black}

\newmdenv[
  hidealllines=true,
  frametitle={Example~\theexample},
  frametitlerule=true,
  frametitlerulecolor=myred,
  frametitlerulewidth=2pt,
  frametitlefont=\bfseries\color{myred},
  innerleftmargin=0pt,
  innerrightmargin=0pt,
  skipabove=.6\topskip,
  skipbelow=.6\topskip
]{lexample}

\newmdenv[
  hidealllines=true,
  frametitle={Example~\theexample},
  frametitlerule=true,
  frametitlerulecolor=myred,
  frametitlerulewidth=2pt,
  frametitlefont=\bfseries\color{myred},
  innerleftmargin=0pt,
  innerrightmargin=0pt,
  skipabove=.6\topskip,
  skipbelow=.6\topskip
]{example}

\newcounter{example}[chapter]
\renewcommand\theexample{\thechapter-\arabic{example}}

\newcommand\Text{% just to generate text for the example
Quisque ullamcorper placerat ipsum. Cras nibh. Morbi vel justo vitae lacus
tincidunt ultrices. Lorem ipsum dolor sit amet, consectetuer adipiscing elit. In
hac habitasse platea dictumst. Integer tempus convallis augue. Etiam facilisis.
Nunc elementum fermentum wisi. Aenean placerat. Ut imperdiet, enim sed
gravida sollicitudin, felis odio placerat quam, ac pulvinar elit purus eget enim.
Nunc vitae tortor. Proin tempus nibh sit amet nisl.
}

\begin{document}

\chapter{Test Chapter}
\begin{lexample}
\Text
\begin{align}
a &= b \\
&= c 
\end{align}
\end{lexample}
\Text
\begin{example}
\Text
\end{example}

\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] LaTeX example environment

[Tex/LaTex] define a new Example environment

Related Question