[Tex/LaTex] Redefine \emph inside theorem using \newshadedtheorem from ntheorem

emphasisframedntheoremtheorems

Using the ntheorem package, the definition of \newshadedtheorem overwrites the \theoremprework, which I wanted to use to redefine \emph inside a custom shaded theorem. The definition of \newshadedtheorem is:

\def\newshadedtheorem#1{%
\expandafter\global\expandafter\xdef\csname#1@shadecolor\endcsname{%
\the\shadecolor}%
\ifx\theoremframecommand\relax
\expandafter\global\expandafter\xdef\csname#1@framecommand\endcsname{%
\noexpand\psframebox[fillstyle=solid,
fillcolor=\csname#1@shadecolor\endcsname,
linecolor=\csname#1@shadecolor\endcsname]}%
\else
\expandafter\global\expandafter\let\csname#1@framecommand\endcsname%
\theoremframecommand%
\fi
\theoremprework{%
\def\FrameCommand{\csname#1@framecommand\endcsname}%
\vskip\theoremframepreskipamount\framed}%
\theorempostwork{\endframed\vskip\theoremframepostskipamount}%
\newtheorem@i{#1}%
}

Minimal example of what I want to do:

\documentclass[a4paper]{scrartcl}
\usepackage{amsmath}
\usepackage{xcolor}
\usepackage{framed}
\usepackage[amsmath,hyperref,noconfig,framed]{ntheorem}
\usepackage{hyperref}

% bakup old emph
\let\oldEmph=\emph

\theoremstyle{plain}
\theorembodyfont{\upshape}
\theoremprework{\renewcommand{\emph}[1]{\oldEmph{{\color{blue}##1}}}}
\theorempostwork{\renewcommand{\emph}[1]{\oldEmph{##1}}}
\def\theoremframecommand{\colorbox{blue!10}}
\newshadedtheorem{definition}{\color{blue}Definition}[section]

\begin{document}
\begin{definition}
  Test of \emph{emph} inside Definiton.
\end{definition}
\end{document}

Does anybody know how to achieve this?

Best Answer

Define an auxiliary environment:

\newshadedtheorem{definition*}{\color{blue}Definition}[section]
\newenvironment{definition}
  {\renewcommand{\emph}[1]{\oldEmph{{\color{blue}##1}}}%
   \begin{definition*}}
  {\end{definition*}}

Related Solutions

[Tex/LaTex] passing a theorem name using ntheorem

Based of the comments I created an approach.

The important part of the code is the redefinition of \mdfcreateextratikz. The package provides this command to put extra material somewhere. The coordinates O and P are used internal. In the file md-frame-1.mdf you can find their meaning.

\documentclass{article}
\usepackage{xcolor}
\usepackage[framemethod=tikz]{mdframed}
\usetikzlibrary{shadows,shadings}
\usepackage{lipsum}

\newcounter{theorem}
\renewcommand\thetheorem{Theorem~\arabic{theorem}}
\makeatletter
\mdf@dolist{\mdf@do@stringoption}{%
    {theoremtitle=={}}%
}
\renewrobustcmd\mdfcreateextratikz{%
      \node[anchor=west,rounded corners,draw,thick,shading=axis,left color=blue!20,xshift=1cm,minimum height=.7cm,minimum width=2cm] at (P-|O) 
              {~\mdf@frametitlefont{\thetheorem}%
                  \ifdefempty{\mdf@theoremtitle}%
                  {~}%
                  {:~\mdf@theoremtitle~}%
              };
}
\makeatother
\mdfdefinestyle{theoremstyle}{%
outerlinewidth=1pt,
innerlinewidth=0pt,
roundcorner=2pt,
linecolor=black,
shadow=true,
tikzsetting={shading=axis,top color=gray!20},
innertopmargin=1.2\baselineskip,
skipabove={\dimexpr0.5\baselineskip+\topskip\relax},
needspace=3\baselineskip,
frametitlefont=\sffamily\bfseries,
settings={\global\stepcounter{theorem}},
}
\newenvironment{theorem}[1][]
{\begin{mdframed}[style=theoremstyle,theoremtitle={#1}]\relax}{\end{mdframed}}

\begin{document}
\begin{theorem}
\lipsum[1]
\end{theorem}
\begin{theorem}[Title of the Theorem]
\lipsum[1]
\end{theorem}
\end{document}

This results in:

enter image description here

[Tex/LaTex] ntheorem and attributions without redefinining a theorem style

The answer to your question involves performing a \renewtheoremstyle on the marginbreak environment. In the MWE below, note that (##3) has been expanded to {\normalfont(##3)}. With this change, only the optional title of the theorem header and the surrounding parentheses are set in the normal (non-bold) font.

Relative to your example code, I've also changed the amount of \theoremindent to 0cm to make the default positioning of the theorem header visible; use a positive (negative) length to right-shift (left-shift) the position of the theorem header.

\documentclass{book}
\usepackage{ntheorem,lipsum}
\makeatletter
\renewtheoremstyle{marginbreak}%
  {\item[\rlap{\vbox{\hbox{\theorem@headerfont
    \llap{##2}\hskip\labelsep\relax ##1\theorem@separator}\hbox{\strut}}}]}
  {\item[\rlap{\vbox{\hbox{\theorem@headerfont
    \llap{##2}\hskip\labelsep\relax ##1        {\normalfont(##3)}\theorem@separator}\hbox{\strut}}}]}
\makeatother

\theoremstyle{marginbreak}
\setlength\theoremindent{0cm} % default
\newtheorem{teo}{Theorem}[chapter]

\begin{document}
\chapter{Start}
\begin{teo}[Pitagora]
$a^2+b^2=c^2$
\end{teo}
\lipsum[2] % filler text
\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] passing a theorem name using ntheorem

[Tex/LaTex] ntheorem and attributions without redefinining a theorem style

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