How to customize an existing LaTeX environment without interfering with other environments? - latex

Question

I'm using Sphinx for documenting a project. It produces LaTeX files from reStructuredText.
I would like to set a gray background color to the tips and notes, so I customized the notice environment after creating a graybox environment:
\definecolor{MyGray}{rgb}{0.80,0.80,0.80}
\makeatletter\newenvironment{graybox}{%
\begin{lrbox}{\#tempboxa}\begin{minipage}{\columnwidth}}{\end{minipage}\end{lrbox}%
\colorbox{MyGray}{\usebox{\#tempboxa}}
}\makeatother
\makeatletter
\renewenvironment{notice}[2]{
\begin{graybox}
\bf\it
\def\py#noticetype{#1}
\par\strong{#2}
\csname py#noticestart##1\endcsname
}
{
\csname py#noticeend#\py#noticetype\endcsname
\end{graybox}
}
\makeatother
Everything works fine except if I place a figure environment inside the notice environment. In that case, I get this error:
LaTeX Error: Not in outer par mode
Is there a way to set a gray background to that notice environment ?

Answer 1

This is a FAQ. It does not make sense to put a figure (or any other "float" which can move elsewhere in the output) inside a gray box; if you want your figure to contain a gray box, put the gray box environment inside the figure environment.

Answer 2

Thank you godbyk and Jouni for answering my question.
The problem is that I don't code directly in LaTeX. I write the documentation in restructured text and Sphinx output the LaTeX files.
But I found a solution: I redefine the figure environment to use the staticfigure from the flowfram package:
\usepackage{flowfram}
\definecolor{MyGray}{rgb}{0.80,0.80,0.80}
\makeatletter\newenvironment{graybox}{%
\begin{lrbox}{\#tempboxa}\begin{minipage}{\columnwidth}}{\end{minipage}\end{lrbox}%
\colorbox{MyGray}{\usebox{\#tempboxa}}
}\makeatother
\makeatletter
\renewenvironment{notice}[2]{
\begin{graybox}
\bf\it
\def\py#noticetype{#1}
\par\strong{#2}
\csname py#noticestart##1\endcsname
}
{
\csname py#noticeend#\py#noticetype\endcsname
\end{graybox}
}
\makeatother
\renewenvironment{figure}[6]{
\begin{staticfigure}
}{
\end{staticfigure}
}
PS: I had to put 6 to the number of arguments when redefining 'figure': if I don't do that it outputs some 'htbp' in the pdf files (I'm not a LaTeX expert. it's just the solution I found for this problem)

Answer 3

As Jouni correctly pointed out, figures and tables (i.e., floats) can be moved around, and your gray box can't contain them. To achieve the desired effect, you have two options:
Put your entire notice into a figure environment (so that the entire notice can be floated around on the page or to a new page if LaTeX so chooses).
Don't use a float (figure environment) -- just use \includegraphics to pop your image directly into the notice environment. You won't be able to use a caption with this non-figure, however, as captions only work inside a figure or table environment. If you want a caption associated with this image, you can use the caption package:
\documentclass{article}
\usepackage{caption}% let's us use captions outside of floats
\usepackage{lipsum}% provides filler text
\begin{document}
\lipsum[1]
\begin{center}
\includegraphics{mypic}
\captionof{figure}{This is my picture.}% makes a caption for non-floats
\label{fig:mypic}
\end{center}
\lipsum[2]
\end{document}
I haven't used Sphinx, so I'm afraid I can't help you too much with integrating this into their output.