[Tex/LaTex] How to prevent page break between two section headings

page-breakingsectioning

I have a custom document class, based on book.cls, for which the following code sometimes produces page breaks between two subsequent sections:

  \section{Introduction}
  % page break may occur here
  \subsection{Getting started}

I am completely puzzled, because my definitions for the sectioning commands are almost identical to those in book.cls:

\newcommand \headingfont {\fontfamily{phv}\fontseries{bc}\fontshape{n}\selectfont}
\newcommand\section{\@startsection {section}{1}{\headerindent}%
                                   {-3.5ex \@plus -1ex \@minus -.2ex}%
                                   {2ex \@plus.2ex}%
                                   {\color{MMIblue}\headingfont\Large}}
\newcommand\subsection{\@startsection{subsection}{2}{\headerindent}%
                                     {-3.25ex\@plus -1ex \@minus -.2ex}%
                                     {2ex \@plus .2ex}%
                                     {\color{MMIblue}\headingfont\large}}
\newcommand\subsubsection{\@startsection{subsubsection}{3}{\headerindent}%
                                     {-3.25ex\@plus -1ex \@minus -.2ex}%
                                     {2ex \@plus .2ex}%
                                     {\color{MMIblue}\headingfont\normalsize}}
% etc.

Any ideas what might cause LaTeX to allow a page break?

Best Answer

The problem is that \color{MMIblue} inserts a whatsit that disrupts the mechanism for disallowing page breaks after sectional titles.

Use

\newcommand\section{%
  \@startsection{section}{1}
    {\headerindent}%
    {-3.5ex \@plus -1ex \@minus -.2ex}%
    {2ex \@plus.2ex}%
    {\headingfont\Large\textcolor{MMIblue}}}

which works because the last instruction in the sixth argument to \@startsection reads the section title (with the number) as a braced group, which can then be interpreted by \textcolor as its second argument.

Related Solutions

[Tex/LaTex] How to prevent a page break between section title and colored rule

Replace {\color{blue}<rule definition>} with \textcolor{blue}{<rule definition>}.

\documentclass[12pt]{article}
\usepackage[explicit]{titlesec}
\usepackage[dvipsnames]{xcolor}

\titleformat{\section}%
{\large\sffamily\bfseries}%
{Section \arabic{section}}%
{0.5em}%
{#1}% \\ \hspace*{-1.5cm}
[\textcolor{blue}{\titlerule[2.5pt]}]

\begin{document}

\section{titre1}
blabla  
\vspace{16cm}\\    blabla  
\section{titre2}
blabla blabla 
\end{document}

EDIT: Note that this solution produces unwanted additional vertical space between title and underline. See Strange behaviour of titlesec, with colored titlerule and particularly egreg's answer for a solution to this follow-up problem.

[Tex/LaTex] How to prevent a page break between paragraphs

Really it would be a lot easier to answer if there was a supplied example document, fragments are much harder to comment on but

\newenvironment{fooquote}%
{ \bgroup
  \let\oldend=\end
  \def\end##1{\oldend{##1}\csname @afterindentfalse\endcsname
                          \csname @afterheading\endcsname}
  \begin{quote}%
  \itshape%
}{%
  \end{quote}
  \egroup
}
\newcommand{\quoteattrib}[1]{\normalfont\flushright#1}

the \bgroup \egroup are not needed as the fooquote environment is already a group, also { \bgroup introduces a space character.

The \end redefinition (which is rather dangerous really) appears to be too early it will affect the \end of any nested environment and in particular the quote environment. You just want to activate it after fooquote (I assume) so it should be right at the end of the end code of the definition.

flushright is intended to be an environment form, the declaration form being \raggedleft but if it's one line I'd probably just use \hspace{\fill}. \nopagebreak ought to be enough to prevent page breaks at that point as long as there is flexibility elsewhere in the page.

enter image description here

\documentclass{book}

\makeatletter
\newenvironment{fooquote}{%
  \begin{quote}%
  \itshape
}{%
  \end{quote}%
\par
\aftergroup\@afterindentfalse
\aftergroup\@afterheading
\ignorespacesafterend
}
\newcommand{\quoteattrib}[1]{\par\nopagebreak\normalfont\hspace*{\fill}#1\par}

\makeatother

\begin{document}

\chapter{CCC}

\begin{fooquote}
red yellow blue
\quoteattrib{me}
\end{fooquote}

One two three. One two three. One two three. One two three.
One two three. One two three. One two three. One two three.
One two three. One two three. One two three. One two three.

One two three. One two three. One two three. One two three.
One two three. One two three. One two three. One two three.
One two three. One two three. One two three. One two three.

\end{document}

Best Answer

Related Solutions

[Tex/LaTex] How to prevent a page break between section title and colored rule

[Tex/LaTex] How to prevent a page break between paragraphs

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