有时，我确实有一些很长的章节标题，需要多行。我想使第二行和后续每一行标题\section都缩进（所谓的“悬挂缩进”）。我知道我可以使用包为段落生成悬挂缩进hanging：
\documentclass[final]{book}
\usepackage{lipsum}
\usepackage{hanging}
\begin{document}
\hangpara{3em}{1} \lipsum[11]
\end{document}
但是，我不知道如何对\section标题执行相同的操作，因为hanging包仅适用于段落而不适用于标题。到目前为止，我的章节标题代码如下：
\documentclass[final]{book}
\usepackage{lipsum}
\begin{document}
\section*{\large{Very long section heading that takes two or more lines when it is typeset on page}}
\end{document}
答案1
这是一个使用titlesec受@egreg 的评论启发的包的解决方案。
标题文本额外缩进 1em。对于第一行，此额外缩进由 取消\hspace{-1em}。节号如下：
<-- -1em
1.1 The first line of title
the second line...
-----> 2em
不含章节编号：
<-- -1em
The first line of title
the second line...
--> 1em
代码：
\documentclass[final]{book}
\usepackage{lipsum}
\usepackage{titlesec}
\titleformat{name=\section}
{\normalfont\Large\bfseries}{\thesection}{2em}{\hspace{-1em}}{}
\titleformat{name=\section,numberless}
{\normalfont\Large\bfseries}{}{1em}{\hspace{-1em}}{}
\titleformat{name=\subsection}
{\normalfont\large\bfseries}{\thesubsection}{2em}{\hspace{-1em}}{}
\titleformat{name=\subsection,numberless}
{\normalfont\large\bfseries}{}{1em}{\hspace{-1em}}{}
\titleformat{name=\subsubsection}
{\normalfont\bfseries}{\thesubsubsection}{2em}{\hspace{-1em}}{}
\titleformat{name=\subsubsection,numberless}
{\normalfont\bfseries}{}{1em}{\hspace{-1em}}{}
\begin{document}
\section*{Very long section heading that takes two or more lines when it is typeset on page}
\subsection*{Very long section heading that takes two or more lines when it is typeset on page}
\subsubsection*{Very long section heading that takes two or more lines when it is typeset on page}
\lipsum
\end{document}
答案2
章节标题由内部命令控制，例如\@startsection。因此，您必须修改这些命令。我重新定义\@startsection，以便它接收一个附加参数（第 4 个参数），该参数定义悬挂缩进量。
以下是代码：
\documentclass[final]{book}
\usepackage{lipsum}
\makeatletter
% \@startsection{name}{level}{indent}{hangindent}{beforeskip}
% {afterskip}{style}*[altheading]{heading}
% New argument: hangindent
\def\@startsection#1#2#3#4#5#6#7{%
\if@noskipsec \leavevmode \fi
\par
\@tempskipa #5\relax
\@afterindenttrue
\ifdim \@tempskipa <\z@
\@tempskipa -\@tempskipa \@afterindentfalse
\fi
\if@nobreak
\everypar{}%
\else
\addpenalty\@secpenalty\addvspace\@tempskipa
\fi
\@ifstar
{\@ssect{#3}{#4}{#5}{#6}{#7}}%
{\@dblarg{\@sect{#1}{#2}{#3}{#4}{#5}{#6}{#7}}}}
\def\@sect#1#2#3#4#5#6#7[#8]#9{%
\ifnum #2>\c@secnumdepth
\let\@svsec\@empty
\else
\refstepcounter{#1}%
\protected@edef\@svsec{\@seccntformat{#1}\relax}%
\fi
\@tempskipa #6\relax
\ifdim \@tempskipa>\z@
\begingroup
#7{%
\@hangfrom{\hskip #3\relax\@svsec}%
\advance\hangindent by #4\relax
\interlinepenalty \@M #9\@@par}%
\endgroup
\csname #1mark\endcsname{#8}%
\addcontentsline{toc}{#1}{%
\ifnum #2>\c@secnumdepth \else
\protect\numberline{\csname the#1\endcsname}%
\fi
#8}%
\else
\def\@svsechd{%
#7{\hskip #3\relax
\@svsec #9}%
\csname #1mark\endcsname{#8}%
\addcontentsline{toc}{#1}{%
\ifnum #2>\c@secnumdepth \else
\protect\numberline{\csname the#1\endcsname}%
\fi
#8}}%
\fi
\@xsect{#6}}
\def\@ssect#1#2#3#4#5#6{%
\@tempskipa #4\relax
\ifdim \@tempskipa>\z@
\begingroup
#5{%
\@hangfrom{\hskip #1}%
\advance\hangindent by #2\relax
\interlinepenalty \@M #6\@@par}%
\endgroup
\else
\def\@svsechd{#5{\hskip #1\relax #6}}%
\fi
\@xsect{#4}}
\renewcommand\section{\@startsection {section}{1}{\z@}{1em}%
{-3.5ex \@plus -1ex \@minus -.2ex}%
{2.3ex \@plus.2ex}%
{\normalfont\Large\bfseries}}
\renewcommand\subsection{\@startsection{subsection}{2}{\z@}{1em}%
{-3.25ex\@plus -1ex \@minus -.2ex}%
{1.5ex \@plus .2ex}%
{\normalfont\large\bfseries}}
\renewcommand\subsubsection{\@startsection{subsubsection}{3}{\z@}{1em}%
{-3.25ex\@plus -1ex \@minus -.2ex}%
{1.5ex \@plus .2ex}%
{\normalfont\normalsize\bfseries}}
\renewcommand\paragraph{\@startsection{paragraph}{4}{\z@}{1em}%
{3.25ex \@plus1ex \@minus.2ex}%
{-1em}%
{\normalfont\normalsize\bfseries}}
\renewcommand\subparagraph{\@startsection{subparagraph}{5}{\parindent}{1em}%
{3.25ex \@plus1ex \@minus .2ex}%
{-1em}%
{\normalfont\normalsize\bfseries}}
\makeatother
\begin{document}
\section*{Very long section heading that takes two or more lines when it is typeset on page}
\lipsum
\end{document}
如果要更改悬挂缩进量，请更改\@startsection相关部分命令定义中的第 4 个参数。例如，如果要将悬挂缩进量增加到\section5em，请替换
\renewcommand\section{\@startsection {section}{1}{\z@}{1em}%
{-3.5ex \@plus -1ex \@minus -.2ex}%
{2.3ex \@plus.2ex}%
{\normalfont\Large\bfseries}}
和
\renewcommand\section{\@startsection {section}{1}{\z@}{5em}% <-- 5em
{-3.5ex \@plus -1ex \@minus -.2ex}%
{2.3ex \@plus.2ex}%
{\normalfont\Large\bfseries}}