这段代码有什么问题（如何修复过满的 \hbox）？

Question

我收到了很多“溢出 \hbox“在编译大型文档时出现警告，显然这是由以下 ToC 定制引起的。编译后的 PDF 输出看起来不错，但我想优化代码并删除所有警告和令人讨厌的过满 hbox 消息。

\RequirePackage[l2tabu,orthodox]{nag}
\documentclass[11pt,twoside,draft]{book}
\usepackage[T1]{fontenc}
\usepackage[nomath]{lmodern}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{microtype,textcomp}
\usepackage[total={6.25in,10in},left=1.25in,top=0.5in,includehead,includefoot]{geometry}

\usepackage[titles]{tocloft}
    \setcounter{tocdepth}{2}
    \renewcommand{\cftsubsubsecfont}{\normalfont\sffamily\footnotesize}%
    % Chapters modification in ToC :
    \renewcommand{\cftchappresnum}{\chaptername\ }
    \renewcommand{\cftchapaftersnumb}{\newline}
    \setlength{\cftchapindent}{0em} % Spacement to left of chapter number.
    \setlength{\cftchapnumwidth}{0em} %

\begin{document}

\frontmatter

\tableofcontents

\mainmatter

\pagestyle{plain}

\chapter{A first chapter}

\section{A section title}

Blabla

\chapter{A second chapter}

\section{A section title}

Blabla

\chapter{A third chapter}

\section{A section title}

Blabla

\chapter{A fourth chapter}

\section{A section title}

Blabla

\chapter{A fifth chapter}

\section{A section title}

Blabla

\end{document}

我draft向文档类添加了该选项，以查看导致这些消息的原因，但我不知道下一步该怎么做。那么上面的 MWE 代码有什么问题？

预览上面的代码所起的作用（黑色矩形来自draft文档类中的选项）：

Answer 1

tocloft用于\cftchapnumwidth包含整个章节号的框。具体使用以下定义：

\renewcommand{\numberline}[1]{%
  \hb@xt@\@tempdima % in case of chapters this is similar to \makebox[\cftchapnumwidth]
  {\@cftbsnum #1\@cftasnum\hfil \@cftasnumb}

您已将其设置\cftchapnumwidth为 0。因此，章节号（无论是否更改\cftchappresnum和\cftchapaftersnumb）始终较宽，这会导致 \hbox 溢出。如果您不想忽略警告，可以尝试在 a\rlap或 a中设置章节号\makebox[0pt][l]。为此，您可以使用 hack，但您也应该知道，这种 hack 将来可能会失效：

\RequirePackage[l2tabu,orthodox]{nag}
\documentclass[11pt,twoside,draft]{book}
\usepackage[T1]{fontenc}
\usepackage[nomath]{lmodern}
\usepackage[utf8]{inputenc}% Not needed any longer
\usepackage[french]{babel}
\usepackage{microtype,textcomp}
\usepackage[total={6.25in,10in},left=1.25in,top=0.5in,includehead,includefoot]{geometry}

\usepackage[titles]{tocloft}
    \setcounter{tocdepth}{2}
    \renewcommand{\cftsubsubsecfont}{\normalfont\sffamily\footnotesize}%
    % Chapters modification in ToC :
    \renewcommand{\cftchappresnum}{\specialchapterintoc}% Warning: Using a command with argument is a hack only and would fail for long numbers
    \renewcommand{\cftchapaftersnumb}{\newline}
    \setlength{\cftchapindent}{0em} % Spacement to left of chapter number.
    \setlength{\cftchapnumwidth}{0em} %

\newcommand*{\specialchapterintoc}[1]{\rlap{\chaptername\ #1}}
    
\begin{document}

\frontmatter

\tableofcontents

\mainmatter

\pagestyle{plain}

\chapter{A first chapter}

\section{A section title}

Blabla

\chapter{A second chapter}

\section{A section title}

Blabla

\chapter{A third chapter}

\section{A section title}

Blabla

\chapter{A fourth chapter}

\section{A section title}

Blabla

\chapter{A fifth chapter}

\section{A section title}

Blabla

\end{document}

另一个建议是修补\numberline不再使用\hbox零宽度，如果\cftXnumwidth为零。假设宽度为线宽的一半就足够了：

\RequirePackage[l2tabu,orthodox]{nag}
\documentclass[11pt,twoside,draft]{book}
\usepackage[T1]{fontenc}
\usepackage[nomath]{lmodern}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{microtype,textcomp}
\usepackage[total={6.25in,10in},left=1.25in,top=0.5in,includehead,includefoot]{geometry}

\usepackage[titles]{tocloft}
\setcounter{tocdepth}{2}
\renewcommand{\cftsubsubsecfont}{\normalfont\sffamily\footnotesize}%
% Chapters modification in ToC :
\renewcommand{\cftchappresnum}{\chaptername\ }
\renewcommand{\cftchapaftersnumb}{\newline}
\setlength{\cftchapindent}{0em} % Spacement to left of chapter number.
\setlength{\cftchapnumwidth}{0em} %
  
\makeatletter
\AddToHook{cmd/numberline/before}{%
  \ifdim \@tempdima=\z@ \@tempdima.5\linewidth\fi
}
\makeatother
    
\begin{document}

\frontmatter
\tableofcontents

\mainmatter

\pagestyle{plain}

\chapter{A first chapter}

\section{A section title}

Blabla

\chapter{A second chapter}

\section{A section title}

Blabla

\chapter{A third chapter}

\section{A section title}

Blabla

\chapter{A fourth chapter}

\section{A section title}

Blabla

\chapter{A fifth chapter}

\section{A section title}

Blabla

\end{document}

这仍然使用的内部结构tocloft，但恕我直言，比第一个建议干净得多。

另一个建议是使用支持数字后换行的包，例如，tocbasic：

\RequirePackage[l2tabu,orthodox]{nag}
\documentclass[11pt,twoside,draft]{book}
\usepackage[T1]{fontenc}
\usepackage[nomath]{lmodern}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{microtype,textcomp}
\usepackage[total={6.25in,10in},left=1.25in,top=0.5in,includehead,includefoot]{geometry}

\usepackage{tocbasic}
\DeclareTOCStyleEntry[%
  breakafternumber=true,% do a linebreak after the number
  entrynumberformat=\chapternumberwithprefix,% see definition below
  numwidth=.5\linewidth,% I think, this would be enough, but …
  dynnumwidth,% if not use the needed width.
]{tocline}{chapter}
\newcommand*{\chapternumberwithprefix}[1]{\chaptername\ #1}
% Following command replaces your redefinition of \cftsubsubsecfont:
\DeclareTOCStyleEntry[
  entrynumberformat=\normalfont\footnotesize\textsf
]{tocline}{subsubsection}

\begin{document}

\frontmatter
\tableofcontents

\mainmatter

\pagestyle{plain}

\chapter{A first chapter}

\section{A section title}

Blabla

\chapter{A second chapter}

\section{A section title}

Blabla

\chapter{A third chapter}

\section{A section title}

Blabla

\chapter{A fourth chapter}

\section{A section title}

Blabla

\chapter{A fifth chapter}

\section{A section title}

Blabla

\end{document}

Answer 2

你可以使用这个：

    {\setbox0\hbox{\cftchapfont\chaptername\ \kern\cftchapnumwidth}%
     \global\cftchapnumwidth\wd0}
    \renewcommand{\cftchapaftersnumb}{\newline\mbox{}\kern-\cftchapnumwidth}

包含上述更改的完整代码：

\RequirePackage[l2tabu,orthodox]{nag}
\documentclass[11pt,twoside,draft]{book}
\usepackage[T1]{fontenc}
\usepackage[nomath]{lmodern}
\usepackage[utf8]{inputenc}
\usepackage[french]{babel}
\usepackage{microtype,textcomp}
\usepackage[total={6.25in,10in},left=1.25in,top=0.5in,includehead,includefoot]{geometry}

\usepackage[titles]{tocloft}
    \setcounter{tocdepth}{2}
    \renewcommand{\cftsubsubsecfont}{\normalfont\sffamily\footnotesize}%
    % Chapters modification in ToC :
    \renewcommand{\cftchappresnum}{\chaptername\ }
    {\setbox0\hbox{\cftchapfont\chaptername\ \kern\cftchapnumwidth}%
     \global\cftchapnumwidth\wd0}
    \renewcommand{\cftchapaftersnumb}{\newline\mbox{}\kern-\cftchapnumwidth}

% from original
%    \setlength{\cftchapindent}{0em} % Spacement to left of chapter number.
%    \setlength{\cftchapnumwidth}{0em} %

\begin{document}

\frontmatter

\tableofcontents

\mainmatter

\pagestyle{plain}

\chapter{A first chapter}

\section{A section title}

Blabla

\chapter{A second chapter}

\section{A section title}

Blabla

\chapter{A third chapter}

\section{A section title}

Blabla

\chapter{A fourth chapter}

\section{A section title}

Blabla

\chapter{A fifth chapter}

\section{A section title}

Blabla

\end{document}