☰

如何从文档主体判断页面是否有顶部浮动？

tag-icon • tag-icon floats conditionals
如何从文档主体判断页面是否有顶部浮动？

对于特定的应用程序，我需要知道页面是否包含顶部浮动。因此，我采用了条件\iftopfloat{<true>}{<false>}以下链接中给出的条件定义：有没有办法确定页面上是否有浮动？。

最初，此条件用于文档页眉和页脚。但就我而言，我需要在文档的“正文”中使用它。然而，此条件在此上下文中不起作用，并且无论是否存在顶部浮动，始终都会执行 true 分支。

如何（从文档“主体”中）确定页面上是否有顶部浮动？

\documentclass{article}

\usepackage{mwe}

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 % From : https://tex.stackexchange.com/questions/56673/is-there-a-way-to-determine-if-there-is-a-float-on-a-page
\makeatletter
\let\latex@makecol\@makecol
\def\@makecol{%
    \let\topfloat\@toplist%
    \latex@makecol%
}
\def\iftopfloat#1#2{\ifx\topfloat\empty #2\else #1\fi}
\makeatother
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{document}
\iftopfloat{Yes}{No}

\clearpage
\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\clearpage\iftopfloat{Yes}{No}

\clearpage
\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\clearpage
\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\clearpage\iftopfloat{Yes}{No}

\clearpage\iftopfloat{Yes}{No}
\end{document}

答案1

您无法在文档正文内进行测试，但您可以检测上次运行时清除页面后的第一行是否设置在页面顶部，从而选择合适的分支。这总是需要至少两次运行才能收敛。

在此处输入图片描述

\documentclass{article}

\usepackage{graphicx}

 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\makeatletter
% pdftex version, others would be similar
\def\iftopfloat{%
    \leavevmode
    \pdfsavepos
    \write\@auxout{\string\gdef\string\TPF\roman{page}{\the\pdflastypos}}%
    \ifdim\ifcsname TPF\roman{page}\endcsname
        \csname TPF\roman{page}\endcsname sp\else\z@\fi
      >400pt
      \expandafter\@secondoftwo
    \else
      \expandafter\@firstoftwo
      \fi    
    }
\makeatother
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\begin{document}
\Huge\bfseries

\iftopfloat{Yes}{No}

\clearpage
\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\clearpage\iftopfloat{Yes}{No}

\clearpage
\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\clearpage
\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\clearpage\iftopfloat{Yes}{No}

\clearpage\iftopfloat{Yes}{No}
\end{document}

答案2

借鉴 David Carlisle 的两次连续编译并写入.aux文件的想法，我修改了命令，以便将有顶部浮动的页面\@combinefloats写入文件。.aux

\documentclass{article}

\usepackage{mwe,lipsum,refcount}

\makeatletter
\def \@combinefloats {%
    \ifx \@toplist\@empty%
    \else%
        \@cflt%
        \immediate\write\@auxout{\string\global\string\@namedef{pageWithTopFloat-\thepage}{1}}%
    \fi%
    \ifx \@botlist\@empty \else \@cflb \fi%
}

\newcounter{ifTopFloatCnt}

\def\iftopfloat#1#2{%
    \global\advance\c@ifTopFloatCnt\@ne%
    \label{\the\c@ifTopFloatCnt @ifTopFloat}%    
    \ifcsname pageWithTopFloat-\getpagerefnumber{\the\c@ifTopFloatCnt @ifTopFloat}\endcsname%
        {\Large\bfseries #1}%
    \else%
        {\Large\bfseries #2}%
    \fi%
}
\makeatother

\begin{document}
\iftopfloat{Yes}{No}

\noindent
p. 1: \ifcsname pageWithTopFloat-1\endcsname yes \else no \fi\\
p. 2: \ifcsname pageWithTopFloat-2\endcsname yes \else no \fi\\
p. 3: \ifcsname pageWithTopFloat-3\endcsname yes \else no \fi\\
p. 4: \ifcsname pageWithTopFloat-4\endcsname yes \else no \fi\\
p. 5: \ifcsname pageWithTopFloat-5\endcsname yes \else no \fi\\
p. 6: \ifcsname pageWithTopFloat-6\endcsname yes \else no \fi\\
p. 7: \ifcsname pageWithTopFloat-7\endcsname yes \else no \fi

\lipsum[1-4]

\clearpage
\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\lipsum[1-4]

\iftopfloat{Yes}{No}

\lipsum[1-4]

\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\lipsum[1-4]

\begin{figure}[t]
\centering
\includegraphics{example-image}
\end{figure}
\iftopfloat{Yes}{No}

\lipsum[1-4]

\iftopfloat{Yes}{No}

\lipsum[1-4]

\iftopfloat{Yes}{No}
\end{document}

相关内容