在两列布局中显示框架/边距

Question

如何在twocolumn文档类别选项下显示列间边距的框架？

该showframe包仅绘制了页边距 + 页眉和页脚。但我想看到两列之间的边距线。

Answer 1

一个选项是使用\@outputdblcol：

\documentclass[twocolumn]{article}
\usepackage{lipsum}
\usepackage{showframe}

\newlength\Fcolumnseprule
\setlength\Fcolumnseprule{0.4pt}

\makeatletter
\def\@outputdblcol{%
  \if@firstcolumn
    \global \@firstcolumnfalse
    \global \setbox\@leftcolumn \box\@outputbox
  \else
    \global \@firstcolumntrue
    \setbox\@outputbox \vbox {%
                         \hb@xt@\textwidth {%
                           \hb@xt@\columnwidth {%
                             \box\@leftcolumn \hss}%
                           \vrule \@width\Fcolumnseprule\hfil
                                {\normalcolor\vrule \@width\columnseprule}%original:
                                                %\normalcolor\vrule \@width\columnseprule
                           \hfil\vrule \@width\Fcolumnseprule
                           \hb@xt@\columnwidth {%
                             \box\@outputbox \hss}%
                                             }%
                              }%
    \@combinedblfloats
    \@outputpage
    \begingroup
      \@dblfloatplacement
      \@startdblcolumn
      \@whilesw\if@fcolmade \fi
        {\@outputpage
         \@startdblcolumn}%
    \endgroup
  \fi
}
\makeatother


\begin{document}

\lipsum[1-30]

\end{document}

补丁使代码更短：

\documentclass[twocolumn]{article}
\usepackage{lipsum}
\usepackage{showframe}
\usepackage{etoolbox}

\newlength\Fcolumnseprule
\setlength\Fcolumnseprule{0.4pt}

\makeatletter
\newcommand\ShowInterColumnFrame{
\patchcmd{\@outputdblcol}
  {{\normalcolor\vrule \@width\columnseprule}}
  {\vrule \@width\Fcolumnseprule\hfil
    {\normalcolor\vrule \@width\columnseprule}
    \hfil\vrule \@width\Fcolumnseprule
  }
  {}
  {}
}

\makeatother
\ShowInterColumnFrame

\begin{document}

\lipsum[1-30]

\end{document}