同一页的三份相同副本

Question

我需要将一页打印三次。在纯 TeX 中，是否可以输出最后一页的两个精确副本而不增加页码？

Answer 1

当然，这可以通过“简单破解”普通 TeX 例程来实现\output。实际上，重新定义\plainoutput普通 TeX 例程使用的宏就足够了\output：

\newcount\nbcopies
\nbcopies=0
% Used to save the page box in case we need to ship it out several times
\newbox\pagebox

\def\additionalcopies#1{%
  \global\nbcopies=#1\relax
}

\catcode`\@=11
\def\plainoutput{%
  \setbox\pagebox=\vbox{\makeheadline\pagebody\makefootline}%
  \loop
    \shipout\copy\pagebox
  \ifnum\nbcopies>\z@
    \global\advance\nbcopies by \m@ne
  \repeat
  \setbox\pagebox=\copy\voidb@x % free the memory used by the page contents
  % The following two lines are exactly as in the plain TeX \output routine.
  \advancepageno
  \ifnum\outputpenalty>-\@MM \else\dosupereject\fi
}

% Convenient macro for repeating things, that supports nesting.
\long\def\myrepeat#1#2#3{%
  #1=#2\relax
  \loop
    \ifnum #1>\z@
    \advance#1by \m@ne
    \begingroup
      #3%
    \endgroup
  \repeat
}
\catcode`\@=12

\newcount\outercount
\newcount\innercount

\myrepeat{\outercount}{20}{%
  Foo bar\myrepeat{\innercount}{40}{ foo bar baz quux}.%
  \endgraf                      % \loop doesn't like \par
}

% One additional copy -> the current page will be output twice.
\additionalcopies{1}\vfil\eject

\myrepeat{\outercount}{10}{%
  \myrepeat{\innercount}{20}{Rest of the text. }\endgraf
  % Due to the implicit \unskip at the end of a paragraph, there won't be any
  % unwanted space after the last 'text.' in each of these paragraphs.
}
% Two additional copies -> the current page will be output three times.
\additionalcopies{2}

\bye

Answer 2

我提供了两个计数器：一个是全局计数器，一个是本地计数器。\repeatallpages=3所有页面都重复三次，但\repeatpages=4(任何值 > 1) 会覆盖当前页面的计数器。

%% first five lines just for a smaller picture
\pdfpageheight=3in
\pdfpagewidth=5in
\hsize=3in
\vsize=1in
\font\bbbigfont=cmr17 \bbbigfont
%%%

\catcode`@=11
\def\repeatplainoutput{%
  \ifnum\repeatallpages>0
    \ifnum\repeatpages>1
    \else
      \global\repeatpages=\repeatallpages
    \fi
  \fi
  \global\advance\repeatpages 1
  % \plainoutput has \vbox{\makeheadline\pagebody\makefootline}
  % we save the contents and \copy it
  \setbox\savedpagebox=\vbox{\makeheadline\pagebody\makefootline}%
  \loop\ifnum\repeatpages>1
    \shipout\copy\savedpagebox
    \global\advance\repeatpages -1
  \repeat
  \advancepageno
  \ifnum\outputpenalty>-\@MM \else\dosupereject\fi
}

\catcode`@=12

\newbox\savedpagebox
\newcount\repeatallpages
\newcount\repeatpages

\output={\repeatplainoutput}

%%% start of the document

\repeatallpages=3

This is page 1 (three times)

\vfill\eject

\repeatpages=4

This is page 2 (four times)

\vfill\eject

This is page 3 (three times)

\bye