<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">%
%Date: Tue, 25 Oct 88 14:11:06 +0100
%From: Joost Zalmstra &lt;mcvax!nat.vu.nl!jjaz@uunet.UU.NET&gt;
%Subject: Re:Page Make-up Challenge
%
%Maybe the following set of macros can contribute to the solution of
%the problem posed by David Rogers in TeXhax #86. It implements a floating
%insertion with the following properties:
% - Every insertion must be put in a \vbox. Customised macros can then
%   be used to place the white space for the figure and the figure caption
%   in this box.
% - The order in which these \vbox-es are inserted is maintained.
% - No more than two boxes are placed on one page: the first on the top
%   and the second on the bottom of the page.
%
%The proposed macro \figplace should create a \vbox with the correct layout
%of the figure and then call \addfigure to put it in the insertionlist:
%
%\def\figplace#1#2#3#4{setbox0=\vbox{%
%% here call macros to place figure and caption
%}
%\addfigure0}
%
%Note that the space separating the figure from the text should not
%be included in the \vbox. The skipregister \figureskip is used for this
%purpose.
%
%The macros are written in plain TeX, in fact the output routine given
%here is an extension of the plain output routine (TeX-book page 364).
%
%The basic idea is that figures that won't fit on the current page
%are kept on a list (the \box \figlist). This list is checked after
%a \shipout and if not empty a maximum of two \vboxes is inserted
%(using plains \topins) for the next page. As the insertions are \vboxes
%it is easy to split the insertion and put one at the top and one at
%the bottom of the page.
%
%Two further refinements should be mentioned here.
%1) If the figures on a page take so much room that less than a specified
%amount of space (given in dimen register \minpagesize) is left for
%the text, this text is shifted through to the next page.
%2) By inserting a \vbox with height \vsize (created by \vbox to \vsize..)
%a page insert is created. No extra \figureskip will be include in this case.
%
%I have tested these macros with real input (16 pages with on the first
%page the insertion of several figures) and it seems to work on the moment.
%However, I'm not a TeX guru and I would expect that these macros can be
%improved. One of the problems left is te fact that \addfigures must
%be called in horizontal mode ( \vadjust won't work). I would therefore
%apreciate comments, both on the macros as they stand and on how this
%contributes to the Challenge.
%
%Joost Zalmstra.
%
%jjaz%nat.vu.nl@hearn.bitnet
\newbox\figlist
\newcount\figuresonpage  \figuresonpage=0
\newcount\figuresonlist  \figuresonlist=0
\newskip\figureskip      \figureskip=1.2 pc plus 1 pc
\newdimen\pagesize
\newdimen\minpagesize    \minpagesize=5 pc
\newdimen\figuresizeonpage

\def\addfigure#1{%	add figure in box #1 to the document
    \ifnum\figuresonpage&gt;1	% allready two figures on this page
	\addtolist{#1}%		% so save for later
    \else
	\ifnum\figuresonlist&gt;0	% figlist is not empty
	    \addtolist{#1}	% so save for later
	\else			% no figures left over, so try to fit this one
	    \dimen0=\ht#1
	    \ifdim\dimen0&lt;\vsize% not a pagesize figure
	       \advance\dimen0 by \dp#1   % size of the box
	       \advance\dimen0 by \figureskip  % extra space below or above
	    \fi
	    \advance\dimen0 by \pagetotal
	    \ifdim\dimen0&gt;\pagegoal  % no space on this page
		\addtolist{#1}	     % so save for later
	    \else 
		\advance\dimen0 by \figuresizeonpage
		\ifdim\dimen0&gt;\dimen\topins % exceding maximum insertion size
		    \addtolist{#1}	      % so save for later
		\else
		    \figureinsert{#1}	      % insert the figure
		\fi
	    \fi
	\fi
    \fi
}

\def\addtolist#1{%	add box #1 to figlist
    \global\setbox\figlist=\vbox{%
	\nointerlineskip
	\box#1
	\unvbox\figlist}
    \global\advance\figuresonlist by 1
}

\def\figureinsert#1{%	insert figure on this page
    \ifdim\ht#1&lt;\vsize
        \insert\topins{\vbox{%
	    \ifnum\figuresonpage=0
	        \unvbox#1\vskip\figureskip	% skip below the figure
	    \else
	        \vskip\figureskip\unvbox#1	% skip above the figure
	    \fi
	}}
    \else
        \pageinsert
	    \unvbox#1
	\endinsert
    \fi
    \global\advance\figuresonpage by 1
    \global\advance\figuresizeonpage by \ht#1
    \global\advance\figuresizeonpage by \dp#1
    \global\advance\figuresizeonpage by \figureskip
}
\def\checkfiglist{%	see if there is a figure in the list that will
		  % fit on the next page
    \ifnum\figuresonlist&gt;0
        \global\setbox\figlist=\vbox{%
	    \unvbox\figlist
	    \setbox0=\lastbox
	    \global\advance\dimen0\ht0
	    \ifdim\ht0&lt;\vsize
	        \global\advance\dimen0 by \dp0
	        \global\advance\dimen0 by \figureskip
	    \fi
	    \ifdim\dimen0&gt;\vsize
	         \vbox{\box0}	% no room ; replace the figure
	    \else
	        \ifdim\dimen0&gt;\dimen\topins
      		    \vbox{\box0}
  		\else
		        \global\advance\figuresonlist by -1
	        \fi
	    \fi
	    \global\setbox0=\box0
	}
    \else
	{\setbox1=\box0		% make box0 void
	\global\setbox0=\box0}
    \fi
}
% Borrowing the macros from plain TeX

\catcode`@=11
\output{\myoutput}
\def\myoutput{\shipout\vbox{\makeheadline\pagebody\makefootline}%
  \advancepageno
  \global\figuresonpage=0
  \dimen0=0pt
  \global\figuresizeonpage = 0pt
  \checkfiglist     % check if there is figure waiting and return it in box 0 
  \ifvoid0          % nothing left
  \else
      \figureinsert0% insert this figure
      \checkfiglist % check for a second figure
      \ifvoid0\else
          \figureinsert0
       \fi
  \fi
  \ifvoid255\else\unvbox255\penalty\outputpenalty\fi % unused page back on list
  \ifnum\outputpenalty&gt;-\@MM \else\dosupereject\fi}

\def\pagecontents{%
    \ifnum\figuresonpage&gt;0      % check for insertion of figures
	\unvbox\topins	% place the figure(s) on top
	\ifnum\figuresonpage=2
	    \setbox0=\lastbox   % remove the second figure
	\fi
	\setbox1=\lastbox
	\unvbox1
    \fi
% Check box 255
     \pagesize=\ht255
     \advance\pagesize by \dp255	   % determine size of box 255
     \ifdim\pagesize&gt;\minpagesize
         \dimen@=\dp255 \unvbox255  % the real page contents
     \else
	\message{tekstsize = \the\ht255, \the\dp255}
	\ifdim\ht255=0pt            % box is empty
	\else
	   \vfil	           	   % to small so leave for next page
	\fi
     \fi
% 
    \ifnum\figuresonpage=2
	\box0		% the second figure
    \fi
    \ifvoid\footins\else % footnote info is present
      \vskip\skip\footins
      \footnoterule
      \unvbox\footins\fi
    \ifr@ggedbottom \kern-\dimen@ \vfil \fi}

\catcode`@=12	% at signs no longer letters
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