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author | Karl Berry <karl@freefriends.org> | 2006-01-11 23:58:32 +0000 |
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committer | Karl Berry <karl@freefriends.org> | 2006-01-11 23:58:32 +0000 |
commit | 8eb89f2adefbbdc3005c34350665a94992d4b300 (patch) | |
tree | 80bb4be1dd47d7481bf4e8d94309477ec3cf22d2 /Master/texmf-dist/source/latex/tools/multicol.dtx | |
parent | 173c95c204f01e6bb18cc852925c9a1cef535740 (diff) |
trunk/Master/texmf-dist/source/latex/tools
git-svn-id: svn://tug.org/texlive/trunk@559 c570f23f-e606-0410-a88d-b1316a301751
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diff --git a/Master/texmf-dist/source/latex/tools/multicol.dtx b/Master/texmf-dist/source/latex/tools/multicol.dtx new file mode 100644 index 00000000000..4575bb41be0 --- /dev/null +++ b/Master/texmf-dist/source/latex/tools/multicol.dtx @@ -0,0 +1,3472 @@ +% \iffalse meta-comment +% +% Copyright 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 +% The LaTeX3 Project and any individual authors listed elsewhere +% in this file. +% +% This file is part of the Standard LaTeX `Tools Bundle'. +% ------------------------------------------------------- +% +% It may be distributed and/or modified under the +% conditions of the LaTeX Project Public License, either version 1.3 +% of this license or (at your option) any later version. +% The latest version of this license is in +% http://www.latex-project.org/lppl.txt +% and version 1.3 or later is part of all distributions of LaTeX +% version 2003/12/01 or later. +% +% The list of all files belonging to the LaTeX `Tools Bundle' is +% given in the file `manifest.txt'. +% +% \fi +% +% \iffalse This is a METACOMMENT +% +%% Package `multicol' to use with LaTeX2e +%% Copyright 1989-2003 Frank Mittelbach +%% +%% In addition to the terms of LPPL any distributed version +%% (unchanged or modified) of multicol has to keep the statement +%% about the moral obligation for using multicol. In case of major +%% changes where this would not be appropriate the author of the +%% changed version should contact the copyright holder. +%% +%% +%% Moral obligation for using multicol: +%% ------------------------------------ +%% +%% Users of multicol who wish to include or use multicol or a modified +%% version in a proprietary and commercially market product are asked +%% under certain conditions (see below) for the payment of a license +%% fee. The size of this fee is to be determined, in each instance, +%% by the commercial user, depending on his/her judgment of the value of +%% multicol for his/her product. +%% +%% +%% The conditions for this are as follows: +%% +%% The producer of a proprietary and commercially market product +%% that involves typesetting using multicol is asked to determine +%% the value of a license fee for using multicol if +%% +%% - the product is a document and the producer has decided to +%% include multicol to typeset (parts of) the document or has +%% directed the author of the document to include multicol (for +%% example, by providing a class file to be used by the author) +%% +%% - the product is a LaTeX class or package that includes multicol +%% +%% +%% There is no moral obligation in case +%% +%% - the product is a document but producer has not directed +%% the author to include multicol (in that case the moral obligation +%% lies with the author of the document) +%% +%% - the product does not involve typesetting, e.g., consists, for +%% example, of distributing multicol and its documentation. +%% +%% - the product is not proprietary, i.e., is made available as free +%% software itself (which doesn't prohibit its commercial marketing) +%% +%% - multicol is used for non-commercial purposes +%% +%% +%% Determinating a license fee might result in a license fee of zero +%% (i.e., no payment) in case a producer has determined that the use +%% of multicol has no enhancing effect on the product. This is a +%% plausible scenario, i.e., in the above two cases the producer is +%% only asked to evaluate the value of multicol for the product +%% not for the payment of a license fee per se (which might or might +%% not follow from this evaluation). +%% +%% The license fee, if any, can be payed either to the LaTeX3 fund +%% (see ltx3info.txt in the base LaTeX distribution) or to the author of +%% the program who can be contacted at +%% +%% Frank.Mittelbach@latex-project.org +%% +%<*dtx> + \ProvidesFile{multicol.dtx} +%</dtx> +%<package>\NeedsTeXFormat{LaTeX2e}[1997/12/01] +%<package>\ProvidesPackage{multicol} +%<driver> \ProvidesFile{multicol.drv} +% \fi +% \ProvidesFile{multicol.dtx} + [2004/02/14 v1.6e multicolumn formatting (FMi)] +% +% +%% \CheckSum{1561} +%% \CharacterTable +%% {Upper-case \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z +%% Lower-case \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z +%% Digits \0\1\2\3\4\5\6\7\8\9 +%% Exclamation \! Double quote \" Hash (number) \# +%% Dollar \$ Percent \% Ampersand \& +%% Acute accent \' Left paren \( Right paren \) +%% Asterisk \* Plus \+ Comma \, +%% Minus \- Point \. Solidus \/ +%% Colon \: Semicolon \; Less than \< +%% Equals \= Greater than \> Question mark \? +%% Commercial at \@ Left bracket \[ Backslash \\ +%% Right bracket \] Circumflex \^ Underscore \_ +%% Grave accent \` Left brace \{ Vertical bar \| +%% Right brace \} Tilde \~} +%% +% +% \changes{v1.5n}{1997/06/05}{Applied improvement of documentation, +% kindly done by Robin Fairbairns.} +% \changes{v1.4h}{1992/06/04}{Added mark tracing with +% tracingmulticols$\ge2$} +% \changes{v1.4a}{1992/02/11}{Added support for multicol in inner mode} +% \changes{v1.0d}{1989/05/17}{All lines shortened to 72 or less.} +% \changes{v1.0e}{1989/06/21}{Redefinition of description env. to use +% \cs{descriptionmargin}\quotechar=5pt +% in documentation.} +% \changes{v1.0f}{1989/07/11}{Changed \cs{z@} to 0pt in redefinition of +% description.} +% \changes{v1.1a}{1989/09/20}{\cs{multicolssep} changed to \cs{multicolsep}.} +% +% \def\description{\list{}{\labelwidth 0pt \leftmargin\descriptionmargin +% \itemindent-\leftmargin \let\makelabel\descriptionlabel}} +% \newdimen\descriptionmargin \descriptionmargin=5pt +% +% \DoNotIndex{\@M,\@Mi,\@bsphack,\@cclv,\@colht,\@currlist,\@deferlist} +% \DoNotIndex{\@elt,\@esphack,\@floatplacement} +% \DoNotIndex{\@ifundefined,\@ifnextchar,\@makecol} +% \DoNotIndex{\@ne,\@outputpage,\@scolelt,\@spaces,\@tempb,\@tempcnta} +% \DoNotIndex{\@width} +% \DoNotIndex{\addvspace,\advance,\allowbreak} +% \DoNotIndex{\baselineskip,\begingroup,\box,\columnsep,\copy,\count} +% \DoNotIndex{\count@,\def,\dimen@,\divide,\docdate} +% \DoNotIndex{\edef,\eject,\egroup,\else,\endgroup,\endinput} +% \DoNotIndex{\fi,\fileversion,\filedate} +% \DoNotIndex{\gdef,\global} +% \DoNotIndex{\hbox,\hfil,\hrule,\ht,\hss} +% \DoNotIndex{\ifdim,\ifnum,\ifvoid,\ignorespaces,\insert,\immediate} +% \DoNotIndex{\let,\loop} +% \DoNotIndex{\maxdepth,\message,\multiply} +% \DoNotIndex{\newbox,\newcount,\newdimen,\newskip,\number,\newpage} +% \DoNotIndex{\outputpenalty,\p@,\penalty} +% \DoNotIndex{\relax,\repeat,\setbox,\skip,\space,\splitmaxdepth} +% \DoNotIndex{\splittopskip,\string,\sixt@@n} +% \DoNotIndex{\the,\thepage,\thr@@,\topskip,\tw@,\typeout} +% \DoNotIndex{\unvbox,\vbox,\vfill,\vsplit,\voidb@x,\vrule} +% \DoNotIndex{\write,\wd} +% \DoNotIndex{\z@} +% +% \MakeShortVerb{\|} +% \newcommand{\mc}{{\sf multicols}} +% \newcommand{\TUB}{{\sl TUGboat\/}} +% \newcommand{\TB}{{\sl\TeX book\/}} +% +% +% \setcounter{StandardModuleDepth}{2} +% \setcounter{collectmore}{3} +% +% \GetFileInfo{multicol.dtx} +% \title{An environment for multicolumn output\thanks{This file +% has version number \fileversion, last +% revised \filedate.}% +% \thanks{Note: This package is released under terms which affect +% its use in commercial applications. Please see the details at +% the top of the source file.}} +% \author{Frank Mittelbach\\ +% {\rm Email:} see top of the source file} +% \date{Printed \today} +% +% \maketitle +% +% \begin{abstract} +% This article describes the use and the implementation of the \mc{} +% environment. This environment allows switching between +% one and multicolumn format on the same page. Footnotes are handled +% correctly (for the most part), but will be placed at the bottom of +% the page and not under each column. \LaTeX{}'s float mechanism, +% however, is partly disabled in the current implementation. At the +% moment only page-wide floats (i.e., star-forms) can be used within +% the scope of the environment. +% \end{abstract} +% +% +% \begin{multicols}{3}[\section*{Preface to version 1.5 + 1.6}] +% \hbadness=10000 +% The 1.5 release contains two major changes: \mc{} will now +% support up to 10 columns and two more tuning possibilities have +% been added to the balancing routine. The balancing routine now +% checks the badness +% of the resulting columns and rejects solutions that are larger +% than a certain treshold. +% At the same time \mc{} has been upgraded to run under \LaTeXe{}. +% +% Later changes to 1.5 include |\columnbreak| and |multicols*|. +% +% For version 1.6 micro-spacing around the boxes produced by \mc{} +% has been improved to allow for baseline-grid typesetting. +% \end{multicols} +% +% +% \setcounter{collectmore}{2} +% \begin{multicols}{3}[\section{Introduction}] +% \hbadness=10000 +% Switching between two column and one column layout is possible in +% \LaTeX{}, but every use of |\twocolumn| or |\onecolumn| +% starts a new page. Moreover, the last page of two column output +% isn't balanced and this often results in an empty, or nearly +% empty, right column. When I started to write macros for {\sf +% doc.sty} (see ``The {\tt doc}--Option'', \TUB\ +% volume 10~\#2, pp.~245--273) I thought that it would be nice to +% place the index +% on the same page as the bibliography. And balancing the last page +% would not only look better, it also would save space; provided of +% course that it is also possible to start the next article on the +% same page. Rewriting the index environment was comparatively easy, +% but the next goal, designing an environment which takes care of +% footnotes, floats etc., was a harder task. It took me a whole +% weekend\footnote{I started with the algorithm given in the \TeX +% book on page 417. Without this help a weekend would not have been +% enough. (This remark was made in the documentation of the initial +% release, since then several hundreds more hours went into it +% improving the original code.)} to get together the few lines of +% code below and there is +% still a good chance that I missed something after all. +% +% Try it and, hopefully, enjoy it; and {\em please\/} direct bug +% reports and suggestions back to Mainz. +% \end{multicols} +% +% +% \setcounter{collectmore}{0} +% \begin{multicols}{3}[\section{The User Interface}] +% \hbadness=10000 +% To use the environment one simply says\\*[2mm] +% \hspace*{2mm}|\begin{multicols}{|\meta{number}|}| +% \hspace*{12mm}\meta{multicolumn text}\\ +% \hspace*{2mm}|\end{multicols}|\\[2mm] +% where \meta{number} is the required number of columns and +%^^A\meta{multicolumn text} +% $\langle${\it multi\-column text\/}$\rangle$ may contain arbitrary +% \LaTeX{} commands, except that floats and marginpars are not +% allowed in the current implementation\footnote{This is dictated by +% lack of time. To implement floats one has to reimplement the +% whole \LaTeX{} output routine.}. +% +% \DescribeMacro\premulticols +% As its first action, the {\sf multicols} environment measures the +% current page to determine whether there is enough room for some +% portion of multicolumn output. This is controlled by the +% \meta{dimen} variable |\premulticols| which can be changed by +% the user with ordinary \LaTeX{} commands. +% \DescribeMacro\multicolsep +% If the space is less than |\premulticols|, a new page is +% started. Otherwise, a |\vskip| of |\multicolsep| is +% added.\footnote{Actually the added space may be less because we use +% \cs{addvspace} (see the \LaTeX{} manual for further +% information about this command).} +% +% \DescribeMacro\postmulticols +% When the end of the \mc{} environment is encountered, an +% analogous mechanism is employed, but now we test whether there is a +% space larger than |\postmulticols| available. Again we add +% |\multicolsep| or start a new page. +% +% It is often convenient to spread some text over all columns, just +% before the multicolumn output, without any page break in between. To +% achieve this the \mc{} environment has an optional second +% argument which can be used for this purpose. For example, the text +% you are now reading was started with +% \begin{verbatim} +% \begin{multicols}{3} +% [\section{The User +% Interface}] ... +%\end{verbatim} +% If such text is unusually long (or short) the value of +% |\premulticols| might need adjusting to prevent a bad page +% break. We therefore provide a third argument which can be used to +% overwrite the default value of |\premulticols| just for this +% occasion. So if you want to combine some longer single column text +% with a multicols environment you could write +% \begin{verbatim} +% \begin{multicols}{3} +% [\section{Index} +% This index contains ...] +% [6cm] +% ... +%\end{verbatim} +% +% +% \DescribeMacro\columnsep +% The space between columns is controlled by the length parameter +% |\columnsep|. The width for the individual columns is automatically +% calculated from this parameter and the current |\linewidth|. In this +% article a value of \textsf{\the\columnsep} was used. +% +% +% \DescribeMacro\columnseprule +% Separation of columns with vertical rules is achieved by setting the +% parameter |\columnseprule| to some positive value. In this +% article a value of {\sf.4pt} was used. +% +% \DescribeMacro\multicolbaselineskip +% Since narrow columns tend to need adjustments in interline spacing +% we also provide a \meta{skip} parameter called +% |\multicolbaselineskip| which is added to the +% |\baselineskip| parameter inside the \mc{} +% environment. Please use this parameter with care or leave it alone; +% it is intended only for package file designers since even small +% changes might produce totally unexpected changes to your document. +% +% +% \subsection{Balancing columns} +% +% Besides the previously mentioned parameters, some others are +% provided to influence the layout of the columns generated. +% +% Paragraphing in \TeX{} is controlled by several parameters. One of +% the most important is called |\tolerance|: this controls the +% allowed `looseness' (i.e.\ the amount of blank space between words). +% Its default value is 200 (the \LaTeX{} |\fussy|) which is too +% small for narrow columns. On the other hand the |\sloppy| +% declaration (which sets |\tolerance| to $10000=\infty$) is too +% large, allowing really bad spacing.\footnote{Look at the next +% paragraph, it was set with the \cs{sloppy} declaration.} +% +% \begin{sloppypar} +% \DescribeMacro\multicoltolerance \DescribeMacro\multicolpretolerance +% We therefore use a |\multicoltolerance| parameter for the +% |\tolerance| value inside the \mc{} environment. Its default value +% is 9999 which is less than infinity but `bad' enough for most +% paragraphs in a multicolumn environment. Changing its value should +% be done outside the \mc{} environment. Since |\tolerance| is set +% to |\multicoltolerance| at the beginning of every {\sf multicols} +% environment one can locally overwrite this default by assigning +% \verb*+\tolerance = +\meta{desired value}. There also exists a +% |\multicolpretolerance| parameter holding the value for +% |\pretolerance| within a \mc{} environment. Both parameters are +% usually used only by package designers. +% \end{sloppypar} +% +% Generation of multicolumn output can be divided into two parts. In +% the first part we are collecting material for a page, shipping it +% out, collecting material for the next page, and so on. As a second +% step, balancing will be done when the end of the \mc{} environment +% is reached. +% In the first step \TeX{} might consider more material whilst +% finding the final columns than it actually use when shipping out the +% page. This might cause a problem if a footnote is encountered in +% the part of the input considered, but not used, on the current page. +% In this case the footnote might show up on the current page, while the +% footnotemark corresponding to this footnote might be set on the next +% one.\footnote{The reason behind this behavior is the asynchronous +% character of the \TeX{} {\it page\_builder}. +% However, this +% could be avoided by defining very complicated output +% routines which don't use \TeX{} primitives like +% \cs{insert} but do everything by hand. +% This is clearly beyond the scope of a weekend problem.} +% Therefore the \mc{} environment gives a warning +% message\footnote{This message will be generated even if there are no +% footnotes in this part of the text.} whenever it is unable to use +% all the material considered so far. +% +% If you don't use footnotes too often the chances of something +% actually going wrong are very slim, but if this happens you can help +% \TeX{} by using a |\pagebreak| command in the final document. +% Another way to influence the behavior of \TeX{} in this respect is +% given by the counter variable `{\sf collectmore}'. If you use the +% |\setcounter| declaration to set this counter to \meta{number}, +% \TeX{} will consider \meta{number} more (or less) lines before +% making its final decision. So a value of $-1$ may solve all your +% problems at the cost of slightly less optimal columns. +% +% In the second step (balancing columns) we have other bells and +% whistles. First of all you can say |\raggedcolumns| if you +% don't want the bottom lines to be aligned. The default is +% |\flushcolumns|, so \TeX{} will normally try to make both the +% top and bottom baselines of all columns align. +% +% \columnbreak +% +% Additionally you can set another counter, the `{\sf unbalance}' +% counter, to some positive \meta{number}. This will make all but the +% right-most column \meta{number} of lines longer than they would +% normally have been. `Lines' in this context refer to normal text +% lines (i.e.\ one |\baselineskip| apart); thus, if your columns +% contain displays, +% for example, you may need a higher \meta{number} +% to shift something from one column into another. +% +% Unlike `{\sf collectmore},' the `{\sf unbalance}' counter is reset +% to zero at the end of the environment so it only applies to one +% \mc{} environment. +% +% The two methods may be combined but I suggest using these features +% only when fine tuning important publications. +% +% Two more general tuning possibilities were added with version~1.5. +% \TeX{} allows to measure the badness of a column in terms of an +% integer value, where 0 means optimal and any higher value means a +% certain amount of extra white space. 10000 is considered to be +% infinitely bad (\TeX{} does not distinguish any further). In addition +% the special value 100000 means overfull (i.e., the column contains +% more text than could possibly fit into it). +% +% The new release now measures every generated column and ignores +% solutions where at least one column has a badness being larger than +% the value of the counter {\sf columnbadness}. The default value for +% this counter is 10000, thus \TeX{} will accept all solutions except +% those being overfull. +% By setting the counter to a smaller value you can force the algorithm +% to search for solutions that do not have columns with a lot of white +% space. +% +% However, if the setting is too low, the algorithm may not find any +% acceptable solution at all and will then finally choose the extreme +% solution of placing all text into the first column. +% +% Often, when colunms are balanced, it is impossible to find a solution +% that distributes the text evenly over all columns. If that is the case +% the last column usually has less text than the others. In the earlier +% releases this text was stretched to produce a column with the same +% height as all others, sometimes resulting in really ugly looking +% columns. +% +% In the new release this stretching is only done if the badness of +% the final column is not larger than the value of the counter +% {\sf finalcolumnbadness}. The default setting is 9999, thus preventing +% the stretching for all columns that \TeX{} would consider infinitely +% bad. In that case the final column is allowed to run short which gives +% a much better result. +% +% And there are two more parameters of some experimental nature, +% one called |\multicolovershoot| the other |\multicolundershoot|. +% They control +% the amount of space a column is allowed to be ``too full'' or ``too +% short'' without affecting the column badness. They are set to 0pt +% and 2pt, respectively. +% +% \subsection{Not balancing the columns} +% +% Although this package was written to solve the problem of balancing +% columns, I got repeated requests to provide a version where all +% white space is automatically placed in the last column or +% columns. Since version v1.5q this now exists: if you use +% \texttt{multicols*} instead of the usual environment the columns on +% the last page are not balanced. Of course, this environment only +% works on top-level, e.g., inside a box one has to balance to +% determine a column height in absense of a fixed value. +% +% +% \subsection{Manually breaking columns} +% +% Another request often voiced was: ``How to I tell \LaTeX{} that it +% should break the first column after this particular line?''. The +% |\pagebreak| command (which works with the two-column option of +% \LaTeX{}) is of no use here since it would end the collection phase +% of \mc{} and thus all columns on that page. So with version 1.5u +% the |\columnbreak| command was added. If used within a paragraph it +% marks the end of the current line as the desired breakpoint. You can +% observe its effect on +% the previous page where three lines of text have been artifically +% forced into the second column (resulting in some white +% space between paragraphs in the first column). +% +% \subsection{Floats inside a \mc{} environment} +% +% Within the \mc{} environment the usual star float commands are +% available but their function is somewhat different as in the +% two-column mode of standard \LaTeX. Stared floats, e.g., {\tt +% figure*}, denote page wide floats that are handled in a similar +% fashion as normal floats outside the \mc{} environment. However, +% they will never show up on the page where they are encountered. In +% other words, one can influence their placement by specifying a +% combination of {\tt t}, {\tt b}, and/or {\tt p} in their optional +% argument, but {\tt h} doesn't work because the first possible place +% is the top of the next page. One should also note, that this means +% that their placement behavior is determined by the values of +% |\topfraction|, etc.\ rather then by |\dbl...|. +% +% +% \subsection{Warnings} +% +% Under certain circumstances the use of the \mc{} environment may +% result in some +% warnings from \TeX{} or \LaTeX{}. Here is a list +% of the important ones and the possible cause: +% \begin{description} +% +% \item[] {\hspace*{-\labelsep}\tt Underfull \string\hbox\space +% (badness ...)} +% +% As the columns are often very narrow \TeX{} wasn't able to find a +% good way to break the paragraph. Underfull denotes a loose line but +% as long the badness values is below $10000$ the result is probably +% acceptable. +% +% \item[] +% {\hspace*{-\labelsep}\tt Underfull \string\vbox\space ... while +% \string\output\space is active} +% +% If a column contains an character with an unusual depth, for +% example a `(', in the bottom line then this message may show up. It +% usually has no significance as long as the value is not more than a +% few points. +% +% \item[] {\hspace*{-\labelsep}\tt LaTeX Warning: I moved some lines +% to the next page} +% +% As mentioned above, \mc{} sometimes screws up the footnote +% numbering. As a precaution, whenever there is a footnote on a +% page that where \mc{} had to leave a remainder for the following +% page this warning appears. Check the footnote numbering on this +% page. If it turns out that it is wrong you have to manually break +% the page using |\newpage| or |\pagebreak[..]|. +% +% \item[] {\hspace*{-\labelsep}\tt Floats and marginpars not allowed +% inside `multicols' environment!} +% +% This message appears if you try to use the |\marginpar| command or +% an unstared version of the {\sf figure} or {\sf table} environment. +% Such floats will disappear! +% +% \item[] {\hspace*{-\labelsep}\tt Very deep columns! +% Grid alignment might be broken} +% +% This message can only appear if the option \texttt{grid} was +% chosen. In that case it will show up if a column has a very large +% depth so that \mc{} is unable to back up to its baseline. This +% is only relevant if one tries to produce a document where all +% text lines are aligned at an invisible grid, something that +% requires careful adjustment of many parameters and macros, e.g., +% heading definitions. +% +% \end{description} +% +% +% \subsection{Tracing the output} +% +% To understand the reasoning behind the decisions \TeX{} makes when +% processing a \mc{} environment, a tracing mechanism is provided. +% If you set the counter `\texttt{tracingmulticols}' +% to a positive \meta{number} you then +% will get some tracing information on the terminal and in the +% transcript file: +% \begin{description} +% \item[$\meta{number}=1$.] \TeX{} will now tell you, whenever it +% enters or leaves a \mc{} environment, the number of columns it +% is working on and its decision about starting a new page before +% or after the environment. +% \item[$\meta{number}=2$.] +% In this case you also get information from the balancing routine: +% the heights tried for the left and right-most columns, +% information about shrinking if the |\raggedcolumns| +% declaration is in force and the value of the `{\sf unbalance}' +% counter if positive. +% \item[$\meta{number}= 3$.] Setting \meta{number}\pagebreak[2] to +% this value will additionally trace the mark handling +% algorithm. It will show what marks are found, what marks are +% considered, etc. To fully understand this information you will +% probably have to read carefully trough the implementation. +% \item[$\meta{number}\geq 4$.] Setting \meta{number}\pagebreak[2] to +% such a high value will additionally place an |\hrule| into your +% output, separating the part of text which had already been +% considered on the previous page from the rest. Clearly this +% setting should {\em not\/} be used for the final output. It will +% also activate even more debugging code for mark handling. +% \end{description} +% +% +% \end{multicols} +% +% \begin{multicols}{3}[\section{Prefaces to older versions} +% \subsection{Preface to version 1.4}] +% \hbadness=10000 +% Beside fixing some bugs as mentioned in the {\sf multicol.bug} file +% this new release enhances the \mc{} environment by allowing for +% balancing in arbitrary contexts. It is now, for example, possible +% to balance text within a \mc{} or a {\sf minipage} as shown in +% \ref{tab:newcmds} where a {\sf multicols} environment within a +% {\sf quote} environment was used. It is now even possible to nest +% \mc{} environments. +% +% The only restriction to such inner \mc{} environments (nested, or +% within \TeX's internal vertical mode) is that such variants will +% produce a box with the balanced material in it, so that they can +% not be broken across pages or columns. +% +% Additionally I rewrote the algorithm for balancing so that it will +% now produce slightly better results. +% +% I updated the source documentation but like to apologize in +% advance for some `left over' parts that slipped through the +% revision. +% +% A note to people who like to improve the balancing algorithm of +% \mc{}: The balancing routine in now placed into a single macro +% which is called |\balance@columns|. This means that one can easily +% try different balancing routines by rewriting this macro. The +% interface for it is explained in table \ref{tab:balance}. There are +% several improvements possible, one can think of integrating the +% |\badness| function of \TeX3, define a faster algorithm for finding +% the right column height, etc. If somebody thinks he/she has an +% enhancement I would be pleased to learn about it. But please obey +% the copyright notice and don't change {\sf multicol.dtx} directly! +% \begin{table*} +% \begin{quote} +% \begin{multicols}{2} +% \raggedcolumns +% The macro |\balance@columns| that contains the code for balancing +% gathered material is a macro without parameters. It assumes that +% the material for balancing is stored in the box |\mult@box| which +% is a |\vbox|. It also ``knows'' about all parameters set up by the +% \mc{} environment, like |\col@number|, etc. It can also assume +% that |\@colroom| is the still available space on the current page. +% +% When it finishes it must return the individual columns in boxes +% suitable for further processing with |\page@sofar|. This means +% that the left column should be stored in box register +% |\mult@gfirstbox|, the next +% in register |\mult@firstbox|${}+2$, \ldots, +% only the last one as an exception in +% register |\mult@grightbox|. Furthermore it has to set up +% two the macros +% |\kept@firstmark| and |\kept@botmark| to hold the values for the +% first and bottom mark as found in the individual columns. There +% are some helper functions defined in section \ref{sec:v14} which +% may be used for this. Getting the marks right ``by hand'' is +% non-trivial and it may pay off to first take a look at the +% documentation and implementation of |\balance@columns| below +% before trying anew. +% \end{multicols} +% \end{quote} +% \vspace*{-3ex} +% \vspace*{-0ex} +% \caption{Interface description for \cs{balance@columns}} +% \label{tab:balance} +% \end{table*} +% \end{multicols} +% +% \begin{multicols}{3}[\subsection{Preface to version 1.2}] +% \hbadness=10000 +% After the article about the \mc{} environment was published in +% \TUB\ 10\#3, I got numerous requests for these macros. However, I +% also got a changed version of my style file, together with a +% letter asking me if I would include the changes to get better +% paragraphing results in the case of narrow lines. The main +% differences to my original style option were additional parameters +% (like |\multicoladjdemerits| to be used for |\adjdemerits|, etc.) +% which would influence the line breaking algorithm. +% +% But actually resetting such parameters to zero or even worse to a +% negative value won't give better line breaks inside the \mc{} +% environment. \TeX{}s line breaking algorithm will only look at +% those possible line breaks which can be reached without a badness +% higher than the current value of |\tolerance| (or |\pretolerance| +% in the first pass). If this isn't possible, then, as a last +% resort, \TeX{} will produce overfull boxes. All those (and only +% those) possible break points will be considered and finally the +% sequence which results in the fewest demerits will be chosen. This +% means that a value of $-1000$ for |\adjdemerits| instructs \TeX{} +% to prefer visibly incompatible lines instead of producing better +% line breaks. +% +% However, with \TeX{} 3.0 it is possible to get decent line breaks +% even in small columns by setting |\emergencystretch| to an +% appropriate value. I implemented a version which is capable of +% running both in the old and the new \TeX{} (actually it will +% simply ignore the new feature if it is not available). The +% calculation of |\emergencystretch| is probably incorrect. I +% made a few tests but of course one has have much more experience +% with the new possibilities to achieve the maximum quality. +% +% Version 1.1a had a nice `feature': the penalty for using the +% forbidden floats was their ultimate removal from \LaTeX{}s +% |\@freelist| so that after a few |\marginpar|s inside the \mc{} +% environment floats where disabled forever. (Thanks to Chris +% Rowley for pointing this out.) I removed this misbehaviour and at +% the same time decided to allow at least floats spanning all +% columns, e.g., generated by the |figure*| environment. You can +% see the new functionality in table~\ref{tab:newcmds} which was +% inserted at this very point. +% \begin{table*} +% \small +% \setlength{\multicolsep}{0pt} +% \begin{quote} +% \begin{multicols}{2} +% |\setemergencystretch|: This is a hook for people who like +% to play around. It is supposed to set the +% |\emergencystretch| \meta{dimen} register provided in the +% new \TeX{} 3.0. The first argument is the number of columns and +% the second one is the current |\hsize|. At the moment the +% default definition is $4\mbox{\tt pt} \times |#1|$, i.e.\ the +% |\hsize| isn't used at all. But maybe there are better +% formulae. +% +% \setlength{\emergencystretch}{20pt} |\set@floatcmds|: This is +% the hook for the experts who like to implement a full float +% mechanism for the \mc{} environment. The |@| in the name +% should signal that this might not be easy. +% \end{multicols} +% \end{quote} +% \vspace*{-1ex} +% \vspace*{-0ex} +% \caption[]{The new commands of {\sf multicol.sty} version 1.2. +% Both commands might be removed if good solutions to these +% open problems are found. I hope that these commands will +% prevent that nearly identical style files derived from +% this one are floating around.} +% \label{tab:newcmds} +% \end{table*} +% However single column floats are still forbidden and I don't think +% I will have time to tackle this problem in the near future. As an +% advice for all who want to try: wait for \TeX{} 3.0. It has a few +% features which will make life much easier in multi-column +% surroundings. Nevertheless we are working here at the edge of +% \TeX{}s capabilities, really perfect solutions would need a +% different approach than it was done in \TeX{}s page builder. +% +% The text below is nearly unchanged, I only added documentation at +% places where new code was added. +% \end{multicols} +% +% \changes{v1.5l}{1996/01/13}{Try hard to explain unresolved reference +% that happens if \cs{OnlyDescription} is used} +% +% \StopEventually{\PrintIndex \PrintChanges +% \ifx\Finale\relax +% \typeout{**********************************} +% \typeout{* Info: Typesetting this document with +% \protect\OnlyDescription\space will} +% \typeout{* Info: result in one unresolved +% reference to `sec:v14'.} +% \typeout{* Info: --- tough, it's just not there in this case!} +% \typeout{**********************************} +% \fi +% } +% +% +% \begin{multicols}{2}[\section{The Implementation} +% We are now switching to two-column output to show the +% abilities of this environment (and bad layout decisions). +% \subsection{The documentation driver file} +% ][10\baselineskip] +% +% \hbadness=10000 +% +% +% The next bit of code contains the documentation driver file for +% \TeX{}, i.e., the file that will produce the documentation you are +% currently reading. It will be extracted from this file by the {\tt +% docstrip} program. +% Since this is the first code in this file one can produce the +% documentation +% simply by running \LaTeX{} on the \texttt{.dtx} file. +% \begin{macrocode} +%<*driver> +\documentclass{ltxdoc} +% \end{macrocode} +% We use the \texttt{balancingshow} option when loading \mc{} so +% that full tracing is produced. This has to be done before the +% \texttt{doc} package is loaded, since \texttt{doc} otherwise +% requires \mc{} without any options. +% \begin{macrocode} +\usepackage{multicol}[1999/05/25] +\usepackage{doc} +% \end{macrocode} +% First we set up the page layout suitable for +% this article. +% \begin{macrocode} +\setlength{\textwidth}{39pc} +\setlength{\textheight}{54pc} +\setlength{\parindent}{1em} +\setlength{\parskip}{0pt plus 1pt} +\setlength{\oddsidemargin}{0pc} +\setlength{\marginparwidth}{0pc} +\setlength{\topmargin}{-2.5pc} +\setlength{\headsep}{20pt} +\setlength{\columnsep}{1.5pc} +% \end{macrocode} +% We want a rule between columns. +% \begin{macrocode} +\setlength\columnseprule{.4pt} +% \end{macrocode} +% We also want to ensure that a new \mc{} environment finds enough +% space at the bottom of the page. +% \begin{macrocode} +\setlength\premulticols{6\baselineskip} +% \end{macrocode} +% When balancing columns we disregard solutions that +% are too bad. Also, if the last column is too bad +% we typeset it without stretch. +% \begin{macrocode} +\setcounter{columnbadness}{7000} +\setcounter{finalcolumnbadness}{7000} +% \end{macrocode} +% The index is supposed to come out in four columns. +% And we don't show macro names in the margin. +% \begin{macrocode} +\setcounter{IndexColumns}{4} +\let\DescribeMacro\SpecialUsageIndex +\let\DescribeEnv\SpecialEnvIndex +\renewcommand\PrintMacroName[1]{} +\CodelineIndex +%\DisableCrossrefs % Partial index +\RecordChanges % Change log +% \end{macrocode} +% Line numbers are very small for this article. +% \begin{macrocode} +\renewcommand{\theCodelineNo} + {\scriptsize\rm\arabic{CodelineNo}} +\settowidth\MacroIndent{\scriptsize\rm 00\ } + +\begin{document} + \typeout + {**************************************** + ^^J* Expect some Under- and overfull boxes. + ^^J****************************************} + \DocInput{multicol.dtx} +\end{document} +%</driver> +% \end{macrocode} +% +% +% \end{multicols} +% +% \begin{multicols}{2}[\subsection{Identification and +% option processing}] +% +% +% We start by identifying the package. Since it makes use of features +% only available in \LaTeXe{} we ensure that this format is available. +% (Now this is done earlier in the file.) +% \begin{macrocode} +%<*package> +% \NeedsTeXFormat{LaTeX2e} +% \ProvidesPackage{multicol}[..../../.. +% v... multicolum formatting] +% \end{macrocode} +% +%^^A \subsection{Option processing} +% +% Next we declare options supported by \mc{}. Twocolumn mode +% and \mc{} do not work together so we warn about possible +% problems. However, since you can revert to |\onecolumn| +% in which case \mc{} does work, we don't make this an error. +% \begin{macrocode} +\DeclareOption{twocolumn} + {\PackageWarning{multicol}{May not work + with the twocolumn option}} +% \end{macrocode} +% Tracing is done using a counter. However +% it is also possible to invoke the tracing +% using the options declared below. +% \begin{macrocode} +\newcount\c@tracingmulticols +\DeclareOption{errorshow} + {\c@tracingmulticols\z@} +\DeclareOption{infoshow} + {\c@tracingmulticols\@ne} +\DeclareOption{balancingshow} + {\c@tracingmulticols\tw@} +\DeclareOption{markshow} + {\c@tracingmulticols\thr@@} +\DeclareOption{debugshow} + {\c@tracingmulticols5\relax} +% \end{macrocode} +% The next option is intended for typesetting on a |\baselineskip| +% grid. Right now it doesn't do anything other than warning if it +% thinks that the grid got lost. +% \changes{v1.6a}{2003/03/15}{New option grid} +% \begin{macrocode} +\let\mc@gridwarn\maxdimen +\DeclareOption{grid}{\def\mc@gridwarn{\maxdepth}} +\ProcessOptions +% \end{macrocode} +% +% +% \end{multicols} +% +% \begin{multicols}{2}[\subsection{Starting and +% Ending the \mc{} Environment}] +% +% \begin{macro}{\multicols} +% As mentioned before, the \mc{} environment has one mandatory +% argument (the number of columns) and up to two optional ones. We +% start by reading the number of columns into the |\col@number| +% register. +% \begin{macrocode} +\def\multicols#1{\col@number#1\relax +% \end{macrocode} +% If the user forgot the argument, \TeX{} will complain about a +% missing number at this point. The error recovery mechanism will +% then use zero, which isn't a good choice in this case. So we +% should now test whether everything is okay. The minimum is two +% columns at the moment. +% \changes{v1.3b}{1990/10/09}{Minimum of two columns} +% \begin{macrocode} + \ifnum\col@number<\tw@ + \PackageWarning{multicol}% + {Using `\number\col@number' + columns doesn't seem a good idea.^^J + I therefore use two columns instead}% + \col@number\tw@ \fi +% \end{macrocode} +% We have only enough box registers for ten columns, so we need to +% check that the user hasn't asked for more. +% \changes{v1.4k}{1992/06/27}{Maximum of 5 columns (temp)} +% \changes{v1.5a}{1992/11/04}{Allow 10 columns again} +% \begin{macrocode} + \ifnum\col@number>10 + \PackageError{multicol}% + {Too many columns}% + {Current implementation doesn't + support more than 10 columns.% + \MessageBreak + I therefore use 10 columns instead}% + \col@number10 \fi +% \end{macrocode} +% Within the environment we need a special version of the +% kernel |\@footnotetext| command since the original sets the +% the |\hsize| to |\columnwidth| which is not correct in the +% multicol environment. Here |\columnwidth| refers to the width of +% the individual column and the footnote should be in |\textwidth|. +% Since |\@footnotetext| has a different definition inside a +% minipage environment we do not redefine it directly. Instead we +% locally set |\columnwidth| to |\textwidth| and call the original +% (current) definition stored in |\orig@footnotetext|. +% \changes{v1.5p}{1997/12/14}{Redefinition of \cs{@footnotetext} +% only within env pr/2689.} +% \changes{v1.5r}{1998/08/17}{Use \cs{@footnotetext} but with +% local change to \cs{columnwidth}.} +% \changes{v1.5w}{1999/10/21}{Make \cs{@footnotetext} long to allow +% multi-paragraph footnotes.} +% If the \mc{} environment is nested inside another \mc{} +% environment then the redefinition has already happened. So be +% better test for this situation. Otherwise, we will get a \TeX{} +% stack overflow as this would generate a self-referencing definition. +% \changes{v1.6e}{2004/02/14}{Avoid self-referencing definition of +% \cs{@footnotetext} (pr/3618)}. +% \begin{macrocode} + \ifx\@footnotetext\mult@footnotetext\else + \let\orig@footnotetext\@footnotetext + \let\@footnotetext\mult@footnotetext + \fi +% \end{macrocode} +% Now we can safely look for the optional arguments. +% \begin{macrocode} + \@ifnextchar[\mult@cols{\mult@cols[]}} +% \end{macrocode} +% \end{macro} +% +% +% +% \begin{macro}{\mult@footnotetext} +% +% \begin{macrocode} +\long\def\mult@footnotetext#1{\begingroup + \columnwidth\textwidth + \orig@footnotetext{#1}\endgroup} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\mult@cols} +% The |\mult@cols| macro grabs the first optional argument +% (if any) and looks for the second one. +% \begin{macrocode} +\def\mult@cols[#1]{\@ifnextchar[% +% \end{macrocode} +% This argument should be a \meta{dimen} denoting the minimum free +% space needed on the current page to start the environment. If the +% user didn't supply one, we use |\premulticols| as a +% default. +% \begin{macrocode} + {\mult@@cols{#1}}% + {\mult@@cols{#1}[\premulticols]}} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\mult@@cols} +% After removing all arguments from the input we are able +% to start with |\mult@@cols|. +% \begin{macrocode} +\def\mult@@cols#1[#2]{% +% \end{macrocode} +% First thing we do is to decide whether or not this is an +% unbounded multicols environment, i.e. one that may split across +% pages, or one that has to be typeset into a box. If we are in +% \TeX's ``inner'' mode (e.g., inside a box already) then we have a +% boxed version of multicols therefore we set the |@boxedmulticols| +% switch to true. The \mc{} should start in vertical mode. If we +% are not already there we now force it with |\par| since otherwise +% the test for ``inner'' mode wouldn't show if we are in a box. +% \changes{v1.4f}{1992/04/28}{\cs{par} added to allow for correct inner test} +% \begin{macrocode} + \par + \ifinner \@boxedmulticolstrue +% \end{macrocode} +% Otherwise we check |\doublecol@number|. This counter is zero +% outside a multicols environment but positive inside (this happens +% a little later on). In the second case we need to process the +% current multicols also in ``boxed mode'' and so change the switch +% accordingly. +% \begin{macrocode} + \else + \ifnum \doublecol@number>\z@ + \@boxedmulticolstrue + \fi + \fi +% \end{macrocode} +% Then we look to see if statistics are requested: +% \begin{macrocode} + \mult@info\z@ + {Starting environment with + \the\col@number\space columns% +% \end{macrocode} +% In boxed mode we add some more info. +% \changes{v1.4f}{1992/04/28}{\cs{on@line} added to tracing info} +% \begin{macrocode} + \if@boxedmulticols\MessageBreak + (boxed mode)\fi + }% +% \end{macrocode} +% Then we measure the current page to see whether a useful portion +% of the multicolumn environment can be typeset. This routine +% might start a new page. +% \changes{v1.4a}{1992/02/14}{Forgotten braces added} +% \begin{macrocode} + \enough@room{#2}% +% \end{macrocode} +% Now we output the first argument and produce vertical space +% above the columns. (Note that this argument corresponds to the +% first optional argument of the {\sf multicols} environment.) +% For many releases this argument was typeset in a group to get +% a similar effect as |\twocolumn[..]| where the argument is +% also implicitly surrounded by braces. However, this conflicts +% with local changes done by things like sectioning commands (which +% account for the majority of commands used in that argument) +% messing up vertical spacing etc.\ later in the document so that +% from version v1.5q on this argument is again typeset at the outer +% level. +% \changes{v1.4e}{1992/03/16}{Typeset optional arg inside group} +% \changes{v1.5q}{1998/01/19}{And removed the group again six years later} +% \begin{macrocode} + #1\par\addvspace\multicolsep +% \end{macrocode} +% When the last line of a paragraph had a positive depth then this +% depth normally taken into account by the baselineskip calculation +% for the next line. However, the columns produced by a following +% \texttt{multicol} are rigid and thus the distance from the +% baseline of a previous text line to the first line in a +% \texttt{multicol} would differ depending on the depth of the +% previous line. To account for this we add a negative space unless +% the depth is \texttt{-1000pt} which signals something special to +% \TeX and is not supposed to be a real depth. +% \changes{v1.5z1}{2003/02/17}{Add a kern to cancel potential depth of +% previous line} +% \begin{macrocode} + \ifdim \prevdepth = -\@m\p@ + \else +% \end{macrocode} +% The actual generation of this corrective space is a little bit +% more complicated as it doesn't make sense to always back up to +% the previous baseline (in case an object with a very large depth +% was placed there, e.g., a centered tabular). So we only back up +% to the extend that we are within the |\baselineskip| grid. We +% know that the box produced by \mc{} has |\topskip| at its top so +% that also needs to be taken into account. +% \changes{v1.6a}{2003/03/15}{Adjust spacing} +% \begin{macrocode} + \@tempcnta\prevdepth + \@tempcntb\baselineskip + \divide\@tempcnta\@tempcntb + \advance\@tempcnta\@ne + \dimen@\prevdepth + \advance\dimen@ -\@tempcnta\baselineskip + \advance\dimen@ \topskip + \kern-\dimen@ + \fi +% \end{macrocode} +% We start a new grouping level to hide all subsequent changes +% (done in |\prepare@multicols| for example). +% \begin{macrocode} + \begingroup + \prepare@multicols +% \end{macrocode} +% If we are in boxed mode we now open a box to typeset all material +% from the multicols body into it, otherwise we simply go ahead. +% \changes{v1.4g}{1992/05/07}{\cs{global} was probably wrong but at least +% unnecessary} +% \begin{macrocode} + \if@boxedmulticols + \setbox\mult@box\vbox\bgroup +% \end{macrocode} +% \changes{v1.5?}{1994/?/?}{Penalty moved to later point} +% We may have to reset some parameters at this point, +% perhaps |\@parboxrestore| +% would be the right action but I leave it for the moment. +% \changes{v1.4l}{1992/08/17}{\cs{@totalleftmargin} now in \cs{prepare@multicols}} +% \begin{macrocode} + \fi +% \end{macrocode} +% We finish by suppressing initial spaces. +% \begin{macrocode} + \ignorespaces} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\if@boxedmulticols} +% Here is the switch and the box for ``boxed'' multicols code. +% \begin{macrocode} +\newif\if@boxedmulticols +\@boxedmulticolsfalse +\newbox\mult@box +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\enough@room} +% \changes{v1.0c}{1989/05/12}{Penalty 0 added to empty the contribution +% list.} +% The |\enough@room| macro used +% above isn't perfect but works reasonably well in this context. We +% measure the free space on the current page by subtracting +% |\pagetotal| from |\pagegoal|. This isn't entirely +% correct since it doesn't take the `shrinking' (i.e.\ +% |\pageshrink|) into account. The `recent contribution list' +% might be nonempty so we start with |\par| and an explicit +% |\penalty|.\footnote{See the documentation of +% \cs{endmulticols} for further details.} +% Actually, we use |\addpenalty| to ensure that a following +% |\addvspace| will `see' the vertical space that might be +% present. +% The use of |\addpenalty| will have the effect that all items from +% the recent contributions will be moved to the main vertical list +% and the |\pagetotal| value will be updated correctly. However, +% the penalty will be placed in front of any dangling glue item +% with the result that the main vertical list may already be +% overfull even if \TeX{} is not invoking the output routine. +% \changes{v1.3b}{1990/10/09}{Do \cs{penalty} with \cs{addpenalty}} +% \changes{v1.4e}{1992/03/16}{But ignore \cs{@nobreak} in \cs{addpenalty}} +% \begin{macrocode} +\def\enough@room#1{% +% \end{macrocode} +% Measuring makes only sense when we are not in ``boxed mode'' so +% the routine does nothing if the switch is true. +% \begin{macrocode} + \if@boxedmulticols\else + \par +% \end{macrocode} +% \label{mac:enoughroom} +% To empty the contribution list the first release contained a +% penalty zero but this had the result that |\addvspace| couldn't +% detect preceding glue. So this was changed to |\addpenalty|. But +% this turned out to be not enough as |\addpenalty| will not add a +% penalty when |@nobreak| is true. Therefore we force this switch +% locally to false. As a result there may be a break between +% preceding text and the start of a multicols environment, but this +% seems acceptable since there is the optional argument for exactly +% this reason. +% \begin{macrocode} + \bgroup\@nobreakfalse\addpenalty\z@\egroup + \page@free \pagegoal + \advance \page@free -\pagetotal +% \end{macrocode} +% To be able to output the value we need to assign it to a register +% first since it might be a register (default) in which case we +% need to use |\the| or it might be a plain value in which case +% |\the| would be wrong. +% \changes{v1.5e}{1994/05/26}{Assign arg to skip register to be able +% to output value} +% \begin{macrocode} + \@tempskipa#1\relax +% \end{macrocode} +% Now we test whether tracing information is required: +% \begin{macrocode} + \mult@info\z@ + {Current page:\MessageBreak + height=% + \the\pagegoal: used \the\pagetotal + \space -> free=\the\page@free + \MessageBreak + needed \the\@tempskipa + \space(for #1)}% +% \end{macrocode} +% Our last action is to force a page break if there isn't enough +% room left. +% \begin{macrocode} + \ifdim \page@free <#1\newpage \fi + \fi} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\prepare@multicols} +% When preparing for multicolumn output several things must +% be done. +% \begin{macrocode} +\def\prepare@multicols{% +% \end{macrocode} +% We start saving the current |\@totalleftmargin| and then +% resetting the |\parshape| in case we are inside some list +% environment. The correct indentation for the \mc{} environment in +% such a case will be produced by moving the result to the right by +% |\multicol@leftmargin| later on. If we would use the value of of +% |\@totalleftmargin| directly then lists inside the \mc{} +% environment could cause a shift of the output. +% \changes{v1.4l}{1992/08/17}{saved \cs{@totalleftmargin}} +% \begin{macrocode} + \multicol@leftmargin\@totalleftmargin + \@totalleftmargin\z@ + \parshape\z@ +% \end{macrocode} +% We also set the register |\doublecol@number| for later use. This +% register should contain $2\times |\col@number|$. This is also an +% indicator that we are within a \mc{} environment as mentioned +% above. +% \changes{v1.5a}{1992/11/04}{Add offset to \cs{doublecolnumber}} +% \begin{macrocode} + \doublecol@number\col@number + \multiply\doublecol@number\tw@ + \advance\doublecol@number\mult@rightbox +% \end{macrocode} +% +% \begin{macrocode} + \if@boxedmulticols + \let\l@kept@firstmark\kept@firstmark + \let\l@kept@botmark\kept@botmark + \global\let\kept@firstmark\@empty + \global\let\kept@botmark\@empty + \else +% \end{macrocode} +% We add an empty box to the main vertical list to ensure that we +% catch any insertions (held over or inserted at the top of the +% page). Otherwise it might happen that the |\eject| is discarded +% without calling the output routine. Inside the output routine we +% remove this box again. Again this code applies only if we are on +% the main vertical list and not within a box. +% However, it is not enough to turn off interline spacing, we also +% have to clear |\topskip| before adding this box, since |\topskip| +% is always inserted before the first box on a page which would +% leave us with an extra space of |\topskip| if \mc{} start on a +% fresh sheet. +% \changes{v1.3c}{1991/03/03}{\cs{null} inserted and removed in output} +% \changes{v1.4a}{1992/02/11}{Conditional code for boxed mode added.} +% \changes{v1.4o}{1992/11/22}{\cs{topskip} locally zeroed.} +% \begin{macrocode} + \nointerlineskip {\topskip\z@\null}% + \output{% + \global\setbox\partial@page\vbox + {% +% \end{macrocode} +% Now we have to make sure that we catch one special situation which +% may result in loss of text! If the user has a huge amount of +% vertical material within the first optional argument that is larger +% then |\premulticols| and we are near the bottom of the page then it +% can happen that not the |\eject| is triggering this special output +% routine but rather the overfull main vertical list. In that case +% we get another breakpoint through the |\eject| penalty. As a result +% this special output routine would be called twice and the contents +% of |\partial@page|, i.e.\ the material before the \mc{} +% environment gets lost. There are several solutions to avoid this +% problem, but for now we will simply detect this and inform the user +% that he/she has to enlarge the |\premulticols| by using a suitable +% value for the second argument. +% \changes{v1.4a}{1992/02/11}{Checking for text losses.} +% \begin{macrocode} +%<*check> + \ifvoid\partial@page\else + \PackageError{multicol}% + {Error saving partial page}% + {The part of the page before + the multicols environment was + nearly full with^^Jthe result + that starting the environment + will produce an overfull + page. Some^^Jtext may be lost! + Please increase \premulticols + either generally or for this% + ^^Jenvironment by specifying a + suitable value in the second + optional argument to^^Jthe + multicols environment.} + \unvbox\partial@page + \box\last@line + \fi +%</check> + \unvbox\@cclv + \global\setbox\last@line\lastbox + }% +% \end{macrocode} +% Finally we need to record the marks that are present within the +% |\partial@page| so that we can construct correct first and bottom +% marks later on. This is done by the following code. +% \changes{v1.4a}{1992/02/14}{kept marks initiated} +% \begin{macrocode} + \prep@keptmarks +% \end{macrocode} +% Finally we have to initialize |\kept@topmark| which should +% ideally be initialized with the mark that is current on ``top'' +% of this page. Unfortunately we can't use |\topmark| because this +% register will not always contain what its name promises because +% \LaTeX{} sometimes calls the output routine for float +% management.\footnote{During such a call the \cs{botmark} +% gets globally copied to \cs{topmark} by the \TeX{} +% program.} Therefore we use the second best solution by +% initializing it with |\firstmark|. In fact, for our purpose this +% doesn't matter as we use |\kept@topmark| only to initialize +% |\firstmark| and |\botmark| of a following page if we don't find +% any marks on the current one. +% \changes{v1.4i}{1992/06/18}{\cs{kept@topmark} initialized.} +% \begin{macrocode} + \global\let\kept@topmark\firstmark + }\eject +% \end{macrocode} +% The next thing to do is to assign a new value to |\vsize|. +% \LaTeX{} maintains the free room on the page (i.e.\ the page +% height without the space for already contributed floats) in the +% register |\@colroom|. We must subtract the height of +% |\partial@page| to put the actual free room into this +% variable. +% \begin{macrocode} + \advance\@colroom-\ht\partial@page +% \end{macrocode} +% Then we have to calulate the |\vsize| value to use during column +% assembly. |\set@mult@vsize| takes an argument which allows to +% make the setting local (|\relax|) or global (|\global|). The +% latter variant is used inside the output routine below. At this +% point here we have to make a local change to |\vsize| because we +% want to get the original value for |\vsize| restored in case +% this \mc{} environment ends on the same page where it has started. +% \changes{v1.4p}{1992/11/26}{Use different \cs{vsize} setting} +% \changes{v1.4p}{1992/11/26}{Code moved to \cs{set@mult@vsize}} +% \begin{macrocode} + \set@mult@vsize\relax +% \end{macrocode} +% Now we switch to a new |\output| routine which will be used +% to put the gathered column material together. +% \begin{macrocode} + \output{\multi@column@out}% +% \end{macrocode} +% Finally we handle the footnote insertions. We have to multiply +% the magnification factor and the extra skip by the number of +% columns since each footnote reduces the space for every column +% (remember that we have pagewide footnotes). If, on the other +% hand, footnotes are typeset at the very end of the document, our +% scheme still works since |\count\footins| is zero then, so it +% will not change. +% To allow even further customization the setting of the |\footins| +% parameters is done in a separate macro. +% \changes{v1.5?}{1994/?/?}{Use \cs{init@mult@footins}} +% \begin{macrocode} + \init@mult@footins +% \end{macrocode} +% For the same reason (pagewide footnotes), the \meta{dimen} +% register controlling the maximum space used for footnotes isn't +% changed. Having done this, we must reinsert all the footnotes +% which are already present (i.e.\ those encountered when the +% material saved in |\partial@page| was first processed). This +% will reduce the free space (i.e.\ |\pagetotal|) by the +% appropriate amount since we have changed the magnification +% factor, etc.\ above. +% \begin{macrocode} + \reinsert@footnotes +% \end{macrocode} +% All the code above was only necessary for the unrestricted \mc{} +% version, i.e.\ the one that allows page breaks. If we are within +% a box there is no point in setting up special output routines or +% |\vsize|, etc. +% \begin{macrocode} + \fi +% \end{macrocode} +% But now we are coming to code that is necessary in all cases. We +% assign new values to |\vbadness|, |\hbadness| and |\tolerance| +% since it's rather hard for \TeX{} to produce `good' paragraphs +% within narrow columns. +% \changes{v1.2a}{1990/02/05}{\cs{vbadness} 10001 now.} +% \begin{macrocode} + \vbadness\@Mi \hbadness5000 + \tolerance\multicoltolerance +% \end{macrocode} +% Since nearly always the first pass will fail we ignore it +% completely telling \TeX{} to hyphenate directly. In fact, we now +% use another register to keep the value for the multicol +% pre-tolerance, so that a designer may allow to use +% |\pretolerance|. +% \changes{v1.2a}{1990/02/05}{\cs{pretolerance} -1 because it nearly never +% succeeds.} +% \changes{v1.4e}{1992/03/20}{Using} +% \begin{macrocode} + \pretolerance\multicolpretolerance +% \end{macrocode} +% For use with the new \TeX{} we set |\emergencystretch| to +% $|\col@number| \times 4pt$. However this is only a guess +% so at the moment this is done in a macro +% |\setemergencystretch| which gets the current |\hsize| +% and the number of columns as arguments. Therefore users are able +% to figure out their own formula. +% \changes{v1.2a}{1990/02/05}{\cs{setemergencystretch} added.} +% \begin{macrocode} + \setemergencystretch\col@number\hsize +% \end{macrocode} +% Another hook to allow people adding their own extensions without +% making a new package is |\set@floatcmds| which handles any +% redefinitions of \LaTeX{}s internal float commands to work with +% the \mc{} environment. At the moment it is only used to redefine +% |\@dblfloat| and |\end@dblfloat|. +% \changes{v1.2a}{1990/02/05}{\cs{set@floatcmds} added.} +% \begin{macrocode} + \set@floatcmds +% \end{macrocode} +% Additionally, we advance |\baselineskip| by +% |\multicolbaselineskip| to allow corrections for narrow +% columns. +% \begin{macrocode} + \advance\baselineskip\multicolbaselineskip +% \end{macrocode} +% \changes{v1.0e}{1989/06/21}{\cs{textwidth} changed to \cs{linewidth}.} +% \changes{v1.0e}{1989/06/21}{So this file will +% work with the `twocolumn' command.} +% The |\hsize| of the columns is given by the formula: +% \[ +% { |\linewidth| - (|\col@number|-1) +% \times +% |\columnsep| +% \over +% |\col@number|} +% \] +% The formula above has changed from release to release. We now +% start with the current value of |\linewidth| so that the column +% width is properly calculated when we are inside a minipage or a +% list or some other environment. +% This will be achieved with: +% \begin{macrocode} + \hsize\linewidth \advance\hsize\columnsep + \advance\hsize-\col@number\columnsep + \divide\hsize\col@number +% \end{macrocode} +% We also set |\linewidth| and |\columnwidth| to |\hsize| In the past +% |\columnwidth| was left unchanged. This is inconsistent, +% but |\columnwidth| is used only by floats (which +% aren't allowed in their current implementation) and by the +% |\footnote| macro. Since we want pagewide +% footnotes\footnote{I'm not sure that I really want pagewide +% footnotes. But balancing of the last page can +% only be achieved with this approach or with a +% multi-path algorithm which is complicated and +% slow. But it's a challenge to everybody to +% prove me wrong! Another possibility is to +% reimplement a small part of the {\it +% fire\_up\/} procedure in \TeX{} (the program). +% I think that this is the best solution if you +% are interested in complex page makeup, but it +% has the disadvantage that the resulting +% program cannot be called \TeX{} thereafter.} +% this simple trick saved us from rewriting the |\footnote| +% macros. However, some applications refered to |\columnwidth| as +% the ``width of the current column'' to typeset displays +% (the \texttt{amsmath} package, for example) and to allow the use +% of such applications together with \texttt{multicol} this is now +% changed. +% +% Before we change |\linewidth| to the new value we record its old +% value in some register called |\full@width|. This value is +% used later on when we package all columns together. +% \changes{v1.0e}{1989/06/21}{Setting of \cs{columnwidth} removed.} +% \changes{v1.5o}{1997/11/16}{Setting of \cs{columnwidth} added again +% pr/2664.} +% \begin{macrocode} + \full@width\linewidth + \linewidth\hsize + \columnwidth\hsize +} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\init@mult@footins} +% This macro is used to set up the parameters associated +% with footnote floats. It can be redefined by applications that +% require different amount of spaces when typesetting footnotes. +% \begin{macrocode} +\def\init@mult@footins{% + \multiply\count\footins\col@number + \multiply\skip \footins\col@number +} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\set@mult@vsize} +% +% Since we have to set |\col@umber| columns on one page, +% each with a height of |\@colroom|, we have to assign +% $ +% |\vsize| = |\col@number| \times |\@colroom| +% $ +% in order to collect enough material before entering the +% |\output| routine again. In fact we have to add another +% $ +% (|\col@number|-1) \times (|\baselineskip|-|\topskip|) +% $ +% if you think about it. +% \changes{v1.4p}{1992/11/26}{Macro added.} +% \begin{macrocode} +\def\set@mult@vsize#1{% + \vsize\@colroom + \@tempdima\baselineskip + \advance\@tempdima-\topskip + \advance\vsize\@tempdima + \vsize\col@number\vsize + \advance\vsize-\@tempdima +% \end{macrocode} +% But this might not be enough since we use |\vsplit| later to +% extract the columns from the gathered material. Therefore we add +% some `extra lines,' one for each column plus a corrective action +% depending on the value of the `\texttt{collectmore}' counter. +% The final value is assigned globally if |#1| is |\global| because +% we want to use this macro later inside the output routine too. +% \changes{v1.6c}{2003/04/08}{Collect one line per column more} +% \begin{macrocode} + \advance\vsize\col@number\baselineskip + #1\advance\vsize + \c@collectmore\baselineskip} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\multicol@leftmargin} +% Here is the dimen register we need for saving away the outer +% value of |\@totalleftmargin|. +% \begin{macrocode} +\newdimen\multicol@leftmargin +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\endmulticols} +% When the end of the \mc{} environment is sensed we have to +% balance the gathered material. Depending on whether or not we are +% inside a boxed multicol different things must happen. But first +% we end the current paragraph with a |\par| command. +% \begin{macrocode} +\def\endmulticols{\par + \if@boxedmulticols +% \end{macrocode} +% In boxed mode we have to close the box in which we have gathered +% all material for the columns. +% \begin{macrocode} + \egroup +% \end{macrocode} +% Now we call |\balance@columns| the routine that balances material +% stored in the box |\mult@box|. +% \changes{v1.5?}{1994/?/?}{Splitting off zero box moved to \cs{balance@columns}} +% \begin{macrocode} + \balance@columns +% \end{macrocode} +% After balancing the result has to be returned by the command +% |\page@sofar|. But before we do this we reinsert any marks found +% in box |\mult@box|. +% \begin{macrocode} + \return@nonemptymark{first}% + \kept@firstmark + \return@nonemptymark{bot}% + \kept@botmark + \page@sofar +% \end{macrocode} +% +% \begin{macrocode} + \global\let\kept@firstmark + \l@kept@firstmark + \global\let\kept@botmark + \l@kept@botmark +%<*marktrace> + \mult@info\tw@ + {Restore kept marks to\MessageBreak + first: \meaning\kept@firstmark + \MessageBreak bot\space\space: + \meaning\kept@botmark }% +%</marktrace> +% \end{macrocode} +% This finishes the code for the ``boxed'' case. +% \begin{macrocode} + \else +% \end{macrocode} +% If there was a |\columnbreak| on the very last line all material +% will have been moved to the |\colbreak@box|. Thus the the galley +% will be ampty and no output routine gets called so that the text +% is lost. To avoid this problem (though unlikely) we check if the +% current galley is empty and the |\colbreak@box| contains text and +% if so return that to the galley. If the galley is non-empty any +% material in |\colbreak@box| is added in the output routine since +% it needs to be put in front. +% \changes{v1.6d}{2003/04/17}{Catch problem with \cs{columnbreak} in +% last line} +% \begin{macrocode} +%<*colbreak> + \ifdim\pagegoal=\maxdimen + \ifvoid\colbreak@box\else + \mult@info\@ne{Re-adding forced + break(s) for splitting}% + \unvbox\colbreak@box\fi + \fi +%</colbreak> +% \end{macrocode} +% +% If we are in an unrestricted \mc{} environment we end the current +% paragraph above with |\par| but this isn't sufficient since \TeX{}s +% {\it page\_builder} will not totally empty the contribution +% list.\footnote{This once caused a puzzling bug where some of the +% material was balanced twice, resulting in some overprints. The +% reason was the \cs{eject} which was placed at the end of +% the contribution list. Then the {\it page\_builder} was called +% (an explicit \cs{penalty} will empty the contribution +% list), but the line with the \cs{eject} didn't fit onto +% the current page. It was then reconsidered after the output +% routine had ended, causing a second break after one line.} +% Therefore we must also add an explicit |\penalty|. Now the +% contribution list will be emptied and, if its material doesn't +% all fit onto the current page then the output routine will be +% called before we change it. +% \changes{v1.3b}{1990/10/09}{Do \cs{penalty} with \cs{addpenalty}} +% \changes{v1.4e}{1992/03/16}{But ignore \cs{@nobreak} in \cs{addpenalty}} +% \changes{v1.5c}{1993/04/18}{Again use \cs{penalty}} +% At this point we need to use |\penalty| not |\addpenalty| to +% ensure that a) the recent contributions are emptied and b) that +% the very last item on the main vertical list is a valid break +% point so that \TeX{} breaks the page in case it is overfull. +% \begin{macrocode} + \penalty\z@ +% \end{macrocode} +% The processed material might consist of a last line with a +% decender in which case the |\prevdepth| will be +% non-zero. However, this material is getting reformatted now so +% that this value is likely to be wrong. We therefore normalize the +% situation by pretending that the depth is zero and arrange later +% that the box containing the assembled columns has in fact this property. +% \changes{v1.6a}{2003/03/15}{Adjusting \cs{prevdepth}} +% \begin{macrocode} + \prevdepth\z@ +% \end{macrocode} +% Now it's safe to change the output routine in order to balance +% the columns. +% \begin{macrocode} + \output{\balance@columns@out}\eject +% \end{macrocode} +% If the \mc{} environment body was completely empty or if a +% multi-page \mc{} just ends at a page boundary we have the unusual +% case that the |\eject| will have no effect (since the main +% vertical list is empty)---thus no output routine is called at +% all. As a result the material preceding the \mc{} (stored in +% |\partial@page| will get lost if we don't take of this by hand. +% \changes{v1.4m}{1992/09/04}{Check \cs{partial@page} being emptied} +% \begin{macrocode} + \ifvbox\partial@page + \unvbox\partial@page\fi +% \end{macrocode} +% After the output routine has acted we restore +% the kept marks to their initial value. +% \begin{macrocode} + \global\let\kept@firstmark\@empty + \global\let\kept@botmark\@empty +%<*marktrace> + \mult@info\tw@ + {Make kept marks empty}% +%</marktrace> + \fi +% \end{macrocode} +% The output routine above will take care of the |\vsize| and +% reinsert the balanced columns, etc. But it can't reinsert the +% |\footnotes| because we first have to restore the +% |\footins| parameter since we are returning to one column +% mode. This will be done in the next line of code; we simply close +% the group started in |\multicols|. +% +% To fix an obscure bug which is the result of the current +% definition of the |\begin| \ldots\ |\end| macros, we check that +% we are still (logically speaking) in the \mc{} environment. If, +% for example, we forget to close some environment inside the +% \mc{} environment, the following |\endgroup| would be +% incorrectly considered to be the closing of this environment. +% \changes{v1.3c}{1991/03/14}{Check closing env.} +% \begin{macrocode} + \@checkend{multicols}% + \endgroup +% \end{macrocode} +% We also set the `{\sf unbalance}' counter to its default. This is +% done globally since \LaTeX{} counters are always changed this +% way.\footnote{Actually, we are still in a group started by the +% \cs{begin} macro, so \cs{global} must be used +% anyway.} +% \begin{macrocode} + \global\c@unbalance\z@ +% \end{macrocode} +% Now it's time to return any footnotes if we are in unrestricted +% mode: +% \begin{macrocode} + \if@boxedmulticols\else + \reinsert@footnotes +% \end{macrocode} +% We also take a look at the amount of free space on the current +% page to see if it's time for a page break. The vertical space +% added thereafter will vanish if |\enough@room| starts a new +% page. +% +% But there is one catch. If the |\end{multicols}| is at the top of +% which can happen if there is a break point just before it (such +% as end ending environment) which was chosen. In that case we +% would do the next page using the internal |\vsize| for multicol +% collection which is a desaster. So we better catch this +% case. Fortunately we can detect it by looking at |\pagegoal|. +% \changes{v1.5x}{2000/05/05}{Detect and fix problem if a multicols +% ends at the top of a page} +% \begin{macrocode} + \ifdim \pagegoal=\maxdimen + \global\vsize\@colroom + \else + \enough@room\postmulticols + \fi + \fi + \addvspace\multicolsep +% \end{macrocode} +% If statistics are required we finally report that we have +% finished everything. +% \begin{macrocode} + \mult@info\z@ + {Ending environment + \if@boxedmulticols + \space(boxed mode)\fi + }} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\c@unbalance} +% \SpecialMainIndex{\c@collectmore} +% \SpecialMainIndex{\col@number} +% \SpecialMainIndex{\doublecol@number} +% \SpecialMainIndex{\premulticols} +% \SpecialMainIndex{\multicoltolerance} +% \SpecialMainIndex{\multicolpretolerance} +% \SpecialMainIndex{\page@free} +% \SpecialMainIndex{\premulticols} +% \SpecialMainIndex{\postmulticols} +% \SpecialMainIndex{\multicolsep} +% \SpecialMainIndex{\multicolbaselineskip} +% \SpecialMainIndex{\partial@page} +% Let us end this section by allocating all the registers used so +% far. +% \begin{macrocode} +\newcount\c@unbalance +\newcount\c@collectmore +% \end{macrocode} +% In the new \LaTeX{} release |\col@number| is already allocated by +% the kernel, so we don't allocate it again. +% \begin{macrocode} +%\newcount\col@number +\newcount\doublecol@number +\newcount\multicoltolerance +\newcount\multicolpretolerance +\newdimen\full@width +\newdimen\page@free +\newdimen\premulticols +\newdimen\postmulticols +\newskip\multicolsep +\newskip\multicolbaselineskip +\newbox\partial@page +\newbox\last@line +% \end{macrocode} +% And here are their default values: +% \begin{macrocode} +\c@unbalance = 0 +\c@collectmore = 0 +% \end{macrocode} +% To allow checking whether some macro is used within the \mc{} +% environment the counter |\col@number| gets a default of |1| +% outside the the environment. +% \changes{v1.3d}{1991/10/23}{\cs{col@number} set to one} +% \begin{macrocode} +\col@number = 1 +\multicoltolerance = 9999 +\multicolpretolerance = -1 +\premulticols = 50pt +\postmulticols= 20pt +\multicolsep = 12pt plus 4pt minus 3pt +\multicolbaselineskip=0pt +% \end{macrocode} +% \end{macro} +% +% \end{multicols} +% +% \begin{multicols}{2}[\subsection{The output routines}] +% +% We first start with some simple macros. When typesetting the page we +% save the columns either in the box registers 0, 2, 4,\ldots\ +% (locally) or 1, 3, 5,\ldots\ (globally). This is \PlainTeX{} policy +% to avoid an overflow of the save stack. +% +% \begin{macro}{\process@cols} +% Therefore we define a |\process@cols| macro to help us in +% using these registers in the output routines below. It has two +% arguments: the first one is a number; the second one is the +% processing information. It loops starting with |\count@=#1| +% (|\count@| is a scratch register defined in \PlainTeX), +% processes argument |#2|, adds two to |\count@|, +% processes argument |#2| again, etc.\ until |\count@| is +% higher than |\doublecol@number|. It might be easier to +% understand it through an example, so we define it now and +% explain its usage afterwards. +% \begin{macrocode} +\def\process@cols#1#2{\count@#1\relax + \loop +%<*debug> + \typeout{Looking at box \the\count@} +%</debug> + #2% + \advance\count@\tw@ + \ifnum\count@<\doublecol@number + \repeat} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\page@sofar} +% We now define |\page@sofar| to give an example of the +% |\process@cols| macro. |\page@sofar| should output everything +% prepared by the balancing routine |\balance@columns|. +% \begin{macrocode} +\def\page@sofar{% +% \end{macrocode} +% |\balance@columns| prepares its output in the even numbered +% scratch box registers. +% Now we output the columns gathered assuming that they are saved +% in the box registers 2 (left column), 4 (second column), \ldots\ +% However, the last column (i.e.\ the right-most) should be saved in +% box register 0.\footnote{You will see the reason for this numbering +% when we look at the output routines +% \cs{multi@column@out} and +% \cs{balance@columns@out}.} +% First we ensure that the columns have equal width. We use +% |\process@cols| for this purpose, starting with +% $|\count@|=|\mult@rightbox|$. Therefore |\count@| loops through +% |\mult@rightbox|, $|\mult@rightbox| + 2$,\ldots +% (to |\doublecol@number|). +% \changes{v1.5a}{1992/11/04}{New box mechanism} +% \begin{macrocode} + \process@cols\mult@rightbox +% \end{macrocode} +% We have to check if the box in question is void, because the +% operation |\wd|\meta{number} on a void box will \emph{not} change +% its dimension (sigh). +% \changes{v1.5h}{1994/08/26}{Check for void boxes} +% \changes{v1.5i}{1994/10/02}{But don't remove original code.} +% \begin{macrocode} + {\ifvoid\count@ + \setbox\count@\hbox to\hsize{}% + \else + \wd\count@\hsize + \fi}% +% \end{macrocode} +% Now we give some tracing information. +% \changes{v1.4l}{1992/08/17}{use \cs{multicol@leftmargin} instead of +% \cs{@totalleftmargin}} +% \changes{v1.6b}{2003/03/15}{Different info display} +% \begin{macrocode} + \count@\col@number \advance\count@\m@ne + \mult@info\z@ + {Column spec: \the\full@width\space = indent + + columns + sep =\MessageBreak + \the\multicol@leftmargin\space + + \the\col@number\space + x \the\hsize\space + + \the\count@\space + x \the\columnsep + }% +% \end{macrocode} +% At this point we should always be in vertical mode. +% \begin{macrocode} +\ifvmode\else\errmessage{Multicol Error}\fi +% \end{macrocode} +% Now we put all columns together in an |\hbox| of width +% |\full@width| (shifting it by |\multicol@leftmargin| to the right +% so that it will be placed correctly if we are within a list +% environment) +% \changes{v1.4l}{1992/08/17}{use \cs{multicol@leftmargin} instead of +% \cs{@totalleftmargin}} +% +% The box containing the columns has a large height and thus will +% always result in using |\lineskip| if the normal |\baselineskip| +% calculations are used. We therefore better cancel that process. +% \changes{v1.5z1}{2003/02/17}{Suppress interline glue at this point} +% \begin{macrocode} + \nointerlineskip +% \end{macrocode} +% As mentioned earlier we want to have the reference point of the +% box we put on the page being at the baseline of the last line of +% the columns but we also want to ensure that the box has no depth +% so that any following skip is automatically starting from that +% baseline. +% We achieve this by recording the depths of all columns and then +% finally backing up by the maximum. (perhaps a simpler method +% would be to assemble the box in a register and set the depth of +% that box to zero (not checked). +% +% We need a global scratch register for this; using standard \TeX{} +% conventions we choose |\dimen2| and initialize it with the depth +% of the character ``p'' since that is one of the depths that +% compete for the maximum. +% \changes{v1.6a}{2003/03/15}{Preparing for adjusting \cs{prevdepth}} +% \begin{macrocode} + \setbox\z@\hbox{p}\global\dimen\tw@\dp\z@ + \moveright\multicol@leftmargin + \hbox to\full@width{% +% \end{macrocode} +% and separating the columns with a rule if desired. +% \changes{v1.5a}{1992/11/04}{New box mechanism} +% \changes{v1.5z}{2000/07/10}{Ensure that column rule has always +% \cs{normalcolor}} +% \begin{macrocode} + \process@cols\mult@gfirstbox{% +% \end{macrocode} +% If the depth of the current box is larger than the maximum found +% so far in |\dimen2| we update that register. +% \changes{v1.6a}{2003/03/15}{Preparing for adjusting \cs{prevdepth}} +% \begin{macrocode} + \ifdim\dp\count@>\dimen\tw@ + \global\dimen\tw@\dp\count@ \fi + \box\count@ + \hss{\normalcolor\vrule + \@width\columnseprule}\hss}% +% \end{macrocode} +% As you will have noticed, we started with box register +% |\mult@gfirstbox| (i.e.\ +% the left column). So this time |\count@| looped through 2, +% 4,\ldots\ (plus the appropriate offset). +% Finally we add box 0 and close the |\hbox|. +% \changes{v1.5a}{1992/11/04}{New box mechanism} +% \changes{v1.6a}{2003/03/15}{Preparing for adjusting \cs{prevdepth}} +% Again we may have to update |\dimen\tw@|. +% \begin{macrocode} + \ifdim\dp\mult@rightbox>\dimen\tw@ + \global\dimen\tw@\dp\mult@rightbox \fi + \box\mult@rightbox +% \end{macrocode} +% The depths of the columns depend on their last lines. To ensure +% that we will always get a similar look as far as the rules are +% concerned we force the depth at least the depth of a letter~`p'. +% \begin{macrocode} + \rlap{\phantom p}% + }% +% \end{macrocode} +% Now after typesetting the box we mack up to its baseline by using +% the value stored in |\dimen2|. +% \changes{v1.6a}{2003/03/15}{Now adjusting \cs{prevdepth}} +% \begin{macrocode} + \kern-\dimen\tw@ +% \end{macrocode} +% However, in case of of the columns was unusually deep \TeX{} may +% have tried some corrective actions in which case backing up by +% the ahve value will not bring us back to the baseline. A good +% indication for this is a depth of |\maxdepth| though it is not an +% absolute proof. If the option \texttt{grid} is used +% |\mc@gridwarn| will expand to this, otherwise to |\maxdimen| in +% which case this warning will not show up. +% \begin{macrocode} + \ifdim\dimen\tw@ = \mc@gridwarn + \PackageWarning{multicol}% + {Very deep columns!\MessageBreak + Grid alignment might be broken}% + \fi +} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\reinsert@footnotes} +% Before we tackle the bigger output routines we define just one +% more macro which will help us to find our way through the +% mysteries later. |\reinsert@footnotes| will do what its name +% indicates: it reinserts the footnotes present in +% |\footinbox| so that they will be reprocessed by \TeX{}'s +% {\it page\_builder}. +% +% Instead of actually reinserting the footnotes we insert an empty +% footnote. This will trigger insertion mechanism as well and since +% the old footnotes are still in their box and we are on a fresh page +% |\skip| |footins| should be correctly taken into account. +% \changes{v1.3c}{1990/03/03}{\cs{unbox}ing avoided.} +% \begin{macrocode} +\def\reinsert@footnotes{\ifvoid\footins\else + \insert\footins{}\fi} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\multi@column@out} +% Now we can't postpone the difficulties any longer. The +% |\multi@column@out| routine will be called in two situations. +% Either the page is full (i.e.\ we have collected enough material +% to generate all the required columns) or a float or marginpar (or +% a |\clearpage| is +% sensed. In the latter case the |\outputpenalty| is less +% than $-10000$, otherwise the penalty which triggered the output +% routine is higher. Therefore it's easy to distinguish both +% cases: we simply test this register. +% \changes{v1.5c}{1993/04/18}{Support \cs{clearpage}} +% \begin{macrocode} +\def\multi@column@out{% + \ifnum\outputpenalty <-\@M +% \end{macrocode} +% If this was a |\clearpage|, a float or a marginpar we call +% |\speci@ls| +% \begin{macrocode} + \speci@ls \else +% \end{macrocode} +% otherwise we construct the final page. +% \changes{v1.5u}{1999/05/25}{Support \cs{columnbreak}} +% \changes{v1.5v}{1999/07/18}{Added debug statements for +% column break support} +% For the next block of code see comments in section~\ref{sec:colbreak}. +% \begin{macrocode} +%<*colbreak> + \ifvoid\colbreak@box\else + \mult@info\@ne{Re-adding forced + break(s) for splitting}% + \setbox\@cclv\vbox{% + \unvbox\colbreak@box + \penalty-\@Mv\unvbox\@cclv}% + \fi +%</colbreak> +% \end{macrocode} +% Let us now consider the +% normal case. We have to |\vsplit| the columns from the +% accumulated material in box 255. Therefore we first assign +% appropriate values to |\splittopskip| and |\splitmaxdepth|. +% \begin{macrocode} + \splittopskip\topskip + \splitmaxdepth\maxdepth +% \end{macrocode} +% Then we calculate the current column height (in |\dimen@|). +% Note that the height of |\partial@page| is already +% subtracted from |\@colroom| so we can use its value as a +% starter. +% \begin{macrocode} + \dimen@\@colroom +% \end{macrocode} +% But we must also subtract the space occupied by footnotes on the +% current page. Note that we first have to reset the skip register +% to its normal value. +% Again, the actual action is carried out in a utility macro, so that +% other applications can modify it. +% \changes{v1.5?}{1994/?/?}{Use \cs{leave@mult@footins}} +% \begin{macrocode} + \divide\skip\footins\col@number + \ifvoid\footins \else + \leave@mult@footins + \fi +% \end{macrocode} +% Now we are able to |\vsplit| off all but the last column. +% Recall that these columns should be saved in the box registers 2, +% 4,\ldots\ (plus offset). +% \changes{v1.5a}{1992/11/04}{New box mechanism} +% \begin{macrocode} + \process@cols\mult@gfirstbox{% + \setbox\count@ + \vsplit\@cclv to\dimen@ +% \end{macrocode} +% After splitting we update the kept marks. +% \begin{macrocode} + \set@keptmarks +% \end{macrocode} +% If |\raggedcolumns| is in force we add a |vfill| at the bottom by +% unboxing the split box. +% \changes{v1.3c}{1990/03/03}{\cs{unbox}ing avoided.} +% \begin{macrocode} + \ifshr@nking + \setbox\count@ + \vbox to\dimen@ + {\unvbox\count@\vfill}% + \fi + }% +% \end{macrocode} +% Then the last column follows. +% \changes{v1.5a}{1992/11/04}{New box mechanism} +% \begin{macrocode} + \setbox\mult@rightbox + \vsplit\@cclv to\dimen@ + \set@keptmarks + \ifshr@nking + \setbox\mult@rightbox\vbox to\dimen@ + {\unvbox\mult@rightbox\vfill}% + \fi +% \end{macrocode} +% Having done this we hope that box 255 is emptied. If not, we +% reinsert its contents. +% \begin{macrocode} + \ifvoid\@cclv \else + \unvbox\@cclv + \penalty\outputpenalty +% \end{macrocode} +% In this case a footnote that happens to fall into the leftover +% bit will be typeset on the wrong page. Therefore we warn the user +% if the current page contains footnotes. The older versions of +% \mc{} produced this warning regardless of whether or not +% footnotes were present, resulting in many unnecessary warnings. +% \changes{v1.3c}{1991/02/17}{Check if footnotes are actually present +% before issuing a warning.} +% \begin{macrocode} + \ifvoid\footins\else + \PackageWarning{multicol}% + {I moved some lines to + the next page.\MessageBreak + Footnotes on page + \thepage\space might be wrong}% + \fi +% \end{macrocode} +% If the `{\sf tracingmulticols}' counter is 4 or higher we also +% add a rule. +% \begin{macrocode} + \ifnum \c@tracingmulticols>\thr@@ + \hrule\allowbreak \fi + \fi +% \end{macrocode} +% To get a correct marks for the current page we have to (locally +% redefine |\firstmark| and |\botmark|. +% If |\kept@firstmark| is non-empty then |\kept@botmark| must be +% non-empty too so we can use their values. Otherwise we use the +% value of |\kept@topmark| which was first initialized when we +% gathered the |\partical@page| and later on was updated to the +% |\botmark| for the preceding page +% +% \changes{v1.4a}{1992/02/14}{\cs{botmark} set to \cs{splitbotmark}} +% \begin{macrocode} + \ifx\@empty\kept@firstmark + \let\firstmark\kept@topmark + \let\botmark\kept@topmark + \else + \let\firstmark\kept@firstmark + \let\botmark\kept@botmark + \fi +% \end{macrocode} +% We also initalize |\topmark| with |\kept@topmark|. This will make +% this mark okay for all middle pages of the \mc{} environment. +% \changes{v1.5d}{1993/09/15}{reinit \cs{topmark}} +% \begin{macrocode} + \let\topmark\kept@topmark +%<*marktrace> + \mult@info\tw@ + {Use kept top mark:\MessageBreak + \meaning\kept@topmark + \MessageBreak + Use kept first mark:\MessageBreak + \meaning\kept@firstmark + \MessageBreak + Use kept bot mark:\MessageBreak + \meaning\kept@botmark + \MessageBreak + Produce first mark:\MessageBreak + \meaning\firstmark + \MessageBreak + Produce bot mark:\MessageBreak + \meaning\botmark + \@gobbletwo}% +%</marktrace> +% \end{macrocode} +% With a little more effort we could have done better. If we had, +% for example, recorded the shrinkage of the material in +% |\partial@page| it would be now possible to try higher +% values for |\dimen@| (i.e.\ the column height) to overcome +% the problem with the nonempty box 255. But this would make the +% code even more complex so I skipped it in the current +% implementation. +% +% Now we use \LaTeX{}'s standard output +% mechanism.\footnote{This will produce a lot of overhead since both +% output routines are held in memory. The correct +% solution would be to redesign the whole output +% routine used in \LaTeX.} +% Admittedly this is a funny way to do it. +% +% \begin{macrocode} + \setbox\@cclv\vbox{\unvbox\partial@page + \page@sofar}% +% \end{macrocode} +% The macro |\@makecol| adds all floats assigned for the current +% page to this page. |\@outputpage| ships out the resulting box. +% Note that it is just possible that such floats are present even +% if we do not allow any inside a \mc{} environment. +% \begin{macrocode} + \@makecol\@outputpage +% \end{macrocode} +% After the page is shipped out we have to prepare the kept marks +% for the following page. |\kept@firstmark| and |\kept@botmark| +% reinitilized by setting them to |\@empty|. The value of +% |\botmark| is then assigned to |\kept@topmark|. +% \changes{v1.4g}{1992/06/03}{Only change \cs{kept@topmark} if +% \cs{kept@botmark} non-empty} +% \changes{v1.4i}{1992/06/18}{Set \cs{kept@topmark} to \cs{botmark}} +% \begin{macrocode} + \global\let\kept@topmark\botmark + \global\let\kept@firstmark\@empty + \global\let\kept@botmark\@empty +%<*marktrace> + \mult@info\tw@ + {(Re)Init top mark:\MessageBreak + \meaning\kept@topmark + \@gobbletwo}% +%</marktrace> +% \end{macrocode} +% Now we reset |\@colroom| to |\@colht| which is \LaTeX's +% saved value of |\textheight|. +% \begin{macrocode} + \global\@colroom\@colht +% \end{macrocode} +% Then we process deferred floats waiting for their chance to be +% placed on the next page. +% \begin{macrocode} + \process@deferreds + \@whilesw\if@fcolmade\fi{\@outputpage + \global\@colroom\@colht + \process@deferreds}% +% \end{macrocode} +% If the user is interested in statistics we inform him about the +% amount of space reserved for floats. +% \begin{macrocode} + \mult@info\@ne + {Colroom:\MessageBreak + \the\@colht\space + after float space removed + = \the\@colroom \@gobble}% +% \end{macrocode} +% Having done all this we must prepare to tackle the next page. +% Therefore we assign a new value to |\vsize|. New, because +% |\partial@page| is now empty and |\@colroom| might be +% reduced by the space reserved for floats. +% \changes{v1.4p}{1992/11/26}{Use different \cs{vsize} setting} +% \begin{macrocode} + \set@mult@vsize \global +% \end{macrocode} +% The |\footins| skip register will be adjusted when the output +% group is closed. +% \changes{v1.3c}{1991/03/03}{Unnecessary code removed} +% \begin{macrocode} + \fi} +% \end{macrocode} +% \end{macro} +% +% +% +% \begin{macro}{\leave@mult@footins} +% This macro is used to subtract the amount of space +% occupied by footnotes for the current space from the +% space available for the current column. The space current column +% is stored in |\dimen@|. See above for the description of the default +% action. +% \changes{v1.5?}{1994/?/?}{Macro added} +% \begin{macrocode} +\def\leave@mult@footins{% + \advance\dimen@-\skip\footins + \advance\dimen@-\ht\footins +} +% \end{macrocode} +% \end{macro} +% +% +% +% \begin{macro}{\speci@ls} +% We left out two macros: |\process@deferreds| and +% |\speci@ls|. +% \changes{v1.5c}{1993/04/18}{Support \cs{clearpage}} +% \begin{macrocode} +\def\speci@ls{% + \ifnum\outputpenalty <-\@Mi +% \end{macrocode} +% If the document ends in the middle of a multicols environment, e.g., +% if the user forgot the |\end{multicols}|, \TeX{} adds a very +% negative penalty to the end of the galley which is intended to signal +% the output routine that it is time to prepare for shipping out +% everything remaining. Since inside multicols the output routine of +% \LaTeX{} is disabled sometimes we better check for this case: if we +% find a very negative penalty we produce an error message and run +% the default output routine for this case. +% \changes{v1.5s}{1998/09/10}{check for \cs{stop} penalty pr/2873} +% \begin{macrocode} + \ifnum \outputpenalty<-\@MM + \PackageError{multicol}{Document end + inside multicols environment}\@ehd + \@specialoutput + \else +% \end{macrocode} +% \changes{v1.5u}{1999/05/25}{Support \cs{columnbreak}} +% \changes{v1.5v}{1999/07/18}{Added debug statements for +% column break support} +% For the next block of code see comments in section~\ref{sec:colbreak}. +% \begin{macrocode} +%<*colbreak> + \ifnum\outputpenalty = -\@Mv + \mult@info\@ne{Forced column + break seen}% + \global\advance\vsize-\pagetotal + \global\setbox\colbreak@box + \vbox{\ifvoid\colbreak@box + \else + \unvbox\colbreak@box + \penalty-\@Mv + \fi + \unvbox\@cclv} + \reinsert@footnotes + \else +%</colbreak> +% \end{macrocode} +% If we encounter a float or a marginpar in the current +% implementation we simply warn the user that this is not allowed. +% Then we reinsert the page and its footnotes. +% \begin{macrocode} + \PackageWarningNoLine{multicol}% + {Floats and marginpars not + allowed inside `multicols' + environment!} + \unvbox\@cclv\reinsert@footnotes +% \end{macrocode} +% Additionally we empty the |\@currlist| to avoid later error +% messages when the \LaTeX{} output routine is again in force. +% But first we have to place the boxes back onto the +% |\@freelist|. (|\@elt|s default is |\relax| so +% this is possible with |\xdef|.) +% \changes{v1.2a}{1990/02/05}{Float boxes freed.} +% \begin{macrocode} + \xdef\@freelist{\@freelist\@currlist}% + \gdef\@currlist{}% +%<*colbreak> + \fi +%</colbreak> + \fi +% \end{macrocode} +% If the penalty is $-10001$ it will come from a |\clearpage| and +% we will execute |\@doclearpage| to get rid of any deferred +% floats. +% \begin{macrocode} + \else \@doclearpage \fi +} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\process@deferreds} +% |\process@deferreds| is a simplified version of \LaTeX{}'s +% |\@startpage|. We first call the macro +% |\@floatplacement| to save the current user parameters in +% internal registers. Then we start a new group and save the +% |\@deferlist| temporarily in the macro |\@tempb|. +% \begin{macrocode} +\def\process@deferreds{% + \@floatplacement + \@tryfcolumn\@deferlist + \if@fcolmade\else + \begingroup + \let\@tempb\@deferlist +% \end{macrocode} +% Our next action is to (globally) empty |\@deferlist| and +% assign a new meaning to |\@elt|. Here |\@scolelt| is a +% macro that looks at the boxes in a list to decide whether they +% should be placed on the next page (i.e.\ on |\@toplist| or +% |\@botlist|) or should wait for further processing. +% \begin{macrocode} + \gdef\@deferlist{}% + \let\@elt\@scolelt +% \end{macrocode} +% Now we call |\@tempb| which has the form +% \begin{center} +% |\@elt|\meta{box register}|\@elt|^^A +% \meta{box register}\ldots{} +% \end{center} +% So |\@elt| (i.e.\ |\@scolelt|) will distribute the +% boxes to the three lists. +% \begin{macrocode} + \@tempb \endgroup + \fi} +% \end{macrocode} +% \end{macro} +% +% +% +% \begin{macro}{ifshr@nking} +% \begin{macro}{\raggedcolumns} +% \begin{macro}{\flushcolumns} +% \changes{v1.1a}{1989/09/20}{\cs{flushedcolumns} renamed to \cs{flushcolumns}.} +% The |\raggedcolumns| and |\flushcolumns| +% declarations are defined with the help of a new |\if...| +% macro. +% \begin{macrocode} +\newif\ifshr@nking +% \end{macrocode} +% The actual definitions are simple: we just switch to {\sf true} +% or {\sf false} depending on the desired action. To avoid extra +% spaces in the output we enclose these changes in +% |\@bsphack|\ldots{}\allowbreak|\@esphack|. +% \begin{macrocode} +\def\raggedcolumns{% + \@bsphack\shr@nkingtrue\@esphack} +\def\flushcolumns{% + \@bsphack\shr@nkingfalse\@esphack} +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \begin{macro}{\balance@columns@out} +% Now for the last part of the show: the column balancing output +% routine. Since this code is called with an explicit penalty +% (|\eject|) there is no need to check for something special (eg +% floats). We start by balancing the material gathered. +% \begin{macrocode} +\def\balance@columns@out{% +% \end{macrocode} +% For this we need to put the contents of box 255 into |\mult@box|. +% \begin{macrocode} +%<-colbreak> \setbox\mult@box +%<-colbreak> \vbox{\unvbox\@cclv}% +% \end{macrocode} +% \changes{v1.5u}{1999/05/25}{Support \cs{columnbreak}} +% \changes{v1.5v}{1999/07/18}{Added debug statements for +% column break support} +% For the next block of code see comments in section~\ref{sec:colbreak}. +% \begin{macrocode} +%<*colbreak> + \setbox\mult@box\vbox{% + \ifvoid\colbreak@box\else + \unvbox\colbreak@box\break + \mult@info\@ne{Re-adding + forced break(s) in balancing}% + \fi + \unvbox\@cclv}% +%</colbreak> + \balance@columns +% \end{macrocode} +% This will bring us into the position to apply |\page@sofar|. +% But first we have to set |\vsize| to a value suitable for +% one column output. +% \begin{macrocode} + \global\vsize\@colroom + \global\advance\vsize\ht\partial@page +% \end{macrocode} +% Then we |\unvbox| the |\partial@page| (which may be void if we +% are not prcessing the first page of this \mc{} environment. +% \begin{macrocode} + \unvbox\partial@page +% \end{macrocode} +% Then we return the first and bottom mark and the gathered +% material to the main vertical list. +% \begin{macrocode} + \return@nonemptymark{first}\kept@firstmark + \return@nonemptymark{bot}\kept@botmark + \page@sofar +% \end{macrocode} +% We need to add a penalty at this point which allows to break at +% this point since calling the output routine may have removed the +% only permissible break point thereby ``glueing'' any following +% skip to the balanced box. In case there are any weird settings +% for |\multicolsep| etc. this could produce funny results. +% \changes{v1.5c}{1993/04/18}{added penalty at output routine exit} +% \begin{macrocode} + \penalty\z@ +} +% \end{macrocode} +% As we already know, reinserting of footnotes will be done in the +% macro |\endmulticols|. +% \end{macro} +% +% +% \begin{macro}{\balance@columns} +% This macro now does the actual balancing. +% \begin{macrocode} +\def\balance@columns{% +% \end{macrocode} +% We start by setting the kept marks by updating them with any +% marks from this box. This has to be done \emph{before} we add a +% penalty of $-10000$ to the top of the box, otherwise only an +% empty box will be considered. +% \changes{v1.5h}{1994/08/26}{Get kept marks first} +% \begin{macrocode} + \get@keptmarks\mult@box +% \end{macrocode} +% We then contine by resetting trying to remove any discardable +% stuff at the end of |\mult@box|. This is rather experimental. We +% also add a forced break point at the very beginning, so that we +% can split the box to height zero later on, thereby adding a known +% |\splittopskip| glue at the beginning. +% \begin{macrocode} + \setbox\mult@box\vbox{% + \penalty-\@M + \unvbox\mult@box + \remove@discardable@items + }% +% \end{macrocode} +% Then follow values assignments to get the |\vsplit|ting right. +% We use the natural part of |\topskip| as the natural part for +% |\splittopskip| and allow for a bit of undershoot and overshoot +% by adding some stretch and shrink. +% \changes{v1.5?}{1994/?/?}{Allow columns to come out a bit long or short} +% \begin{macrocode} + \@tempdima\topskip + \splittopskip\@tempdima + \@plus\multicolundershoot + \@minus\multicolovershoot + \splitmaxdepth\maxdepth +% \end{macrocode} +% The next step is a bit tricky: when \TeX{} assembles material in +% a box, the first line isn't preceded by interline glue, i.e. +% there is no parameter like |\boxtopskip| in \TeX{}. This means +% that the baseline of the first line in our box is at some +% unpredictable point depending on the height of the largest +% character in this line. But of course we want all columns to +% align properly at the baselines of their first lines. For this +% reason we have opened |\mult@box| with a |\penalty| {\sf -10000}. +% This will now allow us to split off from |\mult@box| a tiny bit +% (in fact nothing since the first possible break-point is the +% first item in the box). The result is that |\splittopskip| is +% inserted at the top of |\mult@box| which is exactly what we like +% to achieve. +% \changes{v1.5?}{1994/?/?}{Do splitting to zero here} +% \begin{macrocode} + \setbox\@tempboxa\vsplit\mult@box to\z@ +% \end{macrocode} +% Next we try to find a suitable starting point for the calculation +% of the column height. It should be less than the height finally +% chosen, but large enough to reach this final value in only a few +% iterations. The formula which is now implemented will try to +% start with the nearest value which is a multiple of +% |\baselineskip|. The coding is slightly tricky in \TeX{} and +% there are perhaps better ways \ldots +% \changes{v1.4d}{1992/03/04}{New algorithm for start height} +% \begin{macrocode} + \@tempdima\ht\mult@box + \advance\@tempdima\dp\mult@box + \divide\@tempdima\col@number +% \end{macrocode} +% The code above sets |\@tempdima| to the length of a column if we +% simply divide the whole box into equal pieces. To get to the next +% lower multiple of |\baselineskip| we convert this dimen to a +% number (the number of scaled points) then divide this by +% |\baselineskip| (also in scaled points) and then multiply this +% result with |\baselineskip| assigning the result to |\dimen@|. +% This makes |\dimen@| $\leq$ to |\@tempdimena|. +% \begin{macrocode} + \count@\@tempdima + \divide\count@\baselineskip + \dimen@\count@\baselineskip +% \end{macrocode} +% Next step is to correct our result by taking into account the +% difference between |\topskip| and |\baselineskip|. We start by +% adding |\topskip|; if this makes the result too large then we +% have to subtract one |\baselineskip|. +% \begin{macrocode} + \advance\dimen@\topskip + \ifdim \dimen@ >\@tempdima + \advance\dimen@-\baselineskip + \fi +% \end{macrocode} +% At the user's request we start with a higher value (or lower, but +% this usually only increases the number of tries). +% \begin{macrocode} + \advance\dimen@\c@unbalance\baselineskip +% \end{macrocode} +% We type out statistics if we were asked to do so. +% \changes{v1.4f}{1992/04/28}{\cs{on@line} added to tracing info} +% \begin{macrocode} + \mult@info\@ne + {Balance columns\on@line: + \ifnum\c@unbalance=\z@\else + (off balance=\number\c@unbalance)\fi + \@gobbletwo}% +% \end{macrocode} +% But we don't allow nonsense values for a start. +% \begin{macrocode} + \ifnum\dimen@<\topskip + \mult@info\@ne + {Start value + \the\dimen@ \space -> + \the\topskip \space (corrected)}% + \dimen@\topskip + \fi +% \end{macrocode} +% Now we try to find the final column height. We start by setting +% |\vbadness| to infinity (i.e.\ $10000$) to suppress +% underfull box reports while we are trying to find an acceptable +% solution. We do not need to do it in a group since at the end of +% the output routine everything will be restored. The setting of +% the final columns will nearly always produce underfull boxes with +% badness $10000$ so there is no point in warning the user about +% it. +% \changes{v1.2a}{1990/02/05}{Group around main loop removed.} +% \begin{macrocode} + \vbadness\@M +% \end{macrocode} +% We also allow for overfull boxes while we trying to split the +% columns. +% \begin{macrocode} + \vfuzz \col@number\baselineskip +% \end{macrocode} +% The variable |\last@try| will hold the dimension used in the +% previous trial splitting. We initialize it with a negative value. +% \changes{v1.5?}{1994/?/?}{Initialize \cs{last@try}} +% \begin{macrocode} + \last@try-\p@ + \loop +% \end{macrocode} +% In order not to clutter up \TeX{}'s valuable main memory with +% things that are no longer needed, we empty all globally used box +% registers. This is necessary if we return to this point after an +% unsuccessful trial. We use |\process@cols| for this purpose, +% starting with |\mult@grightbox|. Note the extra braces around +% this macro call. They are needed since \PlainTeX{}'s +% |\loop|\ldots{}\allowbreak|\repeat| mechanism cannot be nested on +% the same level of grouping. +% \changes{v1.5a}{1992/11/04}{New box mechanism} +% \begin{macrocode} + {\process@cols\mult@grightbox + {\global\setbox\count@ + \box\voidb@x}}% +% \end{macrocode} +% The contents of box |\mult@box| are now copied globally to +% box~|\mult@grightbox|. (This will be the right-most column, as +% we shall see later.) +% \begin{macrocode} + \global\setbox\mult@grightbox + \copy\mult@box +% \end{macrocode} +% We start with the assumption that the trial will be successful. +% If we end up with a solution that is too bad we set +% |too@bad| to \texttt{true}. +% \changes{v1.5b}{1992/11/05}{New badness mechanism} +% \begin{macrocode} +%<*badness> + \global\too@badfalse +%</badness> +% \end{macrocode} +% Using |\vsplit| we extract the other columns from box register +% |\mult@grightbox|. This leaves box register |\mult@box| +% untouched so that we can start over again if this trial was +% unsuccessful. +% \begin{macrocode} + {\process@cols\mult@firstbox{% + \global\setbox\count@ + \vsplit\mult@grightbox to\dimen@ +% \end{macrocode} +% After every split we check the badness of the resulting column, +% normally the amount of extra white in the column. +% \begin{macrocode} +%<*badness> + \ifnum\c@tracingmulticols>\@ne + \@tempcnta\count@ + \advance\@tempcnta-\mult@grightbox + \divide\@tempcnta \tw@ + \message{^^JColumn + \number\@tempcnta\space + badness: \the\badness\space}% + \fi +% \end{macrocode} +% If this badness is larger than the allowed column badness +% we reject this solution by setting |too@bad| to \texttt{true}. +% \begin{macrocode} + \ifnum\badness>\c@columnbadness + \ifnum\c@tracingmulticols>\@ne + \message{too bad + (>\the\c@columnbadness)}% + \fi + \global\too@badtrue + \fi +%</badness> + }}% +% \end{macrocode} +% There is one subtle point here: while all other constructed boxes +% have a depth that is determined by |\splitmaxdepth| the last box +% will get a natural depth disregarding the original setting and +% the value of |\splitmaxdepth| or |\boxmaxdepth|. This means that +% we may end up with a very large depth in box |\mult@grightbox| +% which would +% make the result of the testing incorrect. So we change the value +% by unboxing the box into itself. +% \begin{macrocode} + \boxmaxdepth\maxdepth + \global\setbox\mult@grightbox + \vbox{\unvbox\mult@grightbox}% +% \end{macrocode} +% We also save a copy |\mult@firstbox| at its ``natural'' size +% for later use. +% \begin{macrocode} + \setbox\mult@nat@firstbox + \vbox{\unvcopy\mult@firstbox}% +% \end{macrocode} +% After |\process@cols| has done its job we have the following +% situation: +% \begin{center} +% \begin{tabular}{r@{$\:\:\longleftarrow\:\:$}l} +% box |\mult@rightbox| & all material \\ +% box |\mult@gfirstbox| & first column \\ +% box |\mult@gfirstbox|${}+2$ & second column \\ +% \multicolumn{1}{c}{$\vdots$} & +% \multicolumn{1}{c}{$\vdots$} \\ +% box |\mult@grightbox| & last column +% \end{tabular} +% \end{center} +% We report the height of the first column, in brackets +% the natural size is given. +% \changes{v1.5?}{1994/?/?}{Show natural size} +% \begin{macrocode} + \ifnum\c@tracingmulticols>\@ne + \message{^^JFirst column + = \the\dimen@\space + (\the\ht\mult@nat@firstbox)}\fi +% \end{macrocode} +% If |\raggedcolumns| is in force older releases of this file also +% shrank the first column to its natural height at this point. +% This was done so that the first column doesn't run short compared +% to later columns but it is actually producing incorrect results +% (overprinting of text) in boundary cases, so since version v1.5q +% |\raggedcolumns| means allows for all columns to run slightly short. +% \changes{v1.5q}{1998/01/19}{Do not reset \cs{mult@firstbox} (pr2739)} +% \begin{macrocode} +% \ifshr@nking +% \global\setbox\mult@firstbox +% \copy\mult@nat@firstbox +% \fi +% \end{macrocode} +% Then we give information about the last column.\footnote{With +% \TeX{} version 3.141 it is now possible to use \LaTeX's +% \cs{newlinechar} in the \cs{message} command, but +% people with older \TeX{} versions will now get +% \texttt{\string^\string^J} instead of a new line on the screen.} +% \changes{v1.4a}{1992/02/12}{Changed to proper \cs{endlinechar} in\cs{message}} +% \begin{macrocode} + \ifnum\c@tracingmulticols>\@ne + \message{<> last column = + \the\ht\mult@grightbox^^J}% +% \end{macrocode} +% Some tracing code that we don't compile into the production version +% unless asked for. It will produce huge listings of the boxes +% involved in balancing in the transcript file. +% \begin{macrocode} +%<*debug> + \ifnum\c@tracingmulticols>4 + {\showoutput + \batchmode + \process@cols\@ne + {\showbox\count@}}% + \errorstopmode + \fi +%</debug> + \fi +% \end{macrocode} +% We check whether our trial was successful. The test used is very +% simple: we merely compare the first and the last column. Thus +% the intermediate columns may be longer than the first if +% |\raggedcolumns| is used. If the right-most column is +% longer than the first then we start over with a larger value for +% |\dimen@|. +% \changes{v1.3c}{1991/03/03}{\cs{global}\cs{advance} left over from older code} +% \begin{macrocode} + \ifdim\ht\mult@grightbox >\dimen@ +% \end{macrocode} +% If the height of the last box is too large we mark this trial as +% unsuccessful. +% \changes{v1.5v}{1999/07/18}{Added tracing statements for +% trial unsuccesful} +% \begin{macrocode} +%<*badness> + \too@badtrue + \ifnum\c@tracingmulticols>\@ne + \typeout{Rejected: last + column too large!}% + \fi + \else +% \end{macrocode} +% \changes{v1.5v}{1999/07/18}{Check last column if it contains forced +% break and reject trial if that is the case} +% +% To ensure that there isn't a forced break in the last column we +% try to split off a box of size |\maxdimen| from |\mult@grightbox| +% (or rather from a copy of it). This should result in a void box +% after the split, unless there was a forced break somewhere within +% the column in which case the material after the break would have +% stayed in the box. +% \begin{macrocode} +%<*colbreak> + \setbox\@tempboxa + \copy\mult@grightbox + \setbox\z@\vsplit\@tempboxa to\maxdimen + \ifvoid\@tempboxa +%</colbreak> +% \end{macrocode} +% Thus if |\@tempboxa| is void we have a valid solution. +% In this case we take a closer +% look at the last column to decide if this column should be made +% as long as all other columns or if it should be allowed to be +% shorter. +% For this we first have to rebox the column into a box of the +% appropriate height. If tracing is enabled we then display the +% badness for this box. +% \begin{macrocode} + \global\setbox\mult@grightbox + \vbox to\dimen@ + {\unvbox\mult@grightbox}% + \ifnum\c@tracingmulticols>\@ne + \message{Final badness: + \the\badness}% + \fi +% \end{macrocode} +% We then compare this badness with the allowed badness for the final +% column. If it does not exceed this value we use the box, otherwise +% we rebox it once more and add some glue at the bottom. +% \begin{macrocode} + \ifnum\badness>\c@finalcolumnbadness + \global\setbox\mult@grightbox + \vbox to\dimen@ + {\unvbox\mult@grightbox\vfill}% + \ifnum\c@tracingmulticols>\@ne + \message{ setting natural + (> \the\c@finalcolumnbadness)}% + \fi + \fi +% \end{macrocode} +% If |\@tempboxa| above was not void our trial was unsuccessful and +% we report this fact and try again. +% \begin{macrocode} +%<*colbreak> + \else + \too@badtrue + \ifnum\c@tracingmulticols>\@ne + \typeout{Rejected: unprocessed + forced break(s) in last column!}% + \fi + \fi + \fi +%</colbreak> +% \end{macrocode} +% If the natural height of the first box is smaller than the +% current trial size but is larger than the previous trial size it +% is likely that we have missed a potientially better +% solution. (This could have happened if for some reason our first +% trial size was too high.) In that case we dismiss this trial and +% restart using the natural height for the next trial. +% \begin{macrocode} + \ifdim\ht\mult@nat@firstbox<\dimen@ + \ifdim\ht\mult@nat@firstbox>\last@try + \too@badtrue + \ifnum\c@tracingmulticols>\@ne + \typeout{Retry: using natural + height of first column!}% + \fi + \dimen@\ht\mult@nat@firstbox + \last@try\dimen@ + \advance\dimen@-\p@ + \fi + \fi +% \end{macrocode} +% Finally the switch |too@bad| is tested. If it was made true +% either earlier on or due to a rightmost column being too large +% we try again with a slightly larger value for |\dimen@|. +% \begin{macrocode} + \iftoo@bad +%</badness> + \advance\dimen@\p@ + \repeat +% \end{macrocode} +% At that point |\dimen@| holds the height that was determined by +% the balancing loop. +% If that height for the columns turns out to be larger +% than the available space (which is |\@colroom|) we sqeeze the +% columns into the space assuming that they will have enough +% shrinkability to allow this.\footnote{This might be wrong, since +% the shrinkability that accounts for the amount of material might +% be present only in some columns. But it is better to try then to +% give up directly.} +% However, this squeezing should only be done if we are balancing +% columns on the main galley and \emph{not} if we are building a +% boxed multicol (in the latter case the current |\@colroom| is +% irrelevant since the produced box might be moved anywhere at a +% later stage). +% \changes{v1.3c}{1991/03/03}{Limit column height to \cs{@colroom}} +% \changes{v1.5q}{1998/01/19}{Removed setting \cs{dimen@} (pr2739)} +% \changes{v1.5y}{2000/06/10}{Limit column height only in unrestricted +% mode (pr/3212)} +% \begin{macrocode} + \if@boxedmulticols\else + \ifdim\dimen@>\@colroom + \dimen@\@colroom + \fi + \fi +% \end{macrocode} +% Then we move the contents of the odd-numbered box registers to +% the even-numbered ones, shrinking them if requested. +% We have to use |\vbox| not |\vtop| (as it was done in +% the first versions) since otherwise the resulting boxes will have +% no height (\TB\/ page 81). This would mean that extra +% |\topskip| is added when the boxes are returned to the +% page-builder via |\page@sofar|. +% \changes{v1.3a}{1990/05/20}{Changed \cs{vtop} to \cs{vbox}.} +% \begin{macrocode} + \process@cols\mult@rightbox + {\@tempcnta\count@ + \advance\@tempcnta\@ne + \setbox\count@\vbox to\dimen@ + {% +% \end{macrocode} +% +% \begin{macrocode} + \vskip \z@ + \@plus-\multicolundershoot + \@minus-\multicolovershoot + \unvbox\@tempcnta + \ifshr@nking\vfill\fi}}% +} +% \end{macrocode} +% \end{macro} +% +% \end{multicols} +% +% \begin{multicols}{2}[\subsection{The box allocations}] +% +% \begin{macro}{\mult@rightbox} +% \begin{macro}{\mult@grightbox} +% \begin{macro}{\mult@firstbox} +% \begin{macro}{\mult@gfirstbox} +% Early releases of these macros used the first box registers +% 0, 2, 4,\ldots\ for global boxes and 1, 3, 5,\ldots\ for the +% corresponding local boxes. (You might still find some traces +% of this setup in the documentation, sigh.) This produced a problem +% at the moment we had more than 5 columns because then officially +% allocated boxes were overwritten by the algorithm. +% The new release now uses private box registers +% \begin{macrocode} +\newbox\mult@rightbox +\newbox\mult@grightbox +\newbox\mult@gfirstbox +\newbox\mult@firstbox +\newbox\@tempa\newbox\@tempa +\newbox\@tempa\newbox\@tempa +\newbox\@tempa\newbox\@tempa +\newbox\@tempa\newbox\@tempa +\newbox\@tempa\newbox\@tempa +\newbox\@tempa\newbox\@tempa +\newbox\@tempa\newbox\@tempa +\newbox\@tempa\newbox\@tempa +\newbox\@tempa +\let\@tempa\relax +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \end{multicols} +% +% +% \begin{multicols}{2}[\section{New macros and hacks for version 1.2}] +% +% \begin{macro}{\emergencystretch} +% \begin{macro}{\setemergencystretch} +% If we don't use \TeX{} 3.0 |\emergencystretch| is undefined +% so in this case we simply add it as an unused \meta{dimen} +% register. +% \changes{v1.4j}{1992/06/25}{Setting of \cs{emergencystretch} on top +% removed.} +% \begin{macrocode} +\@ifundefined{emergencystretch} + {\newdimen\emergencystretch}{} +% \end{macrocode} +% \changes{v1.2a}{1990/02/05}{Macro added.} +% My tests showed that the following formula worked pretty well. +% Nevertheless the |\setemergencystretch| macro also gets +% |\hsize| as second argument to enable the user to try +% different formulae. +% \begin{macrocode} +\def\setemergencystretch#1#2{% + \emergencystretch 4pt + \multiply\emergencystretch#1} +% \end{macrocode} +% \end{macro} +% \end{macro} + + +% \begin{macro}{\set@floatcmds} +% \changes{v1.2a}{1990/02/05}{Macro added.} +% \changes{v1.5g}{1994/06/07}{Updated since floats have changed} +% \changes{v1.5j}{1994/06/07}{Updated since floats have changed again} +% \changes{v1.5l}{1995/10/19}{Added \cmd{@largefloatcheck}} +% Even if this should be used as a hook we use a |@| in the +% name since it is more for experts. +% \begin{macrocode} +\def\set@floatcmds{% + \let\@dblfloat\@dbflt + \def\end@dblfloat{\par + \vskip\z@ + \egroup + \color@endbox + \@largefloatcheck + \outer@nobreak +% \end{macrocode} +% This is cheap (defering the floats until after the current page) +% but any other solution would go deep into \LaTeX's output +% routine and I don't like to work on it until I know which parts +% of the output routine have to be reimplemented anyway for +% \LaTeX3. +% \begin{macrocode} + \ifnum\@floatpenalty<\z@ +% \end{macrocode} +% We have to add the float to the |\@deferlist| because we assume +% that outside the \mc{} environment we are in one column mode. +% This is not entirely correct, I already used the \mc{} +% environment inside of \LaTeX{}s |\twocolumn| declaration but it +% will do for most applications. +% \begin{macrocode} + \@cons\@deferlist\@currbox + \fi + \ifnum\@floatpenalty=-\@Mii + \@Esphack + \fi}} +% \end{macrocode} +% \end{macro} +% +% \end{multicols} +% +% \begin{multicols}{2}[\subsection{Maintaining the mark registers}] +% \label{sec:v14} +% +% This section contains the routines that set the marks so that they +% will be handled correctly. They have been introduced with version~1.4. +% +% \begin{macro}{\kept@topmark} +% \changes{v1.4h}{1992/06/04}{Init to double brace pair} +% \begin{macro}{\kept@firstmark} +% \begin{macro}{\kept@botmark} +% First thing we do is to reserve three macro names to hold the +% replacement text for \TeX's primitives |\firstmark|, |\botmark| and +% |\topmark|. We initialize the first two to be empty and +% |\kept@topmark| to contain two empty pair of braces. This is +% necessary since |\kept@topmark| is supposed to contain the last +% mark from a preceding page and in \LaTeX{} any ``real'' mark must +% contain two parts representing left and right mark information. +% \begin{macrocode} +\def\kept@topmark{{}{}} +\let\kept@firstmark\@empty +\let\kept@botmark\@empty +% \end{macrocode} +% \end{macro} +% \end{macro} +% \end{macro} +% +% +% \begin{macro}{\return@nonemptymark} +% Sometimes we want to return the value of a ``kept'' mark into a +% |\mark| node on the main vertical list. This is done by the +% function |\return@nonemptymark|. As the name suggests it only acts +% if the replacement text of the kept mark is non-empty. This is done +% to avoid adding an empty mark when no mark was actually present. If +% we would nevertheless add such a mark it would be regarded as a +% valid |\firstmark| later on. +% \begin{macrocode} +\def\return@nonemptymark#1#2{% + \ifx#2\@empty + \else +% \end{macrocode} +% For debugging purposes we take a look at the value of the kept mark +% that we are about to return. This code will get stripped out for +% production. +% \begin{macrocode} +%<*marktrace> + \mult@info\tw@ + {Returned #1 mark:\MessageBreak + \meaning#2}% +% \nobreak +% \fi +%</marktrace> +% \end{macrocode} +% Since the contents of the mark may be arbitrary \LaTeX{} code we +% better make sure that it doesn't get expanded any further. (Some +% expansion have been done already during the execution of +% |\markright| or |\markboth|.) We therefore use the usual mechanism +% of a toks register to prohibit expansion.\footnote{Due to the +% current definition of \cs{markright} etc.\ it wouldn't +% help to define the \cs{protect} command to prohibit +% expansion as any \cs{protect} has already vanished due to +% earlier expansions.} +% \changes{v1.4n}{1992/09/10}{Make marks robust} +% \changes{v1.5t}{1999/03/22}{re-add \cs{mark} command which was commented out +% by mistake at some point in 1998 (pr/2978)} +% \begin{macrocode} + \toks@\expandafter{#2}% + \mark{\the\toks@}% +% \end{macrocode} +% We don't want any breakpoint between such a returned mark and the +% following material (which is usually just the box where the mark +% came from). +% \begin{macrocode} + \nobreak + \fi} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\get@keptmarks} +% If we have some material in a box register we may want to get the +% first and the last mark out of this box. This can be done with +% |\get@keptmarks| which takes one argument: the box register number +% or its nick name defined by |\newbox|. +% \begin{macrocode} +\def\get@keptmarks#1{% +% \end{macrocode} +% For debugging purposes we take a look at the current dimensions +% of the box since in earlier versions of the code I made some +% mistakes in this area. +% \begin{macrocode} +%<*debug> + \typeout{Mark box #1 before: + ht \the\ht#1, dp \the\dp#1}% +%</debug> +% \end{macrocode} +% Now we open a new group an locally copy the box to itself. As a +% result any operation, i.e.\ |\vsplit|, will only have a local +% effect. Without this trick the box content would get lost up to +% the level where the last assignment to the box register was done. +% \begin{macrocode} + \begingroup + \vbadness\@M + \setbox#1\copy#1% +% \end{macrocode} +% Now we split the box to the maximal possible dimension. This +% should split off the full contents of the box so that effectively +% everything is split off. As a result |\splitfirstmark| and +% |\splitbotmark| will contain the first and last mark in the box +% respectively. +% \begin{macrocode} + \setbox#1\vsplit#1to\maxdimen +% \end{macrocode} +% Therefore we can now set the kept marks which is a global +% operation and afterwards close the group. This will restore the +% original box contents. +% \begin{macrocode} + \set@keptmarks + \endgroup +% \end{macrocode} +% For debugging we take again a look at the box dimension which +% shouldn't have changed. +% \begin{macrocode} +%<*debug> + \typeout{Mark box #1 \space after: + ht \the\ht#1, dp \the\dp#1}% +%</debug> +} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\set@keptmarks} +% The macro |\set@keptmarks| is responsible for setting +% |\kept@firstmark| and |\kept@botmark|, by checking the current +% values for |\splitfirstmark| and |\splitbotmark|. +% \begin{macrocode} +\def\set@keptmarks{% +% \end{macrocode} +% If |\kept@firstmark| is empty we assume that it isn't set. This +% is strictly speaking not correct as we loose the ability to have +% marks that are explicitly empty, but for standard \LaTeX{} +% application it is sufficient. If it is non-empty we don't change +% the value---within the output routines it will then be restored +% to |\@empty|. +% \begin{macrocode} + \ifx\kept@firstmark\@empty +% \end{macrocode} +% We now put the contents of |\splitfirstmark| into +% |\kept@firstmark|. In the case that there wasn't any mark at all +% |\kept@firstmark| will not change by that operation. +% \begin{macrocode} + \expandafter\gdef\expandafter + \kept@firstmark + \expandafter{\splitfirstmark}% +% \end{macrocode} +% When debugging we show the assignment but only when something +% actually happened. +% \begin{macrocode} +%<*marktrace> + \ifx\kept@firstmark\@empty\else + \mult@info\tw@ + {Set kept first mark:\MessageBreak + \meaning\kept@firstmark% + \@gobbletwo}% + \fi +%</marktrace> + \fi +% \end{macrocode} +% We always try to set the bottom mark to the |\splitbotmark| but +% of course only when there has been a |\splitbotmark| at all. +% Again, we assume that an empty |\splitbotmark| means that the +% split off box part didn't contain any marks at all. +% \begin{macrocode} + \expandafter\def\expandafter\@tempa + \expandafter{\splitbotmark}% + \ifx\@tempa\@empty\else + \global\let\kept@botmark\@tempa +%<*marktrace> + \mult@info\tw@ + {Set kept bot mark:\MessageBreak + \meaning\kept@botmark% + \@gobbletwo}% +%</marktrace> + \fi}% +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\prep@keptmarks} +% The |\prep@keptmarks| function is used to initialize the kept +% marks from the contents of |\partial@page|, i.e.\ the box that +% holds everything from the top of the current page prior to +% starting the \mc{} environment. However, such a box is only +% available if we are not producing a boxed \mc{}. +% \begin{macrocode} +\def\prep@keptmarks{% + \if@boxedmulticols \else + \get@keptmarks\partial@page + \fi} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\remove@discardable@items} +% +% \begin{macrocode} +\def\remove@discardable@items{% +%<*debug> + \edef\@tempa{s=\the\lastskip, + p=\the\lastpenalty, + k=\the\lastkern}% + \typeout\@tempa +%</debug> + \unskip\unpenalty\unkern +%<*debug> + \edef\@tempa{s=\the\lastskip, + p=\the\lastpenalty, + k=\the\lastkern}% + \typeout\@tempa +%</debug> + \unskip\unpenalty\unkern +%<*debug> + \edef\@tempa{s=\the\lastskip, + p=\the\lastpenalty, + k=\the\lastkern}% + \typeout\@tempa +%</debug> + \unskip\unpenalty\unkern +%<*debug> + \edef\@tempa{s=\the\lastskip, + p=\the\lastpenalty, + k=\the\lastkern}% + \typeout\@tempa +%</debug> + \unskip\unpenalty\unkern +} +% \end{macrocode} +% \end{macro} +% +% \begin{macrocode} +%<*badness> +\newif\iftoo@bad +% \end{macrocode} +% +% \begin{macro}{\c@columnbadness} +% \begin{macro}{\c@finalcolumnbadness} +% \begin{macrocode} +\newcount\c@columnbadness +\c@columnbadness=10000 +\newcount\c@finalcolumnbadness +\c@finalcolumnbadness=9999 + +\newdimen\last@try + +% \end{macrocode} +% +% \changes{v1.5z1}{2003/02/17}{Change wrong default for +% \cs{multicolovershoot} to zero (pr/3465).} +% \begin{macrocode} +\newdimen\multicolovershoot +\newdimen\multicolundershoot +\multicolovershoot=0pt +\multicolundershoot=2pt +\newbox\mult@nat@firstbox +%</badness> +% \end{macrocode} +% \end{macro} +% \end{macro} +% +% \begin{macro}{\mult@info} +% A helper for producing info messages +% \begin{macrocode} +\def\mult@info#1#2{% + \ifnum\c@tracingmulticols>#1% + \GenericWarning + {(multicol)\@spaces\@spaces}% + {Package multicol: #2}% + \fi +} +% \end{macrocode} +% \end{macro} +% +% \end{multicols} +% +% +% \begin{multicols}{2}[\section{Fixing the +% \cs{columnwidth}}] +% +% \begin{macro}{\@footnotetext} +% \changes{v1.5o}{1997/11/16}{Redefinition added pr/2664.} +% \changes{v1.5r}{1998/08/17}{Use \cs{@footnotetext} but with +% local change to \cs{columnwidth}.} +% \begin{macro}{\mult@footnotetext} +% \changes{v1.5r}{1998/08/17}{Macro removed again.} +% If we store the current column width in |\columnwidth| we have +% to redefine the internal |\@footnotetext| macro to use |\textwidth| +% for the width of the footnotes rather then using the original +% definition. +% +% Starting with version v1.5r this is now done in a way that the original +% definition is still used, execpt that locally |\columnwidth| is set to +% |\textwidth|. +% +% This solves two problems: first redefinitions of |\@footnotetext| +% done by a class will correctly survive and second if multicols is +% used inside a minipage environment the special definition of +% |\@footnotetext| in that environment will be picked up and not the +% one for the main galley (the latter would result in all footnotes +% getting lost in that case). +% +% See the definition of the |\multicols| command further up for the exact +% code. +% \end{macro} +% \end{macro} +% \end{multicols} +% +% +% \begin{multicols*}{2}[\section{Further extensions}] +% +% This section does contain code for extensions added to this package +% over time. Not all of them may be active, some might sit dormant and +% wait for being activated in some later release. +% +% \subsection{Not balancing the columns} +% +% This is fairly trivial to implement. we just have to disable the +% balancing output routine and replace it by the one that ships out +% the other pages. +% +% \begin{macro}{\multicols*} +% \changes{v1.5q}{1998/01/19}{Macro added} +% The code for this environment was suggested by Matthias Clasen. +% \begin{macrocode} +%<*nobalance> + \@namedef{multicols*}{% +% \end{macrocode} +% If we are not on the main galley, i.e., inside a box of some +% sort, that approach will not work since we don't have a vertical +% size for the box so we better warn that we balance anyway. +% \begin{macrocode} + \ifinner + \PackageWarning{multicol}% + {multicols* inside a box does + not make sense.\MessageBreak + Going to balance anyway}% + \else + \let\balance@columns@out + \multi@column@out + \fi + \begin{multicols} +} +% \end{macrocode} +% \end{macro} +% +% \begin{macro}{\endmulticols*} +% When ending the environment we simply end the inner +% \texttt{multicols} environment, except that we better also stick +% in some stretchable vertical glue so that the last column still +% containing text is not vertically stretched out. +% \changes{v1.5q}{1998/01/19}{Macro added} +% \begin{macrocode} + \@namedef{endmulticols*}{\vfill + \end{multicols}} +%</nobalance> +% \end{macrocode} +% \end{macro} +% +% +% \subsection{Manual column breaking} \label{sec:colbreak} +% +% The problem with manual page breaks within \mc{} is the fact that +% during collection of material for all columns a page-forcing penalty +% (i.e. -10000 or higher) would stop the collecting pass which is not +% quite what is desired. On the other hand, using a penalty like -9999 +% would mean that there would be occasions where the |\vsplit|ing +% operations within \mc{} would ignore that penalty and still choose a +% different break point. +% +% For this reason the current implementation +% uses a completely different approach. In a nutshell it extends the \LaTeX{} +% output routine handling by introducing an additional penalty flag +% (i.e., a penalty which is forcing but higher than -10000 so that the +% output routine can look at this value and thus knows why it has been +% called). +% +% Inside the output routine we test for this value and if it appears +% we do two things: save the galley up to this point in a special box +% for later use and reduce the |\vsize| by the height of the material +% seen. This way the forcing penalty is now hidden in that box and we +% can restart the collection process for the remaining +% columns. (This is done in |\speci@ls| above.) +% +% In the output routines that do the |\vsplit|ting either for +% balancing or for a full page we simply combine box~255 with the +% saved box thus getting a single box for splitting which now +% contains forcing breaks in the right positions. +% +% +% \begin{macro}{\columnbreak} +% \changes{v1.5u}{1999/05/25}{Macro added} +% |\columnbreak| is modelled after |\pagebreak| except that we +% generate a penalty -10005. +% \begin{macrocode} +%<*colbreak> +\mathchardef\@Mv=10005 +\def\columnbreak{% +% \end{macrocode} +% We have to ensure that it is only used within a \mc{} +% environment since if that penalty would be seen by the unmodified +% \LaTeX{} output routine strange things would happen. +% \begin{macrocode} + \ifnum\col@number<\tw@ + \PackageError{multicol}% + {\noexpand\columnbreak outside multicols}% + {This command can only be used within + a multicols or multicols* environment.}% + \else + \ifvmode + \penalty -\@Mv\relax + \else + \@bsphack + \vadjust{\penalty -\@Mv\relax}% + \@esphack + \fi + \fi} +% \end{macrocode} +% \end{macro} +% +% +% \begin{macro}{\colbreak@box} +% \changes{v1.5u}{1999/05/25}{Macro added} +% Need a box to collect the galley up to the column break. +% \begin{macrocode} +\newbox\colbreak@box +%</colbreak> +%</package> +% \end{macrocode} +% \end{macro} +% +% \end{multicols*} +% +% \Finale +% +\endinput |