source: JEM-EUSO/esaf_lal/tags/v1_r0/esafdoc/DevelopersGuide/framed.sty @ 117

% framed.sty   v 0.8a   21-Jul-2003
% Copyright (C) 1992-2003 by Donald Arseneau
% These macros may be freely transmitted, reproduced, or modified
% provided that this notice is left intact.
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Create framed or shaded regions that can break across pages using 
% \begin{framed} ... \end{framed}    -- ordinary frame box (box at margin)
% \begin{shaded} ... \end{shaded}    -- shaded background (into margin)
%    ... leftbar ...                 -- line on left side
% \begin{MakeFramed}{settings} ... \end{MakeFramed}
%                        -- generic frame (for new environments)
%
% The "framed" environment puts the text into "\fbox" with the
% settings "\fboxrule=\FrameRule" and "\fboxsep=\FrameSep".
% You can change these lengths (using "\setlength") and you
% can even change the definition of "\FrameCommand" to use
% much fancier boxes.
%
% In fact, the "shaded" environment just redefines "\FrameCommand"
% to use "\colorbox{shadecolor}" (and you have to define the
% color "shadecolor": \newcolor{shadecolor}...).
%
% A page break is allowed, and even encouraged, before the framed
% environment.  If you want to attach some text (a box title) to the
% frame, then the text should be inserted by \FrameCommand
%
% The contents of the framed regions are restricted: 
% Floats, footnotes, marginpars and head-line entries will be lost.
% (Some of these may be handled in a later version.)
% This package will not work with the page breaking of multicol.sty,
% or other systems that perform column-balancing.
%
% The MakeFramed environment does the work.  Its "settings" argument
% should contain any adjustments to the text width (applied to \hsize,
% and using the "\width" of the frame itself) as well as a `restore' 
% command -- \@parboxrestore or \FrameRestore or something similar.
% 
% Expert commands:
% \MakeFramed, \endMakeFramed: the "MakeFramed" environment
% \FrameCommand: command to draw the frame around its argument
% \FrameRestore: restore some text settings, but fewer than \@parboxrestore
% \FrameRule: length register; \fboxrule for default "framed".
% \FrameSep: length register; \fboxsep for default "framed".
% \FrameHeightAdjust: macro; height of frame above baseline at top of page
% 
% This is still a `pre-production' version because I can think of many
% features/improvements that should be made.  Nevertheless, starting 
% with version 0.5 it should be bug-free.
%
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\ProvidesPackage{framed}[2003/07/21 v 0.8a: 
   framed or shaded text with page breaks]

\newenvironment{framed}% using default \FrameCommand
  {\MakeFramed {\advance\hsize-\width \FrameRestore}}%
  {\endMakeFramed}

\newenvironment{shaded}{%
  \def\FrameCommand{\colorbox{shadecolor}}%
  \MakeFramed {\FrameRestore}}%
 {\endMakeFramed}

\newenvironment{leftbar}{%
  \def\FrameCommand{\vrule width 3pt \hspace{10pt}}%
  \MakeFramed {\advance\hsize-\width \FrameRestore}}%
 {\endMakeFramed}

\chardef\FrameRestore=\catcode`\| % for debug
\catcode`\|=\catcode`\% % (debug: insert space after backslash)

\def\MakeFramed#1{\par
 % measure added width and height; call result \width and \height
 \setbox\z@\vbox{\vskip-1in \hbox{\hskip-1in 
   \FrameCommand{\hbox{\vrule \@height .7in \@depth.3in \@width 1in}}}%
   \vskip\z@skip}%
 \def\width{\wd\z@}\def\height{\ht\z@}%
 \edef\fb@frw{\the\width}\edef\fb@frh{\the\height}%
 % insert pre-penalties and skips
 \begingroup
 \skip@\lastskip
 \if@nobreak\else 
    \penalty9999 % updates \page parameters
    \ifdim\pagefilstretch=\z@ \ifdim\pagefillstretch=\z@
       \edef\@tempa{\the\skip@}%
       \ifx\@tempa\zero@glue \penalty-30
       \else \vskip-\skip@ \penalty-30 \vskip\skip@
    \fi\fi\fi
    \penalty\z@
    % Give a stretchy breakpoint that will always be taken in preference
    % to the \penalty 9999 used to update page parameters.  The cube root
    % of 10000/100 indicates a multiplier of 0.21545, but the maximum 
    % calculated badness is really 8192, not 10000, so the multiplier
    % is 0.2301. 
    \advance\skip@ \z@ plus-.5\baselineskip
    \advance\skip@ \z@ plus-.231\height
    \advance\skip@ \z@ plus-.231\skip@
    \advance\skip@ \z@ plus-.231\topsep
    \vskip-\skip@ \penalty 1800 \vskip\skip@
 \fi
 \addvspace{\topsep}%
 \endgroup
 % clear out pending page break
 \penalty\@M \vskip 2\baselineskip \vskip\height
 \penalty9999 \vskip -2\baselineskip \vskip-\height
 \penalty9999 % updates \pagetotal
|\message{After clearout, \pagetotal=\the\pagetotal, \pagegoal=\the\pagegoal. }%
 \fb@adjheight 
 \setbox\@tempboxa\vbox\bgroup
   #1% Modifications to \hsize (can use \width and \height)
   \textwidth\hsize \columnwidth\hsize
}

\def\endMakeFramed{\par
     \kern\z@ \penalty-100 % put depth into height
 \egroup
 \begingroup \put@frame \endgroup
}

% \put@frame takes the contents of \@tempboxa and puts all, or a piece,
% of it on the page with a frame (\FrameCommand).  It recurses until
% all of \@tempboxa has been used up. (\@tempboxa must have zero depth.)

\def\put@frame{\relax
 \ifdim\pagegoal=\maxdimen \pagegoal\vsize \fi
|   \message{=============== Entering putframe ====================^^J
|     \pagegoal=\the\pagegoal,  \pagetotal=\the\pagetotal. }%
 \ifinner \else
    \dimen@\pagegoal \advance\dimen@-\pagetotal % natural space left on page
  \ifdim\dimen@<2\baselineskip 
|   \message{Page has only \the\dimen@\space room left; eject. }%
    \eject \fb@adjheight \put@frame
  \else % there's appreciable room left on the page
|    \message{\string\pagetotal=\the\pagetotal,
|        \string\pagegoal=\the\pagegoal, 
|        \string\pagestretch=\the\pagestretch,
|        \string\pageshrink=\the\pageshrink,
|        \string\fb@frh=\fb@frh. \space}
|    \message{Box of size \the\ht\@tempboxa\space + \fb@frh}%
     \begingroup % temporarily set \dimen@ to be...
     \advance\dimen@.8\pageshrink  % maximum space available on page
     \advance\dimen@-\fb@frh\relax % space available for frame's contents
     \expandafter\endgroup
     % restore \dimen@ to real room left on page
     \ifdim\dimen@>\ht\@tempboxa % whole box does fit
|       \message{fits in \the\dimen@. }%
     \else % box must be split
|       \message{must be split to fit in \the\dimen@. }%
        \setbox\@tempboxa\vbox{% simulate frame and flexiblity of the page:
           \vskip \fb@frh \@plus\pagestretch \@minus.8\pageshrink
           \kern137sp\kern-137sp\penalty-30
           \unvbox\@tempboxa}%
        \edef\fb@resto@set{\boxmaxdepth\the\boxmaxdepth \splittopskip\the\splittopskip}%
        \boxmaxdepth\z@ \splittopskip\z@
        \setbox\tw@\vsplit\@tempboxa to\dimen@
        \setbox\tw@\vbox{\unvbox\tw@}% natural-sized
|       \message{Box of size \the\ht\@tempboxa\space split to \the\dimen@. 
|          Natural height of split box is \the\ht\tw@. }%
        % If the split-to size > (\vsize-\topskip), then set box to full size
        \begingroup
          \advance\dimen@\topskip
          \expandafter\endgroup
        \ifdim\dimen@>\pagegoal
|         \message{Frame is big -- Use up the full column. }%
          \dimen@ii\pagegoal
          \advance\dimen@ii -\topskip
          \advance\dimen@ii \FrameHeightAdjust\relax
        \else  % suspect this is wrong:
          % If the split-to size > feasible room_on_page, rebox it smaller.
          \advance\dimen@.8\pageshrink
          \ifdim\ht\tw@>\dimen@
|           \message{Box too tall; rebox it to \the\dimen@. }%
            \dimen@ii\dimen@
          \else % use natural size
            \dimen@ii\ht\tw@
          \fi
        \fi
        % Re-box contents to desired size \dimen@ii
        \advance\dimen@ii -\fb@frh
        \setbox\tw@\vbox to\dimen@ii \bgroup
        % remove simulated frame and page flexibility:
        \vskip -\fb@frh \@plus-\pagestretch \@minus-.8\pageshrink
        \unvbox\tw@ \unpenalty\unpenalty
        \ifdim\lastkern=-137sp % whole box went to next page
|          \message{box split at beginning! }%
           \egroup \fb@resto@set \eject % (\vskip for frame size was discarded) 
           \fb@adjheight
        \else %
           \egroup \fb@resto@set
           \ifvoid\@tempboxa % it all fit after all
|             \message{box split at end! }%
              \setbox\@tempboxa\box\tw@
           \else % it really did split
|             \message{box split as expected. Its reboxed height is \the\ht\tw@. }%
              \ifdim\wd\tw@>\z@
                \centerline{\FrameCommand{\box\tw@}}%  ??? \centerline bad idea
              \else
|               \message{Zero width means likely blank. Don't frame it (guess)}%
                \box\tw@
              \fi
              \hrule \@height\z@
              \eject
              \fb@adjheight
              \put@frame
  \fi\fi\fi\fi\fi
  \ifvoid\@tempboxa\else
    \centerline{\FrameCommand{\box\@tempboxa}}%
    \nointerlineskip \null %{\showoutput \showlists}
    \penalty-30 \vskip\topsep
  \fi}

\def\fb@adjheight{%
  \vbox to\FrameHeightAdjust{}% get proper baseline skip from above.
  \penalty\@M \nointerlineskip
  \vskip-\FrameHeightAdjust
  \penalty\@M} % useful for tops of pages

\edef\zero@glue{\the\z@skip}

\catcode`\|=\FrameRestore

% Provide configuration commands:
\providecommand\FrameCommand{\fboxrule=\FrameRule \fboxsep=\FrameSep \fbox}
\@ifundefined{FrameRule}{\newdimen\FrameRule \FrameRule=\fboxrule}{}
\@ifundefined{FrameSep} {\newdimen\FrameSep  \FrameSep =3\fboxsep}{}

% Height of frame above first baseline when frame starts a page:
\providecommand\FrameHeightAdjust{6pt}

% \FrameRestore has parts of \@parboxrestore.  See how it is used in the 
% "settings" argument of \MakeFrame.  Previous behavior can be restored by 
% using \@parboxrestore there, or redefining:
% \makeatletter \renewcommand\FrameRestore{\@parboxrestore} \makeatother
\def\FrameRestore{%
  \let\if@nobreak\iffalse
  \let\if@noskipsec\iffalse
%  \let\par\@@par  ??
  \let\-\@dischyph
  \let\'\@acci\let\`\@accii\let\=\@acciii
%  \parindent\z@ \parskip\z@skip    Definitely omit!
%  \everypar{}%  ??
  \linewidth\hsize
%  \@totalleftmargin\z@
%  \leftskip\z@skip \rightskip\z@skip \@rightskip\z@skip
%  \parfillskip\@flushglue \lineskip\normallineskip
%  \baselineskip\normalbaselineskip
  \sloppy
%  \let\\\@normalcr
}

%  Compatibility with previous versions (temporary!):
\let\fram@d=\MakeFramed  \let\endfram@d=\endMakeFramed

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