% framed.sty   v 0.95    2007/10/04
% Copyright (C) 1992-2007 by Donald Arseneau  (asnd@triumf.ca)
% These macros may be freely transmitted, reproduced, or modified
% provided that this notice is left intact.
% 
%====================== Begin Instructions =======================
%
%                       framed.sty
%                       ~~~~~~~~~~
% Create framed, shaded, or differently highlighted regions that can 
% break across pages.  The environments defined are 
%   framed    -- ordinary frame box (\fbox) with edge at margin
%   shaded    -- shaded background (\colorbox) bleeding into margin
%   snugshade -- similar
%   leftbar   -- thick vertical line in left margin
% to be used like
% \begin{framed}
%  copious text
% \end{framed}
%
% But the more general purpose of this package is to facilitate the
% creation of environments that enable page breaking
% within arbitrary decorations using a simple new-environment definition
% incorporating \FrameCommand and
% \begin{MakeFramed}{settings} ... \end{MakeFramed}
%
% The "framed" environment uses "\fbox" as its "\FrameCommand" with 
% the additional settings \fboxrule=\FrameRule and \fboxsep=\FrameSep.
% You can change these lengths (using \setlength) and you can change 
% the definition of \FrameCommand to use much fancier boxes.
%
% In fact, the "shaded" environment just redefines \FrameCommand to be
% \colorbox{shadecolor} (and you have to define the color "shadecolor":
% \definecolor{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;
% as an example, the snugshade environment shows how to suppress excess
% spacing within the box, copying the code from minipage.
%
% 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.
%
% ToDo: 
% Test more varieties of list 
% Improve and correct documentation
% Propagation of \marks
% Handle footnotes (how??) floats (?) and marginpars.
% Stretchability modification.
%======================== End Instructions ========================

\ProvidesPackage{framed}[2007/10/04 v 0.95: 
   framed or shaded text with page breaks]

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

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

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

\newenvironment{snugshade}{%
  \def\FrameCommand{\colorbox{shadecolor}}%
  \MakeFramed {\FrameRestore\@setminipage}}%
 {\par\unskip\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
 \fb@sizeofframe\FrameCommand
 \let\width\fb@frw \let\height\fb@frh
 % insert pre-penalties and skips
 \begingroup
 \skip@\lastskip
 \if@nobreak\else 
    \penalty9999 % updates \page parameters
    \ifdim\pagefilstretch=\z@ \ifdim\pagefillstretch=\z@
       % not infinitely stretchable, so encourage a page break here
       \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@
     \hrule\@width\hsize\@height\z@
     \penalty-100 % put depth into height
 \egroup
  % {\showoutput\showbox\@tempboxa}%
 \begingroup 
   \fb@put@frame\FrameCommand\FirstFrameCommand
 \endgroup
}

% \fb@put@frame takes the contents of \@tempboxa and puts all, or a piece,
% of it on the page with a frame (\FrameCommand, \FirstFrameCommand,
% \MidFrameCommand, or \LastFrameCommand).  It recurses until all of 
% \@tempboxa has been used up. (\@tempboxa must have zero depth.)
% #1 = attempted framing command, if no split
% #2 = framing command if split
% First iteration: Try to fit with \FrameCommand. If it does not fit,
% split for \FirstFrameCommand.
% Later iteration: Try to fit with \LastFrameCommand. If it does not
% fit, split for \MidFrameCommand.
\def\fb@put@frame#1#2{\relax
 \ifdim\pagegoal=\maxdimen \pagegoal\vsize \fi
|   \message{=============== Entering putframe ====================^^J
|     \pagegoal=\the\pagegoal,  \pagetotal=\the\pagetotal. }%
 \ifinner
   \fb@putboxa#1%
   \fb@afterframe
 \else
  \dimen@\pagegoal \advance\dimen@-\pagetotal % natural space left on page
  \ifdim\dimen@<2\baselineskip % Too little room on page
|   \message{Page has only \the\dimen@\space room left; eject. }%
    \eject \fb@adjheight \fb@put@frame#1#2%
  \else % there's appreciable room left on the page
     \fb@sizeofframe#1%
|    \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
     % expand \ifdim, then restore \dimen@ to real room left on page
     \ifdim\dimen@>\ht\@tempboxa % whole box does fit
|       \message{fits in \the\dimen@. }%
        % Use vsplit anyway to capture the marks
        % !!!???!!! MERGE THIS WITH THE else CLAUSE!!!
        \fb@putboxa#1%
        \fb@afterframe
     \else % box must be split
|       \message{must be split to fit in \the\dimen@. }%
        % update frame measurement to use \FirstFrameCommand or \MidFrameCommand
        \fb@sizeofframe#2%
        \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@
|       \message{Padded box of size \the\ht\@tempboxa\space split to \the\dimen@}%
        % Split box here
        \setbox\tw@\vsplit\@tempboxa to\dimen@
|       \toks99\expandafter{\splitfirstmark}%
|       \toks98\expandafter{\splitbotmark}%
|       \message{Marks are: \the\toks99, \the\toks98. }%
        \setbox\tw@\vbox{\unvbox\tw@}% natural-sized
|       \message{Natural height of split box is \the\ht\tw@, leaving 
|          \the\ht\@tempboxa\space remainder. }%
        % 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! }%
           % need work here???
           \egroup \fb@resto@set \eject % (\vskip for frame size was discarded) 
           \fb@adjheight
           \fb@put@frame#1#2% INSERTED ???
        \else % Got material split off at the head
           \egroup \fb@resto@set
           \ifvoid\@tempboxa % it all fit after all
|             \message{box split at end! }%
              \setbox\@tempboxa\box\tw@
              \fb@putboxa#1%
              \fb@afterframe
           \else % it really did split
|             \message{box split as expected. Its reboxed height is \the\ht\tw@. }%
              \ifdim\wd\tw@>\z@
                \wd\tw@\wd\@tempboxa
                \centerline{#2{\box\tw@}}%  ??? \centerline bad idea
              \else
|               \message{Zero width means likely blank. Don't frame it (guess)}%
                \box\tw@
              \fi
              \hrule \@height\z@ \@width\hsize
              \eject
              \fb@adjheight
              \fb@put@frame\LastFrameCommand\MidFrameCommand
  \fi\fi\fi\fi\fi
}

\def\fb@putboxa#1{%
  \ifvoid\@tempboxa
    PackageWarning{framed}{Boxa is void -- discard it. }%
  \else
|   \message{Frame and place boxa. }%
|   %{\showoutput\showbox\@tempboxa}%
    \centerline{#1{\box\@tempboxa}}%
  \fi
}

\def\fb@afterframe{%
    \nointerlineskip \null %{\showoutput \showlists}
    \penalty-30 \vskip\topsep \relax
}

% measure width and height added by frame (#1 = frame command)
% call results \fb@frw and \fb@frh
\newdimen\fb@frw
\newdimen\fb@frh
\def\fb@sizeofframe#1{\begingroup
 \setbox\z@\vbox{\vskip-5in \hbox{\hskip-5in 
   #1{\hbox{\vrule \@height 4.7in \@depth.3in \@width 5in}}}%
   \vskip\z@skip}%
|  \message{Measuring frame addition for \string#1 in \@currenvir\space 
|    gives ht \the\ht\z@\space and wd \the\wd\z@. }%
%{\showoutput\showbox\z@}%
 \global\fb@frw\wd\z@ \global\fb@frh\ht\z@
 \endgroup
}

\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{%
 \setlength\fboxrule{\FrameRule}\setlength\fboxsep{\FrameSep}%
 \fbox}
\@ifundefined{FrameRule}{\newdimen\FrameRule \FrameRule=\fboxrule}{}
\@ifundefined{FrameSep} {\newdimen\FrameSep  \FrameSep =3\fboxsep}{}
\providecommand\FirstFrameCommand{\FrameCommand}
\providecommand\MidFrameCommand{\FrameCommand}
\providecommand\LastFrameCommand{\FrameCommand}

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

% \FrameRestore has parts of \@parboxrestore, performing a similar but 
% less complete restoration of a default layouy.  See how it is used in the 
% "settings" argument of \MakeFrame.  Though not a parameter, \hsize 
% should be set to the desired total line width available inside the
% frame before invoking \FrameRestore.  
\def\FrameRestore{%
   \let\if@nobreak\iffalse
   \let\if@noskipsec\iffalse
   \let\-\@dischyph
   \let\'\@acci\let\`\@accii\let\=\@acciii
   %  \message{FrameRestore:
   %    \@totalleftmargin=\the \@totalleftmargin,
   %    \rightmargin=\the\rightmargin, 
   %    \@listdepth=\the\@listdepth.  }%
   % Test if we are in a list (or list-like paragraph)
   \ifnum \ifdim\@totalleftmargin>\z@ 1\fi  
          \ifdim\rightmargin>\z@ 1\fi
          \ifnum\@listdepth>0 1\fi 0>\z@
     %     \message{In a list: \linewidth=\the\linewidth, \@totalleftmargin=\the\@totalleftmargin,
     %       \parshape=\the\parshape, \columnwidth=\the\columnwidth, \hsize=\the\hsize, 
     %       \labelwidth=\the\labelwidth. }%
     \@setminipage % snug fit around the item
     % Now try to propageate changes of width from \hsize to list parameters.
     % This is deficient, but a more advanced way to indicate modification to text 
     % dimensions is not (yet) provided; in particular, no separate left/right
     % adjustment.
     \advance\linewidth-\columnwidth \advance\linewidth\hsize
     \parshape\@ne \@totalleftmargin \linewidth
   \else % Not in list
     \linewidth=\hsize
     %\message{No list, set \string\linewidth=\the\hsize. }%
   \fi
   \sloppy
}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
