sphinxlatexshadowbox.sty

%% TOPIC AND CONTENTS BOXES
%
% change this info string if making any custom modification
\ProvidesFile{sphinxlatexshadowbox.sty}[2022/06/30 sphinxShadowBox]

% Provides support for this output mark-up from Sphinx latex writer:
%
% - sphinxShadowBox (environment)
%
% Dependencies (they do not need to be defined at time of loading):
%
% - of course the various colour and dimension options handled via sphinx.sty
% - dimension register \spx@image@maxheight from sphinxlatexgraphics.sty
% - \savenotes/\spewnotes from sphinxpackagefootnote
% - \ifspx@inframed defined in sphinx.sty
%
% Requires:
\RequirePackage{framed}

% Let's draw the contents first, then the frame and the shadow last,
% to avoid problems with some pdf viewers.
\long\def\spx@ShadowFBox#1{%
  \leavevmode\begingroup
  % First we prepare a box with the contents and some reserved space for the
  % frame and inner separation; with more parameters we could allow various
  % border widths for top, bottom, left, right, but here all are equal.
  \setbox\@tempboxa
   \hbox{\kern\sphinxshadowrule
         \vbox{\kern\sphinxshadowrule
               \kern\sphinxshadowsep
               \hbox{\kern\sphinxshadowsep #1\kern\sphinxshadowsep}%
               \kern\sphinxshadowsep
               \kern\sphinxshadowrule}%
         \kern\sphinxshadowrule}%
  % Now we rebox, adding the colored frame for which space was reserved.
  \setbox\@tempboxa
   \hbox{\unhcopy\@tempboxa % not \unhbox to be able to refer to \ht, \wd later
         \kern-\wd\@tempboxa
         {\color{sphinxshadowBorderColor}% color push here
          \vrule\@width\sphinxshadowrule% TeX auto-computes the height
          \vbox{\hrule\@height\sphinxshadowrule% TeX auto-computes the width
                \kern\dimexpr\ht\@tempboxa-\sphinxshadowrule\relax
                % This empty \hbox is here to give width used by \hrule
                % As \dp\@tempboxa is zero, the \hbox location is at the
                % bottom of frame.
                \hbox{\kern\dimexpr\wd\@tempboxa-2\sphinxshadowrule\relax}%
                \kern\dimexpr\dp\@tempboxa-\sphinxshadowrule\relax
                \hrule\@height\sphinxshadowrule% TeX auto-computes the width
                }%
          \vrule\@width\sphinxshadowrule% TeX auto-computes the height
         }% color pop will happen here
        }%
  % Now we add the shadow.
  %
  % Formerly, shadow was drawn partly on top of frame, but this was before
  % both frame and shadow acquired colors.  The width of the part of the
  % shadow on the right is hidden, so it will stick into the right page
  % margin.
  %
  % The frame borders are included into this final \hbox, which is sent back
  % to \MakeFramed/\endMakeFramed measurements and then finally to page
  % shipout.  As \advance\hsize-\width appears in \MakeFramed, where \width is
  % the computed extra width added by the framing plus inner separation (so
  % actually 2\sphinxshadowrule+2\sphinxshadowsep), this all means that
  % horizontally the frame will be perfectly adjusted to the *total* text
  % width limits (i.e. independent of current list nesting; but anyhow
  % Docutils does not allow nesting of topic within topics or body elements).
  \hbox{\vbox{\offinterlineskip
              \hbox{\copy\@tempboxa % not \box as we need \wd and \ht next
                    % add shadow on right side
                    \lower\sphinxshadowsize
                          \hbox{{\color{sphinxshadowShadowColor}%
                                 \vrule\@height\ht\@tempboxa \@width\sphinxshadowsize}}%
                    }%
              \kern-\sphinxshadowsize % shift back vertically to bottom of frame
              % and add shadow at bottom
              \moveright\sphinxshadowsize
                    \vbox{{\color{sphinxshadowShadowColor}%
                           \hrule\@width\wd\@tempboxa \@height\sphinxshadowsize}}%
              }%
        % move left by the size of right shadow so shadow adds no width, and
        % will stick into right margin
        % (we did not conceal of course from TeX the depth)
        \kern-\sphinxshadowsize
       }%
  \endgroup
}

% Use framed.sty \MakeFramed/\endMakeFramed to allow page breaks for topic
% boxes.  Originally Sphinx used \shadowbox from fancybox.sty but it did not
% allow pagebreaks (which was problematic for "contents" directive if there
% are many subsections).
%
% Docutils does not allow topic to be nested within topics or other body
% elements.  But the LaTeX code here does allow it:
%
% - a topic inside another topic would be rendered in a minipage (thus not
%   allowing pagebreaks).  Its external frame would adapt perfectly to
%   the *current (smaller) width for text*.
%
% - a topic inside (nested) lists or quote environments would have its frame
%   take the *full width* of the page, but its text contents on the other hand
%   would obey exactly the current indentation plus inner separation.  This is
%   in contrast with the framing used for literal blocks, also based, but in a
%   more sophisticated way on usage of \MakeFramed/\endMakeFramed, and
%   adjusting to current text indentation.
\newenvironment{sphinxShadowBox}
  {\def\FrameCommand {\spx@ShadowFBox }%
   \advance\spx@image@maxheight
   -\dimexpr2\sphinxshadowrule
           +2\sphinxshadowsep
           +\sphinxshadowsize
           +\baselineskip\relax
   % configure framed.sty not to add extra vertical spacing
   \ltx@ifundefined{OuterFrameSep}{}{\OuterFrameSep\z@skip}%
   % the \trivlist will add the vertical spacing on top and bottom which is
   % typical of center environment as used in Sphinx <= 1.4.1
   % the \noindent has the effet of an extra blank line on top, to
   % imitate closely the layout from Sphinx <= 1.4.1; the \FrameHeightAdjust
   % will put top part of frame on this baseline.
   \def\FrameHeightAdjust {\baselineskip}%
   % use package footnote to handle footnotes
   \savenotes
   \trivlist\item\noindent
    % use a minipage if we are already inside a framed environment
    \ifspx@inframed\begin{minipage}{\linewidth}\fi
    \MakeFramed {\spx@inframedtrue
    % framed.sty puts into "\width" the added width (=2shadowsep+2shadowrule)
    % adjust \hsize to what the contents must use
    \advance\hsize-\width
    % adjust LaTeX parameters to behave properly in indented/quoted contexts
    \FrameRestore
    % typeset the contents as in a minipage (Sphinx <= 1.4.1 used a minipage and
    % itemize/enumerate are therein typeset more tightly, we want to keep
    % that). We copy-paste from LaTeX source code but don't do a real minipage.
    \@pboxswfalse
    \let\@listdepth\@mplistdepth \@mplistdepth\z@
    \@minipagerestore
    \@setminipage
    }%
  }%
  {% insert the "endminipage" code
    \par\unskip
    \@minipagefalse
   \endMakeFramed
     \ifspx@inframed\end{minipage}\fi
   \endtrivlist
   % output the stored footnotes
   \spewnotes
  }

\endinput