%% COLOURED BOXES
%
% change this info string if making any custom modification
\ProvidesPackage{sphinxpackageboxes}[2023/03/19 v6.2.0 advanced colored boxes]
% Optionally executes \RequirePackage for:
%
% - pict2e.  Ideally we would like to use the v0.4a 2020/08/16 release of this
%   package as it allows dimensional arguments to its \moveto, \lineto, etc...
%   Or we could use extra package "picture".  We opt for custom wrappers
%   \spx@moveto, \spx@lineto, ..., working with old versions.
%
% - ellipse.  This package extends pict2e with elliptical arcs.  Its author
%   Daan Leijen also has contributed package longfbox which is part of
%   TeXLive.  Had I known about it, I would perhaps have based Sphinx CSS on
%   top of longfbox at least partly.  But this would not have spared me all
%   the work in sphinx.sty, which was a long walk until 6.2.0 version.
%   Besides I don't need the breakable boxes from longfbox, as Sphinx has
%   its own rather advanced layer on top of framed.  I would need to check if
%   some thorny color issues solved by Sphinx (and not by tcolorbox) at page
%   breaks are solved by longfbox as well.  (I have not tested)

%   At 6.2.0 refactoring, we do not wait for at begin document to try to load
%   pict2e.  Actually since 6.0.0 the default is for code-blocks to use
%   rounded boxes, and the only reason since then to wait "at begin document"
%   was to check if user had reverted that default and in fact pict2e was not
%   needed.  But with \sphinxbox, we can not know for sure even in that case
%   that pict2e is not needed.  And even back then it would have been possible
%   to user to try to employ \sphinxsetup via raw directive in document body
%   and require some rounded corners (which was thus impossible to satisfy).
%   Time to be much simpler and attempt unconditionally to load pict2e
%   immediately.  This will also have advantage that we can use
%   \@ifpackageloaded{pict2e} and not have to query and save its setting later
%   at begin document.
\IfFileExists{pict2e.sty}
   {\RequirePackage{pict2e}}
   {\PackageWarningNoLine{sphinx}{%
     The package pict2e is required for rounded boxes.\MessageBreak
     It does not seem to be available on your system.\MessageBreak
     Options for setting radii will be ignored%
    }%
    % Formerly a \sphinxbuildwarning was issued but if we did that now it
    % would mean that the produced PDF will always have a red banner near its
    % end about pict2e not being available if indeed it is not available, even
    % if user has reverted the default and dropped rounded corners.  Formerly
    % the serious warning was done after having checked at begin document that
    % indeed a rounded corner option had been used.  As we drop the check now,
    % let's be more discrete and simply duplicate the earlier warning to make
    % it visible near end of compilation log and console output.
    \AtEndDocument{\PackageWarningNoLine{sphinx}{%
     The package pict2e is required for rounded boxes.\MessageBreak
     As it does not seem to be available on your system,\MessageBreak
     options setting radii have all been ignored}}%
   }%

\IfFileExists{ellipse.sty}
   {\RequirePackage{ellipse}}
   {\PackageWarningNoLine{sphinx}{%
     The package ellipse is required for elliptical corners.\MessageBreak
     It does not seem to be available on your system.\MessageBreak
     All non-straight corners will use circle arcs.%
    }%
    \AtEndDocument{\PackageWarningNoLine{sphinx}{%
     The package ellipse is required for elliptical corners.\MessageBreak
     As it does not seem to be available on your system,\MessageBreak
     all non-straight corners have used circle arcs.}}%
   }%

% The pict2e release v0.4b of 2020/09/30 does not allocate scratch dimen
% register \@tempdimd which ellipse package uses.  Thus ellipse package is
% broken since (written on March 20, 2023).  Simply allocate the register
% ourself to fix that, pending some upstream fix.
\@ifpackageloaded{ellipse}{\ifdefined\@tempdimd\else\newdimen\@tempdimd\fi}{}

% Provides box registers \spx@tempboxa, \spx@tempboxb usable in other places
\newbox\spx@tempboxa
\newbox\spx@tempboxb

%%%%%%%%%%%%%%%%
% Internal registers, conditionals, colors to be configured by each caller
% via a preliminary "setup" call
%
\newif\ifspx@boxes@withshadow
\newif\ifspx@boxes@insetshadow
\newif\ifspx@boxes@withbackgroundcolor
\newif\ifspx@boxes@withshadowcolor
\newif\ifspx@boxes@withbordercolor
\newif\ifspx@boxes@shadowinbbox
%
\newdimen\spx@boxes@border
\newdimen\spx@boxes@border@top
\newdimen\spx@boxes@border@right
\newdimen\spx@boxes@border@bottom
\newdimen\spx@boxes@border@left
%
\newdimen\spx@boxes@padding@top
\newdimen\spx@boxes@padding@right
\newdimen\spx@boxes@padding@bottom
\newdimen\spx@boxes@padding@left
%
\newdimen\spx@boxes@shadow@xoffset
\newdimen\spx@boxes@shadow@yoffset
%
\newdimen\spx@boxes@radius@topleft@x
\newdimen\spx@boxes@radius@topright@x
\newdimen\spx@boxes@radius@bottomright@x
\newdimen\spx@boxes@radius@bottomleft@x
\newdimen\spx@boxes@radius@topleft@y
\newdimen\spx@boxes@radius@topright@y
\newdimen\spx@boxes@radius@bottomright@y
\newdimen\spx@boxes@radius@bottomleft@y
%
% These colors will be set to colors defined appropriately by caller of
% \spx@boxes@fcolorbox@setup macro
% spx@boxes@bordercolor
% spx@boxes@backgroundcolor
% spx@boxes@shadowcolor
% spx@boxes@textcolor

%%%%%%%%%%%%%%%%
% "setup" macro
%
% It must be called prior to \spx@boxes@fcolorbox for parameters of the latter
% to be initialized.
%
% It also prepares \spx@boxes@fcolorbox to expand to one of
% \spx@boxes@fcolorbox@rectangle or \spx@boxes@fcolorbox@rounded depending on
% the configuration and availability of the pict2e package.
%
% The #1 is one of: pre, topic, warning, danger, etc....
%
% We delay until here the parsing of radii options to extract x and y
% components.
\def\spx@boxes@setradii#1 #2 #3\@nnil#4#5{%
  #4\dimexpr#1\relax
  #5\dimexpr#2\relax
  \ifdim#5=-\maxdimen#5#4\fi
  % if one of them is zero or negative set both to zero
  \ifdim#4>\z@\else#4\z@#5\z@\fi
  \ifdim#5>\z@\else#4\z@#5\z@\fi
}%
% if ellipse.sty is not available ignore the second component of all radii
% specifications, use circle arcs with radius the x component
\@ifpackageloaded{ellipse}
   {}
   {\def\spx@boxes@setradii#1 #2 #3\@nnil#4#5{#4\dimexpr#1\relax #5#4}}

% Using \dimexpr for maximal user input flexibility.
\def\spx@boxes@fcolorbox@setup#1{%
  \spx@boxes@border@top   \dimexpr\@nameuse{spx@#1@border@top}\relax
  \spx@boxes@border@right \dimexpr\@nameuse{spx@#1@border@right}\relax
  \spx@boxes@border@bottom\dimexpr\@nameuse{spx@#1@border@bottom}\relax
  \spx@boxes@border@left  \dimexpr\@nameuse{spx@#1@border@left}\relax
  \spx@boxes@border       \dimexpr\@nameuse{spx@#1@border}\relax
  %
  \spx@boxes@padding@top   \dimexpr\@nameuse{spx@#1@padding@top}\relax
  \spx@boxes@padding@right \dimexpr\@nameuse{spx@#1@padding@right}\relax
  \spx@boxes@padding@bottom\dimexpr\@nameuse{spx@#1@padding@bottom}\relax
  \spx@boxes@padding@left  \dimexpr\@nameuse{spx@#1@padding@left}\relax
  %
  \edef\spx@temp{\csname spx@#1@radius@topleft\endcsname\space}%
  \expandafter
        \spx@boxes@setradii
        \spx@temp
        {-\maxdimen}
        \@nnil
        \spx@boxes@radius@topleft@x\spx@boxes@radius@topleft@y
  \edef\spx@temp{\csname spx@#1@radius@topright\endcsname\space}%
  \expandafter
        \spx@boxes@setradii
        \spx@temp
        {-\maxdimen}
        \@nnil
        \spx@boxes@radius@topright@x\spx@boxes@radius@topright@y
  \edef\spx@temp{\csname spx@#1@radius@bottomright\endcsname\space}%
  \expandafter
        \spx@boxes@setradii
        \spx@temp
        {-\maxdimen}
        \@nnil
        \spx@boxes@radius@bottomright@x\spx@boxes@radius@bottomright@y
  \edef\spx@temp{\csname spx@#1@radius@bottomleft\endcsname\space}%
  \expandafter
        \spx@boxes@setradii
        \spx@temp
        {-\maxdimen}
        \@nnil
        \spx@boxes@radius@bottomleft@x\spx@boxes@radius@bottomleft@y
  %
  \@nameuse{ifspx@#1@withshadow}%
     \spx@boxes@withshadowtrue
     \spx@boxes@shadow@xoffset \dimexpr\@nameuse{spx@#1@shadow@xoffset}\relax
     \spx@boxes@shadow@yoffset \dimexpr\@nameuse{spx@#1@shadow@yoffset}\relax
  \else
     \spx@boxes@withshadowfalse
  \fi
  % not nesting in previous to avoid TeX conditional subtleties
  \@nameuse{ifspx@#1@insetshadow}%
     \spx@boxes@insetshadowtrue
  \else
     \spx@boxes@insetshadowfalse
  \fi
  %
  \@nameuse{ifspx@#1@withbordercolor}%
    \spx@boxes@withbordercolortrue
    \sphinxcolorlet{spx@boxes@bordercolor}{sphinx#1BorderColor}%
  \else
    \spx@boxes@withbordercolorfalse
  \fi
  %
  \@nameuse{ifspx@#1@withbackgroundcolor}%
    \spx@boxes@withbackgroundcolortrue
    \sphinxcolorlet{spx@boxes@backgroundcolor}{sphinx#1BgColor}%
  \else
    \spx@boxes@withbackgroundcolorfalse
  \fi
  %
  \@nameuse{ifspx@#1@withshadowcolor}%
    \spx@boxes@withshadowcolortrue
    \sphinxcolorlet{spx@boxes@shadowcolor}{sphinx#1ShadowColor}%
  \else
    \spx@boxes@withshadowcolorfalse
  \fi
  % Display elements pre, topic, warning et al. by default do not include
  % shadow in box (legacy; and only topic actually uses a shadow per default)
  % This may be refactored still more in future, but this 6.2.0 extra helped
  % reduce workload from code-blocks (pre), contents (topic) and admonitions.
  % As this conditional is a priori false and should only be changed locally
  % (by \sphinxbox), this line is actually superfluous.
  \spx@boxes@shadowinbboxfalse
  \spx@boxes@fcolorbox@setup@fcolorbox
}
\@ifpackageloaded{pict2e}
{%  pict2e is available and loaded
 \def\spx@boxes@fcolorbox@setup@fcolorbox{%
  \if1% use rounded boxes only if needed (rx>0 iff ry>0)
    \ifdim\spx@boxes@radius@topleft@x    >\z@0\fi
    \ifdim\spx@boxes@radius@topright@x   >\z@0\fi
    \ifdim\spx@boxes@radius@bottomright@x>\z@0\fi
    \ifdim\spx@boxes@radius@bottomleft@x >\z@0\fi
    1\def\spx@boxes@fcolorbox{\spx@boxes@fcolorbox@rectangle}%
  \else
    \def\spx@boxes@fcolorbox{\spx@boxes@fcolorbox@rounded}%
  \fi
 }% end of definition of setup@fcolorbox in case of presence of pict2e
}%
{% pict2e could not be loaded, we must always use fcolorbox@rectangle
 \def\spx@boxes@fcolorbox@setup@fcolorbox{%
    \def\spx@boxes@fcolorbox{\spx@boxes@fcolorbox@rectangle}%
 }% end of definition of setup@fcolorbox in case of absence of pict2e
}% end of "no pict2e" branch

%%%%%%%%%%%%%%%%
% Support of box-decoration-break=slice
%
% 6.2.0 has renamed and moved this here from sphinxlatexliterals.sty,
% to facilitate supporting box-decoration-break=slice for all directives,
% not only code-block.
%
% It also modified when these post actions are executed, in order
% for openboth to be able to trigger usage of fcolorbox@rectangle.
% So now openbottom and opentop also take advantage of this possible
% optimization.
\def\spx@boxes@fcolorbox@setup@openbottom{%
    \spx@boxes@border@bottom     \z@
    \spx@boxes@radius@bottomright@x\z@ \spx@boxes@radius@bottomright@y\z@
    \spx@boxes@radius@bottomleft@x \z@ \spx@boxes@radius@bottomleft@y \z@
    \spx@boxes@fcolorbox@setup@fcolorbox
}%
\def\spx@boxes@fcolorbox@setup@opentop{%
    \spx@boxes@border@top     \z@
    \spx@boxes@radius@topright@x\z@ \spx@boxes@radius@topright@y\z@
    \spx@boxes@radius@topleft@x \z@ \spx@boxes@radius@topleft@y \z@
    \spx@boxes@fcolorbox@setup@fcolorbox
}%
\def\spx@boxes@fcolorbox@setup@openboth{%
    \spx@boxes@border@top     \z@
    \spx@boxes@border@bottom  \z@
    \spx@boxes@radius@bottomright@x\z@ \spx@boxes@radius@bottomright@y\z@
    \spx@boxes@radius@bottomleft@x \z@ \spx@boxes@radius@bottomleft@y \z@
    \spx@boxes@radius@topright@x\z@ \spx@boxes@radius@topright@y\z@
    \spx@boxes@radius@topleft@x \z@ \spx@boxes@radius@topleft@y \z@
    \def\spx@boxes@fcolorbox{\spx@boxes@fcolorbox@rectangle}%
}%

%%%%%%%%%%%%%%%%
% \sphinxbox (added at 6.2.0)
%
% For an inline box, possibly rounded.
\newcommand\sphinxbox[1][]{% #1 stands for the options, they are... optional!
  % \leavevmode makes sure TeX switches to paragraph mode, which is necessary
  % if this is first in a paragraph or a list element.  The \sphinxAtStartPar
  % mechanism also ensures this automatically, if not redefined, but not with
  % lualatex as then it is by default doing nothing.
  \leavevmode
  \begingroup
    \ifcsname spx@boxes@sphinxbox@isnested\endcsname
        % nested boxes reset all box options to be as the \sphinxboxsetup
        % defaults, before applying their specific options
        \spx@boxes@sphinxbox@reset
    \else
        % top layer box, toggle the nested flag
        \csname spx@boxes@sphinxbox@isnested\endcsname
    \fi
    % we do not use \sphinxboxsetup as it is a user command extending the
    % "reset" storage
    \setkeys{sphinxbox}{#1}%
    \spx@boxes@fcolorbox@setup{box}%
    \spx@boxes@shadowinbboxtrue% inline sphinx boxes include shadow in bbox
    \ifspx@box@withtextcolor\color{sphinxboxTextColor}\fi
    %
    % MEMO: the fcolorbox@{rectangle,rounded} draw the contents (which here
    % will be encapsulated as \box\z@) last, i.e.  after shadow, background,
    % and border and their color commands.  The \reset@color from naked
    % top-level \color commands in argument (which can not arise from Sphinx
    % mark-up anyhow) would end up being placed via color.sty \aftergroup core
    % mechanism in token stream after \spx@boxes@sphinxbox@a (which is the
    % first \aftergroup) hence after the box contents with its unbalanced
    % color pushes is shipped to PDF.  So the missing color pop specials are
    % inserted then in correct order at correct place (after the \endgroup at
    % end of \spx@boxes@sphinxbox@a but this is not relevant) and do not end
    % up causing havoc in push/pop pairs (and all this happens on same page).
    %
    % There is thus no reason here to go to the trouble to add an extra
    % \color@begingroup/\color@endgroup or like pair to encapsulate the caught
    % contents in order for the \box\z@ to contain as many color pop's as it
    % has color pushes.  But as this is subtle, this comment was added for
    % future maintenance.  Actually even if the contents were not drawn last,
    % their (purely theoretical, as Sphinx mark-up can not create it) missing
    % color pop's would not have caused trouble I guess as long as the color
    % insertions for shadow, background, border are correctly balanced.
    \setbox0\hbox\bgroup\aftergroup\spx@boxes@sphinxbox@a
    \afterassignment\spx@box@TeXextras
    \let\next=%
}
\def\spx@boxes@sphinxbox@a{\spx@boxes@fcolorbox{%
    \ifspx@opt@box@addstrut\strut\fi\box\z@}\endgroup}

\newcommand\newsphinxbox[2][]{%
   \newcommand#2[1][]{\sphinxbox[#1,##1]}%
}
% Let's catch \renewsphinxbox[...]{\sphinxbox} which would cause \sphinxbox
% to fall into infinite looping on use.
\newcommand\renewsphinxbox[2][]{%
   \in@{#2}{\sphinxbox}%
   \ifin@
      \PackageWarning{sphinx}{Attempt to \string\renewsphinxbox\space
        the \string\sphinxbox\space command\MessageBreak
        itself.  This is not allowed and will be ignored.\MessageBreak
        Reported}%
   \else
     \renewcommand#2[1][]{\sphinxbox[#1,##1]}%
   \fi
}

%%%%%%%%%%%%%%%%
% MACROS
%
% \spx@boxes@fcolorbox expands either to \spx@boxes@fcolorbox@rectangle
% or \spx@boxes@fcolorbox@rounded depending on preliminary set-up.
%
% This is decided by the "setup" which must have been executed by the caller.
% Let's give it some (thus unneeded) default fall-back for clarity.
\def\spx@boxes@fcolorbox{\spx@boxes@fcolorbox@rectangle}
%
% A macro \spx@boxes@fcolorbox@setuphook used to be executed at start of the
% \hbox constructs (rectangle or rounded).  This was used until 6.2.0 for the
% support of pre_box-decoration-break option, hence was really an internal
% non-public macro.  As it is not needed anymore, with some hesitation it got
% entirely removed at 6.2.0 on the occasion of a refactoring of interactions of
% this file with sphinxlatexliterals.sty.  Besides its name should have been
% rather something such as \spx@boxes@fcolorbox@atstartofhbox.
%
% After "setup", \spx@boxes@fcolorbox expands to one of:
%
% - \spx@boxes@fcolorbox@rectangle (4 padding parameters, 4 border widths, 2 shadow widths,
%   and three colours: background, border and shadow; same as in CSS styling)
%
%   It branches to one of:
%   - \spx@boxes@fcolorbox@externalshadow
%   - \spx@boxes@fcolorbox@insetshadow    (same concept of "inset" as in CSS styling)
%
% - \spx@boxes@fcolorbox@rounded: rounded corners using the picture environment
%   and pict2e package for its low-weight interface to PDF graphics operations

% MEMO: we have also successfully tested usage of tcolorbox.sty (its \tcbox) but
% decided to use pict2e.sty for the following reasons:
% 1- PDF build was observed to be an order of magnitude faster,
% 2- the boxes we can do with pict2e appear to be fancy enough,
%    almost matching what one can see in HTML renderings,
% 2- orders of magnitude smaller dependency (tcolorbox uses the pgf TeX
%    framework), although on Ubuntu it seems texlive-pictures is
%    needed which also contains the whole of pgf/TikZ... so this point
%    is a bit moot...

% For code-blocks, attachments of caption and continuation hints are done
% exactly as prior to extension of Sphinx via this package, whether the box
% has straight or rounded corners.  The vertical space occupied is the same,
% if nothing else is changed (perhaps in future the title itself could be also
% rendered in a rounded box?)

%%%%%%%%
%//// \spx@boxes@fcolorbox@rectangle
%
% This box will have the same baseline as its argument (which is typeset in
% horizontal mode).  It takes into account four border widths parameters, four
% padding parameters, two shadow widths (each possibly negative), and three
% colors: background, border and shadow.  Its boundary box takes into account
% border and padding.  Width of shadow is taken into account if the boolean
% \ifspx@boxes@shadowinbbox is \iftrue.  The "setup" sets it to \iffalse.
% Prior to 6.2.0, shadow size was included in bbox but the callers manually
% removed it by extra steps.  The \sphinxbox command sets it to \iftrue after
% the "setup".
%
% It is up to the caller to take extra steps if the border and padding must go
% into margin as well (see sphinxlatexliterals.sty for how this is done in
% \spx@verb@FrameCommand).
%
% In usage as a "FrameCommand" with framed.sty, the argument will already be a
% collection of TeX boxes (and interline glues).
%
% This was designed so that the parameters configured by "setup" are
% interpreted as they would be as CSS properties in an HTML context.
\long\def\spx@boxes@fcolorbox@rectangle#1{%
  \hbox\bgroup
  \setbox\spx@tempboxa
   \hbox{\kern\dimexpr\spx@boxes@border@left+\spx@boxes@padding@left\relax
         {#1}%
         \kern\dimexpr\spx@boxes@padding@right+\spx@boxes@border@right\relax}%
  \ht\spx@tempboxa
     \dimexpr\ht\spx@tempboxa+\spx@boxes@border@top+\spx@boxes@padding@top\relax
  \dp\spx@tempboxa
     \dimexpr\dp\spx@tempboxa+\spx@boxes@padding@bottom+\spx@boxes@border@bottom\relax
  \ifspx@boxes@insetshadow
     \expandafter\spx@boxes@fcolorbox@insetshadow
  \else
     \expandafter\spx@boxes@fcolorbox@externalshadow
  \fi
}

% external shadow
\def\spx@boxes@fcolorbox@externalshadow{%
  % reserve space to external shadow if on left
  \ifspx@boxes@withshadow
   \ifspx@boxes@shadowinbbox
    \ifdim\spx@boxes@shadow@xoffset<\z@\kern-\spx@boxes@shadow@xoffset\fi
   \fi
  \fi
  % BACKGROUND
  % draw background and move back to reference point
  \ifspx@boxes@withbackgroundcolor
   {\color{spx@boxes@backgroundcolor}%
    \vrule\@height\ht\spx@tempboxa
          \@depth\dp\spx@tempboxa
          \@width\wd\spx@tempboxa
    \kern-\wd\spx@tempboxa
    }%
  \fi
  % BOX SHADOW
  % draw shadow and move back to reference point
  \ifspx@boxes@withshadow
  \vbox{%
    \moveright\spx@boxes@shadow@xoffset
    \hbox{\lower\spx@boxes@shadow@yoffset
          \vbox{\ifspx@boxes@withshadowcolor
                    \color{spx@boxes@shadowcolor}%
                \else
                    % 6.2.0: guard against a manually inserted \color command in
                    % contents which could leak at a page break to the shadow
                    \normalcolor
                \fi
                \ifdim\spx@boxes@shadow@yoffset<\z@
                  \hrule\@height-\spx@boxes@shadow@yoffset
                  \kern\spx@boxes@shadow@yoffset
                \fi
                \setbox\spx@tempboxb\hb@xt@\wd\spx@tempboxa{%
                 \ifdim\spx@boxes@shadow@xoffset<\z@\vrule\@width-\spx@boxes@shadow@xoffset\fi
                 \hss
                 \ifdim\spx@boxes@shadow@xoffset>\z@\vrule\@width\spx@boxes@shadow@xoffset\fi
                 }%
                \ht\spx@tempboxb\ht\spx@tempboxa
                \dp\spx@tempboxb\dp\spx@tempboxa
                \box\spx@tempboxb
                \ifdim\spx@boxes@shadow@yoffset>\z@
                  \kern-\spx@boxes@shadow@yoffset
                  \hrule\@height\spx@boxes@shadow@yoffset
                \fi
                \kern-\dp\spx@tempboxa
               }% end of \vbox, attention it will have zero depth if yoffset>0
          \kern-\wd\spx@tempboxa
          \ifdim\spx@boxes@shadow@xoffset>\z@
            \kern-\spx@boxes@shadow@xoffset
          \fi
         }% end of \hbox, attention its depth is only yoffset if yoffset>0
       }% end of \vbox
  \fi % end of shadow drawing, and we are back to horizontal reference point
  % BOX BORDER
  \vbox{\ifspx@boxes@withbordercolor
            \color{spx@boxes@bordercolor}%
        \else
            % 6.2.0: guard against a \color command in contents whose effect
            % could leak to border at a pagebreak
            \normalcolor
        \fi
        \hrule\@height\spx@boxes@border@top
           \kern-\spx@boxes@border@top
        \setbox\spx@tempboxb\hb@xt@\wd\spx@tempboxa
                  {\vrule\@width\spx@boxes@border@left
                   \hss\vrule\@width\spx@boxes@border@right
                  }%
            \ht\spx@tempboxb\ht\spx@tempboxa
            \dp\spx@tempboxb\dp\spx@tempboxa
        \box\spx@tempboxb
        \kern-\spx@boxes@border@bottom
        \hrule\@height\spx@boxes@border@bottom
        \kern-\dp\spx@tempboxa
       }% attention this box has zero depth due to \hrule at bottom
  % step back to horizontal reference point
  \kern-\wd\spx@tempboxa
  % end of border drawing
  % CONTENTS
  % adjust the total depth to include the bottom shadow
  \ifspx@boxes@withshadow
    \ifdim\spx@boxes@shadow@yoffset>\z@
      \dp\spx@tempboxa\dimexpr\dp\spx@tempboxa+\spx@boxes@shadow@yoffset\relax
    \fi
  \fi
  \box\spx@tempboxa
  % include lateral shadow in total width
  \ifspx@boxes@withshadow
   \ifspx@boxes@shadowinbbox
    \ifdim\spx@boxes@shadow@xoffset>\z@\kern\spx@boxes@shadow@xoffset\fi
   \fi
  \fi
  \egroup
}

% inset shadow
%
% The parameters signs are interpreted as in CSS styling.
\def\spx@boxes@fcolorbox@insetshadow{%
  % BACKGROUND
  % draw background and move back to reference point
  \ifspx@boxes@withbackgroundcolor
   {\color{spx@boxes@backgroundcolor}%
    \vrule\@height\ht\spx@tempboxa
          \@depth\dp\spx@tempboxa
          \@width\wd\spx@tempboxa
    \kern-\wd\spx@tempboxa
    }%
  \fi
  % BOX SHADOW
  % draw shadow and move back to reference point
  \ifspx@boxes@withshadow
    \hbox{\vbox{\ifspx@boxes@withshadowcolor
                    \color{spx@boxes@shadowcolor}%
                \else
                    % 6.2.0: guard against a manually inserted \color command in
                    % contents which could leak at a page break to the shadow
                    \normalcolor
                \fi
% NOTA BENE
% We deliberately draw shadow partially under an area later covered by frame
% with the idea to avoid anti-aliasing problems but in fact this may be a bad
% idea with border is thin.
% This may need some extra testing with PDF viewers... reports welcome!
                \ifdim\spx@boxes@shadow@yoffset>\z@
                  \hrule\@height\dimexpr\spx@boxes@border@top+\spx@boxes@shadow@yoffset\relax
                  \kern-\spx@boxes@shadow@yoffset
                  \kern-\spx@boxes@border@top
                \fi
                \setbox\spx@tempboxb\hb@xt@\wd\spx@tempboxa{%
                 \ifdim\spx@boxes@shadow@xoffset>\z@
                  \vrule\@width\dimexpr\spx@boxes@border@left+\spx@boxes@shadow@xoffset\relax\fi
                 \hss
                 \ifdim\spx@boxes@shadow@xoffset<\z@
                  \vrule\@width\dimexpr-\spx@boxes@shadow@xoffset+\spx@boxes@border@right\relax\fi
                 }%
                \ht\spx@tempboxb\ht\spx@tempboxa
                \dp\spx@tempboxb\dp\spx@tempboxa
                \box\spx@tempboxb
                \ifdim\spx@boxes@shadow@yoffset<\z@
                  \kern\spx@boxes@shadow@yoffset
                  \kern-\spx@boxes@border@bottom
                  \hrule\@height\dimexpr-\spx@boxes@shadow@yoffset+\spx@boxes@border@bottom\relax
                \fi
                \kern-\dp\spx@tempboxa
               }% end of \vbox, attention it will have zero depth if yoffset<0
          \kern-\wd\spx@tempboxa
         }% end of \hbox, attention its depth is only |yoffset| if yoffset<0
  \fi % end of inset shadow drawing, and we are back to horizontal reference point
  % BOX BORDER
  \vbox{\ifspx@boxes@withbordercolor
            \color{spx@boxes@bordercolor}%
        \else
            % 6.2.0: guard against a \color command in contents whose effect
            % could leak to border at a pagebreak
            \normalcolor
        \fi
        \hrule\@height\spx@boxes@border@top
           \kern-\spx@boxes@border@top
        \setbox\spx@tempboxb\hb@xt@\wd\spx@tempboxa
                  {\vrule\@width\spx@boxes@border@left
                   \hss\vrule\@width\spx@boxes@border@right
                  }%
            \ht\spx@tempboxb\ht\spx@tempboxa
            \dp\spx@tempboxb\dp\spx@tempboxa
        \box\spx@tempboxb
        \kern-\spx@boxes@border@bottom
        \hrule\@height\spx@boxes@border@bottom
        \kern-\dp\spx@tempboxa
       }% attention this box has zero depth due to \hrule at bottom
  % step back to horizontal reference point
  \kern-\wd\spx@tempboxa
  % end of border drawing
  % CONTENTS
  \box\spx@tempboxa
  \egroup
}

% let's abort input if pict2e package could not be loaded.
% To be extra safe we also alias @rounded to @rectangle but
% a priori the architecture is done so that @rounded will never
% be called in that case by other Sphinx LaTeX components.
\@ifpackageloaded{pict2e}
  {}
  {\def\spx@boxes@fcolorbox@rounded{\spx@boxes@fcolorbox@rectangle}%
   \endinput
  }

% we proceed now in the context of pict2e being available and loaded
% (TeX being a macro-expansion based language it would have
%  swallowed all the coming definitions even if pict2e
%  had in fact not been loaded... but we aborted the input above)
%%%%%%%%
%//// \spx@boxes@fcolorbox@rounded
%
% Prior to 6.2.0, a constant border-width was applied as the border was
% obtained as a \strokepath.  This allowed 4 distinct radii but not to vary the
% border widths.  Now the border is drawn by two \fillpath operation, the first
% one filling up to external border, the second one actually filling for the
% background paradoxically on top of it, up to internal border path.
%
% This 6.2.0 abandonment of \strokepath allowed great simplification in
% supporting opentop, openbottom and openboth situations, and it can
% allow automatic support of openleft and openright analogs.
%
% And 6.2.0 also implements elliptical arcs thanks to ellipse package,
% which extends pict2e.

% Currently, inset shadow is not supported.
%
% Prior to 6.2.0 an inset shadow triggered the rectangle variant, so we never
% ended here, but now it is simply ignored.  This change does not appear to me
% to be breaking, as it changes output only for conf.py's specifying both
% rounded corners and an inset shadow and the documentation said it was
% incompatible.

% wrappers for pict2e usage if old
% Better not to copy over 2020 pict2e definitions in case
% something internal changes
% However our wrappers will work ONLY with dimensional inputs
% No need to pre-expand the arguments
% Braces in case the expression uses parentheses
\def\spx@moveto(#1,#2){\moveto({\strip@pt\dimexpr#1\relax},{\strip@pt\dimexpr#2\relax})}
\def\spx@lineto(#1,#2){\lineto({\strip@pt\dimexpr#1\relax},{\strip@pt\dimexpr#2\relax})}
% attention here the [N] becomes mandatory
% \circlearc[<N>]{<X>}{<Y>}{<RAD>}{<ANGLE1>}{<ANGLE2>}
\def\spx@circlearc[#1]#2#3#4%#5#6
   {\circlearc[#1]{\strip@pt\dimexpr#2\relax}%
                  {\strip@pt\dimexpr#3\relax}%
                  {\strip@pt\dimexpr#4\relax}%
   }
% attention here too the [N] becomes mandatory
% the core path macro of ellipse.sty.  Thanks to Daan Leijen, author of this
% package.
% \elliparc [<initial>]{<center-x>}{<center-y>}{<x-rad>}{<y-rad>}{<start-angle>}{<end-angle>}
% maybe this wrapper is unneeded but I don't have real time to check
\def\spx@elliparc[#1]#2#3#4#5%#6#7
   {\elliparc[#1]{\strip@pt\dimexpr#2\relax}%
                 {\strip@pt\dimexpr#3\relax}%
                 {\strip@pt\dimexpr#4\relax}%
                 {\strip@pt\dimexpr#5\relax}%
   }

% Macro whose execution prepares a path to be either stroked or filled
% Only fill operation is used at 6.2.0.  The radii are given by the set box
% parameters, but the width and height are in \spx@width and \spx@height.  A
% \put command will be used for appropriate shifts.
% 6.2.0 adds elliptical corners!
% But I feel perhaps I need to think about how x-radius and y-radius should
% interact with border-width.  So consider output WIP for time being.
\def\spx@boxes@border@defpath{%
  \spx@moveto(\spx@boxes@radius@bottomleft@x,\z@)% our \spx@moveto is a bit rigid
                                                 % and we must use \z@ not 0 here
  \spx@lineto(\spx@width-\spx@boxes@radius@bottomright@x,\z@)%
  % x and y radii are either both positive or both zero
  % probably not needed to actually guard against the latter case,
  % let's do it nevertheless
  \ifdim\spx@boxes@radius@bottomright@x>\z@
    \ifdim\spx@boxes@radius@bottomright@x=\spx@boxes@radius@bottomright@y
      \spx@circlearc[2]{\spx@width-\spx@boxes@radius@bottomright@x}%
                       {\spx@boxes@radius@bottomright@y}%
                       {\spx@boxes@radius@bottomright@x}{-90}{0}%
    \else
      \spx@elliparc[2]{\spx@width-\spx@boxes@radius@bottomright@x}%
                      {\spx@boxes@radius@bottomright@y}%
                      {\spx@boxes@radius@bottomright@x}
                      {\spx@boxes@radius@bottomright@y}{-90}{0}%
    \fi
  \fi
  \spx@lineto(\spx@width,%
              \spx@height-\spx@boxes@radius@topright@y)%
  \ifdim\spx@boxes@radius@topright@x>\z@
    \ifdim\spx@boxes@radius@topright@x=\spx@boxes@radius@topright@y
      \spx@circlearc[2]{\spx@width-\spx@boxes@radius@topright@x}
                       {\spx@height-\spx@boxes@radius@topright@y}%
                       {\spx@boxes@radius@topright@x}{0}{90}%
    \else
      \spx@elliparc[2]{\spx@width-\spx@boxes@radius@topright@x}
                      {\spx@height-\spx@boxes@radius@topright@y}%
                      {\spx@boxes@radius@topright@x}%
                      {\spx@boxes@radius@topright@y}{0}{90}%
    \fi
  \fi
  \spx@lineto(\spx@boxes@radius@topleft@x,\spx@height)%
  \ifdim\spx@boxes@radius@topleft@x>\z@
    \ifdim\spx@boxes@radius@topleft@x=\spx@boxes@radius@topleft@y
      \spx@circlearc[2]{\spx@boxes@radius@topleft@x}%
                       {\spx@height-\spx@boxes@radius@topleft@y}%
                       {\spx@boxes@radius@topleft@x}{90}{180}%
    \else
      \spx@elliparc[2]{\spx@boxes@radius@topleft@x}%
                      {\spx@height-\spx@boxes@radius@topleft@y}%
                      {\spx@boxes@radius@topleft@x}%
                      {\spx@boxes@radius@topleft@y}{90}{180}%
    \fi
  \fi
  \spx@lineto(\z@,\spx@boxes@radius@bottomleft@y)%
  \ifdim\spx@boxes@radius@bottomleft@x>\z@
    \ifdim\spx@boxes@radius@bottomleft@x=\spx@boxes@radius@bottomleft@y
      \spx@circlearc[2]{\spx@boxes@radius@bottomleft@x}%
                       {\spx@boxes@radius@bottomleft@y}%
                       {\spx@boxes@radius@bottomleft@x}{180}{270}%
    \else
      \spx@elliparc[2]{\spx@boxes@radius@bottomleft@x}%
                      {\spx@boxes@radius@bottomleft@y}%
                      {\spx@boxes@radius@bottomleft@x}%
                      {\spx@boxes@radius@bottomleft@y}{180}{270}%
    \fi
  \fi
}% end of definition of \spx@boxes@border@defpath

% The customization of the various parameters must have been done via an
% appropriate call to \spx@boxes@fcolorbox@setup, which will have set up
% \spx@boxes@fcolorbox to expand to \spx@boxes@fcolorbox@rounded, and will
% have set its various parameters.
%
\long\def\spx@boxes@fcolorbox@rounded #1{%
  \hbox{%
   \ifspx@boxes@withshadow
     \ifspx@boxes@insetshadow
       \spx@boxes@withshadowfalse % ignore inset shadow
     \fi
   \fi
   % reserve space to external shadow if on left
   \ifspx@boxes@withshadow
    \ifspx@boxes@shadowinbbox
     \ifdim\spx@boxes@shadow@xoffset<\z@\kern-\spx@boxes@shadow@xoffset\fi
    \fi
   \fi
   \vbox{%
     % adjust vertical bbox
     \ifspx@boxes@withshadow
       \ifdim\spx@boxes@shadow@yoffset<\z@
           \kern-\spx@boxes@shadow@yoffset
       \fi
     \fi
     \setlength{\unitlength}{1pt}%
     \setbox\spx@tempboxa
     \hbox{\kern\dimexpr\spx@boxes@border@left+\spx@boxes@padding@left\relax
           {#1}%
           \kern\dimexpr\spx@boxes@padding@right+\spx@boxes@border@right\relax}%
     \ht\spx@tempboxa
     \dimexpr\ht\spx@tempboxa+\spx@boxes@border@top+\spx@boxes@padding@top\relax
     \dp\spx@tempboxa
     \dimexpr\dp\spx@tempboxa+\spx@boxes@padding@bottom+\spx@boxes@border@bottom\relax
     \edef\spx@width{\number\wd\spx@tempboxa sp}%
     \edef\spx@height{\number\dimexpr\ht\spx@tempboxa+\dp\spx@tempboxa sp}%
     \hbox{%
   \begin{picture}%
      % \strip@pt\dimexpr to work around "old" LaTeX picture limitation
      % (we could use the "picture" package, this would add another dependency)
      (\strip@pt\dimexpr\spx@width\relax,\strip@pt\dimexpr\spx@height\relax)%
      \spx@boxes@border@defpath
      \ifspx@boxes@withshadow
              \ifspx@boxes@withshadowcolor
                 \color{spx@boxes@shadowcolor}%
              \else
                 % 6.2.0: here and elsewhere guard against a manually inserted
                 % \color command in contents which could leak to the shadow
                 % to the shadow
                 \normalcolor
              \fi
              \put(\strip@pt\spx@boxes@shadow@xoffset,%
                   \strip@pt\dimexpr-\spx@boxes@shadow@yoffset\relax)
                   {\fillpath}%
      \fi
      \spx@boxes@border@defpath% must be redone after each \fillpath! (even if
                               % was in a  \put)
      \ifspx@boxes@withbordercolor
         \color{spx@boxes@bordercolor}%
      \else
         \normalcolor
      \fi
      \fillpath
      \ifspx@boxes@withbackgroundcolor
         \color{spx@boxes@backgroundcolor}%
      \else
         \color{white}%
      \fi
      \edef\spx@width{\number\dimexpr\spx@width-\spx@boxes@border@left
                                               -\spx@boxes@border@right sp}%
      \edef\spx@height{\number\dimexpr\spx@height-\spx@boxes@border@top
                                                 -\spx@boxes@border@bottom sp}%
      % redefine a path (in relative coordinates) matching the area delimited
      % by the internal borders
      \spx@boxes@border@defpath
      % use \put to shift, and fill it with background color
      \put(\strip@pt\spx@boxes@border@left,\strip@pt\spx@boxes@border@bottom)
          {\fillpath}%
   \end{picture}}% end of picture \hbox in \vbox
   % back-up vertically for outputting the contents
   \kern-\dimexpr\ht\spx@tempboxa+\dp\spx@tempboxa\relax
     % adjust vertical bbox
     \ifspx@boxes@withshadow
       \ifdim\spx@boxes@shadow@yoffset>\z@
           \dp\spx@tempboxa\dimexpr\dp\spx@tempboxa+\spx@boxes@shadow@yoffset\relax
       \fi
     \fi
   % inhibit TeX's "line skip" adjustment when piling up hboxes in a vbox
   \nointerlineskip
   \box\spx@tempboxa
   }% end of \vbox
  % include lateral shadow in total width
  \ifspx@boxes@withshadow
   \ifspx@boxes@shadowinbbox
    \ifdim\spx@boxes@shadow@xoffset>\z@\kern\spx@boxes@shadow@xoffset\fi
   \fi
  \fi
  }% end of \hbox
}%


\endinput