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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /macros/latex/contrib/l3backend/l3backend-draw.dtx
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+% \iffalse meta-comment
+%
+%% File: l3backend-draw.dtx
+%
+% Copyright (C) 2019 The LaTeX3 Project
+%
+% It may be distributed and/or modified under the conditions of the
+% LaTeX Project Public License (LPPL), either version 1.3c of this
+% license or (at your option) any later version. The latest version
+% of this license is in the file
+%
+% https://www.latex-project.org/lppl.txt
+%
+% This file is part of the "l3backend bundle" (The Work in LPPL)
+% and all files in that bundle must be distributed together.
+%
+% -----------------------------------------------------------------------
+%
+% The development version of the bundle can be found at
+%
+% https://github.com/latex3/latex3
+%
+% for those people who are interested.
+%
+%<*driver>
+\documentclass[full,kernel]{l3doc}
+\begin{document}
+ \DocInput{\jobname.dtx}
+\end{document}
+%</driver>
+% \fi
+%
+% \title{^^A
+% The \textsf{l3backend-draw} package\\ Backend drawing support^^A
+% }
+%
+% \author{^^A
+% The \LaTeX3 Project\thanks
+% {^^A
+% E-mail:
+% \href{mailto:latex-team@latex-project.org}
+% {latex-team@latex-project.org}^^A
+% }^^A
+% }
+%
+% \date{Released 2019-08-25}
+%
+% \maketitle
+%
+% \begin{documentation}
+%
+% \end{documentation}
+%
+% \begin{implementation}
+%
+% \section{\pkg{l3backend-draw} Implementation}
+%
+% \begin{macrocode}
+%<*initex|package>
+%<@@=draw>
+% \end{macrocode}
+%
+% \subsection{\texttt{dvips} backend}
+%
+% \begin{macrocode}
+%<*dvips>
+% \end{macrocode}
+%
+% \begin{macro}{\@@_backend_literal:n, \@@_backend_literal:x}
+% The same as literal PostScript: same arguments about positioning apply
+% her.
+% \begin{macrocode}
+\cs_new_eq:NN \@@_backend_literal:n \__kernel_backend_literal_postscript:n
+\cs_generate_variant:Nn \@@_backend_literal:n { x }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_begin:, \@@_backend_end:}
+% \begin{macro}{color.fc}
+% The |ps::[begin]| special here deals with positioning but allows us to
+% continue on to a matching |ps::[end]|: contrast with |ps:|, which positions
+% but where we can't split material between separate calls. The
+% |@beginspecial|/|@endspecial| pair are from |special.pro| and correct the
+% scale and $y$-axis direction. The definition of |/color.fc| deals with fill
+% color in paths. In contrast to \pkg{pgf}, we don't save the current point:
+% discussion with Tom Rokici suggested a better way to handle the necessary
+% translations (see \cs{@@_backend_box_use:Nnnnn}). (Note that
+% |@beginspecial|/|@endspecial| forms a backend scope.) The |[begin]|/^^A
+% |[end]| lines are handled differently from the rest as they are
+% conceptually different: not really drawing literals but instructions to
+% \texttt{dvips} itself.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_begin:
+ {
+ \__kernel_backend_literal:n { ps::[begin] }
+ \@@_backend_literal:n { @beginspecial }
+ \@@_backend_literal:n { SDict ~ begin ~ /color.fc ~ { } ~ def ~ end }
+ }
+\cs_new_protected:Npn \@@_backend_end:
+ {
+ \@@_backend_literal:n { @endspecial }
+ \__kernel_backend_literal:n { ps::[end] }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_scope_begin:, \@@_backend_scope_end:}
+% Scope here may need to contain saved definitions, so the entire memory
+% rather than just the graphic state has to be sent to the stack.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_scope_begin:
+ { \@@_backend_literal:n { save } }
+\cs_new_protected:Npn \@@_backend_scope_end:
+ { \@@_backend_literal:n { restore } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_moveto:nn, \@@_backend_lineto:nn}
+% \begin{macro}{\@@_backend_rectangle:nnnn}
+% \begin{macro}{\@@_backend_curveto:nnnnnn}
+% Path creation operations mainly resolve directly to PostScript primitive
+% steps, with only the need to convert to \texttt{bp}. Notice that
+% \texttt{x}-type expansion is included here to ensure that any variable
+% values are forced to literals before any possible caching. There is
+% no native rectangular path command (without also clipping, filling or
+% stroking), so that task is done using a small amount of PostScript.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_moveto:nn #1#2
+ {
+ \@@_backend_literal:x
+ {
+ \dim_to_decimal_in_bp:n {#1} ~
+ \dim_to_decimal_in_bp:n {#2} ~ moveto
+ }
+ }
+\cs_new_protected:Npn \@@_backend_lineto:nn #1#2
+ {
+ \@@_backend_literal:x
+ {
+ \dim_to_decimal_in_bp:n {#1} ~
+ \dim_to_decimal_in_bp:n {#2} ~ lineto
+ }
+ }
+\cs_new_protected:Npn \@@_backend_rectangle:nnnn #1#2#3#4
+ {
+ \@@_backend_literal:x
+ {
+ \dim_to_decimal_in_bp:n {#4} ~ \dim_to_decimal_in_bp:n {#3} ~
+ \dim_to_decimal_in_bp:n {#1} ~ \dim_to_decimal_in_bp:n {#2} ~
+ moveto~dup~0~rlineto~exch~0~exch~rlineto~neg~0~rlineto~closepath
+ }
+ }
+\cs_new_protected:Npn \@@_backend_curveto:nnnnnn #1#2#3#4#5#6
+ {
+ \@@_backend_literal:x
+ {
+ \dim_to_decimal_in_bp:n {#1} ~ \dim_to_decimal_in_bp:n {#2} ~
+ \dim_to_decimal_in_bp:n {#3} ~ \dim_to_decimal_in_bp:n {#4} ~
+ \dim_to_decimal_in_bp:n {#5} ~ \dim_to_decimal_in_bp:n {#6} ~
+ curveto
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_evenodd_rule:, \@@_backend_nonzero_rule:}
+% \begin{variable}{\g_@@_draw_eor_bool}
+% The even-odd rule here can be implemented as a simply switch.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_evenodd_rule:
+ { \bool_gset_true:N \g_@@_draw_eor_bool }
+\cs_new_protected:Npn \@@_backend_nonzero_rule:
+ { \bool_gset_false:N \g_@@_draw_eor_bool }
+\bool_new:N \g_@@_draw_eor_bool
+% \end{macrocode}
+% \end{variable}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_backend_closepath: ,
+% \@@_backend_stroke: ,
+% \@@_backend_closestroke: ,
+% \@@_backend_fill: ,
+% \@@_backend_fillstroke: ,
+% \@@_backend_clip: ,
+% \@@_backend_discardpath:
+% }
+% \begin{variable}{\g_@@_draw_clip_bool}
+% Unlike PDF, PostScript doesn't track separate colors for strokes and other
+% elements. It is also desirable to have the |clip| keyword after a stroke or
+% fill. To achieve those outcomes, there is some work to do. For color, the
+% stoke color is simple but the fill one has to be inserted by hand. For
+% clipping, the required ordering is achieved using a \TeX{} switch. All of
+% the operations end with a new path instruction as they do not terminate
+% (again in contrast to PDF).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_closepath:
+ { \@@_backend_literal:n { closepath } }
+\cs_new_protected:Npn \@@_backend_stroke:
+ {
+ \@@_backend_literal:n { stroke }
+ \bool_if:NT \g_@@_draw_clip_bool
+ {
+ \@@_backend_literal:x
+ {
+ \bool_if:NT \g_@@_draw_eor_bool { eo }
+ clip
+ }
+ }
+ \@@_backend_literal:n { newpath }
+ \bool_gset_false:N \g_@@_draw_clip_bool
+ }
+\cs_new_protected:Npn \@@_backend_closestroke:
+ {
+ \@@_backend_closepath:
+ \@@_backend_stroke:
+ }
+\cs_new_protected:Npn \@@_backend_fill:
+ {
+ \@@_backend_literal:n { gsave }
+ \@@_backend_literal:n { color.fc }
+ \@@_backend_literal:x
+ {
+ \bool_if:NT \g_@@_draw_eor_bool { eo }
+ fill
+ }
+ \@@_backend_literal:n { grestore }
+ \bool_if:NT \g_@@_draw_clip_bool
+ {
+ \@@_backend_literal:x
+ {
+ \bool_if:NT \g_@@_draw_eor_bool { eo }
+ clip
+ }
+ }
+ \@@_backend_literal:n { newpath }
+ \bool_gset_false:N \g_@@_draw_clip_bool
+ }
+\cs_new_protected:Npn \@@_backend_fillstroke:
+ {
+ \@@_backend_literal:n { gsave }
+ \@@_backend_literal:n { color.fc }
+ \@@_backend_literal:x
+ {
+ \bool_if:NT \g_@@_draw_eor_bool { eo }
+ fill
+ }
+ \@@_backend_literal:n { grestore }
+ \@@_backend_literal:n { stroke }
+ \bool_if:NT \g_@@_draw_clip_bool
+ {
+ \@@_backend_literal:x
+ {
+ \bool_if:NT \g_@@_draw_eor_bool { eo }
+ clip
+ }
+ }
+ \@@_backend_literal:n { newpath }
+ \bool_gset_false:N \g_@@_draw_clip_bool
+ }
+\cs_new_protected:Npn \@@_backend_clip:
+ { \bool_gset_true:N \g_@@_draw_clip_bool }
+\bool_new:N \g_@@_draw_clip_bool
+\cs_new_protected:Npn \@@_backend_discardpath:
+ {
+ \bool_if:NT \g_@@_draw_clip_bool
+ {
+ \@@_backend_literal:x
+ {
+ \bool_if:NT \g_@@_draw_eor_bool { eo }
+ clip
+ }
+ }
+ \@@_backend_literal:n { newpath }
+ \bool_gset_false:N \g_@@_draw_clip_bool
+ }
+% \end{macrocode}
+% \end{variable}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_dash_pattern:nn}
+% \begin{macro}{\@@_backend_dash:n}
+% \begin{macro}{\@@_backend_linewidth:n}
+% \begin{macro}{\@@_backend_miterlimit:n}
+% \begin{macro}
+% {
+% \@@_backend_cap_butt:, \@@_backend_cap_round:, \@@_backend_cap_rectangle:,
+% \@@_backend_join_miter:, \@@_backend_join_round:, \@@_backend_join_bevel:
+% }
+% Converting paths to output is again a case of mapping directly to
+% PostScript operations.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_dash_pattern:nn #1#2
+ {
+ \@@_backend_literal:x
+ {
+ [
+ \exp_args:Nf \use:n
+ { \clist_map_function:nN {#1} \@@_backend_dash:n }
+ ] ~
+ \dim_to_decimal_in_bp:n {#2} ~ setdash
+ }
+ }
+\cs_new:Npn \@@_backend_dash:n #1
+ { ~ \dim_to_decimal_in_bp:n {#1} }
+\cs_new_protected:Npn \@@_backend_linewidth:n #1
+ {
+ \@@_backend_literal:x
+ { \dim_to_decimal_in_bp:n {#1} ~ setlinewidth }
+ }
+\cs_new_protected:Npn \@@_backend_miterlimit:n #1
+ { \@@_backend_literal:x { \fp_eval:n {#1} ~ setmiterlimit } }
+\cs_new_protected:Npn \@@_backend_cap_butt:
+ { \@@_backend_literal:n { 0 ~ setlinecap } }
+\cs_new_protected:Npn \@@_backend_cap_round:
+ { \@@_backend_literal:n { 1 ~ setlinecap } }
+\cs_new_protected:Npn \@@_backend_cap_rectangle:
+ { \@@_backend_literal:n { 2 ~ setlinecap } }
+\cs_new_protected:Npn \@@_backend_join_miter:
+ { \@@_backend_literal:n { 0 ~ setlinejoin } }
+\cs_new_protected:Npn \@@_backend_join_round:
+ { \@@_backend_literal:n { 1 ~ setlinejoin } }
+\cs_new_protected:Npn \@@_backend_join_bevel:
+ { \@@_backend_literal:n { 2 ~ setlinejoin } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_backend_color_fill_cmyk:nnnn ,
+% \@@_backend_color_stroke_cmyk:nnnn
+% }
+% \begin{macro}
+% {
+% \@@_backend_color_fill_gray:n ,
+% \@@_backend_color_stroke_gray:n
+% }
+% \begin{macro}
+% {
+% \@@_backend_color_fill_rgb:nnn ,
+% \@@_backend_color_stroke_rgb:nnn
+% }
+% \begin{macro}
+% {
+% \@@_backend_color_fill:n, \@@_backend_color_fill:x,
+% \@@_backend_color_stroke:n, \@@_backend_color_stroke:x
+% }
+% For \texttt{dvips}, we can use the standard color stack to deal with
+% stroke color, but for fills have to switch to raw PostScript. This is
+% thus not handled by the stack, but the context is very restricted. See
+% also how fills are implemented.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_color_fill_cmyk:nnnn #1#2#3#4
+ {
+ \@@_backend_color_fill:x
+ {
+ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~
+ \fp_eval:n {#3} ~ \fp_eval:n {#4} ~
+ setcmykcolor
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_stroke_cmyk:nnnn #1#2#3#4
+ {
+ \@@_backend_color_stroke:x
+ {
+ cmyk ~
+ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~
+ \fp_eval:n {#3} ~ \fp_eval:n {#4}
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_fill_gray:n #1
+ { \@@_backend_color_fill:x { \fp_eval:n {#1} ~ setgray } }
+\cs_new_protected:Npn \@@_backend_color_stroke_gray:n #1
+ { \@@_backend_color_stroke:x { gray ~ \fp_eval:n {#1} } }
+\cs_new_protected:Npn \@@_backend_color_fill_rgb:nnn #1#2#3
+ {
+ \@@_backend_color_fill:x
+ { \fp_eval:n {#1} ~ \fp_eval:n {#2} ~ \fp_eval:n {#3} ~ setrgbcolor }
+ }
+\cs_new_protected:Npn \@@_backend_color_stroke_rgb:nnn #1#2#3
+ {
+ \@@_backend_color_stroke:x
+ { rgb ~ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~ \fp_eval:n {#3} }
+ }
+\cs_new_protected:Npn \@@_backend_color_fill:n #1
+ {
+ \__kernel_backend_postscript:n
+ { SDict ~ begin ~ /color.fc ~ { #1 } ~ def ~ end }
+ }
+\cs_generate_variant:Nn \@@_backend_color_fill:n { x }
+\cs_new_protected:Npn \@@_backend_color_stroke:n #1
+ {
+ \__kernel_backend_literal:n { color~push~#1 }
+ \group_insert_after:N \@@_color_reset:
+ }
+\cs_generate_variant:Nn \@@_backend_color_stroke:n { x }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_cm:nnnn}
+% In \texttt{dvips}, keeping the transformations in line with the engine
+% is unfortunately not possible for scaling and rotations: even if we
+% decompose the matrix into those operations, there is still no backend
+% tracking (\emph{cf.}~\texttt{(x)dvipdfmx}). Thus we take the shortest
+% path available and simply dump the matrix as given.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_cm:nnnn #1#2#3#4
+ {
+ \@@_backend_literal:n
+ {
+ [
+ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~
+ \fp_eval:n {#3} ~ \fp_eval:n {#4} ~
+ 0 ~ 0
+ ] ~
+ concat
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_box_use:Nnnnn}
+% Inside a picture |@beginspecial|/|@endspecial| are active, which is
+% normally a good thing but means that the position and scaling would be off
+% if the box was inserted directly. To deal with that, there are a number of
+% possible approaches. The implementation here was suggested by Tom Rokici
+% (author of \texttt{dvips}). We end the current special placement, then
+% set the current point with a literal |[begin]|. As for general
+% literals, we then use the stack to store the current point and move to
+% it. To insert the required transformation, we have to flip the $y$-axis,
+% once before and once after it. Then we get back to the \TeX{} reference
+% point to insert our content. The clean up has to happen in the right
+% places, hence the |[begin]|/|[end]| pair around |restore|. Finally,
+% we can return to \enquote{normal} drawing mode. Notice that the set up
+% here is very similar to that in \cs{@@_align_currentpoint_\ldots}, but
+% the ordering of saving and restoring is different (intermixed).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_box_use:Nnnnn #1#2#3#4#5
+ {
+ \@@_backend_literal:n { @endspecial }
+ \@@_backend_literal:n { [end] }
+ \@@_backend_literal:n { [begin] }
+ \@@_backend_literal:n { save }
+ \@@_backend_literal:n { currentpoint }
+ \@@_backend_literal:n { currentpoint~translate }
+ \@@_backend_cm:nnnn { 1 } { 0 } { 0 } { -1 }
+ \@@_backend_cm:nnnn {#2} {#3} {#4} {#5}
+ \@@_backend_cm:nnnn { 1 } { 0 } { 0 } { -1 }
+ \@@_backend_literal:n { neg~exch~neg~exch~translate }
+ \@@_backend_literal:n { [end] }
+ \hbox_overlap_right:n { \box_use:N #1 }
+ \@@_backend_literal:n { [begin] }
+ \@@_backend_literal:n { restore }
+ \@@_backend_literal:n { [end] }
+ \@@_backend_literal:n { [begin] }
+ \@@_backend_literal:n { @beginspecial }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macrocode}
+%</dvips>
+% \end{macrocode}
+%
+% \subsection{\texttt{pdfmode} and \texttt{(x)dvipdfmx}}
+%
+% Both \texttt{pdfmode} and \texttt{(x)dvipdfmx} directly produce PDF output
+% and understand a shared set of specials for drawing commands.
+%
+% \begin{macrocode}
+%<*dvipdfmx|pdfmode|xdvipdfmx>
+% \end{macrocode}
+%
+% \subsubsection{Drawing}
+%
+% \begin{macro}{\@@_backend_literal:n, \@@_backend_literal:x}
+% Pass data through using a dedicated interface.
+% \begin{macrocode}
+\cs_new_eq:NN \@@_backend_literal:n \__kernel_backend_literal_pdf:n
+\cs_generate_variant:Nn \@@_backend_literal:n { x }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_begin:, \@@_backend_end:}
+% No special requirements here, so simply set up a drawing scope.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_begin:
+ { \@@_backend_scope_begin: }
+\cs_new_protected:Npn \@@_backend_end:
+ { \@@_backend_scope_end: }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_scope_begin:, \@@_backend_scope_end:}
+% Use the backend-level scope mechanisms.
+% \begin{macrocode}
+\cs_new_eq:NN \@@_backend_scope_begin: \__kernel_backend_scope_begin:
+\cs_new_eq:NN \@@_backend_scope_end: \__kernel_backend_scope_end:
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_moveto:nn, \@@_backend_lineto:nn}
+% \begin{macro}{\@@_backend_curveto:nnnnnn}
+% \begin{macro}{\@@_backend_rectangle:nnnn}
+% Path creation operations all resolve directly to PDF primitive steps, with
+% only the need to convert to \texttt{bp}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_moveto:nn #1#2
+ {
+ \@@_backend_literal:x
+ { \dim_to_decimal_in_bp:n {#1} ~ \dim_to_decimal_in_bp:n {#2} ~ m }
+ }
+\cs_new_protected:Npn \@@_backend_lineto:nn #1#2
+ {
+ \@@_backend_literal:x
+ { \dim_to_decimal_in_bp:n {#1} ~ \dim_to_decimal_in_bp:n {#2} ~ l }
+ }
+\cs_new_protected:Npn \@@_backend_curveto:nnnnnn #1#2#3#4#5#6
+ {
+ \@@_backend_literal:x
+ {
+ \dim_to_decimal_in_bp:n {#1} ~ \dim_to_decimal_in_bp:n {#2} ~
+ \dim_to_decimal_in_bp:n {#3} ~ \dim_to_decimal_in_bp:n {#4} ~
+ \dim_to_decimal_in_bp:n {#5} ~ \dim_to_decimal_in_bp:n {#6} ~
+ c
+ }
+ }
+\cs_new_protected:Npn \@@_backend_rectangle:nnnn #1#2#3#4
+ {
+ \@@_backend_literal:x
+ {
+ \dim_to_decimal_in_bp:n {#1} ~ \dim_to_decimal_in_bp:n {#2} ~
+ \dim_to_decimal_in_bp:n {#3} ~ \dim_to_decimal_in_bp:n {#4} ~
+ re
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_evenodd_rule:, \@@_backend_nonzero_rule:}
+% \begin{variable}{\g_@@_draw_eor_bool}
+% The even-odd rule here can be implemented as a simply switch.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_evenodd_rule:
+ { \bool_gset_true:N \g_@@_draw_eor_bool }
+\cs_new_protected:Npn \@@_backend_nonzero_rule:
+ { \bool_gset_false:N \g_@@_draw_eor_bool }
+\bool_new:N \g_@@_draw_eor_bool
+% \end{macrocode}
+% \end{variable}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_backend_closepath: ,
+% \@@_backend_stroke: ,
+% \@@_backend_closestroke: ,
+% \@@_backend_fill: ,
+% \@@_backend_fillstroke: ,
+% \@@_backend_clip: ,
+% \@@_backend_discardpath:
+% }
+% Converting paths to output is again a case of mapping directly to
+% PDF operations.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_closepath:
+ { \@@_backend_literal:n { h } }
+\cs_new_protected:Npn \@@_backend_stroke:
+ { \@@_backend_literal:n { S } }
+\cs_new_protected:Npn \@@_backend_closestroke:
+ { \@@_backend_literal:n { s } }
+\cs_new_protected:Npn \@@_backend_fill:
+ {
+ \@@_backend_literal:x
+ { f \bool_if:NT \g_@@_draw_eor_bool * }
+ }
+\cs_new_protected:Npn \@@_backend_fillstroke:
+ {
+ \@@_backend_literal:x
+ { B \bool_if:NT \g_@@_draw_eor_bool * }
+ }
+\cs_new_protected:Npn \@@_backend_clip:
+ {
+ \@@_backend_literal:x
+ { W \bool_if:NT \g_@@_draw_eor_bool * }
+ }
+\cs_new_protected:Npn \@@_backend_discardpath:
+ { \@@_backend_literal:n { n } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_dash_pattern:nn}
+% \begin{macro}{\@@_backend_dash:n}
+% \begin{macro}{\@@_backend_linewidth:n}
+% \begin{macro}{\@@_backend_miterlimit:n}
+% \begin{macro}
+% {
+% \@@_backend_cap_butt:, \@@_backend_cap_round:, \@@_backend_cap_rectangle:,
+% \@@_backend_join_miter:, \@@_backend_join_round:, \@@_backend_join_bevel:
+% }
+% Converting paths to output is again a case of mapping directly to
+% PDF operations.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_dash_pattern:nn #1#2
+ {
+ \@@_backend_literal:x
+ {
+ [
+ \exp_args:Nf \use:n
+ { \clist_map_function:nN {#1} \@@_backend_dash:n }
+ ] ~
+ \dim_to_decimal_in_bp:n {#2} ~ d
+ }
+ }
+\cs_new:Npn \@@_backend_dash:n #1
+ { ~ \dim_to_decimal_in_bp:n {#1} }
+\cs_new_protected:Npn \@@_backend_linewidth:n #1
+ {
+ \@@_backend_literal:x
+ { \dim_to_decimal_in_bp:n {#1} ~ w }
+ }
+\cs_new_protected:Npn \@@_backend_miterlimit:n #1
+ { \@@_backend_literal:x { \fp_eval:n {#1} ~ M } }
+\cs_new_protected:Npn \@@_backend_cap_butt:
+ { \@@_backend_literal:n { 0 ~ J } }
+\cs_new_protected:Npn \@@_backend_cap_round:
+ { \@@_backend_literal:n { 1 ~ J } }
+\cs_new_protected:Npn \@@_backend_cap_rectangle:
+ { \@@_backend_literal:n { 2 ~ J } }
+\cs_new_protected:Npn \@@_backend_join_miter:
+ { \@@_backend_literal:n { 0 ~ j } }
+\cs_new_protected:Npn \@@_backend_join_round:
+ { \@@_backend_literal:n { 1 ~ j } }
+\cs_new_protected:Npn \@@_backend_join_bevel:
+ { \@@_backend_literal:n { 2 ~ j } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_backend_color_fill_cmyk:nnnn ,
+% \@@_backend_color_stroke_cmyk:nnnn
+% }
+% \begin{macro}
+% {
+% \@@_backend_color_fill_gray:n ,
+% \@@_backend_color_stroke_gray:n
+% }
+% \begin{macro}
+% {
+% \@@_backend_color_fill_rgb:nnn ,
+% \@@_backend_color_stroke_rgb:nnn
+% }
+% \begin{macro}{\@@_backend_color_select:n, \@@_backend_color_select:x}
+% \begin{macro}{\@@_backend_color_reset:}
+% Color has to be split between \texttt{(x)dvipdfmx} and the PDF engines
+% as there is no color stack for fill/stroke separation in the former.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_color_fill_cmyk:nnnn #1#2#3#4
+ {
+ \@@_backend_color_select:x
+ {
+ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~
+ \fp_eval:n {#3} ~ \fp_eval:n {#4} ~
+ k
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_stroke_cmyk:nnnn #1#2#3#4
+ {
+ \@@_backend_color_select:x
+ {
+ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~
+ \fp_eval:n {#3} ~ \fp_eval:n {#4} ~
+ k
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_fill_gray:n #1
+ { \@@_backend_color_select:x { \fp_eval:n {#1} ~ g } }
+\cs_new_protected:Npn \@@_backend_color_stroke_gray:n #1
+ { \@@_backend_color_select:x { \fp_eval:n {#1} ~ G } }
+\cs_new_protected:Npn \@@_backend_color_fill_rgb:nnn #1#2#3
+ {
+ \@@_backend_color_select:x
+ { \fp_eval:n {#1} ~ \fp_eval:n {#2} ~ \fp_eval:n {#3} ~ rg }
+ }
+\cs_new_protected:Npn \@@_backend_color_stroke_rgb:nnn #1#2#3
+ {
+ \@@_backend_color_select:x
+ { \fp_eval:n {#1} ~ \fp_eval:n {#2} ~ \fp_eval:n {#3} ~ RG }
+ }
+%<*pdfmode>
+\cs_new_protected:Npx \@@_backend_color_select:n #1
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \tex_pdfextension:D colorstack }
+ { \tex_pdfcolorstack:D }
+ \exp_not:N \l__kernel_color_stack_int push {#1}
+ \group_insert_after:N \exp_not:N \@@_backend_color_reset:
+ }
+\cs_new_protected:Npx \@@_backend_color_reset:
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \tex_pdfextension:D colorstack }
+ { \tex_pdfcolorstack:D }
+ \exp_not:N \l__kernel_color_stack_int pop \scan_stop:
+ }
+%</pdfmode>
+%<*dvipdfmx|xdvipdfmx>
+\cs_new_eq:NN \@@_backend_color_select:n \__kernel_backend_literal_pdf:n
+%</dvipdfmx|xdvipdfmx>
+\cs_generate_variant:Nn \@@_backend_color_select:n { x }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_cm:nnnn}
+% \begin{macro}{\@@_backend_cm_aux:nnnn}
+% Another split here between \texttt{pdfmode} and \texttt{(x)dvipdfmx}.
+% In the former, we have a direct method to maintain alignment: the backend
+% can use a matrix itself. For \texttt{(x)dvipdfmx}, we can to decompose the
+% matrix into rotations and a scaling, then use those operations as they
+% are handled by the backend. (There is backend support for matrix operations in
+% \texttt{(x)dvipdfmx}, but as a matched pair so not suitable for the
+% \enquote{stand alone} transformation set up here.)
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_cm:nnnn #1#2#3#4
+ {
+%<*pdfmode>
+ \__kernel_backend_matrix:x
+ {
+ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~
+ \fp_eval:n {#3} ~ \fp_eval:n {#4}
+ }
+%</pdfmode>
+%<*dvipdfmx|xdvipdfmx>
+ \@@_backend_cm_decompose:nnnnN {#1} {#2} {#3} {#4}
+ \@@_backend_cm_aux:nnnn
+%</dvipdfmx|xdvipdfmx>
+ }
+%<*dvipdfmx|xdvipdfmx>
+\cs_new_protected:Npn \@@_backend_cm_aux:nnnn #1#2#3#4
+ {
+ \__kernel_backend_literal:x
+ {
+ x:rotate~
+ \fp_compare:nNnTF {#1} = \c_zero_fp
+ { 0 }
+ { \fp_eval:n { round ( -#1 , 5 ) } }
+ }
+ \__kernel_backend_literal:x
+ {
+ x:scale~
+ \fp_eval:n { round ( #2 , 5 ) } ~
+ \fp_eval:n { round ( #3 , 5 ) }
+ }
+ \__kernel_backend_literal:x
+ {
+ x:rotate~
+ \fp_compare:nNnTF {#4} = \c_zero_fp
+ { 0 }
+ { \fp_eval:n { round ( -#4 , 5 ) } }
+ }
+ }
+%</dvipdfmx|xdvipdfmx>
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_cm_decompose:nnnnN}
+% \begin{macro}
+% {
+% \@@_backend_cm_decompose_auxi:nnnnN,
+% \@@_backend_cm_decompose_auxii:nnnnN,
+% \@@_backend_cm_decompose_auxiii:nnnnN,
+% }
+% Internally, transformations for drawing are tracked as a matrix. Not all
+% engines provide a way of dealing with this: if we use a raw matrix, the
+% engine looses track of positions (for example for hyperlinks), and this is
+% not desirable. They do, however, allow us to track rotations and scalings.
+% Luckily, we can decompose any (two-dimensional) matrix into two rotations
+% and a single scaling:
+% \[
+% \begin{bmatrix}
+% A & B \\ C & D
+% \end{bmatrix}
+% =
+% \begin{bmatrix}
+% \cos\beta & \sin\beta \\ -\sin\beta & \cos\beta
+% \end{bmatrix}
+% \begin{bmatrix}
+% w_{1} & 0 \\ 0 & w_{2}
+% \end{bmatrix}
+% \begin{bmatrix}
+% \cos\gamma & \sin\gamma \\ -\sin\gamma & \cos\gamma
+% \end{bmatrix}
+% \]
+% The parent matrix can be converted to
+% \[
+% \begin{bmatrix}
+% A & B \\ C & D
+% \end{bmatrix}
+% =
+% \begin{bmatrix}
+% E & H \\-H & E
+% \end{bmatrix}
+% +
+% \begin{bmatrix}
+% F & G \\ G & -F
+% \end{bmatrix}
+% \]
+% From these, we can find that
+% \begin{align*}
+% \frac{w_{1} + w_{2}}{2} &= \sqrt{E^{2} + H^{2}} \\
+% \frac{w_{1} - w_{2}}{2} &= \sqrt{F^{2} + G^{2}} \\
+% \gamma - \beta &= \tan^{-1}(G/F) \\
+% \gamma + \beta &= \tan^{-1}(H/E)
+% \end{align*}
+% at which point we just have to do various pieces of re-arrangement to
+% get all of the values. (See J.~Blinn, \emph{IEEE Comput.\ Graph.\ Appl.},
+% 1996, \textbf{16}, 82--88.) There is one wrinkle: the PostScript (and PDF)
+% way of specifying a transformation matrix exchanges where one would
+% normally expect $B$ and $C$ to be.
+% \begin{macrocode}
+%<*dvipdfmx|xdvipdfmx>
+\cs_new_protected:Npn \@@_backend_cm_decompose:nnnnN #1#2#3#4#5
+ {
+ \use:x
+ {
+ \@@_backend_cm_decompose_auxi:nnnnN
+ { \fp_eval:n { (#1 + #4) / 2 } }
+ { \fp_eval:n { (#1 - #4) / 2 } }
+ { \fp_eval:n { (#3 + #2) / 2 } }
+ { \fp_eval:n { (#3 - #2) / 2 } }
+ }
+ #5
+ }
+\cs_new_protected:Npn \@@_backend_cm_decompose_auxi:nnnnN #1#2#3#4#5
+ {
+ \use:x
+ {
+ \@@_backend_cm_decompose_auxii:nnnnN
+ { \fp_eval:n { 2 * sqrt ( #1 * #1 + #4 * #4 ) } }
+ { \fp_eval:n { 2 * sqrt ( #2 * #2 + #3 * #3 ) } }
+ { \fp_eval:n { atand ( #3 , #2 ) } }
+ { \fp_eval:n { atand ( #4 , #1 ) } }
+ }
+ #5
+ }
+\cs_new_protected:Npn \@@_backend_cm_decompose_auxii:nnnnN #1#2#3#4#5
+ {
+ \use:x
+ {
+ \@@_backend_cm_decompose_auxiii:nnnnN
+ { \fp_eval:n { ( #4 - #3 ) / 2 } }
+ { \fp_eval:n { ( #1 + #2 ) / 2 } }
+ { \fp_eval:n { ( #1 - #2 ) / 2 } }
+ { \fp_eval:n { ( #4 + #3 ) / 2 } }
+ }
+ #5
+ }
+\cs_new_protected:Npn \@@_backend_cm_decompose_auxiii:nnnnN #1#2#3#4#5
+ {
+ \fp_compare:nNnTF { abs( #2 ) } > { abs ( #3 ) }
+ { #5 {#1} {#2} {#3} {#4} }
+ { #5 {#1} {#3} {#2} {#4} }
+ }
+%</dvipdfmx|xdvipdfmx>
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_box_use:Nnnnn}
+% Inserting a \TeX{} box transformed to the requested position and using
+% the current matrix is done using a mixture of \TeX{} and low-level
+% manipulation. The offset can be handled by \TeX{}, so only any rotation/^^A
+% skew/scaling component needs to be done using the matrix operation. As this
+% operation can never be cached, the scope is set directly not using the
+% \texttt{draw} version.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_box_use:Nnnnn #1#2#3#4#5
+ {
+ \__kernel_backend_scope_begin:
+%<*pdfmode>
+ \@@_backend_cm:nnnn {#2} {#3} {#4} {#5}
+%</pdfmode>
+%<*dvipdfmx|xdvipdfmx>
+ \__kernel_backend_literal:x
+ {
+ pdf:btrans~matrix~
+ \fp_eval:n {#2} ~ \fp_eval:n {#3} ~
+ \fp_eval:n {#4} ~ \fp_eval:n {#5} ~
+ 0 ~ 0
+ }
+%</dvipdfmx|xdvipdfmx>
+ \hbox_overlap_right:n { \box_use:N #1 }
+%<*dvipdfmx|xdvipdfmx>
+ \__kernel_backend_literal:n { pdf:etrans }
+%</dvipdfmx|xdvipdfmx>
+ \__kernel_backend_scope_end:
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macrocode}
+%</dvipdfmx|pdfmode|xdvipdfmx>
+% \end{macrocode}
+%
+% \subsection{\texttt{dvisvgm} backend}
+%
+% \begin{macrocode}
+%<*dvisvgm>
+% \end{macrocode}
+%
+% \begin{macro}{\@@_backend_literal:n, \@@_backend_literal:x}
+% The same as the more general literal call.
+% \begin{macrocode}
+\cs_new_eq:NN \@@_backend_literal:n \__kernel_backend_literal_svg:n
+\cs_generate_variant:Nn \@@_backend_literal:n { x }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_begin:, \@@_backend_end:}
+% A drawing needs to be set up such that the co-ordinate system is
+% translated. That is done inside a scope, which as described below
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_begin:
+ {
+ \@@_backend_scope_begin:
+ \@@_backend_scope:n { transform="translate({?x},{?y})~scale(1,-1)" }
+ }
+\cs_new_protected:Npn \@@_backend_end:
+ { \@@_backend_scope_end: }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_scope_begin:, \@@_backend_scope_end:}
+% \begin{macro}{\@@_backend_scope:n, \@@_backend_scope:x}
+% \begin{variable}{\g_@@_draw_scope_int, \l_@@_draw_scope_int}
+% Several settings that with other backends are \enquote{stand alone} have
+% to be given as part of a scope in SVG. As a result, there is a need to
+% provide a mechanism to automatically close these extra scopes. That is
+% done using a dedicated function and a pair of tracking variables. Within
+% each graphics scope we use a global variable to do the work, with a group
+% used to save the value between scopes. The result is that no direct action
+% is needed when creating a scope.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_scope_begin:
+ {
+ \int_set_eq:NN
+ \l_@@_draw_scope_int
+ \g_@@_draw_scope_int
+ \group_begin:
+ \int_gzero:N \g_@@_draw_scope_int
+ }
+\cs_new_protected:Npn \@@_backend_scope_end:
+ {
+ \prg_replicate:nn
+ { \g_@@_draw_scope_int }
+ { \@@_backend_literal:n { </g> } }
+ \group_end:
+ \int_gset_eq:NN
+ \g_@@_draw_scope_int
+ \l_@@_draw_scope_int
+ }
+\cs_new_protected:Npn \@@_backend_scope:n #1
+ {
+ \@@_backend_literal:n { <g~ #1 > }
+ \int_gincr:N \g_@@_draw_scope_int
+ }
+\cs_generate_variant:Nn \@@_backend_scope:n { x }
+\int_new:N \g_@@_draw_scope_int
+\int_new:N \l_@@_draw_scope_int
+% \end{macrocode}
+% \end{variable}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_moveto:nn, \@@_backend_lineto:nn}
+% \begin{macro}{\@@_backend_rectangle:nnnn}
+% \begin{macro}{\@@_backend_curveto:nnnnnn}
+% \begin{macro}{\@@_backend_add_to_path:n}
+% \begin{variable}{\g_@@_draw_path_tl}
+% Once again, some work is needed to get path constructs correct. Rather
+% then write the values as they are given, the entire path needs to be
+% collected up before being output in one go. For that we use a dedicated
+% storage routine, which adds spaces as required. Since paths should
+% be fully expanded there is no need to worry about the internal
+% \texttt{x}-type expansion.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_moveto:nn #1#2
+ {
+ \@@_backend_add_to_path:n
+ { M ~ \dim_to_decimal:n {#1} ~ \dim_to_decimal:n {#2} }
+ }
+\cs_new_protected:Npn \@@_backend_lineto:nn #1#2
+ {
+ \@@_backend_add_to_path:n
+ { L ~ \dim_to_decimal:n {#1} ~ \dim_to_decimal:n {#2} }
+ }
+\cs_new_protected:Npn \@@_backend_rectangle:nnnn #1#2#3#4
+ {
+ \@@_backend_add_to_path:n
+ {
+ M ~ \dim_to_decimal:n {#1} ~ \dim_to_decimal:n {#2}
+ h ~ \dim_to_decimal:n {#3} ~
+ v ~ \dim_to_decimal:n {#4} ~
+ h ~ \dim_to_decimal:n { -#3 } ~
+ Z
+ }
+ }
+\cs_new_protected:Npn \@@_backend_curveto:nnnnnn #1#2#3#4#5#6
+ {
+ \@@_backend_add_to_path:n
+ {
+ C ~
+ \dim_to_decimal:n {#1} ~ \dim_to_decimal:n {#2} ~
+ \dim_to_decimal:n {#3} ~ \dim_to_decimal:n {#4} ~
+ \dim_to_decimal:n {#5} ~ \dim_to_decimal:n {#6}
+ }
+ }
+\cs_new_protected:Npn \@@_backend_add_to_path:n #1
+ {
+ \tl_gset:Nx \g_@@_draw_path_tl
+ {
+ \g_@@_draw_path_tl
+ \tl_if_empty:NF \g_@@_draw_path_tl { \c_space_tl }
+ #1
+ }
+ }
+\tl_new:N \g_@@_draw_path_tl
+% \end{macrocode}
+% \end{variable}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_evenodd_rule:, \@@_backend_nonzero_rule:}
+% The fill rules here have to be handled as scopes.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_evenodd_rule:
+ { \@@_backend_scope:n { fill-rule="evenodd" } }
+\cs_new_protected:Npn \@@_backend_nonzero_rule:
+ { \@@_backend_scope:n { fill-rule="nonzero" } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_path:n}
+% \begin{macro}
+% {
+% \@@_backend_closepath: ,
+% \@@_backend_stroke: ,
+% \@@_backend_closestroke: ,
+% \@@_backend_fill: ,
+% \@@_backend_fillstroke: ,
+% \@@_backend_clip: ,
+% \@@_backend_discardpath:
+% }
+% \begin{variable}{\g_@@_draw_clip_bool}
+% \begin{variable}{\g_@@_draw_path_int}
+% Setting fill and stroke effects and doing clipping all has to be done using
+% scopes. This means setting up the various requirements in a shared
+% auxiliary which deals with the bits and pieces. Clipping paths are reused
+% for path drawing: not essential but avoids constructing them twice.
+% Discarding a path needs a separate function as it's not quite the same.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_closepath:
+ { \@@_backend_add_to_path:n { Z } }
+\cs_new_protected:Npn \@@_backend_path:n #1
+ {
+ \bool_if:NTF \g_@@_draw_clip_bool
+ {
+ \int_gincr:N \g_@@_clip_path_int
+ \@@_backend_literal:x
+ {
+ < clipPath~id = " l3cp \int_use:N \g_@@_clip_path_int " >
+ { ?nl }
+ <path~d=" \g_@@_draw_path_tl "/> { ?nl }
+ < /clipPath > { ? nl }
+ <
+ use~xlink:href =
+ "\c_hash_str l3path \int_use:N \g_@@_path_int " ~
+ #1
+ />
+ }
+ \@@_backend_scope:x
+ {
+ clip-path =
+ "url( \c_hash_str l3cp \int_use:N \g_@@_clip_path_int)"
+ }
+ }
+ {
+ \@@_backend_literal:x
+ { <path ~ d=" \g_@@_draw_path_tl " ~ #1 /> }
+ }
+ \tl_gclear:N \g_@@_draw_path_tl
+ \bool_gset_false:N \g_@@_draw_clip_bool
+ }
+\int_new:N \g_@@_path_int
+\cs_new_protected:Npn \@@_backend_stroke:
+ { \@@_backend_path:n { style="fill:none" } }
+\cs_new_protected:Npn \@@_backend_closestroke:
+ {
+ \@@_backend_closepath:
+ \@@_backend_stroke:
+ }
+\cs_new_protected:Npn \@@_backend_fill:
+ { \@@_backend_path:n { style="stroke:none" } }
+\cs_new_protected:Npn \@@_backend_fillstroke:
+ { \@@_backend_path:n { } }
+\cs_new_protected:Npn \@@_backend_clip:
+ { \bool_gset_true:N \g_@@_draw_clip_bool }
+\bool_new:N \g_@@_draw_clip_bool
+\cs_new_protected:Npn \@@_backend_discardpath:
+ {
+ \bool_if:NT \g_@@_draw_clip_bool
+ {
+ \int_gincr:N \g_@@_clip_path_int
+ \@@_backend_literal:x
+ {
+ < clipPath~id = " l3cp \int_use:N \g_@@_clip_path_int " >
+ { ?nl }
+ <path~d=" \g_@@_draw_path_tl "/> { ?nl }
+ < /clipPath >
+ }
+ \@@_backend_scope:x
+ {
+ clip-path =
+ "url( \c_hash_str l3cp \int_use:N \g_@@_clip_path_int)"
+ }
+ }
+ \tl_gclear:N \g_@@_draw_path_tl
+ \bool_gset_false:N \g_@@_draw_clip_bool
+ }
+% \end{macrocode}
+% \end{variable}
+% \end{variable}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_dash_pattern:nn}
+% \begin{macro}{\@@_backend_dash:n}
+% \begin{macro}{\@@_backend_dash_aux:nn}
+% \begin{macro}{\@@_backend_linewidth:n}
+% \begin{macro}{\@@_backend_miterlimit:n}
+% \begin{macro}
+% {
+% \@@_backend_cap_butt:, \@@_backend_cap_round:, \@@_backend_cap_rectangle:,
+% \@@_backend_join_miter:, \@@_backend_join_round:, \@@_backend_join_bevel:
+% }
+% All of these ideas are properties of scopes in SVG. The only slight
+% complexity is converting the dash array properly (doing any required
+% maths).
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_dash_pattern:nn #1#2
+ {
+ \use:x
+ {
+ \@@_backend_dash_aux:nn
+ { \clist_map_function:nn {#1} \@@_backend_dash:n }
+ { \dim_to_decimal:n {#2} }
+ }
+ }
+\cs_new:Npn \@@_backend_dash:n #1
+ { , \dim_to_decimal_in_bp:n {#1} }
+\cs_new_protected:Npn \@@_backend_dash_aux:nn #1#2
+ {
+ \@@_backend_scope:x
+ {
+ stroke-dasharray =
+ "
+ \tl_if_empty:oTF { \use_none:n #1 }
+ { none }
+ { \use_none:n #1 }
+ " ~
+ stroke-offset=" #2 "
+ }
+ }
+\cs_new_protected:Npn \@@_backend_linewidth:n #1
+ { \@@_backend_scope:x { stroke-width=" \dim_to_decimal:n {#1} " } }
+\cs_new_protected:Npn \@@_backend_miterlimit:n #1
+ { \@@_backend_scope:x { stroke-miterlimit=" \fp_eval:n {#1} " } }
+\cs_new_protected:Npn \@@_backend_cap_butt:
+ { \@@_backend_scope:n { stroke-linecap="butt" } }
+\cs_new_protected:Npn \@@_backend_cap_round:
+ { \@@_backend_scope:n { stroke-linecap="round" } }
+\cs_new_protected:Npn \@@_backend_cap_rectangle:
+ { \@@_backend_scope:n { stroke-linecap="square" } }
+\cs_new_protected:Npn \@@_backend_join_miter:
+ { \@@_backend_scope:n { stroke-linejoin="miter" } }
+\cs_new_protected:Npn \@@_backend_join_round:
+ { \@@_backend_scope:n { stroke-linejoin="round" } }
+\cs_new_protected:Npn \@@_backend_join_bevel:
+ { \@@_backend_scope:n { stroke-linejoin="bevel" } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% \@@_backend_color_fill_cmyk:nnnn ,
+% \@@_backend_color_stroke_cmyk:nnnn
+% }
+% \begin{macro}
+% {
+% \@@_backend_color_fill_gray:n ,
+% \@@_backend_color_stroke_gray:n
+% }
+% \begin{macro}
+% {
+% \@@_backend_color_fill_rgb:nnn ,
+% \@@_backend_color_stroke_rgb:nnn
+% }
+% \begin{macro}{\@@_backend_color_fill:nnn}
+% SVG fill color has to be covered outside of the stack, as for
+% \texttt{dvips}. Here, we are only allowed RGB colors so there is some
+% conversion to do.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_color_fill_cmyk:nnnn #1#2#3#4
+ {
+ \use:x
+ {
+ \@@_backend_color_fill:nnn
+ { \fp_eval:n { -100 * ( (#1) * ( 1 - (#4) ) - 1 ) } }
+ { \fp_eval:n { -100 * ( (#2) * ( 1 - (#4) ) + #4 - 1 ) } }
+ { \fp_eval:n { -100 * ( (#3) * ( 1 - (#4) ) + #4 - 1 ) } }
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_stroke_cmyk:nnnn #1#2#3#4
+ {
+ \@@_backend_select:x
+ {
+ cmyk~
+ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~
+ \fp_eval:n {#3} ~ \fp_eval:n {#4}
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_fill_gray:n #1
+ {
+ \use:x
+ {
+ \@@_backend_color_gray_aux:n
+ { \fp_eval:n { 100 * (#1) } }
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_gray_aux:n #1
+ { \@@_backend_color_fill:nnn {#1} {#1} {#1} }
+\cs_new_protected:Npn \@@_backend_color_stroke_gray:n #1
+ { \@@_backend_select:x { gray~ \fp_eval:n {#1} } }
+\cs_new_protected:Npn \@@_backend_color_fill_rgb:nnn #1#2#3
+ {
+ \use:x
+ {
+ \@@_backend_color_fill:nnn
+ { \fp_eval:n { 100 * (#1) } }
+ { \fp_eval:n { 100 * (#2) } }
+ { \fp_eval:n { 100 * (#3) } }
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_fill:nnn #1#2#3
+ {
+ \@@_backend_scope:x
+ {
+ fill =
+ "
+ rgb
+ (
+ #1 \c_percent_str ,
+ #2 \c_percent_str ,
+ #3 \c_percent_str
+ )
+ "
+ }
+ }
+\cs_new_protected:Npn \@@_backend_color_stroke_rgb:nnn #1#2#3
+ {
+ \@@_backend_select:x
+ { rgb~ \fp_eval:n {#1} ~ \fp_eval:n {#2} ~ \fp_eval:n {#3} }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_cm:nnnn}
+% The four arguments here are floats (the affine matrix), the last
+% two are a displacement vector.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_cm:nnnn #1#2#3#4
+ {
+ \@@_backend_scope:n
+ {
+ transform =
+ "
+ matrix
+ (
+ \fp_eval:n {#1} , \fp_eval:n {#2} ,
+ \fp_eval:n {#3} , \fp_eval:n {#4} ,
+ 0pt , 0pt
+ )
+ "
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_box_use:Nnnnn}
+% No special savings can be made here: simply displace the box inside
+% a scope. As there is nothing to re-box, just make the box passed of
+% zero size.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_box_use:Nnnnn #1#2#3#4#5#6#7
+ {
+ \__kernel_backend_scope_begin:
+ \@@_backend_cm:nnnn {#2} {#3} {#4} {#5}
+ \__kernel_backend_literal_svg:n
+ {
+ < g~
+ stroke="none"~
+ transform="scale(-1,1)~translate({?x},{?y})~scale(-1,-1)"
+ >
+ }
+ \box_set_wd:Nn #1 { 0pt }
+ \box_set_ht:Nn #1 { 0pt }
+ \box_set_dp:Nn #1 { 0pt }
+ \box_use:N #1
+ \__kernel_backend_literal_svg:n { </g> }
+ \__kernel_backend_scope_end:
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macrocode}
+%</dvisvgm>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%</initex|package>
+% \end{macrocode}
+%
+% \end{implementation}
+%
+% \PrintIndex