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l3backend-color.dtx
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l3backend-color.dtx
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% \iffalse meta-comment
%
%% File: l3backend-color.dtx
%
% Copyright (C) 2019-2023 The LaTeX 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-color} package\\ Backend color support^^A
% }
%
% \author{^^A
% The \LaTeX{} Project\thanks
% {^^A
% E-mail:
% \href{mailto:latex-team@latex-project.org}
% {latex-team@latex-project.org}^^A
% }^^A
% }
%
% \date{Released 2023-01-16}
%
% \maketitle
%
% \begin{documentation}
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3backend-color} implementation}
%
% \begin{macrocode}
%<*package>
%<@@=color>
% \end{macrocode}
%
% Color support is split into parts: collecting data from \LaTeXe{}, the color
% stack, general color, separations, and color for drawings. We have different
% approaches in each backend, and have some choices to make about
% \texttt{dvipdfmx}/\XeTeX{} in particular. Whilst it is in some ways
% convenient to use the same approach in multiple backends, the fact that
% \texttt{dvipdfmx}/\XeTeX{} is PDF-based means it (largely) sticks closer to
% direct PDF output.
%
% \subsection{Collecting information from \LaTeXe{}}
%
% \subsubsection{\texttt{dvips}-style}
%
% \begin{macrocode}
%<*dvisvgm|dvipdfmx|dvips|xetex>
% \end{macrocode}
%
% \begin{macro}{\@@_backend_pickup:N}
% \begin{macro}{\@@_backend_pickup:w}
% Allow for \LaTeXe{} color. Here, the possible input values are limited:
% \texttt{dvips}-style colors can be taken as-is. The \texttt{x}-type expansion
% is there to cover the case where \pkg{xcolor} is in use.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_pickup:N #1
{
\exp_args:NV \tl_if_head_is_space:nTF \current@color
{
\tl_set:Nn #1 { { gray } { 0 } }
\msg_warning:nnx { color } { unhandled }
{ \current@color }
}
{
\exp_last_unbraced:Nx \@@_backend_pickup:w
{ \current@color } \s_@@_stop #1
}
}
\cs_new_protected:Npn \@@_backend_pickup:w #1 ~ #2 \s_@@_stop #3
{ \tl_set:Nn #3 { {#1} {#2} } }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</dvisvgm|dvipdfmx|dvips|xetex>
% \end{macrocode}
%
% \subsubsection{\LuaTeX{} and \pdfTeX{}}
%
% \begin{macrocode}
%<*luatex|pdftex>
% \end{macrocode}
%
% \begin{macro}{\@@_backend_pickup:N}
% \begin{macro}{\@@_backend_pickup:w}
% Same ideas, but with a different backend-dependent format.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_pickup:N #1
{
\exp_last_unbraced:Nx \@@_backend_pickup:w
{ \current@color } ~ 0 ~ 0 ~ 0 \s_@@_stop #1
}
\cs_new_protected:Npn \@@_backend_pickup:w
#1 ~ #2 ~ #3 ~ #4 ~ #5 ~ #6 \s_@@_stop #7
{
\str_if_eq:nnTF {#2} { g }
{ \tl_set:Nn #7 { { gray } {#1} } }
{
\str_if_eq:nnTF {#4} { rg }
{ \tl_set:Nn #7 { { rgb } { #1 ~ #2 ~ #3 } } }
{
\str_if_eq:nnTF {#5} { k }
{ \tl_set:Nn #7 { { cmyk } { #1 ~ #2 ~ #3 ~ #4 } } }
{
\tl_set:Nn #1 { { gray } { 0 } }
\msg_warning:nnx { color } { unhandled }
{ \current@color }
}
}
}
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</luatex|pdftex>
% \end{macrocode}
%
% \subsection{The color stack}
%
% For PDF-based engines, we have a color stack available inside the specials.
% This is used for concepts beyond color itself: it is needed to manage the
% graphics state generally. Although \texttt{dvipdfmx}/\XeTeX{} have multiple
% color stacks in recent releases, the way these interact with the original
% single stack and with other graphic state operations means that currently it
% is not feasible to use the multiple stacks.
%
% \subsubsection{Common code}
%
% \begin{macrocode}
%<*luatex|pdftex>
% \end{macrocode}
%
% \begin{variable}{\l_@@_backend_stack_int}
% For tracking which stack is in use where multiple stacks are used:
% currently just \pdfTeX{}/\LuaTeX{} but at some future stage may also cover
% \texttt{dvipdfmx}/\XeTeX{}.
% \begin{macrocode}
\int_new:N \l_@@_backend_stack_int
% \end{macrocode}
% \end{variable}
%
% \begin{macrocode}
%</luatex|pdftex>
% \end{macrocode}
%
% \subsubsection{\LuaTeX and \pdfTeX{}}
%
% \begin{macrocode}
%<*luatex|pdftex>
% \end{macrocode}
%
% \begin{macro}{\__kernel_color_backend_stack_init:Nnn}
% \begin{macrocode}
\cs_new_protected:Npn \__kernel_color_backend_stack_init:Nnn #1#2#3
{
\int_const:Nn #1
{
%<*luatex>
\tex_pdffeedback:D colorstackinit ~
%</luatex>
%<*pdftex>
\tex_pdfcolorstackinit:D
%</pdftex>
\tl_if_blank:nF {#2} { #2 ~ }
{#3}
}
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\__kernel_color_backend_stack_push:nn}
% \begin{macro}{\__kernel_color_backend_stack_pop:n}
% \begin{macrocode}
\cs_new_protected:Npn \__kernel_color_backend_stack_push:nn #1#2
{
%<*luatex>
\tex_pdfextension:D colorstack ~
%</luatex>
%<*pdftex>
\tex_pdfcolorstack:D
%</pdftex>
\int_eval:n {#1} ~ push ~ {#2}
}
\cs_new_protected:Npn \__kernel_color_backend_stack_pop:n #1
{
%<*luatex>
\tex_pdfextension:D colorstack ~
%</luatex>
%<*pdftex>
\tex_pdfcolorstack:D
%</pdftex>
\int_eval:n {#1} ~ pop \scan_stop:
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</luatex|pdftex>
% \end{macrocode}
%
% \subsection{General color}
%
% \subsubsection{\texttt{dvips}-style}
%
% \begin{macrocode}
%<*dvips|dvisvgm>
% \end{macrocode}
%
% \begin{macro}
% {
% \@@_backend_select_cmyk:n ,
% \@@_backend_select_gray:n ,
% \@@_backend_select_named:n ,
% \@@_backend_select_rgb:n ,
% \@@_backend_select:n
% }
% \begin{macro}{\@@_backend_reset:}
% \begin{macro}{color.sc}
% Push the data to the stack. In the case of \texttt{dvips} also saves the
% drawing color in raw PostScript. The |spot| model is for handling data
% in classical format.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select_cmyk:n #1
{ \@@_backend_select:n { cmyk ~ #1 } }
\cs_new_protected:Npn \@@_backend_select_gray:n #1
{ \@@_backend_select:n { gray ~ #1 } }
\cs_new_protected:Npn \@@_backend_select_named:n #1
{ \@@_backend_select:n { ~ #1 } }
\cs_new_protected:Npn \@@_backend_select_rgb:n #1
{ \@@_backend_select:n { rgb ~ #1 } }
\cs_new_protected:Npn \@@_backend_select:n #1
{
\__kernel_backend_literal:n { color~push~ #1 }
%<*dvips>
\__kernel_backend_postscript:n { /color.sc ~ { } ~ def }
%</dvips>
}
\cs_new_protected:Npn \@@_backend_reset:
{ \__kernel_backend_literal:n { color~pop } }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</dvips|dvisvgm>
% \end{macrocode}
%
% \subsubsection{\LuaTeX{} and \pdfTeX{}}
%
% \begin{macrocode}
%<*luatex|pdftex>
% \end{macrocode}
%
% \begin{variable}{\l_@@_backend_fill_tl, \l_@@_backend_stroke_tl}
% \begin{macrocode}
\tl_new:N \l_@@_backend_fill_tl
\tl_new:N \l_@@_backend_stroke_tl
% \end{macrocode}
% \end{variable}
%
% \begin{macro}
% {
% \@@_backend_select_cmyk:n ,
% \@@_backend_select_gray:n ,
% \@@_backend_select_rgb:n
% }
% \begin{macro}{\@@_backend_select:nn}
% \begin{macro}{\@@_backend_reset:}
% \begin{macro}{\@@_backend_stack_push:nn}
% Store the values then pass to the stack. The abstraction here allows for
% transparency needing the same fundamental approach but with switchable
% code for \LuaTeX{}.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select_cmyk:n #1
{ \@@_backend_select:nn { #1 ~ k } { #1 ~ K } }
\cs_new_protected:Npn \@@_backend_select_gray:n #1
{ \@@_backend_select:nn { #1 ~ g } { #1 ~ G } }
\cs_new_protected:Npn \@@_backend_select_rgb:n #1
{ \@@_backend_select:nn { #1 ~ rg } { #1 ~ RG } }
\cs_new_protected:Npn \@@_backend_select:nn #1#2
{
\tl_set:Nn \l_@@_backend_fill_tl {#1}
\tl_set:Nn \l_@@_backend_stroke_tl {#2}
\__kernel_color_backend_stack_push:nn \l_@@_backend_stack_int { #1 ~ #2 }
}
\cs_new_protected:Npn \@@_backend_reset:
{ \__kernel_color_backend_stack_pop:n \l_@@_backend_stack_int }
\cs_new_eq:NN \@@_backend_stack_push:nn \__kernel_color_backend_stack_push:nn
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</luatex|pdftex>
% \end{macrocode}
%
% \subsubsection{\texttt{dvipmdfx}/\XeTeX{}}
%
% These backends have the most possible approaches: it recognises both
% \texttt{dvips}-based color specials and its own format, plus one can
% include PDF statements directly. Recent releases also have a color stack
% approach similar to \pdfTeX{}. Of the stack methods, the dedicated
% the most versatile is the latter as it can cover all of the use cases
% we have. However, at present this interacts problematically with any color
% on the original stack. We therefore stick to a single-stack approach here.
%
% \begin{macrocode}
%<*dvipdfmx|xetex>
% \end{macrocode}
%
% \begin{macro}
% {
% \@@_backend_select:n ,
% \@@_backend_select_cmyk:n ,
% \@@_backend_select_gray:n ,
% \@@_backend_select_rgb:n
% }
% \begin{macro}{\@@_backend_reset:}
% Using the single stack is relatively easy as there is only one route.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select:n #1
{ \__kernel_backend_literal:n { pdf : bc ~ [ #1 ] } }
\cs_new_eq:NN \@@_backend_select_cmyk:n \@@_backend_select:n
\cs_new_eq:NN \@@_backend_select_gray:n \@@_backend_select:n
\cs_new_eq:NN \@@_backend_select_rgb:n \@@_backend_select:n
\cs_new_protected:Npn \@@_backend_reset:
{ \__kernel_backend_literal:n { pdf : ec } }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\@@_backend_select_named:n}
% For classical named colors, the only value we should get is |Black|.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select_named:n #1
{
\str_if_eq:nnTF {#1} { Black }
{ \@@_backend_select_gray:n { 0 } }
{ \msg_error:nnn { color } { unknown-named-color } {#1} }
}
\msg_new:nnn { color } { unknown-named-color }
{ Named~color~'#1'~is~not~known. }
% \end{macrocode}
% \end{macro}
%
% \begin{macrocode}
%</dvipdfmx|xetex>
% \end{macrocode}
%
% \subsection{Separations}
%
% Here, life gets interesting and we need essentially one approach per
% backend.
%
% \begin{macrocode}
%<*dvipdfmx|luatex|pdftex|xetex|dvips>
% \end{macrocode}
%
% But we start with some functionality needed for both PostScript and
% PDF based backends.
%
% \begin{variable}{\g_@@_backend_colorant_prop}
% \begin{macrocode}
\prop_new:N \g_@@_backend_colorant_prop
% \end{macrocode}
% \end{variable}
%
% \begin{macro}[EXP]{\@@_backend_devicen_colorants:n}
% \begin{macro}[EXP]{\@@_backend_devicen_colorants:w}
% \begin{macrocode}
\cs_new:Npx \@@_backend_devicen_colorants:n #1
{
\exp_not:N \tl_if_blank:nF {#1}
{
\c_space_tl
<< ~
/Colorants ~
<< ~
\exp_not:N \@@_backend_devicen_colorants:w #1 ~
\exp_not:N \q_recursion_tail \c_space_tl
\exp_not:N \q_recursion_stop
>> ~
>>
}
}
\cs_new:Npn \@@_backend_devicen_colorants:w #1 ~
{
\quark_if_recursion_tail_stop:n {#1}
\prop_if_in:NnT \g_@@_backend_colorant_prop {#1}
{
#1 ~
\prop_item:Nn \g_@@_backend_colorant_prop {#1} ~
}
\@@_backend_devicen_colorants:w
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</dvipdfmx|luatex|pdftex|xetex|dvips>
% \end{macrocode}
%
% \begin{macrocode}
%<*dvips>
% \end{macrocode}
%
% \begin{macro}{\@@_backend_select_separation:nn, \@@_backend_select_devicen:nn}
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select_separation:nn #1#2
{ \@@_backend_select:n { separation ~ #1 ~ #2 } }
\cs_new_eq:NN \@@_backend_select_devicen:nn \@@_backend_select_separation:nn
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_backend_select_iccbased:nn}
% No support.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select_iccbased:nn #1#2 { }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}
% {
% \@@_backend_separation_init:nnnnn,
% \@@_backend_separation_init:nxxnn
% }
% \begin{macro}
% {\@@_backend_separation_init_aux:nnnnnn}
% \begin{macro}[EXP]
% {
% \@@_backend_separation_init_/DeviceCMYK:nnn ,
% \@@_backend_separation_init_/DeviceGray:nnn ,
% \@@_backend_separation_init_/DeviceRGB:nnn
% }
% \begin{macro}[EXP]{\@@_backend_separation_init_Device:Nn}
% \begin{macro}[EXP]{\@@_backend_separation_init:nnn}
% \begin{macro}[EXP]{\@@_backend_separation_init_count:n}
% \begin{macro}[EXP]{\@@_backend_separation_init_count:w}
% \begin{macro}[EXP]{\@@_backend_separation_init:nnnn}
% \begin{macro}[EXP]{\@@_backend_separation_init:w}
% \begin{macro}[EXP]{\@@_backend_separation_init:n}
% \begin{macro}[EXP]{\@@_backend_separation_init:nw}
% \begin{macro}{\@@_backend_separation_init_CIELAB:nnn}
% Initialising here means creating a small header set up plus massaging
% some data. This comes about as we have to deal with PDF-focussed data,
% which makes most sense \enquote{higher-up}. The approach is based on
% ideas from \url{https://tex.stackexchange.com/q/560093} plus using
% the PostScript manual for other aspects.
% \begin{macrocode}
\cs_new_protected:Npx \@@_backend_separation_init:nnnnn #1#2#3#4#5
{
\bool_if:NT \g__kernel_backend_header_bool
{
\exp_args:Nx \__kernel_backend_first_shipout:n
{
\exp_not:N \@@_backend_separation_init_aux:nnnnnn
{ \exp_not:N \int_use:N \g_@@_model_int }
{#1} {#2} {#3} {#4} {#5}
}
\prop_gput:Nxx \exp_not:N \g_@@_backend_colorant_prop
{ / \exp_not:N \str_convert_pdfname:n {#1} }
{
<< ~
/setcolorspace ~ {} ~
>> ~ begin ~
color \exp_not:N \int_use:N \g_@@_model_int \c_space_tl
end
}
}
}
\cs_generate_variant:Nn \@@_backend_separation_init:nnnnn { nxx }
\cs_new_protected:Npn \@@_backend_separation_init_aux:nnnnnn #1#2#3#4#5#6
{
\__kernel_backend_literal:e
{
!
TeXDict ~ begin ~
/color #1
{
[ ~
/Separation ~ ( \str_convert_pdfname:n {#2} ) ~
[ ~ #3 ~ ] ~
{
\cs_if_exist_use:cF { @@_backend_separation_init_ #3 :nnn }
{ \@@_backend_separation_init:nnn }
{#4} {#5} {#6}
}
] ~ setcolorspace
} ~ def ~
end
}
}
\cs_new:cpn { @@_backend_separation_init_ /DeviceCMYK :nnn } #1#2#3
{ \@@_backend_separation_init_Device:Nn 4 {#3} }
\cs_new:cpn { @@_backend_separation_init_ /DeviceGray :nnn } #1#2#3
{ \@@_backend_separation_init_Device:Nn 1 {#3} }
\cs_new:cpn { @@_backend_separation_init_ /DeviceRGB :nnn } #1#2#3
{ \@@_backend_separation_init_Device:Nn 2 {#3} }
\cs_new:Npn \@@_backend_separation_init_Device:Nn #1#2
{
#2 ~
\prg_replicate:nn {#1}
{ #1 ~ index ~ mul ~ #1 ~ 1 ~ roll ~ }
\int_eval:n { #1 + 1 } ~ -1 ~ roll ~ pop
}
% \end{macrocode}
% For the generic case, we cannot use |/FunctionType 2| unfortunately, so
% we have to code that idea up in PostScript. Here, we will therefore assume
% that a range is \emph{always} given. First, we count values in each argument:
% at the backend level, we can assume there are always well-behaved with
% spaces present.
% \begin{macrocode}
\cs_new:Npn \@@_backend_separation_init:nnn #1#2#3
{
\exp_args:Ne \@@_backend_separation_init:nnnn
{ \@@_backend_separation_init_count:n {#2} }
{#1} {#2} {#3}
}
\cs_new:Npn \@@_backend_separation_init_count:n #1
{ \int_eval:n { 0 \@@_backend_separation_init_count:w #1 ~ \s_@@_stop } }
\cs_new:Npn \@@_backend_separation_init_count:w #1 ~ #2 \s_@@_stop
{
+1
\tl_if_blank:nF {#2}
{ \@@_backend_separation_init_count:w #2 \s_@@_stop }
}
% \end{macrocode}
% Now we implement the algorithm. In the terms in the PostScript manual,
% we have $\mathbf{N} = 1$ and $\mathbf{Domain} = [0~1]$, with
% $\mathbf{Range}$ as |#2|, $\mathbf{C0}$ as |#3| and $\mathbf{C1}$
% as |#4|, with the number of output components in |#1|. So all we have
% to do is implement $y_{i} = \mathbf{C0}_{i} + x(\mathbf{C1}_{i} -
% \mathbf{C0}_{i})$ with lots of stack manipulation, then check the
% ranges. That's done by adding everything to the stack first, then using
% the fact we know all of the offsets. As manipulating the stack is tricky,
% we start by re-formatting the $\mathbf{C0}$ and $\mathbf{C1}$ arrays to
% be interleaved, and add a \texttt{0} to each pair: this is used
% to keep the stack of constant length while we are doing the first pass of
% mathematics. We then working through that list, calculating from the
% last to the first value before tidying up by removing all of the input
% values. We do that by first copying all of the final $y$ values to the
% end of the stack, then rolling everything so we can pop the now-unneeded
% material.
% \begin{macrocode}
\cs_new:Npn \@@_backend_separation_init:nnnn #1#2#3#4
{
\@@_backend_separation_init:w #3 ~ \s_@@_stop #4 ~ \s_@@_stop
\prg_replicate:nn {#1}
{
pop ~ 1 ~ index ~ neg ~ 1 ~ index ~ add ~
\int_eval:n { 3 * #1 } ~ index ~ mul ~
2 ~ index ~ add ~
\int_eval:n { 3 * #1 } ~ #1 ~ roll ~
}
\int_step_function:nnnN {#1} { -1 } { 1 }
\@@_backend_separation_init:n
\int_eval:n { 4 * #1 + 1 } ~ #1 ~ roll ~
\prg_replicate:nn { 3 * #1 + 1 } { pop ~ }
\tl_if_blank:nF {#2}
{ \@@_backend_separation_init:nw {#1} #2 ~ \s_@@_stop }
}
\cs_new:Npn \@@_backend_separation_init:w
#1 ~ #2 \s_@@_stop #3 ~ #4 \s_@@_stop
{
#1 ~ #3 ~ 0 ~
\tl_if_blank:nF {#2}
{ \@@_backend_separation_init:w #2 \s_@@_stop #4 \s_@@_stop }
}
\cs_new:Npn \@@_backend_separation_init:n #1
{ \int_eval:n { #1 * 2 } ~ index ~ }
% \end{macrocode}
% Finally, we deal with the range limit if required. This is handled
% by splitting the range into pairs. It's then just a question of doing
% the comparisons, this time dropping everything except the desired
% result.
% \begin{macrocode}
\cs_new:Npn \@@_backend_separation_init:nw #1#2 ~ #3 ~ #4 \s_@@_stop
{
#2 ~ #3 ~
2 ~ index ~ 2 ~ index ~ lt ~
{ ~ pop ~ exch ~ pop ~ } ~
{ ~
2 ~ index ~ 1 ~ index ~ gt ~
{ ~ exch ~ pop ~ exch ~ pop ~ } ~
{ ~ pop ~ pop ~ } ~
ifelse ~
}
ifelse ~
#1 ~ 1 ~ roll ~
\tl_if_blank:nF {#4}
{ \@@_backend_separation_init:nw {#1} #4 \s_@@_stop }
}
% \end{macrocode}
% CIELAB support uses the detail from the PostScript reference, page 227;
% other than that block of PostScript, this is the same as for PDF-based
% routes.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_separation_init_CIELAB:nnn #1#2#3
{
\@@_backend_separation_init:nxxnn
{#2}
{
/CIEBasedABC ~
<< ~
/RangeABC ~ [ ~ \c_@@_model_range_CIELAB_tl \c_space_tl ] ~
/DecodeABC ~
[ ~
{ ~ 16 ~ add ~ 116 ~ div ~ } ~ bind ~
{ ~ 500 ~ div ~ } ~ bind ~
{ ~ 200 ~ div ~ } ~ bind ~
] ~
/MatrixABC ~ [ ~ 1 ~ 1 ~ 1 ~ 1 ~ 0 ~ 0 ~ 0 ~ 0 ~ -1 ~ ] ~
/DecodeLMN ~
[ ~
{ ~
dup ~ 6 ~ 29 ~ div ~ ge ~
{ ~ dup ~ dup ~ mul ~ mul ~ ~ } ~
{ ~ 4 ~ 29 ~ div ~ sub ~ 108 ~ 841 ~ div ~ mul ~ } ~
ifelse ~
0.9505 ~ mul ~
} ~ bind ~
{ ~
dup ~ 6 ~ 29 ~ div ~ ge ~
{ ~ dup ~ dup ~ mul ~ mul ~ } ~
{ ~ 4 ~ 29 ~ div ~ sub ~ 108 ~ 841 ~ div ~ mul ~ } ~
ifelse ~
} ~ bind ~
{ ~
dup ~ 6 ~ 29 ~ div ~ ge ~
{ ~ dup ~ dup ~ mul ~ mul ~ } ~
{ ~ 4 ~ 29 ~ div ~ sub ~ 108 ~ 841 ~ div ~ mul ~ } ~
ifelse ~
1.0890 ~ mul ~
} ~ bind
] ~
/WhitePoint ~
[ ~ \tl_use:c { c_@@_model_whitepoint_CIELAB_ #1 _tl } ~ ] ~
>>
}
{ \c_@@_model_range_CIELAB_tl }
{ 100 ~ 0 ~ 0 }
{#3}
}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\@@_backend_devicen_init:nnn}
% Trivial as almost all of the work occurs in the shared code.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_devicen_init:nnn #1#2#3
{
\__kernel_backend_literal:e
{
!
TeXDict ~ begin ~
/color \int_use:N \g_@@_model_int
{
[ ~
/DeviceN ~
[ ~ #1 ~ ] ~
#2 ~
{ ~ #3 ~ } ~
\@@_backend_devicen_colorants:n {#1}
] ~ setcolorspace
} ~ def ~
end
}
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_backend_iccbased_init:nnn}
% No support at present.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_iccbased_init:nnn #1#2#3 { }
% \end{macrocode}
% \end{macro}
%
% \begin{macrocode}
%</dvips>
% \end{macrocode}
%
% \begin{macrocode}
%<*dvisvgm>
% \end{macrocode}
%
% \begin{macro}
% {
% \@@_backend_select_separation:nn,
% \@@_backend_select_devicen:nn
% }
% No support at present.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select_separation:nn #1#2 { }
\cs_new_eq:NN \@@_backend_select_devicen:nn \@@_backend_select_separation:nn
% \end{macrocode}
% \end{macro}
%
% \begin{macro}
% {\@@_backend_separation_init:nnnnn, \@@_backend_separation_init_CIELAB:nnn}
% No support at present.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_separation_init:nnnnn #1#2#3#4#5 { }
\cs_new_protected:Npn \@@_backend_separation_init_CIELAB:nnnnnn #1#2#3 { }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_backend_select_iccbased:nn}
% As detailed in \url{https://www.w3.org/TR/css-color-4/#at-profile},
% we can apply a color profile using CSS. As we have a local file, we use
% a relative URL.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select_iccbased:nn #1#2
{
\__kernel_backend_literal_svg:x
{
<style>
@color-profile ~
\str_if_eq:nnTF {#2} { cmyk }
{ device-cmyk }
{ --color \int_use:N \g_@@_model_int }
\c_space_tl
{
src:("#1")
}
</style>
}
}
% \end{macrocode}
% \end{macro}
%
% \begin{macrocode}
%</dvisvgm>
% \end{macrocode}
%
% \begin{macrocode}
%<*dvipdfmx|luatex|pdftex|xetex>
% \end{macrocode}
%
% \begin{macro}
% {
% \@@_backend_select_separation:nn,
% \@@_backend_select_devicen:nn ,
% \@@_backend_select_iccbased:nn
% }
% \begin{macrocode}
%<*dvipdfmx|xetex>
\cs_new_protected:Npn \@@_backend_select_separation:nn #1#2
{ \__kernel_backend_literal:x { pdf : bc ~ \pdf_object_ref:n {#1} ~ [ #2 ] } }
%</dvipdfmx|xetex>
%<*luatex|pdftex>
\cs_new_protected:Npn \@@_backend_select_separation:nn #1#2
{ \@@_backend_select:nn { /#1 ~ cs ~ #2 ~ scn } { /#1 ~ CS ~ #2 ~ SCN } }
%</luatex|pdftex>
\cs_new_eq:NN \@@_backend_select_devicen:nn \@@_backend_select_separation:nn
\cs_new_eq:NN \@@_backend_select_iccbased:nn \@@_backend_select_separation:nn
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_backend_init_resource:n}
% Resource initiation comes up a few times. For \texttt{dvipdfmx}/\XeTeX{},
% we skip this as at present it's handled by the backend.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_init_resource:n #1
{
%<*luatex|pdftex>
\bool_lazy_and:nnT
{ \cs_if_exist_p:N \pdfmanagement_if_active_p: }
{ \pdfmanagement_if_active_p: }
{
\use:x
{
\pdfmanagement_add:nnn
{ Page / Resources / ColorSpace }
{ #1 }
{ \pdf_object_ref_last: }
}
}
%</luatex|pdftex>
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_backend_separation_init:nnnnn}
% \begin{macro}{\@@_backend_separation_init:nn}
% \begin{macro}{\@@_backend_separation_init_CIELAB:nnn}
% Initialising the PDF structures needs two parts: creating an object
% containing the \enquote{real} name of the Separation, then adding a reference
% to that to each page. We use a separate object for the tint transformation
% following the model in the PDF reference. The object here for the color
% needs to be named as that way it's accessible to
% \texttt{dvipdfmx}/\XeTeX{}.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_separation_init:nnnnn #1#2#3#4#5
{
\pdf_object_unnamed_write:nx { dict }
{
/FunctionType ~ 2
/Domain ~ [0 ~ 1]
\tl_if_blank:nF {#3} { /Range ~ [#3] }
/C0 ~ [#4] ~
/C1 ~ [#5] /N ~ 1
}
\exp_args:Nx \@@_backend_separation_init:nn
{ \str_convert_pdfname:n {#1} } {#2}
\@@_backend_init_resource:n { color \int_use:N \g_@@_model_int }
}
\cs_new_protected:Npn \@@_backend_separation_init:nn #1#2
{
\use:x
{
\pdf_object_new:n { color \int_use:N \g_@@_model_int }
\pdf_object_write:nnn { color \int_use:N \g_@@_model_int } { array }
{ /Separation /#1 ~ #2 ~ \pdf_object_ref_last: }
}
\prop_gput:Nnx \g_@@_backend_colorant_prop { /#1 }
{ \pdf_object_ref_last: }
}
% \end{macrocode}
% For CIELAB colors, we need one object per document for the illuminant,
% plus initialisation of the color space referencing that object.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_separation_init_CIELAB:nnn #1#2#3
{
\pdf_object_if_exist:nF { @@_illuminant_CIELAB_ #1 }
{
\pdf_object_new:n { @@_illuminant_CIELAB_ #1 }
\pdf_object_write:nnx { @@_illuminant_CIELAB_ #1 } { array }
{
/Lab ~
<<
/WhitePoint ~
[ \tl_use:c { c_@@_model_whitepoint_CIELAB_ #1 _tl } ]
/Range ~ [ \c_@@_model_range_CIELAB_tl ]
>>
}
}
\@@_backend_separation_init:nnnnn
{#2}
{ \pdf_object_ref:n { @@_illuminant_CIELAB_ #1 } }
{ \c_@@_model_range_CIELAB_tl }
{ 100 ~ 0 ~ 0 }
{#3}
}
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\@@_backend_devicen_init:nnn}
% \begin{macro}[EXP]{\@@_backend_devicen_init:w}
% Similar to the Separations case, but with an arbitrary function for
% the alternative space work.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_devicen_init:nnn #1#2#3
{
\pdf_object_unnamed_write:nx { stream }
{
{
/FunctionType ~ 4 ~
/Domain ~
[ ~
\prg_replicate:nn
{ 0 \@@_backend_devicen_init:w #1 ~ \s_@@_stop }
{ 0 ~ 1 ~ }
] ~
/Range ~
[ ~
\str_case:nn {#2}
{
{ /DeviceCMYK } { 0 ~ 1 ~ 0 ~ 1 ~ 0 ~ 1 ~ 0 ~ 1 }
{ /DeviceGray } { 0 ~ 1 }
{ /DeviceRGB } { 0 ~ 1 ~ 0 ~ 1 ~ 0 ~ 1 }
} ~
]
}
{ {#3} }
}
\use:x
{
\pdf_object_new:n { color \int_use:N \g_@@_model_int }
\pdf_object_write:nnn { color \int_use:N \g_@@_model_int } { array }
{
/DeviceN ~
[ ~ #1 ~ ] ~
#2 ~
\pdf_object_ref_last:
\@@_backend_devicen_colorants:n {#1}
}
}
\@@_backend_init_resource:n { color \int_use:N \g_@@_model_int }
}
\cs_new:Npn \@@_backend_devicen_init:w #1 ~ #2 \s_@@_stop
{
+ 1
\tl_if_blank:nF {#2}
{ \@@_backend_devicen_init:w #2 \s_@@_stop }
}
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\@@_backend_iccbased_init:nnn}
% Lots of data to save here: we only want to do that once per file,
% so track it by name.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_iccbased_init:nnn #1#2#3
{
\pdf_object_if_exist:nF { @@_icc_ #1 }
{
\pdf_object_new:n { @@_icc_ #1 }
\pdf_object_write:nnx { @@_icc_ #1 } { fstream }
{
{
/N ~ \exp_not:n { #2 } ~
\tl_if_empty:nF { #3 } { /Range~[ #3 ] }
}
{#1}
}
}
\pdf_object_unnamed_write:nx { array }
{ /ICCBased ~ \pdf_object_ref:n { @@_icc_ #1 } }
\@@_backend_init_resource:n { color \int_use:N \g_@@_model_int }
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_backend_iccbased_device:nnn}
% This is very similar to setting up a color space: the only part we
% add to the page resources differently.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_iccbased_device:nnn #1#2#3
{
\pdf_object_if_exist:nF { @@_icc_ #1 }
{
\pdf_object_new:n { @@_icc_ #1 }
\pdf_object_write:nnn { @@_icc_ #1 } { fstream }
{
{ /N ~ #3 }
{#1}
}
}
\pdf_object_unnamed_write:nx { array }
{ /ICCBased ~ \pdf_object_ref:n { @@_icc_ #1 } }
\@@_backend_init_resource:n { Default #2 }
}
% \end{macrocode}
% \end{macro}
%
% \begin{macrocode}
%</dvipdfmx|luatex|pdftex|xetex>
% \end{macrocode}