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l3color-base.dtx
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l3color-base.dtx
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% \iffalse meta-comment
%
%% File: l3color-base.dtx Copyright(C) 2011,2012,2014,2016-2019 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 "l3kernel 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{l3color-base} package\\ Color 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 2019-01-01}
%
% \maketitle
%
% \begin{documentation}
%
% This module provides support for color in \LaTeX3{}. At present, the
% material here is mainly intended to support a small number of low-level
% requirements in other \pkg{l3kernel} modules.
%
% \section{Color in boxes}
%
% Controlling the color of text in boxes requires a small number of control
% functions, so that the boxed material uses the color at the point where
% it is set, rather than where it is used.
%
% \begin{function}[added = 2011-09-03]{\color_group_begin:, \color_group_end:}
% \begin{syntax}
% \cs{color_group_begin:}
% \ldots
% \cs{color_group_end:}
% \end{syntax}
% Creates a color group: one used to \enquote{trap} color settings.
% \end{function}
%
% \begin{function}[added = 2011-09-03]{\color_ensure_current:}
% \begin{syntax}
% \cs{color_ensure_current:}
% \end{syntax}
% Ensures that material inside a box uses the foreground color
% at the point where the box is set, rather than that in force when the
% box is used. This function should usually be used within a
% \cs{color_group_begin:} \ldots \cs{color_group_end:} group.
% \end{function}
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3color-base} Implementation}
%
% \begin{macrocode}
%<*initex|package>
% \end{macrocode}
%
% \begin{macrocode}
%<@@=color>
% \end{macrocode}
%
% \begin{variable}
% {\l_@@_current_tl}
% The color currently active for foreground (text, \emph{etc.}) material.
% This is stored in the form of a color model followed by one or more
% values. There are four pre-defined models, three of which take numerical
% values in the range $[0,1]$:
% \begin{itemize}
% \item \texttt{gray \meta{gray}} Grayscale color with the \meta{gray}
% value running from $0$ (fully black) to $1$ (fully white)
% \item \texttt{cmyk \meta{cyan} \meta{magenta} \meta{yellow} \meta{black}}
% \item \texttt{rgb \meta{red} \meta{green} \meta{blue}}
% \end{itemize}
% Notice that the value are separated by spaces. There is a fourth pre-defined
% model using a string value and a numerical one:
% \begin{itemize}
% \item \texttt{spot \meta{name} \meta{tint}} A pre-defined spot color,
% where the \meta{name} should be a pre-defined string color name and the
% \meta{tint} should be in the range $[0,1]$.
% \end{itemize}
%
% Additional models may be created to allow mixing of spot colors. The
% number of data entries these require will depend on the number of
% colors to be mixed.
% \begin{texnote}
% The content of \cs{l_@@_current_tl} is space-separated as
% this allows it to be used directly in specials in many common cases.
% This internal representation is close to that used by the \texttt{dvips}
% program.
% \end{texnote}
% \end{variable}
%
% \begin{macro}{\color_group_begin:, \color_group_end:}
% Grouping for color is the same as using the basic \cs{group_begin:}
% and \cs{group_end:} functions. However, for semantic reasons, they
% are renamed here.
% \begin{macrocode}
\cs_new_eq:NN \color_group_begin: \group_begin:
\cs_new_eq:NN \color_group_end: \group_end:
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\color_ensure_current:}
% A driver-independent wrapper for setting the foreground color to the
% current color \enquote{now}.
% \begin{macrocode}
\cs_new_protected:Npn \color_ensure_current:
{
%<*package>
\driver_color_pickup:N \l_@@_current_tl
%</package>
\@@_select:V \l_@@_current_tl
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_select:n, \@@_select:V}
% \begin{macro}{\@@_select:w}
% \begin{macro}
% {\@@_select_cmyk:w, \@@_select_gray:w, \@@_select_rgb:w, \@@_select_spot:w}
% Take an internal color specification and pass it to the driver. This code
% is needed to ensure the current color but will also be used by the
% higher-level experimental material.
% \begin{macrocode}
\cs_new_protected:Npn \@@_select:n #1
{ \@@_select:w #1 \q_stop }
\cs_generate_variant:Nn \@@_select:n { V }
\cs_new_protected:Npn \@@_select:w #1 ~ #2 \q_stop
{ \use:c { @@_select_ #1 :w } #2 \q_stop }
\cs_new_protected:Npn \@@_select_cmyk:w #1 ~ #2 ~ #3 ~ #4 \q_stop
{ \driver_color_cmyk:nnnn {#1} {#2} {#3} {#4} }
\cs_new_protected:Npn \@@_select_gray:w #1 \q_stop
{ \driver_color_gray:n {#1} }
\cs_new_protected:Npn \@@_select_rgb:w #1 ~ #2 ~ #3 \q_stop
{ \driver_color_rgb:nnn {#1} {#2} {#3} }
\cs_new_protected:Npn \@@_select_spot:w #1 ~ #2 \q_stop
{ \driver_color_spot:nn {#1} {#2} }
% \end{macrocode}
% \end{macro}
% \end{macro}
% \end{macro}
%
% \begin{variable}{\l_@@_current_tl}
% As the setting data is used only
% for specials, and those are always space-separated, it makes most sense to
% hold the internal information in that form.
% \begin{macrocode}
\tl_new:N \l_@@_current_tl
\tl_set:Nn \l_@@_current_tl { gray~0 }
% \end{macrocode}
% \end{variable}
%
% \begin{macrocode}
%</initex|package>
% \end{macrocode}
%
% \end{implementation}
%
% \PrintIndex