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% \iffalse meta-comment
%
%% File: l3backend-opacity.dtx
%
% Copyright (C) 2021 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-opacity} package\\ Backend opacity 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 2020-01-29}
%
% \maketitle
%
% \begin{documentation}
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3backend-opacity} Implementation}
%
% \begin{macrocode}
%<*package>
%<@@=opacity>
% \end{macrocode}
%
% Although opacity is not color, it needs to be managed in a somewhat
% similar way: using a dedicated stack if possible. Depending on the backend,
% that may not be possible. There is also the need to cover fill/stroke setting
% as well as more general running opacity. It is easiest to describe the value
% used in terms of opacity, although commonly this is referred to as
% transparency.
%
% \begin{macrocode}
%<*dvips>
% \end{macrocode}
%
% \begin{macro}{\@@_backend_select:n,\@@_backend_select_aux:n}
% No stack so set values directly.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select:n #1
{
\exp_args:Nx \@@_backend_select_aux:n
{ \fp_eval:n { min(max(0,#1),1) } }
}
\cs_new_protected:Npn \@@_backend_select_aux:n #1
{
\__kernel_backend_postscript:n
{ #1 ~ .setfillconstantalpha ~ #1 ~ .setstrokeconstantalpha }
}
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_backend_fill:n, \@@_backend_stroke:n}
% \begin{macro}{\@@_backend:nn, \@@_backend:xn}
% Similar to the above but with no stack and only adding to one or other of
% the entries.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_fill:n #1
{ \@@_backend:xn { \fp_eval:n { min(max(0,#1),1) } } { fill } }
\cs_new_protected:Npn \@@_backend_stroke:n #1
{ \@@_backend:xn { \fp_eval:n { min(max(0,#1),1) } } { stroke } }
\cs_new_protected:Npn \@@_backend:nn #1#2
{
\__kernel_backend_postscript:n { #1 ~ .set #2 constantalpha }
}
\cs_generate_variant:Nn \@@_backend:nn { x }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</dvips>
% \end{macrocode}
%
% \begin{macrocode}
%<*dvipdfmx|luatex|pdftex|xetex>
% \end{macrocode}
%
% \begin{variable}{\c_@@_backend_stack_int}
% Set up a stack.
% \begin{macrocode}
\cs_if_exist:NT \pdfmanagement_add:nnn
{
\__kernel_color_backend_stack_init:Nnn \c_@@_backend_stack_int
{ page ~ direct } { /opacity 1 ~ gs }
\pdfmanagement_add:nnn { Page / Resources / ExtGState }
{ opacity 1 } { << /ca ~ 1 /CA ~ 1 >> }
}
% \end{macrocode}
% \end{variable}
%
% \begin{variable}{\l_@@_backend_fill_tl, \l_@@_backend_stroke_tl}
% We use |tl| here for speed: at the backend, this should be reasonable.
% \begin{macrocode}
\tl_new:N \l_@@_backend_fill_tl
\tl_new:N \l_@@_backend_stroke_tl
% \end{macrocode}
% \end{variable}
%
% \begin{macro}{\@@_backend_select:n, \@@_backend_select_aux:n}
% \begin{macro}{\@@_backend_reset:}
% Other than the need to evaluate the opacity as an \texttt{fp}, much the
% same as color.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select:n #1
{
\exp_args:Nx \@@_backend_select_aux:n
{ \fp_eval:n { min(max(0,#1),1) } }
}
\cs_new_protected:Npn \@@_backend_select_aux:n #1
{
\tl_set:Nn \l_@@_backend_fill_tl {#1}
\tl_set:Nn \l_@@_backend_stroke_tl {#1}
\pdfmanagement_add:nnn { Page / Resources / ExtGState }
{ opacity #1 }
{ << /ca ~ #1 /CA ~ #1 >> }
\@@_backend_stack_push:nn \c_@@_backend_stack_int
{ /opacity #1 ~ gs }
\group_insert_after:N \@@_backend_reset:
}
\cs_if_exist:NF \pdfmanagement_add:nnn
{
\cs_gset_protected:Npn \@@_backend_select_aux:n #1 { }
}
\cs_new_protected:Npn \@@_backend_reset:
{ \@@_backend_stack_pop:n \c_@@_backend_stack_int }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macro}{\@@_backend_fill:n, \@@_backend_stroke:n}
% \begin{macro}{\@@_backend_fillstroke:nn, \@@_backend_fillstroke:xx}
% For separate fill and stroke, we need to work out if we need to do
% more work or if we can stick to a single setting.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_fill:n #1
{
\@@_backend_fill_stroke:xx
{ \fp_eval:n { min(max(0,#1),1) } }
\l_@@_backend_stroke_tl
}
\cs_new_protected:Npn \@@_backend_stroke:n #1
{
\@@_backend_fill_stroke:xx
\l_@@_backend_fill_tl
{ \fp_eval:n { min(max(0,#1),1) } }
}
\cs_new_protected:Npn \@@_backend_fill_stroke:nn #1#2
{
\str_if_eq:nnTF {#1} {#2}
{ \@@_backend_select_aux:n {#1} }
{
\tl_set:Nn \l_@@_backend_fill_tl {#1}
\tl_set:Nn \l_@@_backend_stroke_tl {#2}
\pdfmanagement_add:nnn { Page / Resources / ExtGState }
{ opacity.fill #1 }
{ << /ca ~ #1 >> }
\pdfmanagement_add:nnn { Page / Resources / ExtGState }
{ opacity.stroke #1 }
{ << /CA ~ #2 >> }
\@@_backend_stack_push:nn \c_@@_backend_stack_int
{ /opacity.fill #1 ~ gs /opacity.stroke #2 ~ gs }
\group_insert_after:N \@@_backend_reset:
}
}
\cs_generate_variant:Nn \@@_backend_fill_stroke:nn { xx }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</dvipdfmx|luatex|pdftex|xetex>
% \end{macrocode}
%
% \begin{macrocode}
%<*dvipdfmx|xdvipdfmx>
% \end{macrocode}
%
% \begin{macro}{\@@_backend_select:n}
% Older backends have no stack support, so everything is done directly.
% \begin{macrocode}
\int_compare:nNnT \c__kernel_sys_dvipdfmx_version_int < { 20201111 }
{
\cs_gset_protected:Npn \@@_backend_select_aux:n #1
{
\tl_set:Nn \l_@@_backend_fill_tl {#1}
\tl_set:Nn \l_@@_backend_stroke_tl {#1}
\pdfmanagement_add:nnn { Page / Resources / ExtGState }
{ opacity #1 }
{ << /ca ~ #1 /CA ~ #1 >> }
\__kernel_backend_literal_pdf:n { /opacity #1 ~ gs }
}
\cs_gset_protected:Npn \@@_backend_fill_stroke:nn #1#2
{
\str_if_eq:nnTF {#1} {#2}
{ \@@_backend_select_aux:n {#1} }
{
\tl_set:Nn \l_@@_backend_fill_tl {#1}
\tl_set:Nn \l_@@_backend_stroke_tl {#2}
\pdfmanagement_add:nnn { Page / Resources / ExtGState }
{ opacity.fill #1 }
{ << /ca ~ #1 >> }
\pdfmanagement_add:nnn { Page / Resources / ExtGState }
{ opacity.stroke #1 }
{ << /CA ~ #2 >> }
\__kernel_backend_literal_pdf:n
{ /opacity.fill #1 ~ gs /opacity.stroke #2 ~ gs }
}
}
}
% \end{macrocode}
% \end{macro}
%
% \begin{macrocode}
%</dvipdfmx|xdvipdfmx>
% \end{macrocode}
%
% \begin{macrocode}
%<*dvisvgm>
% \end{macrocode}
%
% \begin{macro}{\@@_backend_select:n, \@@_backend_fill:n, \@@_backend_stroke:n}
% \begin{macro}{\@@_backend:nn}
% Once again, we use a scope here. There is a general opacity function for
% SVG, but that is of course not set up using the stack.
% \begin{macrocode}
\cs_new_protected:Npn \@@_backend_select:n #1
{ \@@_backend:nn {#1} { } }
\cs_new_protected:Npn \@@_backend_fill:n #1
{ \@@_backend:nn {#1} { fill- } }
\cs_new_protected:Npn \@@_backend_stroke:n #1
{ \@@_backend:nn { {#1} } { stroke- } }
\cs_new_protected:Npn \@@_backend:nn #1#2
{ \__kernel_backend_scope:x { #2 opacity = " \fp_eval:n { min(max(0,#1),1) } " } }
% \end{macrocode}
% \end{macro}
% \end{macro}
%
% \begin{macrocode}
%</dvisvgm>
% \end{macrocode}
%
% \begin{macrocode}
%</package>
% \end{macrocode}
%
% \end{implementation}
%
% \PrintIndex
|
