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authorNorbert Preining <norbert@preining.info>2021-01-30 03:00:54 +0000
committerNorbert Preining <norbert@preining.info>2021-01-30 03:00:54 +0000
commit431a21790bcbf7d842f7a3d5e6e3eaef4ae823af (patch)
tree5ae95f1f34bf81d03294fc88ed5cab6eb0e25a88 /macros/latex/contrib/l3backend/l3backend-opacity.dtx
parentbc31a53b31d92ddf5db3e7df811734a0141f8b3f (diff)
CTAN sync 202101300300
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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