% \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} % % \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 2021-10-17} % % \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} % \begin{macro}{\@@_backend_fill:n, \@@_backend_stroke:n} % \begin{macro}{\@@_backend:nnn, \@@_backend:xnn} % No stack so set values directly. The need to deal with Distiller and % Ghostscript separately means we use a common auxiliary: the two % systems require different PostScript for transparency. This is % of course not quite as efficient as doing one test for setting all % transparency, but it keeps things clearer here. Thanks to Alex Grahn % for the detail on testing for GhostScript. % \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 { \@@_backend:nnn {#1} { fill } { ca } \@@_backend:nnn {#1} { stroke } { CA } } \cs_new_protected:Npn \@@_backend_fill:n #1 { \@@_backend:xnn { \fp_eval:n { min(max(0,#1),1) } } { fill } { ca } } \cs_new_protected:Npn \@@_backend_stroke:n #1 { \@@_backend:xnn { \fp_eval:n { min(max(0,#1),1) } } { stroke } { CA } } \cs_new_protected:Npn \@@_backend:nnn #1#2#3 { \__kernel_backend_postscript:n { product ~ (Ghostscript) ~ search { pop ~ pop ~ pop ~ #1 ~ .set #2 constantalpha } { pop ~ mark ~ /#3 ~ #1 /SetTransparency ~ pdfmark } ifelse } } \cs_generate_variant:Nn \@@_backend:nnn { x } % \end{macrocode} % \end{macro} % \end{macro} % \end{macro} % % \begin{macrocode} % % \end{macrocode} % % \begin{macrocode} %<*dvipdfmx|luatex|pdftex|xetex> % \end{macrocode} % % \begin{variable}{\c_@@_backend_stack_int} % Set up a stack. % \begin{macrocode} \bool_lazy_and:nnT { \cs_if_exist_p:N \pdfmanagement_if_active_p: } { \pdfmanagement_if_active_p:} { \__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 >> } \__kernel_color_backend_stack_push:nn \c_@@_backend_stack_int { /opacity #1 ~ gs } \group_insert_after:N \@@_backend_reset: } \bool_lazy_and:nnF { \cs_if_exist_p:N \pdfmanagement_if_active_p: } { \pdfmanagement_if_active_p:} { \cs_gset_protected:Npn \@@_backend_select_aux:n #1 { } } \cs_new_protected:Npn \@@_backend_reset: { \__kernel_color_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 >> } \__kernel_color_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} % % \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} % % \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} % % \end{macrocode} % % \begin{macrocode} % % \end{macrocode} % % \end{implementation} % % \PrintIndex