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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /macros/latex/contrib/l3backend/l3backend-pdf.dtx
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+% \iffalse meta-comment
+%
+%% File: l3backend-pdf.dtx
+%
+% Copyright (C) 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 "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-pdf} package\\ Backend PDF features^^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 2019-08-25}
+%
+% \maketitle
+%
+% \begin{documentation}
+%
+% \end{documentation}
+%
+% \begin{implementation}
+%
+% \section{\pkg{l3backend-pdf} Implementation}
+%
+% \begin{macrocode}
+%<*initex|package>
+%<@@=pdf>
+% \end{macrocode}
+%
+% Setting up PDF resources is a complex area with only limited documentation
+% in the engine manuals. The following code builds heavily on existing ideas
+% from \pkg{hyperref} work by Sebastian Rahtz and Heiko Oberdiek, and
+% significant contributions by Alexander Grahn, in addition to the specific
+% code referenced a various points.
+%
+% \subsection{Shared code}
+%
+% A very small number of items that belong at the backend level but which
+% are common to all backends.
+%
+% \begin{variable}{\l_@@_internal_boxf}
+% \begin{macrocode}
+\box_new:N \l_@@_internal_box
+% \end{macrocode}
+% \end{variable}
+%
+% \subsection{\texttt{dvips} backend}
+%
+% \begin{macrocode}
+%<*dvips>
+% \end{macrocode}
+%
+% \begin{macro}{\@@_backend_pdfmark:n, \@@_backend_pdfmark:x}
+% Used often enough it should be a separate function.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_pdfmark:n #1
+ { \__kernel_backend_postscript:n { mark #1 ~ pdfmark } }
+\cs_generate_variant:Nn \@@_backend_pdfmark:n { x }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Catalogue entries}
+%
+% \begin{macro}{\@@_backend_catalog_gput:nn, \@@_backend_info_gput:nn}
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_catalog_gput:nn #1#2
+ { \@@_backend_pdfmark:n { { Catalog } << /#1 ~ #2 >> /PUT } }
+\cs_new_protected:Npn \@@_backend_info_gput:nn #1#2
+ { \@@_backend_pdfmark:n { /#1 ~ #2 /DOCINFO } }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Objects}
+%
+% \begin{variable}{\g_@@_backend_object_int, \g_@@_backend_object_prop}
+% For tracking objects to allow finalisation.
+% \begin{macrocode}
+\int_new:N \g_@@_backend_object_int
+\prop_new:N \g_@@_backend_object_prop
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_backend_object_new:nn}
+% \begin{macro}[EXP]{\@@_backend_object_ref:n}
+% Tracking objects is similar to \texttt{dvipdfmx}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_object_new:nn #1#2
+ {
+ \int_gincr:N \g_@@_backend_object_int
+ \int_const:cn
+ { c_@@_backend_object_ \tl_to_str:n {#1} _int }
+ { \g_@@_backend_object_int }
+ \prop_gput:Nnn \g_@@_backend_object_prop {#1} {#2}
+ }
+\cs_new:Npn \@@_backend_object_ref:n #1
+ { { pdf.obj \int_use:c { c_@@_backend_object_ \tl_to_str:n {#1} _int } } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_object_write:nn, \@@_backend_object_write:nx}
+% \begin{macro}
+% {
+% \@@_backend_object_write_array:nn ,
+% \@@_backend_object_write_dict:nn ,
+% \@@_backend_object_write_stream:nn
+% }
+% \begin{macro}{\@@_backend_object_write_stream:nnn}
+% This is where we choose the actual type: some work to get things
+% right.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_object_write:nn #1#2
+ {
+ \@@_backend_pdfmark:x
+ {
+ /_objdef ~ \@@_backend_object_ref:n {#1}
+ /type
+ \str_case_e:nn
+ { \prop_item:Nn \g_@@_backend_object_prop {#1} }
+ {
+ { array } { /array }
+ { dict } { /dict }
+ { fstream } { /stream }
+ { stream } { /stream }
+ }
+ /OBJ
+ }
+ \use:c
+ { @@_backend_object_write_ \prop_item:Nn \g_@@_backend_object_prop {#1} :nn }
+ { \@@_backend_object_ref:n {#1} } {#2}
+ }
+\cs_generate_variant:Nn \@@_backend_object_write:nn { nx }
+\cs_new_protected:Npn \@@_backend_object_write_array:nn #1#2
+ {
+ \@@_backend_pdfmark:x
+ { #1 [ ~ \exp_not:n {#2} ~ ] ~ /PUTINTERVAL }
+ }
+\cs_new_protected:Npn \@@_backend_object_write_dict:nn #1#2
+ {
+ \@@_backend_pdfmark:x
+ { #1 << \exp_not:n {#2} >> /PUT }
+ }
+\cs_new_protected:Npn \@@_backend_object_write_stream:nn #1#2
+ {
+ \exp_args:Nx
+ \@@_backend_object_write_stream:nnn {#1} #2
+ }
+\cs_new_protected:Npn \@@_backend_object_write_stream:nnn #1#2#3
+ {
+ \@@_postscript:n
+ {
+ [nobreak]
+ mark ~ #1 ~ ( #3 ) /PUT ~ pdfmark ~
+ mark ~ #1 ~ << #2 >> /PUT ~ pdfmark
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_object_now:nn, \@@_backend_object_now:nx}
+% No anonymous objects, so things are done manually.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_object_now:nn #1#2
+ {
+ \int_gincr:N \g_@@_backend_object_int
+ \@@_backend_pdfmark:x
+ {
+ /_objdef ~ { pdf.obj \int_use:N \g_@@_backend_object_int }
+ /type
+ \str_case:nn
+ {#1}
+ {
+ { array } { /array }
+ { dict } { /dict }
+ { fstream } { /stream }
+ { stream } { /stream }
+ }
+ /OBJ
+ }
+ \exp_args:Nnx \use:c { @@_backend_object_write_ #1 :nn }
+ { { pdf.obj \int_use:N \g_@@_backend_object_int } } {#2}
+ }
+\cs_generate_variant:Nn \@@_backend_object_now:nn { nx }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_object_last:}
+% Much like the annotation version.
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_object_last:
+ { { pdf.obj \int_use:N \g_@@_backend_object_int } }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Annotations}
+%
+% In \texttt{dvips}, annotations have to be constructed manually. As such,
+% we need the object code above for some definitions.
+%
+% \begin{macro}{pdf.globaldict}
+% A small global dictionary for backend use.
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ true ~ setglobal ~
+ /pdf.globaldict ~ 4 ~ dict ~ def ~
+ false ~ setglobal
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% pdf.cvs ,
+% pdf.dvi.pt ,
+% pdf.pt.dvi ,
+% pdf.rect.ht
+% }
+% Small utilities for PostScript manipulations. Conversion to DVI dimensions
+% is done here to allow for |Resolution|. The total height of a rectangle
+% (an array) needs a little maths, in contrast to simply extracting a value.
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ /pdf.cvs { 65534 ~ string ~ cvs } def
+ /pdf.dvi.pt { 72.27 ~ mul ~ Resolution ~ div } def
+ /pdf.pt.dvi { 72.27 ~ div ~ Resolution ~ mul } def
+ /pdf.rect.ht { dup ~ 1 ~ get ~ neg ~ exch ~ 3 ~ get ~ add } def
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{pdf.linkmargin, pdf.linkdp.pad, pdf.linkht.pad}
+% Settings which are defined up-front in |SDict|.
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ /pdf.linkmargin { 1 ~ pdf.pt.dvi } def
+ /pdf.linkdp.pad { 0 } def
+ /pdf.linkht.pad { 0 } def
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% pdf.rect ,
+% pdf.save.ll ,
+% pdf.save.ur ,
+% pdf.save.linkll ,
+% pdf.save.linkur ,
+% pdf.llx ,
+% pdf.lly ,
+% pdf.urx ,
+% pdf.ury
+% }
+% Functions for marking the limits of an annotation/link, plus drawing the
+% border. We separate links for generic annotations to support adding a
+% margin and setting a minimal size.
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ /pdf.rect
+ { /Rect [ pdf.llx ~ pdf.lly ~ pdf.urx ~ pdf.ury ] } def
+ /pdf.save.ll
+ {
+ currentpoint
+ /pdf.lly ~ exch ~ def
+ /pdf.llx ~ exch ~ def
+ }
+ def
+ /pdf.save.ur
+ {
+ currentpoint
+ /pdf.ury ~ exch ~ def
+ /pdf.urx ~ exch ~ def
+ }
+ def
+ /pdf.save.linkll
+ {
+ currentpoint ~
+ pdf.linkmargin ~ add ~
+ pdf.linkdp.pad ~ add
+ /pdf.lly ~ exch ~ def ~
+ pdf.linkmargin ~ sub
+ /pdf.llx ~ exch ~ def
+ }
+ def
+ /pdf.save.linkur
+ {
+ currentpoint ~
+ pdf.linkmargin ~ sub ~
+ pdf.linkht.pad ~ sub
+ /pdf.ury ~ exch ~ def ~
+ pdf.linkmargin ~ add
+ /pdf.urx ~ exch ~ def
+ }
+ def
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% pdf.dest.anchor ,
+% pdf.dest.x ,
+% pdf.dest.y ,
+% pdf.dest.point ,
+% pdf.dest2device ,
+% pdf.dev.x ,
+% pdf.dev.y ,
+% pdf.tmpa ,
+% pdf.tmpb ,
+% pdf.tmpc ,
+% pdf.tmpd
+% }
+% For finding the anchor point of a destination link. We make the use case
+% a separate function as it comes up a lot, and as this makes it easier to
+% adjust if we need additional effects. We also need a more complex approach
+% to convert a co-ordinate pair correctly when defining a rectangle: this
+% can otherwise be out when using a landscape page. (Thanks to Alexander
+% Grahn for the approach here.)
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ /pdf.dest.anchor
+ {
+ currentpoint ~ exch ~
+ pdf.dvi.pt ~ 72 ~ add ~
+ /pdf.dest.x ~ exch ~ def ~
+ pdf.dvi.pt ~
+ vsize ~ 72 ~ sub ~ exch ~ sub ~
+ /pdf.dest.y ~ exch ~ def
+ }
+ def
+ /pdf.dest.point
+ { pdf.dest.x ~ pdf.dest.y } def
+ /pdf.dest2device
+ {
+ /pdf.dest.y ~ exch ~ def
+ /pdf.dest.x ~ exch ~ def ~
+ matrix ~ currentmatrix ~
+ matrix ~ defaultmatrix ~
+ matrix ~ invertmatrix ~
+ matrix ~ concatmatrix ~
+ cvx ~ exec
+ /pdf.dev.y ~ exch ~ def
+ /pdf.dev.x ~ exch ~ def
+ /pdf.tmpd ~ exch ~ def
+ /pdf.tmpc ~ exch ~ def
+ /pdf.tmpb ~ exch ~ def
+ /pdf.tmpa ~ exch ~ def ~
+ pdf.dest.x ~ pdf.tmpa ~ mul ~
+ pdf.dest.y ~ pdf.tmpc ~ mul ~ add ~
+ pdf.dev.x ~ add ~
+ pdf.dest.x ~ pdf.tmpb ~ mul ~
+ pdf.dest.y ~ pdf.tmpd ~ mul ~ add ~
+ pdf.dev.y ~ add
+ }
+ def
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% pdf.bordertracking ,
+% pdf.bordertracking.begin ,
+% pdf.bordertracking.end ,
+% pdf.leftboundary ,
+% pdf.rightboundary ,
+% pdf.brokenlink.rect ,
+% pdf.brokenlink.skip ,
+% pdf.brokenlink.dict ,
+% pdf.bordertracking.endpage ,
+% pdf.bordertracking.continue ,
+% pdf.originx ,
+% pdf.originy
+% }
+% To know where a breakable link can go, we need to track the boundary
+% rectangle. That can be done by hooking into |a| and |x| operations:
+% those names have to be retained. The boundary is stored at the end of
+% the operation. Special effort is needed at the start and end of pages
+% (or rather galleys), such that everything works properly.
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ /pdf.bordertracking ~ false ~ def
+ /pdf.bordertracking.begin
+ {
+ SDict ~ /pdf.bordertracking ~ true ~ put ~
+ SDict ~ /pdf.leftboundary ~ undef ~
+ SDict ~ /pdf.rightboundary ~ undef ~
+ /a ~ where
+ {
+ /a
+ {
+ currentpoint ~ pop ~
+ SDict /pdf.rightboundary ~ known ~ dup
+ {
+ SDict /pdf.rightboundary ~ get ~ 2 ~ index ~ lt
+ { not }
+ if
+ }
+ if
+ { pop }
+ { SDict ~ exch /pdf.rightboundary ~ exch ~ put }
+ ifelse ~
+ moveto ~
+ currentpoint ~ pop ~
+ SDict /pdf.leftboundary ~ known ~ dup
+ {
+ SDict /pdf.leftboundary ~ get ~ 2 ~ index ~ gt
+ { not }
+ if
+ }
+ if
+ { pop }
+ { SDict ~ exch /pdf.leftboundary ~ exch ~ put }
+ ifelse
+ }
+ put
+ }
+ if
+ }
+ def
+ /pdf.bordertracking.end
+ {
+ /a ~ where { /a { moveto } put } if
+ /x ~ where { /x { 0 ~ exch ~ rmoveto } put } if ~
+ SDict /pdf.leftboundary ~ known
+ { pdf.outerbox ~ 0 ~ pdf.leftboundary ~ put }
+ if ~
+ SDict /pdf.rightboundary ~ known
+ { pdf.outerbox ~ 2 ~ pdf.rightboundary ~ put }
+ if ~
+ SDict /pdf.bordertracking ~ false ~ put
+ }
+ def
+ /pdf.bordertracking.endpage
+ {
+ pdf.bordertracking
+ {
+ pdf.bordertracking.end ~
+ true ~ setglobal ~
+ pdf.globaldict
+ /pdf.brokenlink.rect [ pdf.outerbox ~ aload ~ pop ] put ~
+ pdf.globaldict
+ /pdf.brokenlink.skip ~ pdf.baselineskip ~ put ~
+ pdf.globaldict
+ /pdf.brokenlink.dict ~
+ pdf.link.dict ~ pdf.cvs ~ put ~
+ false ~ setglobal ~
+ mark ~ pdf.link.dict ~ cvx ~ exec ~ /Rect
+ [
+ pdf.llx ~
+ pdf.lly ~
+ pdf.outerbox ~ 2 ~ get ~ pdf.linkmargin ~ add ~
+ currentpoint ~ exch ~ pop ~
+ pdf.outerbox ~ pdf.rect.ht ~ sub ~ pdf.linkmargin ~ sub
+ ]
+ /ANN ~ pdf.pdfmark
+ }
+ if
+ }
+ def
+ /pdf.bordertracking.continue
+ {
+ /pdf.link.dict ~ pdf.globaldict
+ /pdf.brokenlink.dict ~ get ~ def
+ /pdf.outerbox ~ pdf.globaldict
+ /pdf.brokenlink.rect ~ get ~ def
+ /pdf.baselineskip ~ pdf.globaldict
+ /pdf.brokenlink.skip ~ get ~ def ~
+ pdf.globaldict ~ dup ~ dup
+ /pdf.brokenlink.dict ~ undef
+ /pdf.brokenlink.skip ~ undef
+ /pdf.brokenlink.rect ~ undef ~
+ currentpoint
+ /pdf.originy ~ exch ~ def
+ /pdf.originx ~ exch ~ def
+ /a ~ where
+ {
+ /a
+ {
+ moveto ~
+ SDict ~
+ begin ~
+ currentpoint ~ pdf.originy ~ ne ~ exch ~
+ pdf.originx ~ ne ~ or
+ {
+ pdf.save.linkll
+ /pdf.lly ~
+ pdf.lly ~ pdf.outerbox ~ 1 ~ get ~ sub ~ def ~
+ pdf.bordertracking.begin
+ }
+ if ~
+ end
+ }
+ put
+ }
+ if
+ /x ~ where
+ {
+ /x
+ {
+ 0 ~ exch ~ rmoveto ~
+ SDict~
+ begin ~
+ currentpoint ~
+ pdf.originy ~ ne ~ exch ~ pdf.originx ~ ne ~ or
+ {
+ pdf.save.linkll
+ /pdf.lly ~
+ pdf.lly ~ pdf.outerbox ~ 1 ~ get ~ sub ~ def ~
+ pdf.bordertracking.begin
+ }
+ if ~
+ end
+ }
+ put
+ }
+ if
+ }
+ def
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% pdf.breaklink ,
+% pdf.breaklink.write ,
+% pdf.count ,
+% pdf.currentrect
+% }
+% Dealing with link breaking itself has multiple stage. The first step is to
+% find the |Rect| entry in the dictionary, looping over key--value pairs.
+% The first line is handled first, adjusting the rectangle to stay inside the
+% text area. The second phase is a loop over the height of the bulk of the
+% link area, done on the basis of a number of baselines. Finally, the end of
+% the link area is tidied up, again from the boundary of the text area.
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ /pdf.breaklink
+ {
+ pop ~
+ counttomark ~ 2 ~ mod ~ 0 ~ eq
+ {
+ counttomark /pdf.count ~ exch ~ def
+ {
+ pdf.count ~ 0 ~ eq { exit } if ~
+ counttomark ~ 2 ~ roll ~
+ 1 ~ index ~ /Rect ~ eq
+ {
+ dup ~ 4 ~ array ~ copy ~
+ dup ~ dup ~
+ 1 ~ get ~
+ pdf.outerbox ~ pdf.rect.ht ~
+ pdf.linkmargin ~ 2 ~ mul ~ add ~ sub ~
+ 3 ~ exch ~ put ~
+ dup ~
+ pdf.outerbox ~ 2 ~ get ~
+ pdf.linkmargin ~ add ~
+ 2 ~ exch ~ put ~
+ dup ~ dup ~
+ 3 ~ get ~
+ pdf.outerbox ~ pdf.rect.ht ~
+ pdf.linkmargin ~ 2 ~ mul ~ add ~ add ~
+ 1 ~ exch ~ put
+ /pdf.currentrect ~ exch ~ def ~
+ pdf.breaklink.write
+ {
+ pdf.currentrect ~
+ dup ~
+ pdf.outerbox ~ 0 ~ get ~
+ pdf.linkmargin ~ sub ~
+ 0 ~ exch ~ put ~
+ dup ~
+ pdf.outerbox ~ 2 ~ get ~
+ pdf.linkmargin ~ add ~
+ 2 ~ exch ~ put ~
+ dup ~ dup ~
+ 1 ~ get ~
+ pdf.baselineskip ~ add ~
+ 1 ~ exch ~ put ~
+ dup ~ dup ~
+ 3 ~ get ~
+ pdf.baselineskip ~ add ~
+ 3 ~ exch ~ put ~
+ /pdf.currentrect ~ exch ~ def ~
+ pdf.breaklink.write
+ }
+ 1 ~ index ~ 3 ~ get ~
+ pdf.linkmargin ~ 2 ~ mul ~ add ~
+ pdf.outerbox ~ pdf.rect.ht ~ add ~
+ 2 ~ index ~ 1 ~ get ~ sub ~
+ pdf.baselineskip ~ div ~ round ~ cvi ~ 1 ~ sub ~
+ exch ~
+ repeat ~
+ pdf.currentrect ~
+ dup ~
+ pdf.outerbox ~ 0 ~ get ~
+ pdf.linkmargin ~ sub ~
+ 0 ~ exch ~ put ~
+ dup ~ dup ~
+ 1 ~ get ~
+ pdf.baselineskip ~ add ~
+ 1 ~ exch ~ put ~
+ dup ~ dup ~
+ 3 ~ get ~
+ pdf.baselineskip ~ add ~
+ 3 ~ exch ~ put ~
+ dup ~ 2 ~ index ~ 2 ~ get ~ 2 ~ exch ~ put
+ /pdf.currentrect ~ exch ~ def ~
+ pdf.breaklink.write ~
+ SDict /pdf.pdfmark.good ~ false ~ put ~
+ exit
+ }
+ { pdf.count ~ 2 ~ sub /pdf.count ~ exch ~ def }
+ ifelse
+ }
+ loop
+ }
+ if
+ /ANN
+ }
+ def
+ /pdf.breaklink.write
+ {
+ counttomark ~ 1 ~ sub ~
+ index /_objdef ~ eq
+ {
+ counttomark ~ -2 ~ roll ~
+ dup ~ wcheck ~
+ {
+ readonly ~
+ counttomark ~ 2 ~ roll
+ }
+ { pop ~ pop }
+ ifelse
+ }
+ if ~
+ counttomark ~ 1 ~ add ~ copy ~
+ pop ~ pdf.currentrect
+ /ANN ~ pdfmark
+ }
+ def
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {
+% pdf.pdfmark ,
+% pdf.pdfmark.good ,
+% pdf.outerbox ,
+% pdf.baselineskip ,
+% pdf.pdfmark.dict
+% }
+% The business end of breaking links starts by hooking into |pdfmarks|.
+% Unlike \pkg{hypdvips}, we avoid altering any links we have not created
+% by using a copy of the core |pdfmarks| function. Only mark types which
+% are known are altered. At present, this is purely |ANN| marks, which are
+% measured relative to the size of the baseline skip. If they are
+% more than one apparent line high, breaking is applied.
+% \begin{macrocode}
+\__kernel_backend_postscript_header:n
+ {
+ /pdf.pdfmark
+ {
+ SDict /pdf.pdfmark.good ~ true ~ put ~
+ dup /ANN ~ eq
+ {
+ pdf.pdfmark.store ~
+ pdf.pdfmark.dict ~
+ begin ~
+ Subtype /Link ~ eq ~
+ currentdict /Rect ~ known ~ and ~
+ SDict /pdf.outerbox ~ known ~ and ~
+ SDict /pdf.baselineskip ~ known ~ and ~
+ {
+ Rect ~ 3 ~ get ~
+ pdf.linkmargin ~ 2 ~ mul ~ add ~
+ pdf.outerbox ~ pdf.rect.ht ~ add ~
+ Rect ~ 1 ~ get ~ sub ~
+ pdf.baselineskip ~ div ~ round ~ cvi ~ 0 ~ gt
+ { pdf.breaklink }
+ if
+ }
+ if ~
+ end ~
+ SDict /pdf.outerbox ~ undef ~
+ SDict /pdf.baselineskip ~ undef ~
+ currentdict /pdf.pdfmark.dict ~ undef ~
+ }
+ if ~
+ pdf.pdfmark.good
+ { pdfmark }
+ { cleartomark }
+ ifelse
+ }
+ def
+ /pdf.pdfmark.store
+ {
+ /pdf.pdfmark.dict ~ 65534 ~ dict ~ def ~
+ counttomark ~ 1 ~ add ~ copy ~
+ pop
+ {
+ dup ~ mark ~ eq
+ {
+ pop ~
+ exit
+ }
+ {
+ pdf.pdfmark.dict ~
+ begin ~ def ~ end
+ }
+ ifelse
+ }
+ loop
+ }
+ def
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{variable}{\l_@@_backend_content_box}
+% The content of an annotation.
+% \begin{macrocode}
+\box_new:N \l_@@_backend_content_box
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_backend_model_box}
+% For creating model sizing for links.
+% \begin{macrocode}
+\box_new:N \l_@@_backend_model_box
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_backend_annotation_int}
+% Needed as objects which are not annotations could be created.
+% \begin{macrocode}
+\int_new:N \g_@@_backend_annotation_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_backend_annotation:nnnn, \@@_backend_annotation_aux:nnnn}
+% \begin{macro}{pdf.llx, pdf.lly, pdf.urx, pdf.ury}
+% Annotations are objects, but we track them separately. Notably, they are
+% not in the object data lists. Here, to get the co-ordinates of the
+% annotation, we need to have the data collected at the PostScript level.
+% That requires a bit of box trickery (effectively a \LaTeXe{} |picture|
+% of zero size). Once the data is collected, use it to set up the annotation
+% border. There is a split into two parts here to allow an easy way of
+% applying the Adobe Reader fix.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_annotation:nnnn #1#2#3#4
+ {
+ \@@_backend_annotation_aux:nnnn {#1} {#2} {#3} {#4}
+ \int_gincr:N \g_@@_backend_object_int
+ \int_gset_eq:NN \g_@@_backend_annotation_int \g_@@_backend_object_int
+ \@@_backend_pdfmark:x
+ {
+
+ /_objdef { pdf.obj \int_use:N \g_@@_backend_object_int }
+ pdf.rect ~
+ #4 ~
+ /ANN
+ }
+ }
+\cs_new_protected:Npn \@@_backend_annotation_aux:nnnn #1#2#3#4
+ {
+ \box_move_down:nn {#3}
+ { \hbox:n { \@@_postscript:n { pdf.save.ll } } }
+ \hbox:n {#4}
+ \box_move_up:nn {#2}
+ {
+ \hbox:n
+ {
+ \tex_kern:D \dim_eval:n {#1} \scan_stop:
+ \@@_postscript:n { pdf.save.ur }
+ }
+ }
+ \int_gincr:N \g_@@_backend_object_int
+ \int_gset_eq:NN \g_@@_backend_annotation_int \g_@@_backend_object_int
+ \@@_backend_pdfmark:x
+ {
+ /_objdef { pdf.obj \int_use:N \g_@@_backend_object_int }
+ pdf.rect
+ /ANN
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_annotation_last:}
+% Provide the last annotation we created: could get tricky of course if
+% other packages are loaded.
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_annotation_last:
+ { { pdf.obj \int_use:N \g_@@_backend_annotation_int } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{variable}{\g_@@_backend_link_int}
+% To track annotations which are links.
+% \begin{macrocode}
+\int_new:N \g_@@_backend_link_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_backend_link_dict_tl}
+% To pass information to the end-of-link function.
+% \begin{macrocode}
+\tl_new:N \g_@@_backend_link_dict_tl
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_backend_link_sf_int}
+% Needed to save/restore space factor, which is needed to deal with the face
+% we need a box.
+% \begin{macrocode}
+\int_new:N \g_@@_backend_link_sf_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_backend_link_math_bool}
+% Needed to save/restore math mode.
+% \begin{macrocode}
+\bool_new:N \g_@@_backend_link_math_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_backend_link_bool}
+% Track link formation: we cannot nest at all.
+% \begin{macrocode}
+\bool_new:N \g_@@_backend_link_bool
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\l_@@_breaklink_pdfmark_tl}
+% Swappable content for link breaking.
+% \begin{macrocode}
+\tl_new:N \l_@@_breaklink_pdfmark_tl
+\tl_set:Nn \l_@@_breaklink_pdfmark_tl { pdfmark }
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_breaklink_postscript:n}
+% To allow dropping material unless link breaking is active.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_breaklink_postscript:n #1 { }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_breaklink_usebox:N}
+% Swappable box unpacking or use.
+% \begin{macrocode}
+\cs_new_eq:NN \@@_breaklink_usebox:N \box_use:N
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_link_begin_goto:nnw, \@@_backend_link_begin_user:nnw}
+% \begin{macro}{\@@_backend_link:nw, \@@_backend_link_aux:nw}
+% \begin{macro}{\@@_backend_link_end:, \@@_backend_link_end_aux:}
+% \begin{macro}{\@@_backend_link_minima:}
+% \begin{macro}{\@@_backend_link_outerbox:n}
+% \begin{macro}{\@@_backend_link_sf_save:, \@@_backend_link_sf_restore:}
+% \begin{macro}
+% {
+% pdf.linkdp.pad ,
+% pdf.linkht.pad ,
+% pdf.llx, pdf.lly ,
+% pdf.ury, pdf.ury ,
+% pdf.link.dict ,
+% pdf.outerbox ,
+% pdf.baselineskip
+% }
+% Links are crated like annotations but with dedicated code to allow for
+% adjusting the size of the rectangle. In contrast to \pkg{hyperref}, we
+% grab the link content as a box which can then unbox: this allows the same
+% interface as for \pdfTeX{}.
+%
+% Taking the idea of |evenboxes| from \pkg{hypdvips}, we implement a minimum
+% box height and depth for link placement. This means that \enquote{underlining}
+% with a hyperlink will generally give an even appearance. However, to ensure
+% that the full content is always above the link border, we do not allow
+% this to be negative (contrast \pkg{hypdvips} approach). The result should
+% be similar to \pdfTeX{} in the vast majority of foreseeable cases.
+%
+% The object number for a link is saved separately from the rest of the
+% dictionary as this allows us to insert it just once, at either an
+% unbroken link or only in the first line of a broken one. That makes the
+% code clearer but also avoids a low-level PostScript error with the code
+% as taken from \pkg{hypdvips}.
+%
+% Getting the outer dimensions of the text area may be better using a two-pass
+% approach and |\tex_savepos:D|. That plus format mode are still to re-examine.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_link_begin_goto:nnw #1#2
+ { \@@_backend_link_begin:nw { #1 /Subtype /Link /A << /S /GoTo /D ( #2 ) >> } }
+\cs_new_protected:Npn \@@_backend_link_begin_user:nnw #1#2
+ { \@@_backend_link_begin:nw {#1#2} }
+\cs_new_protected:Npn \@@_backend_link_begin:nw #1
+ {
+ \bool_if:NF \g_@@_backend_link_bool
+ { \@@_backend_link_begin_aux:nw {#1} }
+ }
+\cs_new_protected:Npn \@@_backend_link_begin_aux:nw #1
+ {
+ \bool_gset_true:N \g_@@_backend_link_bool
+ \@@_postscript:n
+ { /pdf.link.dict ( #1 ) def }
+ \tl_gset:Nn \g_@@_backend_link_dict_tl {#1}
+ \@@_backend_link_sf_save:
+ \mode_if_math:TF
+ { \bool_gset_true:N \g_@@_backend_link_math_bool }
+ { \bool_gset_false:N \g_@@_backend_link_math_bool }
+ \hbox_set:Nw \l_@@_backend_content_box
+ \@@_backend_link_sf_restore:
+ \bool_if:NT \g_@@_backend_link_math_bool
+ { \c_math_toggle_token }
+ }
+\cs_new_protected:Npn \@@_backend_link_end:
+ {
+ \bool_if:NT \g_@@_backend_link_bool
+ { \@@_backend_link_end_aux: }
+ }
+\cs_new_protected:Npn \@@_backend_link_end_aux:
+ {
+ \bool_if:NT \g_@@_backend_link_math_bool
+ { \c_math_toggle_token }
+ \@@_backend_link_sf_save:
+ \hbox_set_end:
+ \@@_backend_link_minima:
+ \hbox_set:Nn \l_@@_backend_model_box { Gg }
+ \exp_args:Nx \@@_backend_link_outerbox:n
+ {
+%<*initex>
+ \l_galley_total_left_margin_dim
+%</initex>
+%<*package>
+ \int_if_odd:nTF { \value { page } }
+ { \oddsidemargin }
+ { \evensidemargin }
+%</package>
+ }
+ \box_move_down:nn { \box_dp:N \l_@@_backend_content_box }
+ { \hbox:n { \@@_postscript:n { pdf.save.linkll } } }
+ \@@_breaklink_postscript:n { pdf.bordertracking.begin }
+ \@@_breaklink_usebox:N \l_@@_backend_content_box
+ \@@_breaklink_postscript:n { pdf.bordertracking.end }
+ \box_move_up:nn { \box_ht:N \l_@@_backend_content_box }
+ {
+ \hbox:n
+ { \@@_postscript:n { pdf.save.linkur } }
+ }
+ \int_gincr:N \g_@@_backend_object_int
+ \int_gset_eq:NN \g_@@_backend_link_int \g_@@_backend_object_int
+ \@@_postscript:x
+ {
+ mark
+ /_objdef { pdf.obj \int_use:N \g_@@_backend_link_int }
+ \g_@@_backend_link_dict_tl \c_space_tl
+ pdf.rect
+ /ANN ~ \l_@@_breaklink_pdfmark_tl
+ }
+ \@@_backend_link_sf_restore:
+ \bool_gset_false:N \g_@@_backend_link_bool
+ }
+\cs_new_protected:Npn \@@_backend_link_minima:
+ {
+ \hbox_set:Nn \l_@@_backend_model_box { Gg }
+ \@@_postscript:x
+ {
+ /pdf.linkdp.pad ~
+ \dim_to_decimal:n
+ {
+ \dim_max:nn
+ {
+ \box_dp:N \l_@@_backend_model_box
+ - \box_dp:N \l_@@_backend_content_box
+ }
+ { 0pt }
+ } ~
+ pdf.pt.dvi ~ def
+ /pdf.linkht.pad ~
+ \dim_to_decimal:n
+ {
+ \dim_max:nn
+ {
+ \box_ht:N \l_@@_backend_model_box
+ - \box_ht:N \l_@@_backend_content_box
+ }
+ { 0pt }
+ } ~
+ pdf.pt.dvi ~ def
+ }
+ }
+\cs_new_protected:Npn \@@_backend_link_outerbox:n #1
+ {
+ \@@_postscript:x
+ {
+ /pdf.outerbox
+ [
+ \dim_to_decimal:n {#1} ~
+ \dim_to_decimal:n { -\box_dp:N \l_@@_backend_model_box } ~
+%<*initex>
+ \dim_to_decimal:n { #1 + \l_galley_text_width_dim } ~
+%</initex>
+%<*package>
+ \dim_to_decimal:n { #1 + \textwidth } ~
+%</package>
+ \dim_to_decimal:n { \box_ht:N \l_@@_backend_model_box }
+ ]
+ [ exch { pdf.pt.dvi } forall ] def
+ /pdf.baselineskip ~
+ \dim_to_decimal:n { \tex_baselineskip:D } ~ dup ~ 0 ~ gt
+ { pdf.pt.dvi ~ def }
+ { pop ~ pop }
+ ifelse
+ }
+ }
+\cs_new_protected:Npn \@@_backend_link_sf_save:
+ {
+ \int_gset:Nn \g_@@_backend_link_sf_int
+ {
+ \mode_if_horizontal:TF
+ { \tex_spacefactor:D }
+ { 0 }
+ }
+ }
+\cs_new_protected:Npn \@@_backend_link_sf_restore:
+ {
+ \mode_if_horizontal:T
+ {
+ \int_compare:nNnT \g_@@_backend_link_sf_int > { 0 }
+ { \int_set_eq:NN \tex_spacefactor:D \g_@@_backend_link_sf_int }
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@makecol@hook}
+% Hooks to allow link breaking: something will be needed in format mode
+% at some stage. At present this code is disabled as there is an open
+% question about the name of the hook: to be resolved at the \LaTeXe{}
+% end.
+% \begin{macrocode}
+%<*package>
+\use_none:n
+ {
+ \cs_if_exist:NT \@makecol@hook
+ {
+ \tl_put_right:Nn \@makecol@hook
+ {
+ \box_if_empty:NF \@cclv
+ {
+ \vbox_set:Nn \@cclv
+ {
+ \@@_postscript:n
+ {
+ pdf.globaldict /pdf.brokenlink.rect ~ known
+ { pdf.bordertracking.continue }
+ if
+ }
+ \vbox_unpack_drop:N \@cclv
+ \@@_postscript:n
+ { pdf.bordertracking.endpage }
+ }
+ }
+ }
+ \tl_set:Nn \l_@@_breaklink_pdfmark_tl { pdf.pdfmark }
+ \cs_set_eq:NN \@@_breaklink_postscript:n \@@_postscript:n
+ \cs_set_eq:NN \@@_breaklink_usebox:N \hbox_unpack:N
+ }
+ }
+%</package>
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_link_last:}
+% The same as annotations, but with a custom integer.
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_link_last:
+ { { pdf.obj \int_use:N \g_@@_backend_link_int } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_link_margin:n}
+% Convert to big points and pass to PostScript.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_link_margin:n #1
+ {
+ \@@_postscript:x
+ {
+ /pdf.linkmargin { \dim_to_decimal:n {#1} ~ pdf.pt.dvi } def
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_destination:nn, \@@_backend_destination_rectangle:nn}
+% Here, we need to turn the zoom into a scale. We also need to know where
+% the current anchor point actually is: worked out in PostScript. For the
+% rectangle version, we have a bit more PostScript: we need two points.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_destination:nn #1#2
+ {
+ \@@_postscript:n { pdf.dest.anchor }
+ \@@_backend_pdfmark:x
+ {
+ /View
+ [
+ \str_case:nnF {#2}
+ {
+ { xyz } { /XYZ ~ pdf.dest.point ~ null }
+ { fit } { /Fit }
+ { fitb } { /FitB }
+ { fitbh } { /FitBH ~ pdf.dest.y }
+ { fitbv } { /FitBV ~ pdf.dest.x }
+ { fith } { /FitH ~ pdf.dest.y }
+ { fitv } { /FitV ~ pdf.dest.x }
+ }
+ {
+ /XYZ ~ pdf.dest.point ~ \fp_eval:n { (#2) / 100 }
+ }
+ ]
+ /Dest ( \exp_not:n {#1} ) cvn
+ /DEST
+ }
+ }
+\cs_new_protected:Npn \@@_backend_destination_rectangle:nn #1#2
+ {
+ \group_begin:
+ \hbox_set:Nn \l_@@_internal_box {#2}
+ \box_move_down:nn
+ { \box_dp:N \l_@@_internal_box }
+ { \hbox:n { \@@_postscript:n { pdf.save.ll } } }
+ \box_use:N \l_@@_internal_box
+ \box_move_up:nn
+ { \box_ht:N \l_@@_internal_box }
+ { \hbox:n { \@@_postscript:n { pdf.save.ur } } }
+ \@@_backend_pdfmark:n
+ {
+ /View
+ [
+ /FitR ~
+ pdf.llx ~ pdf.lly ~ pdf.dest2device ~
+ pdf.urx ~ pdf.ury ~ pdf.dest2device
+ ]
+ /Dest ( #1 ) cvn
+ /DEST
+ }
+ \group_end:
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Structure}
+%
+% \begin{macro}{\@@_backend_compresslevel:n}
+% \begin{macro}{\@@_backend_compress_objects:n}
+% These are all no-ops.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_compresslevel:n #1 { }
+\cs_new_protected:Npn \@@_backend_compress_objects:n #1 { }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {\@@_backend_version_major_gset:n, \@@_backend_version_minor_gset:n}
+% Data not available!
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_version_major_gset:n #1 { }
+\cs_new_protected:Npn \@@_backend_version_minor_gset:n #1 { }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_version_major:, \@@_backend_version_minor:}
+% Data not available!
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_version_major: { -1 }
+\cs_new:Npn \@@_backend_version_minor: { -1 }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Marked content}
+%
+% \begin{macro}{\@@_backend_bdc:nn}
+% \begin{macro}{\@@_backend_emc:}
+% Simple wrappers.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_bdc:nn #1#2
+ { \@@_backend_pdfmark:n { /#1 ~ #2 /BDC } }
+\cs_new_protected:Npn \@@_backend_emc:
+ { \@@_backend_pdfmark:n { /EMC } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macrocode}
+%</dvips>
+% \end{macrocode}
+%
+% \subsection{\texttt{pdfmode} backend}
+%
+% \begin{macrocode}
+%<*pdfmode>
+% \end{macrocode}
+%
+% \subsubsection{Annotations}
+%
+% \begin{macro}{\@@_backend_annotation:nnnn}
+% Simply pass the raw data through, just dealing with evaluation of dimensions.
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_backend_annotation:nnnn #1#2#3#4
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \tex_pdfextension:D annot ~ }
+ { \tex_pdfannot:D }
+ width ~ \exp_not:N \dim_eval:n {#1} ~
+ height ~ \exp_not:N \dim_eval:n {#2} ~
+ depth ~ \exp_not:N \dim_eval:n {#3} ~
+ {#4}
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_annotation_last:}
+% A tiny amount of extra data gets added here.
+% \begin{macrocode}
+\cs_new:Npx \@@_backend_annotation_last:
+ {
+ \exp_not:N \int_value:w
+ \cs_if_exist:NTF \tex_pdffeedback:D
+ { \exp_not:N \tex_pdffeedback:D lastannot ~ }
+ { \exp_not:N \tex_pdflastannot:D }
+ \c_space_tl 0 ~ R
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {\@@_backend_link_begin_goto:nnw, \@@_backend_link_begin_user:nnw}
+% \begin{macro}{\@@_backend_link_begin:nnnw}
+% \begin{macro}{\@@_backend_link_end:}
+% Links are all created using the same internals.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_link_begin_goto:nnw #1#2
+ { \@@_backend_link_begin:nnnw {#1} { goto~name } {#2} }
+\cs_new_protected:Npn \@@_backend_link_begin_user:nnw #1#2
+ { \@@_backend_link_begin:nnnw {#1} { user } {#2} }
+\cs_new_protected:Npx \@@_backend_link_begin:nnnw #1#2#3
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \tex_pdfextension:D startlink ~ }
+ { \tex_pdfstartlink:D }
+ attr {#1}
+ #2 {#3}
+ }
+\cs_new_protected:Npx \@@_backend_link_end:
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \tex_pdfextension:D endlink \scan_stop: }
+ { \tex_pdfendlink:D }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_link_last:}
+% Formatted for direct use.
+% \begin{macrocode}
+\cs_new:Npx \@@_backend_link_last:
+ {
+ \exp_not:N \int_value:w
+ \cs_if_exist:NTF \tex_pdffeedback:D
+ { \exp_not:N \tex_pdffeedback:D lastlink ~ }
+ { \exp_not:N \tex_pdflastlink:D }
+ \c_space_tl 0 ~ R
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_link_margin:n}
+% A simple task: pass the data to the primitive.
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_backend_link_margin:n #1
+ {
+ \cs_if_exist:NTF \tex_pdfvariable:D
+ { \exp_not:N \tex_pdfvariable:D linkmargin }
+ { \exp_not:N \tex_pdflinkmargin:D }
+ \exp_not:N \dim_eval:n {#1} \scan_stop:
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_destination:nn, \@@_backend_destination_rectangle:nn}
+% A simple task: pass the data to the primitive. The |\scan_stop:| deals
+% with the danger of an unterminated keyword. The zoom given here is a
+% percentage, but we need to pass it as \emph{per mille}. The rectangle
+% version is also easy as everything is build in.
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_backend_destination:nn #1#2
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \exp_not:N \tex_pdfextension:D dest ~ }
+ { \exp_not:N \tex_pdfdest:D }
+ name {#1}
+ \exp_not:N \str_case:nnF {#2}
+ {
+ { xyz } { xyz }
+ { fit } { fit }
+ { fitb } { fitb }
+ { fitbh } { fitbh }
+ { fitbv } { fitbv }
+ { fith } { fith }
+ { fitv } { fitv }
+ }
+ { xyz ~ zoom \exp_not:N \fp_eval:n { #2 * 10 } }
+ \scan_stop:
+ }
+\cs_new_protected:Npx \@@_backend_destination_rectangle:nn #1#2
+ {
+ \group_begin:
+ \hbox_set:Nn \l_@@_internal_box {#2}
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \exp_not:N \tex_pdfextension:D dest ~ }
+ { \exp_not:N \tex_pdfdest:D }
+ name {#1}
+ fitr ~
+ width \exp_not:N \box_wd:N \l_@@_internal_box
+ height \exp_not:N \box_ht:N \l_@@_internal_box
+ depth \exp_not:N \box_dp:N \l_@@_internal_box
+ \box_use:N \l_@@_internal_box
+ \group_end:
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Catalogue entries}
+%
+% \begin{macro}{\@@_backend_catalog_gput:nn, \@@_backend_info_gput:nn}
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_backend_catalog_gput:nn #1#2
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \tex_pdfextension:D catalog }
+ { \tex_pdfcatalog:D }
+ { / #1 ~ #2 }
+ }
+\cs_new_protected:Npx \@@_backend_info_gput:nn #1#2
+ {
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \tex_pdfextension:D info }
+ { \tex_pdfinfo:D }
+ { / #1 ~ #2 }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Objects}
+%
+% \begin{variable}{\g_@@_backend_object_prop}
+% For tracking objects to allow finalisation.
+% \begin{macrocode}
+\prop_new:N \g_@@_backend_object_prop
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_backend_object_new:nn}
+% \begin{macro}[EXP]{\@@_backend_object_ref:n}
+% Declaring objects means reserving at the PDF level plus starting
+% tracking.
+% \begin{macrocode}
+\group_begin:
+ \cs_set_protected:Npn \@@_tmp:w #1#2
+ {
+ \cs_new_protected:Npx \@@_backend_object_new:nn ##1##2
+ {
+ #1 reserveobjnum ~
+ \int_const:cn
+ { c_@@_backend_object_ \exp_not:N \tl_to_str:n {##1} _int }
+ {#2}
+ \prop_gput:Nnn \exp_not:N \g_@@_backend_object_prop {##1} {##2}
+ }
+ }
+ \cs_if_exist:NTF \tex_pdfextension:D
+ {
+ \@@_tmp:w
+ { \tex_pdfextension:D obj ~ }
+ { \exp_not:N \tex_pdffeedback:D lastobj }
+ }
+ { \@@_tmp:w { \tex_pdfobj:D } { \tex_pdflastobj:D } }
+\group_end:
+\cs_new:Npn \@@_backend_object_ref:n #1
+ { \int_use:c { c_@@_backend_object_ \tl_to_str:n {#1} _int } ~ 0 ~ R }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_object_write:nn,\@@_backend_object_write:nx}
+% \begin{macro}[EXP]{\@@_exp_not_i:nn, \@@_exp_not_ii:nn}
+% Writing the data needs a little information about the structure of the
+% object.
+% \begin{macrocode}
+\group_begin:
+ \cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new_protected:Npn \@@_backend_object_write:nn ##1##2
+ {
+ \tex_immediate:D #1 useobjnum ~
+ \int_use:c
+ { c_@@_backend_object_ \tl_to_str:n {##1} _int }
+ \str_case_e:nn
+ { \prop_item:Nn \g_@@_backend_object_prop {##1} }
+ {
+ { array } { { [ ~ \exp_not:n {##2} ~ ] } }
+ { dict } { { << ~ \exp_not:n {##2} ~ >> } }
+ { fstream }
+ {
+ stream ~ attr ~ { \@@_exp_not_i:nn ##2 } ~
+ file ~ { \@@_exp_not_ii:nn ##2 }
+ }
+ { stream }
+ {
+ stream ~ attr ~ { \@@_exp_not_i:nn ##2 } ~
+ { \@@_exp_not_ii:nn ##2 }
+ }
+ }
+ }
+ }
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \@@_tmp:w { \tex_pdfextension:D obj ~ } }
+ { \@@_tmp:w { \tex_pdfobj:D } }
+\group_end:
+\cs_generate_variant:Nn \@@_backend_object_write:nn { nx }
+\cs_new:Npn \@@_exp_not_i:nn #1#2 { \exp_not:n {#1} }
+\cs_new:Npn \@@_exp_not_ii:nn #1#2 { \exp_not:n {#2} }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_object_now:nn, \@@_backend_object_now:nx}
+% Much like writing, but direct creation.
+% \begin{macrocode}
+\group_begin:
+ \cs_set_protected:Npn \@@_tmp:w #1
+ {
+ \cs_new_protected:Npn \@@_backend_object_now:nn ##1##2
+ {
+ \tex_immediate:D #1
+ \str_case:nn
+ {##1}
+ {
+ { array } { { [ ~ \exp_not:n {##2} ~ ] } }
+ { dict } { { << ~ \exp_not:n {##2} ~ >> } }
+ { fstream }
+ {
+ stream ~ attr ~ { \@@_exp_not_i:nn ##2 } ~
+ file ~ { \@@_exp_not_ii:nn ##2 }
+ }
+ { stream }
+ {
+ stream ~ attr ~ { \@@_exp_not_i:nn ##2 } ~
+ { \@@_exp_not_ii:nn ##2 }
+ }
+ }
+ }
+ }
+ \cs_if_exist:NTF \tex_pdfextension:D
+ { \@@_tmp:w { \tex_pdfextension:D obj ~ } }
+ { \@@_tmp:w { \tex_pdfobj:D } }
+\group_end:
+\cs_generate_variant:Nn \@@_backend_object_now:nn { nx }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_object_last:}
+% Much like annotation.
+% \begin{macrocode}
+\cs_new:Npx \@@_backend_object_last:
+ {
+ \exp_not:N \int_value:w
+ \cs_if_exist:NTF \tex_pdffeedback:D
+ { \exp_not:N \tex_pdffeedback:D lastobj ~ }
+ { \exp_not:N \tex_pdflastobj:D }
+ \c_space_tl 0 ~ R
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Structure}
+%
+% \begin{macro}{\@@_backend_compresslevel:n}
+% \begin{macro}{\@@_backend_compress_objects:n}
+% \begin{macro}{\@@_backend_objcompresslevel:n}
+% Simply pass data to the engine.
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_backend_compresslevel:n #1
+ {
+ \exp_not:N \tex_global:D
+ \cs_if_exist:NTF \tex_pdfcompresslevel:D
+ { \tex_pdfcompresslevel:D }
+ { \tex_pdfvariable:D compresslevel }
+ \exp_not:N \int_value:w \exp_not:N \int_eval:n {#1} \scan_stop:
+ }
+\cs_new_protected:Npn \@@_backend_compress_objects:n #1
+ {
+ \bool_if:nTF {#1}
+ { \@@_backend_objcompresslevel:n { 2 } }
+ { \@@_backend_objcompresslevel:n { 0 } }
+ }
+\cs_new_protected:Npx \@@_backend_objcompresslevel:n #1
+ {
+ \exp_not:N \tex_global:D
+ \cs_if_exist:NTF \tex_pdfobjcompresslevel:D
+ { \tex_pdfobjcompresslevel:D }
+ { \tex_pdfvariable:D objcompresslevel }
+ #1 \scan_stop:
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {\@@_backend_version_major_gset:n, \@@_backend_version_minor_gset:n}
+% At present, we don't have a primitive for the major version in \pdfTeX{},
+% but we anticipate one \ldots
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_backend_version_major_gset:n #1
+ {
+ \cs_if_exist:NTF \tex_pdfvariable:D
+ {
+ \int_compare:nNnT \tex_luatexversion:D > { 106 }
+ {
+ \exp_not:N \tex_global:D \tex_pdfvariable:D majorversion
+ \exp_not:N \int_eval:n {#1} \scan_stop:
+ }
+ }
+ {
+ \cs_if_exist:NT \tex_pdfmajorversion:D
+ {
+ \exp_not:N \tex_global:D \tex_pdfmajorversion:D
+ \exp_not:N \int_eval:n {#1} \scan_stop:
+ }
+ }
+ }
+\cs_new_protected:Npx \@@_backend_version_minor_gset:n #1
+ {
+ \exp_not:N \tex_global:D
+ \cs_if_exist:NTF \tex_pdfminorversion:D
+ { \exp_not:N \tex_pdfminorversion:D }
+ { \tex_pdfvariable:D minorversion }
+ \exp_not:N \int_eval:n {#1} \scan_stop:
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_version_major:, \@@_backend_version_minor:}
+% At present, we don't have a primitive for the major version!
+% \begin{macrocode}
+\cs_new:Npx \@@_backend_version_major:
+ {
+ \cs_if_exist:NTF \tex_pdfvariable:D
+ {
+ \int_compare:nNnTF \tex_luatexversion:D > { 106 }
+ { \exp_not:N \tex_the:D \tex_pdfvariable:D majorversion }
+ { 1 }
+ }
+ {
+ \cs_if_exist:NTF \tex_pdfmajorversion:D
+ { \exp_not:N \tex_the:D \tex_pdfmajorversion:D }
+ { 1 }
+ }
+ }
+\cs_new:Npx \@@_backend_version_minor:
+ {
+ \exp_not:N \tex_the:D
+ \cs_if_exist:NTF \tex_pdfminorversion:D
+ { \exp_not:N \tex_pdfminorversion:D }
+ { \tex_pdfvariable:D minorversion }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Marked content}
+%
+% \begin{macro}{\@@_backend_bdc:nn}
+% \begin{macro}{\@@_backend_emc:}
+% Simple wrappers. May need refinement: see
+% \url{https://chat.stackexchange.com/transcript/message/49970158#49970158}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_bdc:nn #1#2
+ { \__kernel_backend_literal_page:n { /#1 ~ #2 ~ BDC } }
+\cs_new_protected:Npn \@@_backend_emc:
+ { \__kernel_backend_literal_page:n { EMC } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macrocode}
+%</pdfmode>
+% \end{macrocode}
+%
+% \subsection{\texttt{dvipdfmx} backend}
+%
+% \begin{macrocode}
+%<*dvipdfmx|xdvipdfmx>
+% \end{macrocode}
+%
+% \begin{macro}{\@@_backend:n, \@@_backend:x}
+% A generic function for the backend PDF specials: used where we can.
+% \begin{macrocode}
+\cs_new_protected:Npx \@@_backend:n #1
+ { \__kernel_backend_literal:n { pdf: #1 } }
+\cs_generate_variant:Nn \@@_backend:n { x }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Catalogue entries}
+%
+% \begin{macro}{\@@_backend_catalog_gput:nn, \@@_backend_info_gput:nn}
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_catalog_gput:nn #1#2
+ { \@@_backend:n { put ~ @catalog << /#1 ~ #2 >> } }
+\cs_new_protected:Npn \@@_backend_info_gput:nn #1#2
+ { \@@_backend:n { docinfo << /#1 ~ #2 >> } }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Objects}
+%
+% \begin{variable}{\g_@@_backend_object_int, \g_@@_backend_object_prop}
+% For tracking objects to allow finalisation.
+% \begin{macrocode}
+\int_new:N \g_@@_backend_object_int
+\prop_new:N \g_@@_backend_object_prop
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_backend_object_new:nn}
+% \begin{macro}[EXP]{\@@_backend_object_ref:n}
+% Objects are tracked at the macro level, but we don't have to do anything
+% at this stage.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_object_new:nn #1#2
+ {
+ \int_gincr:N \g_@@_backend_object_int
+ \int_const:cn
+ { c_@@_backend_object_ \tl_to_str:n {#1} _int }
+ { \g_@@_backend_object_int }
+ \prop_gput:Nnn \g_@@_backend_object_prop {#1} {#2}
+ }
+\cs_new:Npn \@@_backend_object_ref:n #1
+ { @pdf.obj \int_use:c { c_@@_backend_object_ \tl_to_str:n {#1} _int } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_object_write:nn, \@@_backend_object_write:nx}
+% \begin{macro}{\@@_backend_object_write:nnn}
+% \begin{macro}
+% {
+% \@@_backend_object_write_array:nn ,
+% \@@_backend_object_write_dict:nn ,
+% \@@_backend_object_write_fstream:nn ,
+% \@@_backend_object_write_stream:nn
+% }
+% \begin{macro}{\@@_backend_object_write_stream:nnnn}
+% This is where we choose the actual type.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_object_write:nn #1#2
+ {
+ \exp_args:Nx \@@_backend_object_write:nnn
+ { \prop_item:Nn \g_@@_backend_object_prop {#1} } {#1} {#2}
+ }
+\cs_generate_variant:Nn \@@_backend_object_write:nn { nx }
+\cs_new_protected:Npn \@@_backend_object_write:nnn #1#2#3
+ {
+ \use:c { @@_backend_object_write_ #1 :nn }
+ { \@@_backend_object_ref:n {#2} } {#3}
+ }
+\cs_new_protected:Npn \@@_backend_object_write_array:nn #1#2
+ {
+ \@@_backend:x
+ { obj ~ #1 ~ [ ~ \exp_not:n {#2} ~ ] }
+ }
+\cs_new_protected:Npn \@@_backend_object_write_dict:nn #1#2
+ {
+ \@@_backend:x
+ { obj ~ #1 ~ << ~ \exp_not:n {#2} ~ >> }
+ }
+\cs_new_protected:Npn \@@_backend_object_write_fstream:nn #1#2
+ { \@@_backend_object_write_stream:nnnn { f } {#1} #2 }
+\cs_new_protected:Npn \@@_backend_object_write_stream:nn #1#2
+ { \@@_backend_object_write_stream:nnnn { } {#1} #2 }
+\cs_new_protected:Npn \@@_backend_object_write_stream:nnnn #1#2#3#4
+ {
+ \@@_backend:x
+ {
+ #1 stream ~ #2 ~
+ ( \exp_not:n {#4} ) ~ << \exp_not:n {#3} >>
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_object_now:nn, \@@_backend_object_now:nx}
+% No anonymous objects with \texttt{dvipdfmx} so we have to give an
+% object name.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_object_now:nn #1#2
+ {
+ \int_gincr:N \g_@@_backend_object_int
+ \exp_args:Nnx \use:c { @@_backend_object_write_ #1 :nn }
+ { @pdf.obj \int_use:N \g_@@_backend_object_int }
+ {#2}
+ }
+\cs_generate_variant:Nn \@@_backend_object_now:nn { nx }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_object_last:}
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_object_last:
+ { @pdf.obj \int_use:N \g_@@_backend_object_int }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Annotations}
+%
+% \begin{variable}{\g_@@_landscape_bool}
+% There is a bug in \texttt{(x)dvipdfmx} which means annotations do
+% not rotate. As such, we need to know if landscape is active.
+% \begin{macrocode}
+\bool_new:N \g_@@_landscape_bool
+%<*package>
+\AtBeginDocument
+ {
+ \cs_if_exist:NT \landscape
+ {
+ \tl_put_right:Nn \landscape
+ { \bool_gset_true:N \g_@@_landscape_bool }
+ \tl_put_left:Nn \endlandscape
+ { \bool_gset_false:N \g_@@_landscape_bool }
+ }
+ }
+%</package>
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{variable}{\g_@@_backend_annotation_int}
+% Needed as objects which are not annotations could be created.
+% \begin{macrocode}
+\int_new:N \g_@@_backend_annotation_int
+% \end{macrocode}
+% \end{variable}
+%
+% \begin{macro}{\@@_backend_annotation:nnnn, \@@_backend_annotation_aux:nnnn}
+% Simply pass the raw data through, just dealing with evaluation of dimensions.
+% The only wrinkle is landscape: we have to adjust by hand.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_annotation:nnnn #1#2#3#4
+ {
+ \bool_if:NTF \g_@@_landscape_bool
+ {
+ \box_move_up:nn {#2}
+ {
+ \vbox:n
+ {
+ \@@_backend_annotation_aux:nnnn
+ { #2 + #3 } {#1} { 0pt } {#4}
+ }
+ }
+ }
+ { \@@_backend_annotation_aux:nnnn {#1} {#2} {#3} {#4} }
+ }
+\cs_new_protected:Npn \@@_backend_annotation_aux:nnnn #1#2#3#4
+ {
+ \int_gincr:N \g_@@_backend_object_int
+ \int_gset_eq:NN \g_@@_backend_annotation_int \g_@@_backend_object_int
+ \@@_backend:x
+ {
+ ann ~ @pdf.obj \int_use:N \g_@@_backend_object_int \c_space_tl
+ width ~ \dim_eval:n {#1} ~
+ height ~ \dim_eval:n {#2} ~
+ depth ~ \dim_eval:n {#3} ~
+ << #4 >>
+ }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_annotation_last:}
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_annotation_last:
+ { @pdf.obj \int_use:N \g_@@_backend_annotation_int }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}
+% {\@@_backend_link_begin_goto:nnw, \@@_backend_link_begin_user:nnw}
+% \begin{macro}{\@@_backend_link_begin:n}
+% \begin{macro}{\@@_backend_link_end:}
+% All created using the same internals.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_link_begin_goto:nnw #1#2
+ { \@@_backend_link_begin:n { #1 /Subtype /Link /A << /S /GoTo /D ( #2 ) >> } }
+\cs_new_protected:Npn \@@_backend_link_begin_user:nnw #1#2
+ { \@@_backend_link_begin:n {#1#2} }
+\cs_new_protected:Npn \@@_backend_link_begin:n #1
+ {
+ \@@_backend:n
+ {
+ bann
+ <<
+ /Type /Annot
+ #1
+ >>
+ }
+ }
+\cs_new_protected:Npn \@@_backend_link_end:
+ { \@@_backend:n { eann } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_link_last:}
+% Data not available.
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_link_last: { }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_link_margin:n}
+% Pass to \texttt{dvipdfmx}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_link_margin:n #1
+ { \__kernel_backend_literal:x { dvipdfmx:config~g~ \dim_eval:n {#1} } }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_destination:nn, \@@_backend_destination_rectangle:nn}
+% Here, we need to turn the zoom into a scale. The method for \texttt{FitR}
+% is from Alexander Grahn: the idea is to avoid needing to do any calculations
+% in \TeX{} by using the backend data for \texttt{@xpos} and \texttt{@ypos}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_destination:nn #1#2
+ {
+ \@@_backend:x
+ {
+ dest ~ ( \exp_not:n {#1} )
+ [
+ @thispage
+ \str_case:nnF {#2}
+ {
+ { xyz } { /XYZ ~ @xpos ~ @ypos ~ null }
+ { fit } { /Fit }
+ { fitb } { /FitB }
+ { fitbh } { /FitBH }
+ { fitbv } { /FitBV ~ @xpos }
+ { fith } { /FitH ~ @ypos }
+ { fitv } { /FitV ~ @xpos }
+ }
+ { /XYZ ~ @xpos ~ @ypos ~ \fp_eval:n { (#2) / 100 } }
+ ]
+ }
+ }
+\cs_new_protected:Npn \@@_backend_destination_rectangle:nn #1#2
+ {
+ \group_begin:
+ \hbox_set:Nn \l_@@_internal_box {#2}
+ \box_move_down:nn { \box_dp:N \l_@@_internal_box }
+ {
+ \hbox:n
+ {
+ \@@_backend:n { obj ~ @pdf_ #1 _llx ~ @xpos }
+ \@@_backend:n { obj ~ @pdf_ #1 _lly ~ @ypos }
+ }
+ }
+ \box_use:N \l_@@_internal_box
+ \box_move_up:nn { \box_ht:N \l_@@_internal_box }
+ {
+ \hbox:n
+ {
+ \@@_backend:n
+ {
+ dest ~ (#1)
+ [
+ @thispage
+ /FitR ~
+ @pdf_ #1 _llx ~ @pdf_ #1 _lly ~
+ @xpos ~ @ypos
+ ]
+ }
+ }
+ }
+ \group_end:
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Structure}
+%
+% \begin{macro}{\@@_backend_compresslevel:n}
+% \begin{macro}{\@@_backend_compress_objects:n}
+% Pass data to the backend: these are a one-shot.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_compresslevel:n #1
+ { \__kernel_backend_literal:x { dvipdfmx:config~z~ \int_eval:n {#1} } }
+\cs_new_protected:Npn \@@_backend_compress_objects:n #1
+ {
+ \bool_if:nF {#1}
+ { \__kernel_backend_literal:n { dvipdfmx:config~C~0x40 } }
+ }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {\@@_backend_version_major_gset:n, \@@_backend_version_minor_gset:n}
+% We start with the assumption that the default is active.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_version_major_gset:n #1
+ {
+ \cs_gset:Npx \@@_backend_version_major: { \int_eval:n {#1} }
+ \__kernel_backend_literal:x { pdf:majorversion~ \@@_backend_version_major: }
+ }
+\cs_new_protected:Npn \@@_backend_version_minor_gset:n #1
+ {
+ \cs_gset:Npx \@@_backend_version_minor: { \int_eval:n {#1} }
+ \__kernel_backend_literal:x { pdf:minorversion~ \@@_backend_version_minor: }
+ }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_version_major:, \@@_backend_version_minor:}
+% We start with the assumption that the default is active.
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_version_major: { 1 }
+\cs_new:Npn \@@_backend_version_minor: { 5 }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Marked content}
+%
+% \begin{macro}{\@@_backend_bdc:nn}
+% \begin{macro}{\@@_backend_emc:}
+% Simple wrappers. May need refinement: see
+% \url{https://chat.stackexchange.com/transcript/message/49970158#49970158}.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_bdc:nn #1#2
+ { \__kernel_backend_literal_page:n { /#1 ~ #2 ~ BDC } }
+\cs_new_protected:Npn \@@_backend_emc:
+ { \__kernel_backend_literal_page:n { EMC } }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macrocode}
+%</dvipdfmx|xdvipdfmx>
+% \end{macrocode}
+%
+% \subsection{\texttt{dvisvgm} backend}
+%
+% \begin{macrocode}
+%<*dvisvgm>
+% \end{macrocode}
+%
+% \subsubsection{Catalogue entries}
+%
+% \begin{macro}{\@@_backend_catalog_gput:nn, \@@_backend_info_gput:nn}
+% No-op.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_catalog_gput:nn #1#2 { }
+\cs_new_protected:Npn \@@_backend_info_gput:nn #1#2 { }
+% \end{macrocode}
+% \end{macro}
+%
+% \subsubsection{Objects}
+%
+% \begin{macro}{\@@_backend_object_new:nn}
+% \begin{macro}[EXP]{\@@_backend_object_ref:n}
+% \begin{macro}{\@@_backend_object_write:nn, , \@@_backend_object_write:nx}
+% \begin{macro}{\@@_backend_object_now:nn, , \@@_backend_object_now:nx}
+% \begin{macro}{\@@_backend_object_last:}
+% All no-ops here.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_object_new:nn #1#2 { }
+\cs_new:Npn \@@_backend_object_ref:n #1 { }
+\cs_new_protected:Npn \@@_backend_object_write:nn #1#2 { }
+\cs_new_protected:Npn \@@_backend_object_write:nx #1#2 { }
+\cs_new_protected:Npn \@@_backend_object_now:nn #1#2 { }
+\cs_new_protected:Npn \@@_backend_object_now:nx #1#2 { }
+\cs_new:Npn \@@_backend_object_last: { }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+% \end{macro}
+%
+% \subsubsection{Structure}
+%
+% \begin{macro}{\@@_backend_compresslevel:n}
+% \begin{macro}{\@@_backend_compress_objects:n}
+% These are all no-ops.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_compresslevel:n #1 { }
+\cs_new_protected:Npn \@@_backend_compress_objects:n #1 { }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macro}
+% {\@@_backend_version_major_gset:n, \@@_backend_version_minor_gset:n}
+% Data not available!
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_version_major_gset:n #1 { }
+\cs_new_protected:Npn \@@_backend_version_minor_gset:n #1 { }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}[EXP]{\@@_backend_version_major:, \@@_backend_version_minor:}
+% Data not available!
+% \begin{macrocode}
+\cs_new:Npn \@@_backend_version_major: { -1 }
+\cs_new:Npn \@@_backend_version_minor: { -1 }
+% \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@@_backend_bdc:nn}
+% \begin{macro}{\@@_backend_emc:}
+% More no-ops.
+% \begin{macrocode}
+\cs_new_protected:Npn \@@_backend_bdc:nn #1#2 { }
+\cs_new_protected:Npn \@@_backend_emc: { }
+% \end{macrocode}
+% \end{macro}
+% \end{macro}
+%
+% \begin{macrocode}
+%</dvisvgm>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%</initex|package>
+% \end{macrocode}
+%
+% \end{implementation}
+%
+% \PrintIndex