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1%D \module
2%D   [       file=page-spr,
3%D        version=2002.11.11,
4%D          title=\CONTEXT\ Page Macros,
5%D       subtitle=Spreading,
6%D         author=Hans Hagen,
7%D           date=\currentdate,
8%D      copyright={PRAGMA ADE \& \CONTEXT\ Development Team}]
9%C
10%C This module is part of the \CONTEXT\ macro||package and is
11%C therefore copyrighted by \PRAGMA. See mreadme.pdf for
12%C details.
13
14\writestatus{loading}{ConTeXt Page Macros / Spreading}
15
16% This module is experimental and not yet official!
17
18\unprotect
19
20\newbox        \b_page_spread_content
21\newconditional\c_page_spread_busy
22\newconditional\c_page_spread_once     % when true only one flush (writes etc)
23
24% beware, ugly overload, to be redone
25
26% \def\normalsettextpagecontent#1#2#3% #2 and #3 will disappear
27%   {\setbox#1\hbox
28%      {\setlayoutcomponentattribute{\v!page:\v!text}%
29%       \vbox \layoutcomponentboxattribute to \textheight
30%         {\offinterlineskip
31%          \freezetextwidth
32%          \hsize\textwidth   % local variant of \sethsize
33%          \boxmaxdepth\maxdepth
34%          \noindent             % content can be < \hsize
35%          \page_otr_command_package_contents#2#3}}%
36%    \dp#1\zeropoint
37%    \ifconditional\c_page_spread_busy
38%       \normalsettextpagecontent_spread{#1}%
39%    \else
40%       \normalsettextpagecontent_normal{#1}%
41%    \fi}
42
43\def\normalsettextpagecontent#1#2#3% #2 and #3 will disappear
44  {\setbox#1\hpack
45     {\setlayoutcomponentattribute{\v!page:\v!text}%
46      \vpack \layoutcomponentboxattribute to \textheight
47        {\offinterlineskip
48         \freezetextwidth
49         \hsize\textwidth   % local variant of \sethsize
50         \boxmaxdepth\maxdepth
51         \noindent          % content can be < \hsize
52         \page_otr_command_package_contents#2#3}}%
53   \dp#1\zeropoint
54   \ifconditional\c_page_spread_busy
55      \normalsettextpagecontent_spread{#1}%
56   \else
57      \normalsettextpagecontent_normal{#1}%
58   \fi}
59
60% \def\normalsettextpagecontent_normal#1%
61%   {\setbox#1\hbox to \makeupwidth
62%      {\hss\box#1\hss}} % never change the \hss's
63
64\def\normalsettextpagecontent_normal#1%
65  {\ifdim\wd#1=\makeupwidth\else
66     \setbox#1\hpack to \makeupwidth
67       {\hss\box#1\hss}% never change the \hss's
68   \fi}
69
70\def\normalsettextpagecontent_spread#1%
71  {\setbox#1\hpack to \makeupwidth
72     {\ifvoid\b_page_spread_content
73        \ifconditional\c_page_spread_once
74          \box#1%
75        \else
76          \global\setbox\b_page_spread_content\box#1%
77          \copy\b_page_spread_content
78        \fi
79        \hss % left page
80      \else
81        \hss % right page
82        \ifarrangingpages
83          % writes don't matter anyway
84        \else\ifconditional\c_page_spread_once
85          \global\setbox\b_page_spread_content\emptyhbox
86          \wd\b_page_spread_content\makeupwidth
87          \ht\b_page_spread_content\textheight
88        \else
89          % writes can interfere (todo: write stripper, but how about hyperlinks)
90        \fi \fi
91        \box\b_page_spread_content
92      \fi}}
93
94\unexpanded\def\page_spread_flush
95  {\ifconditional\c_page_spread_busy \ifvoid\b_page_spread_content\else
96     % this page will be discarded later
97     \emptyhbox \page
98   \fi \fi }
99
100\unexpanded\def\startspread
101  {\ifdoublesided
102     \ifconditional\c_page_spread_busy
103       \doubleexpandafter\page_spread_start_nop
104     \else
105       \doubleexpandafter\page_spread_start_yes
106     \fi
107   \else
108     \expandafter\page_spread_start_nop
109   \fi}
110
111\let\stopspread\relax
112
113\unexpanded\def\page_spread_start_yes
114  {\bgroup
115   \page[\v!left]%
116  %\setsystemmode{spread}%
117   \settrue\c_page_spread_busy
118   \expanded{\setuplayout[\c!textwidth=\the\dimexpr2\textwidth+2\backspace\relax]}%
119   \let\stopspread\page_spread_stop_yes}
120
121\unexpanded\def\page_spread_stop_yes
122  {\kern\zeropoint
123   \page
124   \setuplayout[\c!textwidth=\textwidth]%
125   \page[\v!left]%
126   \egroup}
127
128\unexpanded\def\page_spread_start_nop
129  {\bgroup
130   \let\stopspread\page_spread_stop_nop}
131
132\unexpanded\def\page_spread_stop_nop
133  {\egroup}
134
135\protect \endinput
136
137% texexec --arr --pdf test
138%
139% \setuplayout[width=middle]
140% \setuppapersize[A4][A3,landscape]
141% \setuppagenumbering[alternative=doublesided]
142% \setuparranging[2UP]
143%
144% \starttext
145%
146% \dorecurse{3}{\input tufte }
147%
148% \startspread
149%   \dorecurse{10}{\input tufte }
150% \stopspread
151%
152% \dorecurse{3}{\input tufte }
153%
154% \stoptext
155