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1%D \module
2%D   [       file=anch-bck, % moved from anch-pgr (1999.08.01)
3%D        version=2011.12.19,
4%D          title=\CONTEXT\ Anchoring Macros,
5%D       subtitle=Backgrounds,
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 Anchoring Macros / Backgrounds}
15
16%D This module is quite okay but at some point I might add methods
17%D that use attributes although not too much is to be expected,
18%D apart from better anchoring. In fact better anchoring can be
19%D done independent of that.
20
21\unprotect
22
23% This might be overloaded later on:
24
25% \defineoverlay[\v!text-2][\positionoverlay{\v!text-2}]
26% \defineoverlay[\v!text-1][\positionoverlay{\v!text-1}]
27% \defineoverlay[\v!text+1][\positionoverlay{\v!text+1}]
28% \defineoverlay[\v!text+2][\positionoverlay{\v!text+2}]
29
30% Paragraph positions:
31
32\newcount\c_anch_backgrounds_text_n
33
34\def\v_anch_backgrounds_text_current    {tbg:0}
35\def\v_anch_backgrounds_anchor_current_b{b:\v_anch_backgrounds_text_current}
36\def\v_anch_backgrounds_anchor_current_e{e:\v_anch_backgrounds_text_current}
37
38\def\anch_backgrounds_text_initialize_next
39  {\global\advance\c_anch_backgrounds_text_n\plusone
40   \edef\v_anch_backgrounds_text_current{tbg:\number\c_anch_backgrounds_text_n}}
41
42% The first position can be used in the middle of a paragraph in which case we're
43% too late with initializing par positions. Therefore we check if positions are
44% used at all.
45%
46% tricky: we need to catch newly set! otherwise an old run can have positions
47
48\unexpanded\def\anch_backgrounds_text_initialize
49  {\doifelsepositionsused\enableparpositions\donothing
50   \glet\anch_backgrounds_text_initialize\relax}
51
52\appendtoks
53    \anch_backgrounds_text_initialize
54\to \everystarttext
55
56%D Some MP
57
58\newcount\MPparcounter
59
60\def\MPself     {\MPvar{self}}
61\def\MPbself    {b:\MPvar{self}}
62\def\MPeself    {e:\MPvar{self}}
63\def\MPparanchor{p:\number\MPparcounter}
64
65% \carryoverpar is needed for left/right floats
66
67% \definetextbackground[more][state=start,backgroundcolor=red] % location=paragraph
68% \definetextbackground[test][state=start,backgroundcolor=green]
69%
70% \page \placefigure[left]{}{}
71%
72% \starttextbackground[test]
73%   \readfile{ward}{}{}
74%   \starttextbackground[more]
75%     \readfile{ward}{}{}
76%   \stoptextbackground
77%   \readfile{ward}{}{}
78% \stoptextbackground
79%
80% \page \placefigure[right]{}{}
81%
82% \starttextbackground[test]
83%   \readfile{ward}{}{}
84%   \starttextbackground[more]
85%     \readfile{ward}{}{}
86%   \stoptextbackground
87%   \readfile{ward}{}{}
88% \stoptextbackground
89
90\newcount\c_anch_backgrounds_text_level
91
92\installcorenamespace{textbackground}
93\installcorenamespace{textbackgroundlevel}
94
95\installcommandhandler \??textbackground {textbackground} \??textbackground
96
97\appendtoks
98    \setuevalue{\currenttextbackground}{\groupedcommand{\starttextbackground[\currenttextbackground]}{\stoptextbackground}}%
99    \setuevalue{\e!start\currenttextbackground}{\starttextbackground[\currenttextbackground]}%
100    \setuevalue{\e!stop \currenttextbackground}{\stoptextbackground}%
101\to \everydefinetextbackground
102
103\newconstant   \c_anch_backgrounds_pos_state
104\newconditional\c_anch_backgrounds_pos_no_shape
105
106\def\anch_backgrounds_bpos
107  {\ifconditional\c_anch_backgrounds_pos_no_shape
108     \bposkind\v_anch_backgrounds_text_current\plusthree
109   \else
110     \bposkind\v_anch_backgrounds_text_current\c_anch_backgrounds_pos_state
111   \fi}
112
113\def\anch_backgrounds_epos
114  {\ifconditional\c_anch_backgrounds_pos_no_shape
115     \eposkind\v_anch_backgrounds_text_current\plusthree
116   \else
117     \eposkind\v_anch_backgrounds_text_current\c_anch_backgrounds_pos_state
118   \fi}
119
120\unexpanded\def\starttextbackground
121  {\begingroup
122   \advance\c_anch_backgrounds_text_level\plusone
123   \dodoubleempty\anch_backgrounds_text_start}
124
125\def\anch_backgrounds_text_start[#tag][#settings]%
126  {%\checkpositionoverlays
127   \def\currenttextbackground{#tag}%
128   \anch_backgrounds_text_initialize_next
129   \ifsecondargument
130     \setupcurrenttextbackground[#settings]%
131   \fi
132   \doifelse{\textbackgroundparameter\c!state}\v!start
133     \anch_backgrounds_text_preset_yes
134     \anch_backgrounds_text_preset_nop
135   \anch_backgrounds_text_start_indeed}
136
137% ugly hack to register usage
138
139\newcount   \c_anch_backgrounds_text_count
140\newcount   \c_anch_backgrounds_text_check
141\newconstant\c_anch_backgrounds_text_state
142
143\unexpanded\def\starttextbackground
144  {\begingroup
145   \global\advance\c_anch_backgrounds_text_count\plusone
146   \advance\c_anch_backgrounds_text_level\plusone
147   \dodoubleempty\anch_backgrounds_text_start}
148
149\def\anch_backgrounds_text_level_start
150  {\c_anch_backgrounds_text_check\c_anch_backgrounds_text_count}
151
152\def\anch_backgrounds_text_level_stop
153  {\c_anch_backgrounds_text_state
154     \ifnum\c_anch_backgrounds_text_count>\c_anch_backgrounds_text_check
155       \plusone
156     \else
157       \zerocount
158     \fi}
159
160% todo \backgroundvariable\c!variant
161
162% criterium determines when we fall back on text
163% always is always forcing paragraphs
164
165\let\anch_backgrounds_text_start_indeed\relax
166\let\anch_backgrounds_text_stop_indeed \relax
167
168\setvalue{\??textbackgroundlevel\v!text}%
169  {\let\anch_backgrounds_text_start_indeed\anch_backgrounds_text_start_txt
170   \let\anch_backgrounds_text_stop_indeed \anch_backgrounds_text_stop_txt}
171
172\setvalue{\??textbackgroundlevel\v!paragraph}%
173  {\ifnum\c_anch_backgrounds_text_level>\textbackgroundparameter\c!criterium\relax
174     \let\anch_backgrounds_text_start_indeed\anch_backgrounds_text_start_txt
175     \let\anch_backgrounds_text_stop_indeed \anch_backgrounds_text_stop_txt
176   \else
177     \let\anch_backgrounds_text_start_indeed\anch_backgrounds_text_start_par
178     \let\anch_backgrounds_text_stop_indeed \anch_backgrounds_text_stop_par
179   \fi}
180
181\setvalue{\??textbackgroundlevel\v!always}%
182  {\let\anch_backgrounds_text_start_indeed\anch_backgrounds_text_start_par
183   \let\anch_backgrounds_text_stop_indeed \anch_backgrounds_text_stop_par}
184
185\setvalue{\??textbackgroundlevel\v!none}%
186  {\anch_backgrounds_text_preset_nop}
187
188\def\anch_backgrounds_text_preset_nop
189  {\let\anch_backgrounds_text_start_indeed\relax
190   \let\anch_backgrounds_text_stop_indeed \relax}
191
192\def\anch_backgrounds_text_preset_yes
193  {\anch_backgrounds_text_preset_nop
194   \csname\??textbackgroundlevel\textbackgroundparameter\c!location\endcsname
195   \edef\p_anch_backgrounds_text_frame     {\textbackgroundparameter\c!frame}%
196   \edef\p_anch_backgrounds_text_corner    {\textbackgroundparameter\c!corner}%
197   \edef\p_anch_backgrounds_text_background{\textbackgroundparameter\c!background}%
198   \ifx\p_anch_backgrounds_text_frame\v!on
199     \ifx\p_anch_backgrounds_text_corner\v!round
200       \let\p_anch_backgrounds_text_frame\!!plustwo
201     \else
202       \let\p_anch_backgrounds_text_frame\!!plusone
203     \fi
204   \else
205     \let\p_anch_backgrounds_text_frame\!!zerocount
206   \fi
207   \ifx\p_anch_backgrounds_text_background\v!color
208     \let\p_anch_backgrounds_text_background\!!plusone
209   \else
210     \let\p_anch_backgrounds_text_background\!!zerocount
211   \fi
212   \startpositionoverlay{\textbackgroundoverlay{\textbackgroundparameter\c!level}}%
213     \anch_backgrounds_text_meta_graphic % gets expanded directly
214   \stoppositionoverlay}
215
216\def\anch_backgrounds_text_meta_graphic
217  {\normalexpanded
218     {\setMPpositiongraphicrange % needs to be optimized
219        {\v_anch_backgrounds_anchor_current_b}%
220        {\v_anch_backgrounds_anchor_current_e}%
221        {\textbackgroundparameter\c!method}%
222        {self=\v_anch_backgrounds_text_current,
223         mp=\textbackgroundparameter\c!mp,
224         gridtype=\textbackgroundparameter\c!alternative,
225         filltype=\p_anch_backgrounds_text_background,
226         linetype=\p_anch_backgrounds_text_frame,
227         dashtype=\textbackgroundparameter\c!dash,
228         gridcolor=\textbackgroundparameter\c!framecolor,
229         linecolor=\textbackgroundparameter\c!framecolor,
230         lineoffset=\textbackgroundparameter\c!frameoffset,
231         fillcolor=\textbackgroundparameter\c!backgroundcolor,
232         filloffset=\textbackgroundparameter\c!backgroundoffset,
233         gridwidth=\textbackgroundparameter\c!rulethickness,
234         gridshift=\textbackgroundparameter\c!voffset,
235         linewidth=\textbackgroundparameter\c!rulethickness,
236         lineradius=\textbackgroundparameter\c!radius}}}
237
238\unexpanded\def\stoptextbackground
239  {\anch_backgrounds_text_stop_indeed
240   \carryoverpar\endgroup} % why doesn't this work ?
241
242\unexpanded\def\starttextbackgroundmanual
243  {\begingroup
244   \c_anch_backgrounds_pos_state\plusone
245   \usetextbackgroundstyleandcolor\c!style\c!color
246   \anch_backgrounds_bpos}
247
248\unexpanded\def\stoptextbackgroundmanual
249  {\anch_backgrounds_epos
250   \carryoverpar\endgroup}
251
252\def\anch_backgrounds_text_start_txt
253  {\ifvmode \dontleavehmode \fi
254   \begingroup
255   \c_anch_backgrounds_pos_state\plusone
256   \usetextbackgroundstyleandcolor\c!style\c!color
257   \anch_backgrounds_bpos}
258
259\def\anch_backgrounds_text_stop_txt
260  {\anch_backgrounds_epos
261   \carryoverpar\endgroup}
262
263\newskip\textbackgroundskip
264
265% maybe we should have a resetter for such compensation struts
266
267\def\anch_backgrounds_reset_attributes
268  {\scratchcounter\c_attr_snapmethod
269   \resetallattributes % \c_attr_linenumber\attributeunsetvalue
270   \c_attr_snapmethod\scratchcounter}
271
272\def\anch_backgrounds_text_start_par % beware .. background shapes
273  {\endgraf % new
274   \textbackgroundparameter\c!before
275   \begingroup
276   \c_anch_backgrounds_pos_state\plustwo
277   \begingroup
278   \anch_backgrounds_reset_attributes
279   \noindent
280   \ifgridsnapping
281     \spac_helpers_assign_skip\textbackgroundskip{\textbackgroundparameter\c!topoffset}%
282     \ifdim\textbackgroundskip>\zeropoint
283       \struttedbox % not always ok (e.g. setups)
284         {\hpack{\raise\textbackgroundskip\hpack{\anch_backgrounds_bpos}}}%
285     \else
286       \anch_backgrounds_bpos
287     \fi
288   \else
289     \anch_backgrounds_bpos
290   \fi
291   \endgraf % we need a vertical nobreak - 29/06/2004
292   \endgroup
293   \nobreak
294   \vskip-\lineheight
295   \nobreak
296   \ifgridsnapping \else
297     \spac_helpers_assign_skip\textbackgroundskip{\textbackgroundparameter\c!topoffset}%
298     \ifdim\textbackgroundskip>\zeropoint
299        \kern\textbackgroundskip\nobreak
300     \fi
301   \fi
302   \dosetleftskipadaption{\textbackgroundparameter\c!leftoffset}%
303   \advance\leftskip\leftskipadaption
304   \dosetleftskipadaption{\textbackgroundparameter\c!rightoffset}%
305   \advance\rightskip\leftskipadaption
306   % new
307   \dosetraggedcommand{\textbackgroundparameter\c!align}%
308   \raggedcommand
309   %
310   \usetextbackgroundstyleandcolor\c!style\c!color
311   \nowhitespace
312   \seteffectivehsize
313   \doinhibitblank %   \blank[\v!disable]% new
314   \par}
315
316\def\anch_backgrounds_text_stop_par
317  {\par
318   \removelastskip % new
319   \spac_helpers_assign_skip\textbackgroundskip{\textbackgroundparameter\c!bottomoffset}%
320   \ifdim\lastskip>\zeropoint
321     \advance\textbackgroundskip-\lastskip
322   \fi
323   \ifgridsnapping \else \ifdim\textbackgroundskip>\zeropoint
324     \kern\textbackgroundskip\nobreak
325   \fi \fi
326   \nobreak
327   \vskip-\dimexpr\lineheight+\parskip\relax % problem: we loose the hangindent
328   \nobreak
329   \endgroup
330   \begingroup
331   \forgeteverypar % NOT REALLY NEEDED, SAVES HASH/MEM
332   \anch_backgrounds_reset_attributes
333   \nobreak \noindent \strut \hfill \kern\zeropoint
334   % so far
335   \spac_helpers_assign_skip\textbackgroundskip{\textbackgroundparameter\c!bottomoffset}%
336   \ifgridsnapping % experimental, pascal (todo: topoffset in same way)
337     \ifdim\textbackgroundskip>\zeropoint
338       \struttedbox % not always ok (e.g. setups)
339         {\hpack{\lower\textbackgroundskip\hpack{\anch_backgrounds_epos}}}%
340     \else
341       \anch_backgrounds_epos
342     \fi
343   \else
344     \anch_backgrounds_epos
345   \fi
346   \endgraf
347   \carryoverpar\endgroup
348   \endgraf % new
349   \textbackgroundparameter\c!after}
350
351\unexpanded\def\checkpositionoverlays % overloads \relax in anch-pgr
352  {\ifproductionrun
353     \enabletextarearegistration
354     \enablehiddenbackground
355     \glet\checkpositionoverlays\relax
356   \fi}
357
358% shape handling
359
360\definesystemattribute[textbackground][public]
361
362% \def\page_prepare_backgrounds#1%
363%   {\clf_collectbackgrounds\realpageno#1\relax}
364
365\def\anch_backgrounds_bpos
366  {\ifconditional\c_anch_backgrounds_pos_no_shape
367     \c_attr_textbackground\attributeunsetvalue
368     \bposkind\v_anch_backgrounds_text_current\plusthree
369   \else\ifnum\c_anch_backgrounds_pos_state=\plusone
370     \bposkind\v_anch_backgrounds_text_current\c_anch_backgrounds_pos_state
371     \clf_registerbackground{\v_anch_backgrounds_text_current}%
372   \else
373     \bposkind\v_anch_backgrounds_text_current\c_anch_backgrounds_pos_state
374     \c_attr_textbackground\attributeunsetvalue
375   \fi\fi}
376
377% plugs into other code
378
379\def\strc_floats_wrap_free_region
380  {\global\setbox\floatbox\hpack % we always need to wrap
381     {\ifconditional\c_strc_floats_trace_free
382        \strc_floats_show_free_region
383      \fi
384      \box\floatbox}}
385
386\startuseMPgraphic{floatfree}
387    draw_free_region(
388        \the\wd\floatbox,
389        \the\ht\floatbox,
390        \the\dp\floatbox,
391        \the\d_free_offset_left,
392        \the\d_free_offset_right,
393        \the\d_free_offset_top,
394        \the\d_free_offset_bottom
395    ) ;
396\stopuseMPgraphic
397
398\def\strc_floats_show_free_region
399  {\lower\dp\floatbox\hpack to \zeropoint {\useMPgraphic{floatfree}}}
400
401\newconditional\c_strc_floats_mark_as_free
402\newconditional\c_strc_floats_trace_free
403\newconstant   \c_free_offset_kind
404\newdimen      \d_free_offset_left
405\newdimen      \d_free_offset_right
406\newdimen      \d_free_offset_top
407\newdimen      \d_free_offset_bottom
408
409\installtextracker{floats.freeregion}
410  {\settrue \c_strc_floats_trace_free}
411  {\setfalse\c_strc_floats_trace_free}
412
413\def\strc_floats_mark_as_free#1#2#3#4#5%
414  {\c_free_offset_kind  #1%
415   \d_free_offset_left  #2%
416   \d_free_offset_right #3%
417   \d_free_offset_top   #4%
418   \d_free_offset_bottom#5%
419   \strc_floats_wrap_free_region
420   \anch_mark_tagged_box_free
421     \floatbox
422     \c_free_offset_kind
423     \d_free_offset_left
424     \d_free_offset_right
425     \d_free_offset_top
426     \d_free_offset_bottom}
427
428\ifx\strc_floats_mark_pag_as_free\relax \else
429    \writestatus{error}{wrong place for pag_as_free}\wait
430\fi
431
432\ifx\strc_floats_mark_par_as_free\relax \else
433    \writestatus{error}{wrong place for par_as_free}\wait
434\fi
435
436\def\strc_floats_mark_pag_as_free
437  {\ifpositioning
438     \ifconditional\c_strc_floats_mark_as_free
439       \strc_floats_mark_as_free
440         \plusone
441         \zeropoint
442         \zeropoint
443         \d_strc_floats_top
444         \d_strc_floats_bottom
445     \fi
446   \fi}
447
448\def\strc_floats_mark_par_as_free
449  {\ifpositioning
450     \ifconditional\c_strc_floats_mark_as_free
451       \ifcase\c_page_sides_float_type
452       \or % backspace
453         \strc_floats_mark_as_free
454           \plustwo
455           \zeropoint
456           \d_page_sides_rightoffset
457           \d_page_sides_topskip
458           \d_page_sides_bottomskip
459       \or   % leftedge
460         \strc_floats_mark_as_free
461           \plustwo
462           \zeropoint
463           \d_page_sides_rightoffset
464           \d_page_sides_topskip
465           \d_page_sides_bottomskip
466       \or   % leftmargin
467         \strc_floats_mark_as_free
468           \plustwo
469           \zeropoint
470           \d_page_sides_rightoffset
471           \d_page_sides_topskip
472           \d_page_sides_bottomskip
473       \or   % leftside
474         \strc_floats_mark_as_free
475           \plustwo
476           \d_page_sides_leftskip % maybe too
477           \d_page_sides_margin
478           \d_page_sides_topskip
479           \d_page_sides_bottomskip
480       \or   % rightside
481         \strc_floats_mark_as_free
482           \plusthree
483           \d_page_sides_margin
484           \d_page_sides_rightskip % maybe too
485           \d_page_sides_topskip
486           \d_page_sides_bottomskip
487       \or   % rightmargin
488         \strc_floats_mark_as_free
489           \plusthree
490           \d_page_sides_leftoffset
491           \zeropoint
492           \d_page_sides_topskip
493           \d_page_sides_bottomskip
494       \or   % rightedge
495         \strc_floats_mark_as_free
496           \plusthree
497           \d_page_sides_leftoffset
498           \zeropoint
499           \d_page_sides_topskip
500           \d_page_sides_bottomskip
501       \or   % cutspace
502         \strc_floats_mark_as_free
503           \plusthree
504           \d_page_sides_leftoffset
505           \zeropoint
506           \d_page_sides_topskip
507           \d_page_sides_bottomskip
508       \fi
509     \fi
510   \fi}
511
512% so far
513
514\setuptextbackground
515  [\c!mp=mpos:region:draw,
516   \c!method=mpos:region,
517   \c!state=\v!start,
518   \c!location=\v!text,
519   \c!leftoffset=\!!zeropoint, % 1em,
520   \c!rightoffset=\textbackgroundparameter\c!leftoffset,
521   \c!topoffset=\!!zeropoint,  % \v!medium,
522   \c!bottomoffset=\textbackgroundparameter\c!topoffset,
523   \c!criterium=\plusone,
524   \c!level=-1,
525   \c!alternative=0,
526   \c!align=,
527   \c!dash=0, % to be internationalized
528   \c!background=\v!color,
529   \c!backgroundcolor=lightgray,
530   \c!backgroundoffset=\!!zeropoint,
531   \c!corner=\v!rectangular,
532   \c!radius=.5\bodyfontsize,
533   \c!voffset=\!!zeropoint,
534   \c!frame=\v!on,
535   \c!framecolor=blue,
536   \c!frameoffset=\!!zeropoint,
537   \c!rulethickness=\linewidth]
538
539%D The \METAPOST\ connection:
540
541% gridtype = 1 => baseline
542% gridtype = 2 => betweenline
543
544\setupMPvariables
545  [mpos:region]
546  [mp=mpos:region:unset,
547   gridtype=0,
548   linetype=1,
549   filltype=1,
550   dashtype=0, % 1 = dashed, 2 = dashed with background
551   gridcolor=red,
552   linecolor=blue,
553   fillcolor=lightgray,
554   filloffset=\!!zeropoint,
555   linewidth=\linewidth,
556   gridwidth=\linewidth,
557   gridshift=\!!zeropoint,
558   lineradius=.5\bodyfontsize,
559   lineoffset=\!!zeropoint,
560   dashtype=1]
561
562\startuseMPgraphic{mpos:region:setup}
563    boxgridtype   := \MPvar{gridtype} ;
564    boxlinetype   := \MPvar{linetype} ;
565    boxfilltype   := \MPvar{filltype} ;
566    boxdashtype   := \MPvar{dashtype} ;
567    boxfilloffset := \MPvar{filloffset} ;
568    boxlinewidth  := \MPvar{linewidth} ;
569    boxgridwidth  := \MPvar{gridwidth} ;
570    boxgridshift  := \MPvar{gridshift} ;
571    boxlineradius := \MPvar{lineradius} ;
572    boxlineoffset := \MPvar{lineoffset} ;
573    %
574    def boxgridcolor = \MPvar{gridcolor} enddef ;
575    def boxlinecolor = \MPvar{linecolor} enddef ;
576    def boxfillcolor = \MPvar{fillcolor} enddef ;
577    %
578    def boxgridoptions = withcolor boxgridcolor enddef ;
579    def boxlineoptions = withcolor boxlinecolor enddef ;
580    def boxfilloptions = withcolor boxfillcolor enddef ;
581\stopuseMPgraphic
582
583\startuseMPgraphic{mpos:region:extra}
584    % user stuff
585\stopuseMPgraphic
586
587\startuseMPgraphic{mpos:region:anchor}
588    setbounds currentpicture to multibox ;
589\stopuseMPgraphic
590
591\startMPpositiongraphic{mpos:region}{fillcolor,filloffset,linecolor,gridcolor,linewidth,gridwidth,gridshift,lineradius,lineoffset}
592    \includeMPgraphic{mpos:region:setup} ;
593    \includeMPgraphic{mpos:region:extra} ;
594    \MPgetmultipars{\MPvar{self}}{\MPanchorid} ;
595    \includeMPgraphic{\MPvar{mp}} ;
596    \includeMPgraphic{mpos:region:anchor} ;
597\stopMPpositiongraphic
598
599%D For old times sake:
600
601\startMPpositiongraphic{mpos:box}{fillcolor,linecolor,linewidth}
602    string tag; tag := "\MPvar{self}" ;
603    path box ; box := positionbox(tag) ;
604
605    box := box enlarged  \MPvar{filloffset} ;
606    fill box withcolor \MPvar{fillcolor} ;
607    draw box withcolor \MPvar{linecolor} withpen pencircle scaled \MPvar{linewidth} ;
608
609    positioninregion;
610\stopMPpositiongraphic
611
612\startMPpositionmethod{mpos:region}
613    \MPpositiongraphic{mpos:region}{}%
614\stopMPpositionmethod
615
616\startuseMPgraphic{mpos:region:draw}
617    draw_multi_pars
618\stopuseMPgraphic
619
620\startuseMPgraphic{mpos:region:show}
621    show_multi_pars
622\stopuseMPgraphic
623
624\startuseMPgraphic{mpos:region:kind}
625    show_multi_kind
626\stopuseMPgraphic
627
628\startuseMPgraphic{mpos:region:sideline}
629    draw_multi_side
630\stopuseMPgraphic
631
632\startuseMPgraphic{mpos:region:sideline:dashed}
633    draw_multi_side_path dashed evenly ;
634\stopuseMPgraphic
635
636%D As an example we define a grid background:
637
638\definetextbackground
639  [\v!grid]
640  [\c!state=\v!stop,
641   \c!location=\v!paragraph,
642   \c!frame=\v!off,
643   \c!framecolor=red,
644   \c!background=,
645   \c!alternative=1]
646
647\ifx\basegrid\undefined \else \letvalue\v!grid=\basegrid \fi
648
649%D Some examples (that might become modules anch-imp-whatever):
650
651\setupMPvariables
652  [mpos:encircle]
653  [fillcolor=lightgray,
654   filloffset=\!!zeropoint,
655   linecolor=blue,
656   lineoffset=5pt,
657   linewidth=1pt]
658
659\startMPpositiongraphic{mpos:encircle}{linecolor,fillcolor,linewidth,lineoffset}
660    \MPgetposboxes{\MPvar{self}}{\MPanchorid}
661    if nofposboxes = 1 :
662        posboxes[1] := posboxes[1] enlarged \MPvar{lineoffset} cornered \MPvar{lineoffset}  ;
663        fill posboxes[1] withcolor \MPvar{fillcolor} ;
664        draw posboxes[1] withpen pencircle scaled \MPvar{linewidth} withcolor \MPvar{linecolor} ;
665    fi ;
666\stopMPpositiongraphic
667
668\setupMPvariables
669  [mpos:connect]
670  [linecolor=red,
671   lineoffset=.25ex,
672   linewidth=1pt]
673
674\startMPpositiongraphic{mpos:connect}{linecolor,lineoffset,linewidth}
675    boxlinewidth  := \MPvar{linewidth} ;
676    boxlineoffset := \MPvar{lineoffset} ;
677    def boxlineoptions = withcolor \MPvar{linecolor} enddef ;
678    \MPgetposboxes{\MPvar{from},\MPvar{to}}{\MPanchorid}
679    connect_positions ;
680\stopMPpositiongraphic
681
682\protect \endinput
683
684\definetextbackground[underline]    [location=text,alternative=1,background=,frame=off]
685\definetextbackground[overstrike]   [location=text,alternative=2,background=,frame=off]
686\definetextbackground[exlines]      [location=text,alternative=3,background=,frame=off]
687\definetextbackground[strikethrough][location=text,alternative=4,background=,frame=off]
688
689\definestartstop [underline]
690  [before={\starttextbackground[underline]},
691   after=\stoptextbackground]
692
693\definestartstop
694  [overstrike]
695  [before={\starttextbackground[overstrike]},
696   after=\stoptextbackground]
697
698\definestartstop
699  [exlines]
700  [before={\starttextbackground[exlines]},
701   after=\stoptextbackground]
702
703\definestartstop
704  [strikethrough]
705  [before={\starttextbackground[strikethrough]},
706   after=\stoptextbackground]
707
708\definetextbackground
709  [sideline]
710  [mp=mpos:region:sideline,
711   location=paragraph,
712   framecolor=red,
713   frameoffset=5mm]
714
715\definestartstop [sideline]
716  [before={\starttextbackground[sideline]},
717   after=\stoptextbackground]
718
719\starttext
720
721    \startunderline     \input tufte \stopunderline      \blank
722    \startoverstrike    \input tufte \stopoverstrike     \blank
723    \startexlines       \input tufte \stopexlines        \blank
724    \startstrikethrough \input tufte \stopstrikethrough  \blank
725    \startsideline      \input tufte \stopsideline       \blank
726
727    \page
728
729    \startpositionoverlay{text-1}
730        \setMPpositiongraphic{connect-1-b}{mpos:connect}{from=connect-1-b,to=connect-1-e}
731        \setMPpositiongraphic{connect-1-e}{mpos:connect}{from=connect-1-b,to=connect-1-e}
732    \stoppositionoverlay
733
734    \startpositionoverlay{text-1}
735        \setMPpositiongraphic{encircle-1}{mpos:encircle}{self=encircle-1}
736    \stoppositionoverlay
737
738    test \hpos{connect-1-b}{START}
739        \dorecurse{10}{\input ward}
740    \hpos{encircle-1}{\strut HERE}
741        \dorecurse{10}{\input ward}
742    \hpos{connect-1-e}{STOP} test
743
744\stoptext
745