Hi,

I uploaded a new lmtx version. This time a new mechanism.

-----------------------------
 From an upcoming details chapter:
-----------------------------

The mechanism described here is still experimental. Although it could be 
implemented in \MKIV\ it is only available in \LMTX. Already early in 
\MKII\ we had a positioning mechanism available. At that time we had 
\DVI\ output and specials were used to track positions. A script 
calculated the positions that were then fed back into the second run. 
Later Taco wrote \DVIPOS\ which sped up the analysis between runs. When 
\PDFTEX\ showed, an equivalent positioning mechanism was added there. In 
\MKIV\ positioning support was optimized a bit as part of the upgrading 
process but the principles remained the same. The interface to 
positioning comes with a lot of commands and many of them relate to what 
we want to do with \METAFUN. The alternative interface discussed here is 
a bit simpler and has (at least now) less commands and, combined with 
local name spaces, can be easier to use in more local situations. It's 
also integrated in the frequently used \type {\framed} commands and has 
basic support at the \METAFUN\ end. The performance is comparable to the 
regular positioning mechanisms but especially at the \METAPOST\ end has 
less overhead.

-----------------------------
Here are some examples:
-----------------------------

\framed [synchronize=yes,align=normal] {%
   test test test 1      \sync{one}{1}test test 2      \crlf
   test test 1           \sync{one}{1}test test test 2 \crlf
   test 1                \sync{one}{1}test 2           \crlf
   test test test test 1 \sync{one}{1}test test 2
}

\framed [synchronize=yes,align=normal] {%
     one one     \sync{a}{1}two     \sync{a}{2}three \crlf
     one one     \sync{a}{1}two two \sync{a}{2}three \crlf
     one         \sync{a}{1}two     \sync{a}{2}three \crlf
     one one one \sync{a}{1}two     \sync{a}{2}three
}

\framed [synchronize=yes,align=normal] {%
     \syncanchor{one}{1}{1}A
     \syncanchor{one}{2}{1}BBB
     \syncanchor{one}{3}{1}C \crlf
     \syncanchor{one}{1}{2}AA
     \syncanchor{one}{3}{2}C \crlf
     \syncanchor{one}{1}{3}AAA
     \syncanchor{one}{2}{3}BB
     \syncanchor{one}{3}{3}C
}

\framed [synchronize=yes,align=normal] {%
     \alignanchor{one}{1}{1}{l}A
     \alignanchor{one}{1}{2}{m}AA
     \alignanchor{one}{1}{3}{r}AAA
     \syncanchor {one}{1}{4}\crlf
     \alignanchor{one}{2}{1}{right}B
     \alignanchor{one}{2}{2}{middle}BB
     \alignanchor{one}{2}{3}{left}BBB
     \syncanchor {one}{2}{4}
}

\startuseMPgraphic{whatever-1}
     fill OverlayBox withcolor "lightgray" ;
     drawdot anchorxy("one", 0, 1)
         withpen pencircle scaled 1mm
         withcolor "red" ;
     drawdot anchorxy("one", 0, 2)
         withpen pencircle scaled 1mm
         withcolor "red" ;
     drawdot anchorxy("two", 0, 1)
         withpen pencircle scaled 1mm
         withcolor "red" ;
     drawdot anchorxy("two", 0, 2)
         withpen pencircle scaled 1mm
         withcolor "red" ;
     drawdot anchorxy("three", 0, 1)
         withpen pencircle scaled 1mm
         withcolor "red" ;
     setbounds currentpicture to OverlayBox ;
\stopuseMPgraphic

\startuseMPgraphic{whatever-2}
     pair a ; a := anchorxy("one", 0, 1) ;
     pair b ; b := anchorxy("one", 0, 2) ;
     drawarrow
         anchorxy("one", 0, 1) { right } ..
         anchorxy("one", 0, 2)
         withcolor "blue" withtransparency (1,.75) ;
     drawarrow
         anchorxy("two", 0, 1) { down } ..
         anchorxy("two", 0, 2)
         withcolor "blue" withtransparency (1,.75) ;
     drawarrow
         anchorxy("two", 0, 1) { dir 30 } ..
         anchorxy("three", 0, 1)
         withcolor "blue" withtransparency (1,.75) ;
     setbounds currentpicture to OverlayBox ;
\stopuseMPgraphic

\defineoverlay[whatever-1][\useMPgraphic{whatever-1}]
\defineoverlay[whatever-2][\useMPgraphic{whatever-2}]

\framed
   [synchronize=yes,
    align=normal,
    offset=10pt,
    frame=off,
    background={whatever-1,foreground,whatever-2}]
   {%
     \markanchor{two}{0}{1}{\red\bf foo}%
     \markanchor{one}{0}{1} bar rab oof\crlf
     foo bar rab oof\crlf
     oof rab bar foo\crlf
     oof rab \markanchor{two}{0}{2}{\red\bf bar}%
     \markanchor{one}{0}{2} foo%
     \markanchor{three}{0}{1}%
   }

\framed
   [synchronize=yes,
    align=normal,
    offset=10pt,
    frame=off,
    background={whatever-1,foreground,whatever-2}]
   {%
     one one one \syncanchor{a}{1}{1}two two two
                 \syncanchor{a}{2}{1}three three\par
     one         \syncanchor{a}{1}{2}two
                 \syncanchor{a}{2}{2}three\par
     one         \syncanchor{a}{1}{3}two
                 \syncanchor{a}{2}{3}three\par
     \blank
     \markanchor{two}{0}{1}{\red\bf foo}%
     \markanchor{one}{0}{1} bar rab oof\crlf
     foo bar rab oof\crlf
     oof rab bar foo\crlf
     oof rab \markanchor{two}{0}{2}{\red\bf bar}%
     \markanchor{one}{0}{2} foo%
     \markanchor{three}{0}{1}%
     \blank
     one one \syncanchor{a}{1}{4}two two
             \syncanchor{a}{2}{4}three\par
     one one \syncanchor{a}{1}{5}two two
             \syncanchor{a}{2}{5}three three%
     \markanchor{three}{0}{1}%
   }

\framed[synchronize=yes,align=normal]{%
     one one \sync{a}{1}two     \sync{a}{2}three\par
     one one \sync{a}{1}two two \sync{a}{2}three\par
     \blank
     tst tst \sync{b}{1}tst     \sync{b}{2}tst\par
     tst     \sync{b}{1}tst tst \sync{b}{2}tst\par
     \blank
     one     \sync{a}{1}two     \sync{a}{2}three
}

\page

\startpacked
     $a = b + c $\par
     $b = c + d $\par
     $c = e + f $\par
\stoppacked

\startpacked
\startsynchronizing
     $a \syncanchor{one}{1}{1}= b \syncanchor{one}{2}{1}+ c$\par
     $b \syncanchor{one}{1}{2}= c \syncanchor{one}{2}{2}+ d$\par
     $c \syncanchor{one}{1}{3}= e \syncanchor{one}{2}{3}+ f$\par
\stopsynchronizing
\stoppacked

\startpacked
\startsynchronizing
     $a \sync{one}{1}= b \sync{one}{2}+ c$\par
     $b \sync{one}{1}= c \sync{one}{2}+ d$\par
     $c \sync{one}{1}= e \sync{one}{2}+ f$\par
\stopsynchronizing
\stoppacked

\startpacked
\startsynchronizing
     $a \mathsync{1}= b \mathsync{2}+ c$\par
     $b \mathsync{1}= c \mathsync{2}+ d$\par
     $  \mordsync{1}= e \mathsync{2}+ f$\par
\stopsynchronizing
\stoppacked

-----------------------------
remark
-----------------------------

So, it's a varaant on the positioning mechanism. It also works in framed 
when the synchronization option is enabled. Don't enable that when not 
used (as there is some overhead involved).

I have no clue how useful it is but users always find a way to use 
mechanisms. One can do really freaky things with it. Who knows what gets 
added over time.

Also, it doesn't replace the existing positioning mechanism which served 
us well for decades; it's just a lightweight variant with different pros 
and cons.

Hans



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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
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