stable 1998.04.15

1 files changed, 565 insertions, 445 deletions

diff --git a/tex/context/base/core-grd.tex b/tex/context/base/core-grd.tex
index 4a91fd35a..548a1408e 100644
--- a/tex/context/base/core-grd.tex
+++ b/tex/context/base/core-grd.tex
@@ -1,445 +1,565 @@
-%D \module
-%D   [       file=core-grd,
-%D        version=1998.03.10,
-%D          title=\CONTEXT\ Core Macros,
-%D       subtitle=Grid Snapping (Experimental),
-%D         author=Hans Hagen,
-%D           date=\currentdate,
-%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]
-%C
-%C This module is part of the \CONTEXT\ macro||package and is
-%C therefore copyrighted by \PRAGMA. Non||commercial use is
-%C granted.
-
-\writestatus{loading}{Context Core Macros / Grid Snapping}
-
-\unprotect
-
-%D Moved from supp-box:
-
-%D \macros
-%D  {startbaselinecorrection,baselinecorrection,
-%D   showbaselinecorrection,offbaselinecorrection}
-%D
-%D Spacing around ruled boxes can get pretty messed up. The
-%D next macro tries as good as possible to fix this.
-%D
-%D \startbuffer[1]
-%D \startbaselinecorrection
-%D \ruledhbox{Rule Brittanica}
-%D \stopbaselinecorrection
-%D \stopbuffer
-%D
-%D \typebuffer[1]
-%D
-%D The macros put some white space around the box:
-%D
-%D \haalbuffer[1]
-%D
-%D A simple alternative is \type {\baselinecorrection}, which
-%D only looks at the previous line. 
-%D
-%D \startbuffer[2]
-%D \baselinecorrection
-%D \ruledhbox{Rule Brittanica}
-%D \baselinecorrection
-%D \stopbuffer
-%D
-%D \typebuffer[2]
-%D
-%D This time the last preceding line gets a correction,%
-%D dependant on the depth. 
-%D
-%D \haalbuffer[2]
-%D
-%D One can make the correction visible by saying \type
-%D {\showbaselinecorrection}. Part of the correction is
-%D calculated from the dimensions of a~(. One can disble the
-%D correction by calling \type {\offbaselinecorrection}. 
-%D 
-%D When visulaize the first example looks like:
-%D
-%D {\showbaselinecorrection\haalbuffer[1]}
-%D
-%D and the second one comes out as:
-%D
-%D {\showbaselinecorrection\haalbuffer[2]}
-
-\def\setbaselinecorrections%
-  {\setbox0=\hbox{\setstrut\strut}%
-   \setbox2=\hbox{(}%
-   \dimen0=\ht0\advance\dimen0 by -\ht2
-   \ifdim\dimen0<\!!zeropoint\dimen0=\!!zeropoint\fi
-   \dimen2=\dp0\advance\dimen2 by -\dp2
-   \ifdim\dimen2<\!!zeropoint\dimen2=\!!zeropoint\fi
-   \edef\thetopbaselinecorrection{\the\dimen0}%
-   \edef\thebotbaselinecorrection{\the\dimen2}}
-
-\def\dotopbaselinecorrection%
-  {\kern\thetopbaselinecorrection}  
-
-\def\dobotbaselinecorrection%
-  {\kern\thebotbaselinecorrection}  
-
-\def\showbaselinecorrection%
-  {\def\dobaselinecorrection% visualization is not watertight!
-     {\bgroup
-      \kern-\prevdepth
-      \setbox0=\null
-      \wd0=\hsize\dp0=\dp\strutbox
-      \nointerlineskip 
-      \ruledvbox{\box0}%
-      \egroup
-      \prevdepth=\dp\strutbox}%
-   \def\dotopbaselinecorrection%
-     {\hrule\!!height\thetopbaselinecorrection}%
-   \def\dobotbaselinecorrection%
-     {\hrule\!!height\thebotbaselinecorrection}}
-
-\def\dobaselinecorrection%
-  {\kern-\prevdepth
-   \kern\dp\strutbox
-   \prevdepth=\dp\strutbox}
-
-\def\baselinecorrection%
-  {\endgraf
-   \ifvmode
-     \ifdim\prevdepth<\maxdimen
-       \ifdim\prevdepth<\!!zeropoint \else
-         \ifdim\prevdepth<\dp\strutbox
-           \dobaselinecorrection
-         \fi
-       \fi
-     \fi
-   \fi}
-
-\def\startbaselinecorrection%
-  {\baselinecorrection
-   \ifvmode
-     \bgroup
-     \setbox\scratchbox=\vbox\bgroup
-     \ignorespaces
-     \let\stopbaselinecorrection=\dostopbaselinecorrection
-   \else
-     \let\stopbaselinecorrection=\relax
-   \fi}
-
-%D We do a bit more checking than needed. The pageborder check
-%D is not needed, but I want to look the visualization as good 
-%D as possible too.
-
-\def\dostopbaselinecorrection% I have to check columns yet.
-  {\endgraf
-   \egroup
-   \topbaselinecorrection
-   \box\scratchbox
-   \botbaselinecorrection
-   \egroup}
-
-\let\stopbaselinecorrection=\relax
-
-\def\offbaselinecorrection% Can be used inside correction.
-  {\def\startbaselinecorrection%
-     {\bgroup
-      \let\stopbaselinecorrection=\egroup}}
-
-%D \macros
-%D  {topbaselinecorrection,botbaselinecorrection}
-%D
-%D The actual top and bottom corrections are implemented as:
-
-\def\topbaselinecorrection%
-  {\ifvmode 
-     \bgroup
-     \setbaselinecorrections
-     \ifdim\pagegoal<\maxdimen
-       \ifdim\pagetotal<\pagegoal
-         \dimen2=\ht\scratchbox
-         \advance\dimen2 by \dp\scratchbox
-         \advance\dimen2 by \parskip
-         \advance\dimen2 by \thetopbaselinecorrection
-         \advance\dimen2 by \thebotbaselinecorrection
-         \dimen0=\pagetotal
-         \advance\dimen0 by \dimen2
-         \ifdim\dimen0<\pagegoal
-           \witruimte
-           \nointerlineskip
-           \dotopbaselinecorrection
-         \else
-           \ifbinnenkolommen           % should be supp-status
-             \vskip\dimen2             % this could definitely
-             \penalty\outputpenalty    % be improved
-           \else  
-             %                         % should be supp-control
-             % \vfill\eject            % old 
-             %
-             \nobreak                  % needed for headings 
-             \vskip\parskip            % cross your fingers
-             \vskip\dimen2             % anyhow
-             \penalty\outputpenalty  
-             \vskip-\dimen2
-           \fi   
-         \fi
-       \else                           % probably a preceding 
-         \witruimte                    % one-liner 
-         \nointerlineskip
-         \dotopbaselinecorrection
-       \fi
-     \fi
-     \egroup
-   \fi}
-
-\def\botbaselinecorrection%
-  {\ifvmode
-     \bgroup
-     \setbaselinecorrections
-     \dobotbaselinecorrection
-     \prevdepth\dp\strutbox
-     \egroup
-   \fi}
-
-%D An old one, still to be translated:
-%D
-%D \macros
-%D   {getnoflines}
-%D   {}
-%D
-%D Het commando \type{\getnoflines} converteert een hoogte
-%D (dimensie) in een aantal regels en kent dit toe aan
-%D \type{\noflines}.
-%D
-%D \starttypen
-%D \getnoflines{dimensie}
-%D \stoptypen
-%D
-%D Er wordt gedeeld door \type{\openlineheight} en een hoogte
-%D van~0pt komt overeen met 0~regels.
-
-\newcount\noflines
-\newdimen\noflinesheight
-
-\def\getnoflines#1%
-  {\noflinesheight=#1\relax
-   \ifdim\noflinesheight=\!!zeropoint\relax
-     \noflines=0
-   \else
-     \divide\noflinesheight by \openlineheight
-     \noflines=\noflinesheight
-     \ifdim\noflines\openlineheight=#1\relax \else
-       \advance\noflines by 1
-     \fi
-   \fi}
-
-%D Still very experimental and therefore undocumented.
-
-\newif\ifgridsnapping  % UNDER DEVELOPMENT, USE WITH CARE
-
-\def\positiveextrasnap {\gdef\extrasnapsign{+}}
-\def\negativeextrasnap {\gdef\extrasnapsign{-}}
-
-\def\extrasnapreset  {\global\chardef\@@extrasnap=0 
-                      \positiveextrasnap} 
-\def\extrasnapbefore {\global\chardef\@@extrasnap=1 }
-\def\extrasnaparound {\global\chardef\@@extrasnap=2 }
-\def\extrasnapafter  {\global\chardef\@@extrasnap=3 }
-
-\def\enablepresnapcorrection  {\global\chardef\@@presnap=0 }
-\def\disablepresnapcorrection {\global\chardef\@@presnap=1 }
-
-\extrasnapreset \enablepresnapcorrection  
-
-\newif\iftracegridsnapping 
-
-\def\snaptogrid#1% #1 == \hbox or \vbox
-  {\ifgridsnapping\expandafter\dosnaptogrid\expandafter#1\fi}
-
-\def\tracesnapping%
-  {\iftracegridsnapping
-     \llap
-       {\infofont
-        \doglobal\increment\currentsnap
-        \color[red]{\vl\presnapskip
-                    \vl\presnap
-                    \vl\postsnap
-                    \vl\ifcase\@@extrasnap
-                            00\or
-               \extrasnapsign0\or
-  \extrasnapsign\extrasnapsign\or
-               0\extrasnapsign\fi
-                    \vl\currentsnap\vl}}%
-   \fi}
-
-\def\dosnaptogrid%
-  {\dowithnextbox
-     {\bgroup
-      \forgetall
-      \par
-      \ifvbox\nextbox
-        \setbox\nextbox=\hbox{\box\nextbox}% don't ask
-      \fi
-      \scratchskip=\lastskip
-      \edef\presnapskip{\the\lastskip}%
-      \vbox{\strut}\nobreak\vskip-\openlineheight
-      \ifdim\ht\nextbox>\ht\strutbox
-        \scratchdimen=\ht\nextbox
-        \ifcase\@@presnap 
-          \ifdim\scratchskip>\!!zeropoint\relax
-            \scratchcounter=\scratchskip
-            \advance\scratchcounter by -\openlineheight
-            \ifnum\scratchcounter<0
-              \scratchcounter=-\scratchcounter
-            \fi
-            \ifnum\scratchcounter<10 % \lastkip is about \openlineheight
-              \advance\scratchdimen by -\openstrutdepth
-               \edef\presnapskip{*\presnapskip}%
-            \else\ifdim\scratchskip>\openlineheight 
-                                  %<\openlineheight \else
-              \advance\scratchdimen by -\openstrutdepth
-              \edef\presnapskip{*\presnapskip}%
-            \fi\fi
-          \fi
-        \fi
-        \getnoflines\scratchdimen
-        \advance\noflines by -1
-        \ifnum\noflines>0
-          \scratchdimen=\noflines\lineheight
-        \else
-          \scratchdimen=\!!zeropoint
-        \fi
-      \else
-        \scratchdimen=\!!zeropoint
-      \fi
-      \ifnum\@@extrasnap=1 \advance\scratchdimen by \extrasnapsign\lineheight \fi
-      \ifnum\@@extrasnap=2 \advance\scratchdimen by \extrasnapsign.5\lineheight \fi
-      \edef\presnap{\the\scratchdimen}%
-      \ifdim\scratchdimen=\!!zeropoint\else\vskip\scratchdimen\fi
-      \ifdim\dp\nextbox>\dp\strutbox
-        \getnoflines{\dp\nextbox}%
-        \advance\noflines by -1
-        \ifnum\noflines>0
-          \scratchdimen=\noflines\lineheight
-        \else
-          \scratchdimen=\!!zeropoint
-        \fi
-      \else
-        \scratchdimen=\!!zeropoint
-      \fi
-      \ifnum\@@extrasnap=2 \advance\scratchdimen by \extrasnapsign.5\lineheight \fi
-      \ifnum\@@extrasnap=3 \advance\scratchdimen by \extrasnapsign\lineheight \fi
-      \edef\postsnap{\the\scratchdimen}%
-      \ht\nextbox=\ht\strutbox
-      \dp\nextbox=\dp\strutbox
-      \hbox{\tracesnapping\box\nextbox}%
-      \ifdim\scratchdimen=\!!zeropoint\else\vskip\scratchdimen\fi
-      \extrasnapreset 
-      \enablepresnapcorrection  
-      \egroup}}
-
-\def\snaptomathgrid%
-  {\ifgridsnapping
-     \dowithnextbox
-       {\blanko[\v!regel] 
-        \snaptogrid\vbox{\box\nextbox}
-        \blanko[\v!regel]}
-     \vbox\bgroup
-       \let\setdisplayskips=\relax
-       \abovedisplayskip=\!!zeropoint
-       \abovedisplayshortskip=\!!zeropoint
-       \belowdisplayskip=\!!zeropoint
-       \belowdisplayshortskip=\!!zeropoint
-       \@EA\let\@EA\next
-   \fi}
-
-\def\topsnaptogrid% 
-  {\ifgridsnapping
-     \dowithnextbox
-       {\scratchdimen=\ht\nextbox
-        \advance\scratchdimen by -\ht\strutbox
-        \advance\scratchdimen by \topskip
-        \ht\nextbox=\scratchdimen
-        \dp\nextbox=\!!zeropoint
-        \box\nextbox
-        \kern\lineheight
-        \kern-\topskip
-        \nointerlineskip} 
-       \hbox
-   \fi}
-
-\def\centertogrid%
-  {\ifgridsnapping
-     \dowithnextbox
-       {\bgroup
-        \par
-        \scratchdimen=\ht\nextbox
-        \advance\scratchdimen by \dp\nextbox
-        \getnoflines\scratchdimen
-        \setbox\nextbox=\vbox to \noflines\lineheight
-          {\forgetall  
-           \vskip\!!zeropoint plus \ht\nextbox
-           \copy\nextbox
-           \kern.5\dp\strutbox % VOORLOPIGE WAARDE 
-           \vskip\!!zeropoint plus \dp\nextbox}
-        \noindent\snaptogrid\vbox{\box\nextbox}%
-        \egroup}
-       \hbox
-   \fi}
-
-\ifx\startbaselinecorrection\undefined \wait \fi % change order
-
-\let\normalstartbaselinecorrection=\startbaselinecorrection
-
-\def\startbaselinecorrection%
-  {\ifgridsnapping
-     \centertogrid\bgroup
-     \let\stopbaselinecorrection=\egroup
-   \else
-     \normalstartbaselinecorrection
-   \fi}
-
-\def\setgridbox#1#2#3%
-  {\setbox#1=\ruledvbox to #3
-     {\forgetall
-      \offinterlineskip
-      \hsize=#2
-      \getnoflines{#3}%
-      \vskip\topskip
-      \vskip-\ht\strutbox
-      \scratchdimen=#2\advance\scratchdimen by \lineheight
-      \dorecurse
-        {\noflines}
-        {\strut
-         \hskip-.5\lineheight
-         \rlap
-           {\hskip\scratchdimen\hskip2pt\infofont
-            \hbox to 1em{\hss\recurselevel}}%
-         \vrule
-           \!!height .5\testrulewidth
-           \!!depth .5\testrulewidth
-           \!!width \scratchdimen
-         \par}
-      \vfill}}
-
-\def\doverplaatsopgrid[#1]%
-  {\processaction
-     [#1]
-     [  \v!boven=>\positiveextrasnap\extrasnapbefore,
-        \v!onder=>\positiveextrasnap\extrasnapafter,
-        \v!beide=>\positiveextrasnap\extrasnaparound,
-       -\v!boven=>\negativeextrasnap\extrasnapbefore,
-       -\v!onder=>\negativeextrasnap\extrasnapafter,
-       -\v!beide=>\negativeextrasnap\extrasnaparound,
-      \s!default=>\positiveextrasnap\extrasnaparound,
-      \s!unknown=>\positiveextrasnap\extrasnapreset]}
-
-\def\verplaatsopgrid%
-  {\dosingleempty\doverplaatsopgrid}
-
-\def\doplaatsopgrid[#1]%
-  {\doverplaatsopgrid[#1]\snaptogrid\vbox}
-
-\def\plaatsopgrid%
-  {\dosingleempty\doplaatsopgrid}
-
-\protect
-
-\endinput 
+%D \module

+%D   [       file=core-grd,

+%D        version=1998.03.10,

+%D          title=\CONTEXT\ Core Macros,

+%D       subtitle=Grid Snapping (Experimental),

+%D         author=Hans Hagen,

+%D           date=\currentdate,

+%D      copyright={PRAGMA / Hans Hagen \& Ton Otten}]

+%C

+%C This module is part of the \CONTEXT\ macro||package and is

+%C therefore copyrighted by \PRAGMA. Non||commercial use is

+%C granted.

+

+\writestatus{loading}{Context Core Macros / Grid Snapping}

+

+\unprotect

+

+%D Moved from supp-box:

+

+%D \macros

+%D  {startbaselinecorrection,baselinecorrection,

+%D   showbaselinecorrection,offbaselinecorrection}

+%D

+%D Spacing around ruled boxes can get pretty messed up. The

+%D next macro tries as good as possible to fix this.

+%D

+%D \startbuffer[1]

+%D \startbaselinecorrection

+%D \ruledhbox{Rule Brittanica}

+%D \stopbaselinecorrection

+%D \stopbuffer

+%D

+%D \typebuffer[1]

+%D

+%D The macros put some white space around the box:

+%D

+%D \haalbuffer[1]

+%D

+%D A simple alternative is \type {\baselinecorrection}, which

+%D only looks at the previous line. 

+%D

+%D \startbuffer[2]

+%D \baselinecorrection

+%D \ruledhbox{Rule Brittanica}

+%D \baselinecorrection

+%D \stopbuffer

+%D

+%D \typebuffer[2]

+%D

+%D This time the last preceding line gets a correction,%

+%D dependant on the depth. 

+%D

+%D \haalbuffer[2]

+%D

+%D One can make the correction visible by saying \type

+%D {\showbaselinecorrection}. Part of the correction is

+%D calculated from the dimensions of a~(. One can disble the

+%D correction by calling \type {\offbaselinecorrection}. 

+%D 

+%D When visulaize the first example looks like:

+%D

+%D {\showbaselinecorrection\haalbuffer[1]}

+%D

+%D and the second one comes out as:

+%D

+%D {\showbaselinecorrection\haalbuffer[2]}

+

+\def\setbaselinecorrections%

+  {\setbox0=\hbox{\setstrut\strut}%

+   \setbox2=\hbox{(}%

+   \dimen0=\ht0\advance\dimen0 by -\ht2

+   \ifdim\dimen0<\!!zeropoint\dimen0=\!!zeropoint\fi

+   \dimen2=\dp0\advance\dimen2 by -\dp2

+   \ifdim\dimen2<\!!zeropoint\dimen2=\!!zeropoint\fi

+   \edef\thetopbaselinecorrection{\the\dimen0}%

+   \edef\thebotbaselinecorrection{\the\dimen2}}

+

+\def\dotopbaselinecorrection%

+  {\kern\thetopbaselinecorrection}  

+

+\def\dobotbaselinecorrection%

+  {\kern\thebotbaselinecorrection}  

+

+\def\showbaselinecorrection%

+  {\def\dobaselinecorrection% visualization is not watertight!

+     {\bgroup

+      \kern-\prevdepth

+      \setbox0=\null

+      \wd0=\hsize\dp0=\dp\strutbox

+      \nointerlineskip 

+      \ruledvbox{\box0}%

+      \egroup

+      \prevdepth=\dp\strutbox}%

+   \def\dotopbaselinecorrection%

+     {\hrule\!!height\thetopbaselinecorrection}%

+   \def\dobotbaselinecorrection%

+     {\hrule\!!height\thebotbaselinecorrection}}

+

+\def\dobaselinecorrection%

+  {\kern-\prevdepth

+   \kern\dp\strutbox

+   \prevdepth=\dp\strutbox}

+

+\def\baselinecorrection%

+  {\endgraf

+   \ifvmode

+     \ifdim\prevdepth<\maxdimen

+       \ifdim\prevdepth<\!!zeropoint \else

+         \ifdim\prevdepth<\dp\strutbox

+           \dobaselinecorrection

+         \fi

+       \fi

+     \fi

+   \fi}

+

+\def\startbaselinecorrection%

+  {\baselinecorrection

+   \ifvmode

+     \bgroup

+     \setbox\scratchbox=\vbox\bgroup

+     \ignorespaces

+     \let\stopbaselinecorrection=\dostopbaselinecorrection

+   \else

+     \let\stopbaselinecorrection=\relax

+   \fi}

+

+%D We do a bit more checking than needed. The pageborder check

+%D is not needed, but I want to look the visualization as good 

+%D as possible too.

+

+\def\dostopbaselinecorrection% I have to check columns yet.

+  {\endgraf

+   \egroup

+   \topbaselinecorrection

+   \box\scratchbox

+   \botbaselinecorrection

+   \egroup}

+

+\let\stopbaselinecorrection=\relax

+

+\def\offbaselinecorrection% Can be used inside correction.

+  {\def\startbaselinecorrection%

+     {\bgroup

+      \let\stopbaselinecorrection=\egroup}}

+

+%D \macros

+%D  {topbaselinecorrection,botbaselinecorrection}

+%D

+%D The actual top and bottom corrections are implemented as:

+

+\def\topbaselinecorrection%

+  {\ifvmode 

+     \bgroup

+     \setbaselinecorrections

+     \ifdim\pagegoal<\maxdimen

+       \ifdim\pagetotal<\pagegoal

+         \dimen2=\ht\scratchbox

+         \advance\dimen2 by \dp\scratchbox

+         \advance\dimen2 by \parskip

+         \advance\dimen2 by \thetopbaselinecorrection

+         \advance\dimen2 by \thebotbaselinecorrection

+         \dimen0=\pagetotal

+         \advance\dimen0 by \dimen2

+         \ifdim\dimen0<\pagegoal

+           \witruimte

+           \nointerlineskip

+           \dotopbaselinecorrection

+         \else

+           \ifbinnenkolommen           % should be supp-status

+             \vskip\dimen2             % this could definitely

+             \penalty\outputpenalty    % be improved

+           \else  

+             %                         % should be supp-control

+             % \vfill\eject            % old 

+             %

+             \nobreak                  % needed for headings 

+             \vskip\parskip            % cross your fingers

+             \vskip\dimen2             % anyhow

+             \penalty\outputpenalty  

+             \vskip-\dimen2

+           \fi   

+         \fi

+       \else                           % probably a preceding 

+         \witruimte                    % one-liner 

+         \nointerlineskip

+         \dotopbaselinecorrection

+       \fi

+     \fi

+     \egroup

+   \fi}

+

+\def\botbaselinecorrection%

+  {\ifvmode

+     \bgroup

+     \setbaselinecorrections

+     \dobotbaselinecorrection

+     \prevdepth\dp\strutbox

+     \egroup

+   \fi}

+

+%D An old one, still to be translated:

+%D

+%D \macros

+%D   {getnoflines}

+%D   {}

+%D

+%D Het commando \type{\getnoflines} converteert een hoogte

+%D (dimensie) in een aantal regels en kent dit toe aan

+%D \type{\noflines}.

+%D

+%D \starttypen

+%D \getnoflines{dimensie}

+%D \stoptypen

+%D

+%D Er wordt gedeeld door \type{\openlineheight} en een hoogte

+%D van~0pt komt overeen met 0~regels.

+

+\newcount\noflines

+\newdimen\noflinesheight

+

+\def\getnoflines#1%

+  {\noflinesheight=#1\relax

+   \ifdim\noflinesheight=\!!zeropoint\relax

+     \noflines=0

+   \else

+     \divide\noflinesheight by \openlineheight

+     \noflines=\noflinesheight

+     \ifdim\noflines\openlineheight=#1\relax \else

+       \advance\noflines by 1

+     \fi

+   \fi}

+

+%D Still very experimental and therefore undocumented.

+

+\newif\ifgridsnapping  % UNDER DEVELOPMENT, USE WITH CARE

+

+\def\positiveextrasnap {\gdef\extrasnapsign{+}}

+\def\negativeextrasnap {\gdef\extrasnapsign{-}}

+

+\def\extrasnapreset  {\global\chardef\@@extrasnap=0 

+                      \positiveextrasnap} 

+\def\extrasnapbefore {\global\chardef\@@extrasnap=1 }

+\def\extrasnaparound {\global\chardef\@@extrasnap=2 }

+\def\extrasnapafter  {\global\chardef\@@extrasnap=3 }

+

+\def\enablepresnapcorrection  {\global\chardef\@@presnap=0 }

+\def\disablepresnapcorrection {\global\chardef\@@presnap=1 }

+

+\extrasnapreset \enablepresnapcorrection  

+

+\newif\iftracegridsnapping 

+

+\def\snaptogrid#1% #1 == \hbox or \vbox

+  {\ifgridsnapping\expandafter\dosnaptogrid\expandafter#1\fi}

+

+\def\tracesnapping%

+  {\iftracegridsnapping

+     \llap

+       {\infofont

+        \doglobal\increment\currentsnap

+        \color[red]{\vl\presnapskip

+                    \vl\presnap

+                    \vl\postsnap

+                    \vl\ifcase\@@extrasnap

+                            00\or

+               \extrasnapsign0\or

+  \extrasnapsign\extrasnapsign\or

+               0\extrasnapsign\fi

+                    \vl\currentsnap\vl}}%

+   \fi}

+

+\def\dosnaptogrid%

+  {\dowithnextbox

+     {\bgroup

+      \forgetall

+      \par

+      \ifvbox\nextbox

+        \setbox\nextbox=\hbox{\box\nextbox}% don't ask

+      \fi

+      \scratchskip=\lastskip

+      \edef\presnapskip{\the\lastskip}%

+      \vbox{\strut}\nobreak\vskip-\openlineheight

+      \ifdim\ht\nextbox>\ht\strutbox

+        \scratchdimen=\ht\nextbox

+        \ifcase\@@presnap 

+          \ifdim\scratchskip>\!!zeropoint\relax

+            \scratchcounter=\scratchskip

+            \advance\scratchcounter by -\openlineheight

+            \ifnum\scratchcounter<0

+              \scratchcounter=-\scratchcounter

+            \fi

+            \ifnum\scratchcounter<10 % \lastkip is about \openlineheight

+              \advance\scratchdimen by -\openstrutdepth

+               \edef\presnapskip{*\presnapskip}%

+            \else\ifdim\scratchskip>\openlineheight 

+                                  %<\openlineheight \else

+              \advance\scratchdimen by -\openstrutdepth

+              \edef\presnapskip{*\presnapskip}%

+            \fi\fi

+          \fi

+        \fi

+        \getnoflines\scratchdimen

+        \advance\noflines by -1

+        \ifnum\noflines>0

+          \scratchdimen=\noflines\lineheight

+        \else

+          \scratchdimen=\!!zeropoint

+        \fi

+      \else

+        \scratchdimen=\!!zeropoint

+      \fi

+      \ifnum\@@extrasnap=1 \advance\scratchdimen by \extrasnapsign\lineheight \fi

+      \ifnum\@@extrasnap=2 \advance\scratchdimen by \extrasnapsign.5\lineheight \fi

+      \edef\presnap{\the\scratchdimen}%

+      \ifdim\scratchdimen=\!!zeropoint\else\vskip\scratchdimen\fi

+      \ifdim\dp\nextbox>\dp\strutbox

+        \getnoflines{\dp\nextbox}%

+        \advance\noflines by -1

+        \ifnum\noflines>0

+          \scratchdimen=\noflines\lineheight

+        \else

+          \scratchdimen=\!!zeropoint

+        \fi

+      \else

+        \scratchdimen=\!!zeropoint

+      \fi

+      \ifnum\@@extrasnap=2 \advance\scratchdimen by \extrasnapsign.5\lineheight \fi

+      \ifnum\@@extrasnap=3 \advance\scratchdimen by \extrasnapsign\lineheight \fi

+      \edef\postsnap{\the\scratchdimen}%

+      \ht\nextbox=\ht\strutbox

+      \dp\nextbox=\dp\strutbox

+      \hbox{\tracesnapping\box\nextbox}%

+      \ifdim\scratchdimen=\!!zeropoint\else\vskip\scratchdimen\fi

+      \extrasnapreset 

+      \enablepresnapcorrection  

+      \egroup}}

+

+\def\snaptomathgrid%

+  {\ifgridsnapping

+     \dowithnextbox

+       {\blanko[\v!regel] 

+        \snaptogrid\vbox{\box\nextbox}

+        \blanko[\v!regel]}

+     \vbox\bgroup

+       \let\setdisplayskips=\relax

+       \abovedisplayskip=\!!zeropoint

+       \abovedisplayshortskip=\!!zeropoint

+       \belowdisplayskip=\!!zeropoint

+       \belowdisplayshortskip=\!!zeropoint

+       \@EA\let\@EA\next

+   \fi}

+

+\def\topsnaptogrid% 

+  {\ifgridsnapping

+     \dowithnextbox

+       {\scratchdimen=\ht\nextbox

+        \advance\scratchdimen by -\ht\strutbox

+        \advance\scratchdimen by \topskip

+        \ht\nextbox=\scratchdimen

+        \dp\nextbox=\!!zeropoint

+        \box\nextbox

+        \kern\lineheight

+        \kern-\topskip

+        \nointerlineskip} 

+       \hbox

+   \fi}

+

+\def\centertogrid%

+  {\ifgridsnapping

+     \dowithnextbox

+       {\bgroup

+        \par

+        \scratchdimen=\ht\nextbox

+        \advance\scratchdimen by \dp\nextbox

+        \getnoflines\scratchdimen

+        \setbox\nextbox=\vbox to \noflines\lineheight

+          {\forgetall  

+           \vskip\!!zeropoint plus \ht\nextbox

+           \copy\nextbox

+           \kern.5\dp\strutbox % VOORLOPIGE WAARDE 

+           \vskip\!!zeropoint plus \dp\nextbox}

+        \noindent\snaptogrid\vbox{\box\nextbox}%

+        \egroup}

+       \hbox

+   \fi}

+

+\ifx\startbaselinecorrection\undefined \wait \fi % change order

+

+\let\normalstartbaselinecorrection=\startbaselinecorrection

+

+\def\startbaselinecorrection%

+  {\ifgridsnapping

+     \centertogrid\bgroup

+     \let\stopbaselinecorrection=\egroup

+   \else

+     \normalstartbaselinecorrection

+   \fi}

+

+\def\setgridbox#1#2#3%

+  {\setbox#1=\ruledvbox to #3

+     {\forgetall

+      \offinterlineskip

+      \hsize=#2

+      \getnoflines{#3}%

+      \vskip\topskip

+      \vskip-\ht\strutbox

+      \scratchdimen=#2\advance\scratchdimen by \lineheight

+      \dorecurse

+        {\noflines}

+        {\strut

+         \hskip-.5\lineheight

+         \rlap

+           {\hskip\scratchdimen\hskip2pt\infofont

+            \hbox to 1em{\hss\recurselevel}}%

+         \vrule

+           \!!height .5\testrulewidth

+           \!!depth .5\testrulewidth

+           \!!width \scratchdimen

+         \par}

+      \vfill}}

+

+%D Some intervention macros:

+

+\def\doverplaatsopgrid[#1]%

+  {\processaction

+     [#1]

+     [  \v!boven=>\positiveextrasnap\extrasnapbefore,

+        \v!onder=>\positiveextrasnap\extrasnapafter,

+        \v!beide=>\positiveextrasnap\extrasnaparound,

+       -\v!boven=>\negativeextrasnap\extrasnapbefore,

+       -\v!onder=>\negativeextrasnap\extrasnapafter,

+       -\v!beide=>\negativeextrasnap\extrasnaparound,

+      \s!default=>\positiveextrasnap\extrasnaparound,

+      \s!unknown=>\positiveextrasnap\extrasnapreset]}

+

+\def\verplaatsopgrid%

+  {\dosingleempty\doverplaatsopgrid}

+

+\def\doplaatsopgrid[#1]%

+  {\doverplaatsopgrid[#1]\snaptogrid\vbox}

+

+\def\plaatsopgrid%

+  {\dosingleempty\doplaatsopgrid}

+

+%D Snapping is rather robust as long as we use whole lines.

+%D Half lines of white space can however be handled when they

+%D come in pairs. The corrections needed when crossing page

+%D boundaries in the middle of such a pair, are handled by

+%D macros that are (named) sort of fuzzy. This fuzzy mechanism

+%D was written as an extension to the grid typesetting needed

+%D for typesetting (part of) the \MAPS. 

+%D 

+%D \starttypen

+%D \setuptyping

+%D   [before={\blank[halfline]},

+%D    after={\blank[halfline]}]

+%D \stoptypen

+

+\newif\iffuzzysnapdone

+\newif\iffuzzysnapping

+\newif\iffuzzysnapped

+

+\newsignal\fuzzysnapbegin

+\newsignal\fuzzysnapend

+

+\chardef\fuzzysnappedleft=0 % =1 when fuzzybegin still open

+

+\def\beginfuzzysnapping%

+  {\ifgridsnapping

+     \global\fuzzysnappingtrue 

+     \iffuzzysnapping

+       \kern\fuzzysnapbegin

+       \kern-\fuzzysnapbegin

+     \fi

+   \fi}

+

+\def\endfuzzysnapping%

+  {\ifgridsnapping

+     \global\fuzzysnappingtrue

+     \iffuzzysnapping

+       \kern\fuzzysnapend

+       \kern-\fuzzysnapend

+     \fi

+   \fi}

+

+\def\fuzzyvskip#1%

+  {\iffuzzysnapdone

+     \vskip#1\relax

+     \endfuzzysnapping

+     \global\fuzzysnapdonefalse

+   \else

+     \beginfuzzysnapping

+     \vskip#1\relax

+     \global\fuzzysnapdonetrue

+   \fi}

+

+\def\removelastfuzzyvskip%

+  {\ifgridsnapping 

+     \iffuzzysnapping

+       \ifdim\lastskip<\openlineheight 

+       \else

+         \removelastskip

+       \fi

+     \else

+       \removelastskip

+     \fi

+   \else

+     \removelastskip

+   \fi}

+

+\def\dodocheckfuzzysnap%

+  {\ifdim\shapekern=\fuzzysnapbegin

+     \ifcase\fuzzysnappedleft

+       \global\chardef\fuzzysnappedleft=1

+     \fi

+     \global\fuzzysnappedfalse

+   \else\ifdim\shapekern=\fuzzysnapend

+     \ifcase\fuzzysnappedleft

+       \global\chardef\fuzzysnappedleft=2

+     \fi

+     \global\fuzzysnappedtrue 

+   \fi\fi}

+

+\def\docheckfuzzysnap#1%

+  {\beginofshapebox

+   \unvcopy#1\relax

+   \endofshapebox

+   \global\fuzzysnappedfalse

+   \global\chardef\fuzzysnappedleft=0

+   \doreshapebox{}{}{\dodocheckfuzzysnap}{}}

+

+\def\getfuzzysnapcorrection#1%

+  {\global\let\presnapcorrection =\relax

+   \global\let\postsnapcorrection=\relax

+   \ifgridsnapping\iffuzzysnapping

+     \docheckfuzzysnap{#1}%

+     \iffuzzysnapped

+       \iftracegridsnapping

+         \gdef\presnapcorrection{\color[red]{\hrule\!!height.5\openlineheight}}%

+       \else

+         \gdef\presnapcorrection{\kern.5\openlineheight}%

+       \fi

+       \gdef\postsnapcorrection{\kern.5\openlineheight}%

+     \fi

+   \fi\fi}

+

+\def\fuzzysnappedbox#1#2% \box<n> \unvbox<n> 

+  {\getfuzzysnapcorrection{#2}%

+   \presnapcorrection

+   #1#2%

+   \postsnapcorrection}

+

+\def\adaptfuzzypagegoal%

+  {\ifgridsnapping\iffuzzysnapping\ifcase\fuzzysnappedleft\or % see dopagecontents

+     \scratchdimen=\pagegoal  

+     \advance\scratchdimen by -.5\openlineheight 

+     \global\pagegoal=\scratchdimen

+     \global\advance\vsize by -.5\openlineheight 

+     \global\chardef\fuzzysnappedleft=0

+   \fi\fi\fi}

+

+\protect

+

+\endinput 

+
\ No newline at end of file