Hiding the content (drawing empty boxes?)

* Hiding the content (drawing empty boxes?)
@ 2005-07-07 21:45 Mojca Miklavec
  2005-07-07 21:57 ` Hans Hagen
  0 siblings, 1 reply; 10+ messages in thread
From: Mojca Miklavec @ 2005-07-07 21:45 UTC (permalink / raw)

[-- Attachment #1: Type: text/plain, Size: 877 bytes --]

Hello,

Some TeX challenge (probably not solvable?): for gurus only.

Is there a way to somehow

\starthidden
...
\stophidden,

which would leave exactly the same amount of blank space as if the 
content would be typeset?

Adam suggested to use transparent font colour, but this doesn't solve 
the problem as this won't stop the images, frames and nested 
\color[red]{font color changing commands} being displayed.

I tried to adapt the macro \demobox from the TeXBOOK which processes 
token by token and draws an empty box instead of that token. It works 
perfectly as long as there is only plain text between the braces, but as 
soon there is something more complex, it breaks. This behaviour is 
probably to be expected, but I have no idea how to let all the commands 
do what they are expected to do and only prohibit placing any boxes with 
some content.

Thanks,
	Mojca

[-- Attachment #2: demobox.tex --]
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% the portion of code adapted from the TeXBOOK, Excercise 11.5 %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def\dolist{\afterassignment\dodolist\let\next= }
\def\dodolist{\ifx\next\endlist\let\next\relax
  \else \\\let\next\dolist \fi
\next}
\def\endlist{\endlist}

\def\\{\if\space\next\ % assume that \next is unexpandable
\else\setbox0=\hbox{\next}\setbox1=\hbox{}%
  \dp1=\dp0\ht1=\ht0\wd1=\wd0\box1\fi}

\def\demobox#1{{\dolist#1\endlist}}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\setupframed[strut=no,offset=0pt]
\setupcolors[state=start]
\starttext

%%%%%%%%%%%%%%
% this works %
%%%%%%%%%%%%%%

\color[blue]{This works OK:}

bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla \demobox{bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla} bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla

bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla bla

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% The examples below have some troubles %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\color[blue]{This is not 100\% properly aligned, but works:}\par
a\demobox{Tough exercise.}b\par
a\hbox{Tough exercise.}b\par
a\framed{\hbox{Tough exercise.}}b\par
a\framed{\demobox{Tough exercise.}}b\par
%a\demobox{\framed{Tough exercise.}}b\par % this doesn't work

a\externalfigure[cow]b\par
\color[blue]{This cow has shrinked:}\par
a\demobox{\externalfigure[cow]}b\par
a\framed{\externalfigure[cow]}b\par
\color[blue]{And this cow disappeared:}\par
a\framed{\demobox{\externalfigure[cow]}}b\par
% a\demobox{\framed{\externalfigure[cow]}}b\par % this doesn't work

\color[blue]{The commented stuff didn't even dare to compile.}

%\input tufte \demobox{{\input tufte }}\input tufte\par
%\input tufte \input tufte \input tufte

%\dorecurse{10}{bla }
%\demobox{\dorecurse{10}{bla }}
%\dorecurse{10}{bla }\par
%\dorecurse{10}{bla }
%\dorecurse{10}{bla }
%\dorecurse{10}{bla }

\stoptext

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