Kerning and Scaling

["Charles P. Schaum" <verbo.solo@sbcglobal.net>]

Hi Folks,

I wanted to confirm that Hans is **Correct** about font fitting. In
fact, I think that scaling is superior.

One thing I did find is that one must go real easy with the scaling,
e.g., compute the difference between the size you want/need, and see
that it isn't too great, as the test shows.

This test suite, written for plain, nevertheless will work in ConText IF
you set the conditional value \havecontexttrue, which I did below.

Some of the exact font results will, however, differ between the two.
That was just my not trying to rectify differences in the default fonts
and sizes.

I found this exercise to be fun for learning about macro expansion, as
well as dealing with multiple constraints and tail recursion.

Charles

----Cut Here-----

%Testing insertion of kerns and stuff

\newif\ifhavecontext

%\havecontextfalse
\havecontexttrue

% Here we have two kerns that are equally smaller and larger
\newdimen\KernSmall
\newdimen\KernLarge
\KernSmall=-0.033333em
\KernLarge=0.033333em

% This is Knuth's length macro from the \Tex Book
\def\length#1{\count30=0 \getlength#1\end \number\count30}
\def\getlength#1{\ifx#1\end \let\next=\relax
  \else\advance\count30 by1 \let\next=\getlength\fi \next}

% This is a modified version of the length macro.
% It's existence is to stuff kerns between any two internal tokens.
\newcount\intraword
\newdimen\intrakern
{\catcode`@=11
\gdef\InsertKern#1#2{\intraword=0\intrakern=#1\@ppend#2\end}
\gdef\@ppend#1{\ifx#1\end \def\insertium{}\else \def\insertium{\kern
\intrakern}\fi \ifnum\intraword>0\insertium\fi \ifx#1\end \let\next=
\relax\else\advance\intraword by1\let\next=\@ppend#1\fi\next}}

% But who says you have to use only kerns?
{\catcode`@=11
\gdef\InsertStuff#1#2{\intraword=0\gdef\StickIt{#1}\@ppendstuff#2\end}
\gdef\@ppendstuff#1{\ifx#1\end \def\insertium{}\else \def
\insertium{\StickIt}\fi \ifnum\intraword>0\insertium\fi \ifx#1\end \let
\next=\relax\else\advance\intraword by1\let\next=\@ppendstuff#1\fi
\next}}

% SDF-1 will control the scaled box to equal the negative kerning
\newdimen\SDFONE
\newdimen\fitdimone
\newdimen\fitdimtwo

\def\fitbox#1{%
\setbox30=\hbox{\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out.}}
\SDFONE=\wd30
\font\custfont=cmr10 scaled 1000
\setbox30=\hbox{\custfont#1}
\fitdimone=\SDFONE
\fitdimtwo=\wd30
\divide\fitdimtwo by 1000
\divide\fitdimone\fitdimtwo
\count30=\fitdimone
\font\custfont=cmr10 scaled \count30
\hbox{\custfont#1}
}

% Okay, and this is what it all comes to\dots
\ifhavecontext\starttext\fi

\fitbox{OK, Class\dots}\par
\bigskip

Garbage in, garbage out.\par
Ignore spaces and get Knuth's count of \length{Garbage in, garbage
out.}.\par
Count spaces and get Knuth's count of \length{Garbage\ in,\ garbage\
out.}.\par
\smallskip
This includes punctuation.\par
\bigskip

Here you can see the insertion points of the macro.\par
\InsertStuff{$_\wedge$}{Garbage\ in,\ garbage\ out.}
\medskip Hungry? Want {\bf \InsertStuff{$^{Snacks}$}{Food}}?
\medskip Warning! You can put funky stuff in the insertium, but not in
the text.\par If you do that, \TeX\ will either produce an error or give
you strange results.
\bigskip


\newdimen\compn
\newdimen\comps
\newdimen\compl

Inserting kerns does have an effect:\par
\smallskip
Length of ``Garbage in, garbage out'' is \setbox30=\hbox{Garbage in,
garbage out}\the\wd30 \compn=\wd30\par

Length of ``\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out}'' is
\setbox30=\hbox{\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out}}
\the\wd30 \comps=\wd30\par

Length of ``\InsertKern{\KernLarge}{Garbage\ in,\ garbage\ out}'' is
\setbox30=\hbox{\InsertKern{\KernLarge}{Garbage\ in,\ garbage\ out}}
\the\wd30 \compl=\wd30\par
\bigskip

Size matters\dots
\smallskip
{\tt N:} Garbage in, garbage out.\par
{\tt S:} {\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out.}\par
{\tt L:} {\InsertKern{\KernLarge}{Garbage\ in,\ garbage\ out.}\par
\bigskip

Which looks better? Scaled \the\KernSmall
\smallskip
Negative kern insertion (top) vs. font scaling (bottom):\par
\ \ \ \hbox{\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out.}}\par
\ \fitbox{Garbage in, garbage out.}
\bigskip

I had in mind something a little more radical\dots
\KernSmall=-0.066667em
\ Scaled \the\KernSmall
\smallskip
Negative kern insertion (top) vs. font scaling (bottom):\par
\ \ \ \hbox{\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out.}}\par
\ \fitbox{Garbage in, garbage out.}
\bigskip

This is just sick\dots\par
\KernSmall=-0.1em
Scaled \the\KernSmall
\smallskip
Negative kern insertion (top) vs. font scaling (bottom):\par
\ \ \ \hbox{\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out.}}\par
\ \fitbox{Garbage in, garbage out.}
\smallskip
\KernSmall=-0.2em
Scaled \the\KernSmall
\smallskip
Negative kern insertion (top) vs. font scaling (bottom):\par
\ \ \ \hbox{\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out.}}\par
\ \fitbox{Garbage in, garbage out.}
\smallskip
\KernSmall=-0.3em
Scaled \the\KernSmall
\smallskip
Negative kern insertion (top) vs. font scaling (bottom):\par
\ \ \ \hbox{\InsertKern{\KernSmall}{Garbage\ in,\ garbage\ out.}}\par
\ \fitbox{Garbage in, garbage out.}

\ifhavecontext\stoptext\else\bye\fi

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