[XeTeX] vertical spacing

[Jonathan Kew]

On 9 Feb 2005, at 3:59 pm, Adam Lindsay wrote:

> Hi all.
>
> Thanks to Will and Jonathan's exchange earlier, I'm also smashing the
> descenders in the \TeX and \XeTeX logos, which really helps vertical 
> spacing.
>
> With that sorted, I was playing around with ConTeXt's grid typesetting
> capabilities, and came across another limitation (I think) imposed by
> ATSUI: There's a limit to how close lines can come. Using a 12 point 
> type
> within XeTeX, the closest I could get was an interline space of 15.2pt.
> Now, that might be the limits of good taste, according to Apple, but 
> not
> according to some designers out there. :)
>
> It seems like something in XeTeX is preventing ConTeXt from putting 
> lines
> too close together. (When used with pdfTeX, ConTeXt will happily set 
> on a
> 12/12 grid.) Has anyone else found a solution to this?
> (I tried fooling around with \lineskiplimit, but it didn't do anything
> useful here.)
>

I think ConTeXt must be doing something to reset \lineskiplimit, as 
XeTeX is perfectly capable of setting lines as close as you like. The 
closest you'll get *without* relying on a negative \lineskiplimit 
depends on the ascent and descent specified in the font metrics (which 
may add up to more than the point size; depends entirely on the whim of 
the font designer).

Here's a Plain example that shows Hoefler Text, which seems happy to 
set at 12/12 before \lineskip kicks in; compare the left column (using 
default Plain TeX settings for \lineskip and \lineskiplimit) and the 
right (with negative \lineskiplimit).
- - - - -
\font\x="Hoefler Text" at 12pt \x

\def\text{The quick brown fox jumps over the lazy dog.
Pack my box with five dozen liquor jugs.
The quick brown fox jumps over the lazy dog.
Pack my box with five dozen liquor jugs.\par}

\def\try#1{\line{\llap{#1: }\grid{#1}%
   \vtop{\hsize=3in \baselineskip=#1 \text}\hfil
   \vtop{\hsize=3in \baselineskip=#1 \lineskiplimit=-99pt \text}}
   \bigskip}
\def\grid#1{\dimen0=#1 \hbox to 0pt{\vtop to 0pt{\hrule height 0pt
  \gridrule\gridrule\gridrule\gridrule\gridrule \vss}\hss}}
\def\gridrule{\hrule width \hsize height .2pt \kern-.2pt \kern\dimen0 }
\special{x:rulecolor=880000}

\try{15pt}
\try{14pt}
\try{13pt}
\try{12pt}
\try{11pt}
\try{10pt}
\try{9pt}
\try{8pt}

\bye
- - - - -

JK