Re: [Groff] tbl and large font

[Clarke Echols]

walter harms wrote:
> Am 19.01.2011 16:34, schrieb Tadziu Hoffmann:
> > > > .ps 16
> > > I have tried but the result is not realy different. The
> > > postscript files differ only in two lines. (i admit i have
> > > no idea why).  And that do not affect the box size.
> > The important part was also changing the linespacing,
> >
> >   .vs 20
> >
> > otherwise you're setting 16-point type on a (default)
> > 12-point baseline distance.
>
> this works much better. Is there any reason why changing the
> font should not change the baseline also ?

*roff (and xhtml and other typographically intelligent systems)
treat the size of the typeface (point size) and the leading
("line-height" in xhtml for web pages) as independent layout
parameters.

When you increase the point size, the letters are taller and
wider.  But for readability and other good reasons, the
typographer, graphic designer, or someone else may need to
vary the spacing between lines -- even, in extreme cases,
"pile" lines on top of each other.

Thus with a point size of 20, and a line spacing of 8, you can
get lines that overlap nearly 2/3 of the letter height.  Also
multi-line headlines sometimes look better with the leading
set at 115% or even 110% if there are no descenders in the
text (y, g, q, etc.).

And when you change point size, you must also increase the
leading (vertical space -- ".vs") to keep the same
proportions.  Since TBL does layout based on what it thinks
the leading is supposed to be (inherited from outside the
TS-TE boundaries of the table coding), it cannot change the
leading inside the table (in general, there may be exceptions
inside a table cell, but I haven't tried it).

Thus it works to set .ps and .vs outside the table before the .TS,
then restore it after the .TE.

Clarke

> It is confusing.

Like most things in life, it's simpler once you know the
mechanics of what's going on.

Clarke