# [texhax] TeX Queries (2): Artificial Break

Paul Stanley paulrichardstanley at gmail.com
Wed Jul 18 07:29:28 CEST 2012

``` > Then he adds \break after the word ``an'' so that TeX breaks the line
> here instead of elsewhere, because TeX's default result here is not very
> good. His remark about a tighter line comments on the use of \break, not
> italic correction at all.
>
> Thank you. It seems we were at cross purposes there.  I won't ask you
> about the "default result"; however, I get the impression that
> without looking at the end result one wouldn't be able to make the
> necessary comparison and decide whether or not the `\break' insertion
> was preferable.
[snip]

With the \break, TeX makes three lines for this subparagraph, as follows:

LINE 1: you get italicized and slanted words that look better. The
`\/' tells TeX to add an
LINE 2: ``italic correction'' to the previous letter, depending on
that letter; this correction
LINE 3: is about four times as much for an `f' as for a `c, in a
typical italic font.

Without the \break, i.e. with TeX left to its own devices, you get
four lines as follows:

LINE 1: you get italicized and slanted words that look better. The
`\/' tells TeX
LINE 2: to add an ``italic correction'' to the previous letter,
depending on that letter; this
LINE 3: correction is about four times as much for an `f' as for a
`c, in a typical italic
LINE 4: font.

The latter result isn't so bad, but the lines are quite stretched,
and of course there is that fourth single-word line, smaller than the
paragraph indentation, which is quite bad-looking.

By "stretched" do you mean the tracking space is too wide?

Interestingly, I've browsed the first fifteen chapters of the
TeXbook, and I haven't been able to find any last line of a paragraph
being smaller than the indentation (at least when directly followed
by an indented paragraph). So it seems that Knuth paid much attention
to that, and what we're discussing here might be a situation where he
had to rely on \break to do so. (There aren't so many \break's
elsewhere in the text.)

Is there a substitute for the visual inspection of the lines --- for
example, a formula or some other heuristics --- in determining the
appropriate amount of tracking in a paragraph (to ensure the glyphs
aren't too stretched or compressed together)?

[snip]
I'll try to complement Reinhard's answer.

> How is the declared width actually measured (i.e. where are the
start > and end points of the declared width)?

That's up to the font designer; as Reinhard said, glyphs should
simply be able to go along without kerning in most cases.

> is there a declared height as well, and if so, can the declared width
> be different at different declared heights?

No, a glyph's height is its topmost point; vertical spacing, at least
in horizontal writing systems, deals with lines, not individual
glyphs, so there is no use in adjusting the latter.

Could you expand a little more on vertical spacing please? I'm
assuming it's not the same as leading, or is it?

[snip]

Finally, how, if at all, can tracking and kerning affect
one-another?  for example, does the kerning of a pair of glyphs
override the tracking in the line?

Many thanks,
Paul

```