[HarfBuzz] Streamlining hb_font_t some more

[John Labovitz]

On Oct 26, 2015, at 4:30 AM, Simon Cozens <simon at simon-cozens.org> wrote:

> I am not a typographer, I just play one on the Internet, so I am not
> sure what someone who was actually typesetting a book would do in that
> situation. 

I’ve been a typographer/typesetter for 30 years, working in both digital indirect/batch & direct/WYSIWYG systems, as well as in hand-set metal type. Most of my work these days is in book design, and I’m writing software (in Ruby, using Harfbuzz) to help me do that.

In most projects, I might start out with default line spacing (whether from a font or from a simple formula, like the usual 120% rule), but I’ll almost always change that to an explicit value (say, 12/15) once the project evolves past a simple mockup. Optimum line spacing is determined by many factors, including font style, point size, line measure, page proportions, etc. In other words, there *is* no default — at least for the kind of projects that typographers work on.

What’s far more important to me is control and predictability — I want to specify exactly where a line starts on a page (usually by ascender/cap height), and then ensure that successive lines are vertically aligned by baselines. So line spacing comes out of those issues, not out of a somewhat arbitrary default. You can imagine how both TeX and CSS drive me crazy in this regard. ;-)

So, although it’s nice to have minimally useful defaults (so that lines don’t overlap, for example), it’s probably *non*-typographers who really need these.

Hope this helps,
—John