[webkit-dev] Stretchy Characters

Alex Milowski alex at milowski.org
Wed Sep 9 13:20:30 PDT 2009

On Tue, Sep 8, 2009 at 10:17 PM, Roland Steiner<rolandsteiner at google.com> wrote:
> Hi Alex,
> AFAIK, the approach of stacking special characters goes back to TeX, and you
> even have special Unicode code points for this purpose (see
> http://www.unicode.org/charts/PDF/U2300.pdf), so the approach at least has
> broad consensus. ^_-
> You're right however, that having the right font glyphs is essential.
> Furthermore, e.g. TeX's MetaFont has several glyphs for the same bracket
> part in different point sizes to absolutely get the layout and optical
> weight right. The difference this makes is most noticeable on the parts that
> make up a (square,etc.) root symbol.

Thanks for the pointer.  I've been able to make a mockup of the use
of these code points.  I should now be able to stack a set of glyphs
for certain symbols that can stretch.

I've attached the mock-up if you are interested.

> However, since these are still only a handful of code points, I wonder if it
> wouldn't be safer to have a special font consisting of only those glyphs
> linked with WebKit directly, so you can be sure that they are available.

The 'Symbol' font on the Mac actually handles the stackable glyphs quite
nicely. I'll have to test on other platforms.

The STIX fonts (beta version) that I have seem to have some problems.

I'll have to see what kind of metrics I can get about certain characters
because I suspect the vertical adjustments for the start and end of the
stack are different depending on the font used.

Is there a precedence for packaging a font with WebKit?

--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language

Bertrand Russell in a footnote of Principles of Mathematics
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