[Haskell-cafe] Re: Finding the contents of haskell platform?
john-ng at pybus.org
Wed Nov 10 10:06:25 EST 2010
Stephen Tetley wrote:
> I thought I read that Firefox does a font swap if it can't find a
> glyph, but thinking about it myself I can't see that this would make
> sense - Firefox would have to know an awful lot about the OSes fonts
> to know if they have "missing" glyphs.
You're pretty much right, Firefox does read the font metrics information
of _all_ fonts on the system at startup . It chooses substitute
glyphs based on which fonts have the required glyph and matching metrics.
This font substitution can cause odd looking results if you use odd
characters in a run of ascii text, but seems to do a reasonable job
with displaying mathematical symbols.
 Yes, this can cause significant slowdown for users with many fonts:
<https://bugzilla.mozilla.org/show_bug.cgi?id=600713>. I think Chrome
just relies on a set fallback font with known wide unicode coverage.
 See what can happen if you cut and paste fancy content into the web
browser, but only have ligatures defined in some unusual font:
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