From: Harshula (firstname.lastname@example.org)
Date: Thu Sep 03 2009 - 09:44:01 CDT
On Thu, 2009-09-03 at 07:30 -0600, Doug Ewell wrote:
> "Harshula" <harshula at gmail dot com> wrote:
> > It is pointless having a Level 1 compliant Sinhala font sitting
> > *unused* on the filesystem, whilst the operating system choses a
> > random non-compliant font that will present an incorrect and
> > non-standard UI to the user. Therefore, the operating system needs to
> > select a Level 1 compliant font by default to ensure a correct and
> > standardised UI.
> I agree in principle that it is pointless to use a less-capable font
> when a more-capable font is available.
Glad we agree on that. :-)
> But are you familiar enough with
> font technology, and the way operating systems and rendering engines
> support font technology, to understand the burden this sort of checking
> imposes at runtime EVERY TIME text is to be displayed?
Thanks for your question.
Every time text is displayed, it should incur the cost of a simple
lookup in an in-memory data structure or at worst opening and reading a
font metadata file from the buffer cache.
The layer that manages the fonts needs to be notified (using a
technology like inotify) when a font file changes and when the mtime of
a directory containing fonts changes. The font management layer can then
handle the cases where a font file has been added, deleted or changed.
In the case of a font file being added/changed, it can trigger parsing
of the font file, which could be computationally intensive, to
generate/update a metadata file.
I do not see any need to do computationally intensive parsing of fonts
every time text is displayed in-order to choose a compliant font.
Does that sound plausible?
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