Unicode Digest, Vol 50, Issue 20

[Neil Patel via Unicode]

Does the ulUnicodeRange bits get used to dictate rendering behavior or
script recognition?

I am just wondering about whether the lack of bits to indicate an Adlam
charset can cause other issues in applications.


-Neil


On Sat, Feb 24, 2018 at 1:00 PM, via Unicode <unicode at unicode.org> wrote:

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> Today's Topics:
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>    1. Re: metric for block coverage (Norbert Lindenberg via Unicode)
>
>
> ---------- Forwarded message ----------
> From: Norbert Lindenberg via Unicode <unicode at unicode.org>
> To: Khaled Hosny <khaledhosny at eglug.org>
> Cc: James Kass <jameskasskrv at gmail.com>, Adam Borowski <
> kilobyte at angband.pl>, Unicode Public <unicode at unicode.org>, Norbert
> Lindenberg <unicode at lindenbergsoftware.com>
> Bcc:
> Date: Fri, 23 Feb 2018 10:15:32 -0800
> Subject: Re: metric for block coverage
>
> > On Feb 18, 2018, at 3:26 , Khaled Hosny via Unicode <unicode at unicode.org>
> wrote:
> >
> > On Sun, Feb 18, 2018 at 02:14:46AM -0800, James Kass via Unicode wrote:
> >> Adam Borowski wrote,
> >>
> >>> I'm looking for a way to determine a font's coverage of available
> scripts.
> >>> It's probably reasonable to do this per Unicode block.  Also, it's a
> safe
> >>> assumption that a font which doesn't know a codepoint can do no complex
> >>> shaping of such a glyph, thus looking at just codepoints should be
> adequate
> >>> for our purposes.
> >>
> >> You probably already know that basic script coverage information is
> >> stored internally in OpenType fonts in the OS/2 table.
> >>
> >> https://docs.microsoft.com/en-us/typography/opentype/spec/os2
> >>
> >> Parsing the bits in the "ulUnicodeRange..." entries may be the
> >> simplest way to get basic script coverage info.
> >
> > Though this might not be very reliable since OpenType does not have a
> > definition of what it means for a Unicode block to be supported; some
> > font authoring tools use a percentage, others use the presence of any
> > characters in the range, and fonts might even provide incorrect data for
> > any reason.
> >
> > However, I don’t think script or block coverage is that useful, what
> > users are usually interested in is the language coverage.
> >
> > Regards,
> > Khaled
>
>
> All true. In addition, ulUnicodeRange ran out of bits around Unicode 5.1,
> so scripts/blocks added to Unicode after that, such as Javanese, Tangut, or
> Adlam, cannot be represented.
>
> Norbert
>
>
>
>
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