Re: metric for block coverage

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
Received on Sun Feb 18 2018 - 05:26:37 CST