metric for block coverage

[Adam Borowski via Unicode]

On Sun, Feb 18, 2018 at 02:14:46AM -0800, James Kass 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

It's only a single bit without a meaning beyond "range is considered
functional".  No "basic coverage" vs "good coverage" vs "full coverage".


On the other hand, listing raw codepoints in an universal way is as simple
as:
.----
#!/usr/bin/perl -w
use Font::FreeType;
$#ARGV==0 or die "Usage: $0 <font>\n";
Font::FreeType->new->face($ARGV[0])->foreach_char(sub {
    printf("%04X\n", $_->char_code);
});
`----

These codepoints can then be grouped by block -- but interpreting such lists
is what's unobvious.


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