[ft-devel] language ID on MacOS is used? (Re: Dynalab SJIS cmap)

[mpsuzuki]

Hi all,

On Tue, 08 Jan 2008 09:21:33 +0100 (CET)
Werner LEMBERG <address@hidden> wrote:
>> By the way, at present, Dynalab fonts for MacOS has Apple SJIS cmap
>> but lacks Microsoft SJIS cmap (thus, ftview cannot specify Apple
>> SJIS cmap by "-e" option). Does anybody wants FT_Encoding tag to
>> specify Apple SJIS?
>
>AFAIK, Microsoft SJIS (or rather, cp932) is not the same as Apple
>SJIS.  If we are going to support this, we need a new tag, I think.

I thank Werner for positive comment to distinguish Apple
SJIS from MS cp932. I have slightly off-topic question
about cmap selection for MacOS.

Apple TrueType specification has an entry of "languageID"
in each cmap subtables, although Microsoft TrueType specification
uses the entry as "version" that is fixed to zero. Now I'm
checking my MacOS font collection, but it seems that
a font with non-zero languageID is quite rare. In most fonts,
all cmap subtables set languageID to 0 (English, language
independent).

There is a scenario that I don't want to think:
TrueType font has multiple cmap subtables with same platform
ID and platform-specific encoding ID but different language IDs.
Understanding the name of entries literally, same encoding ID
means that such subtables must share same encoding, but the
coverage may not be guaranteed to be same.
For example, for Roman script, there is only one MacOS-specific
encoding ID (=0). But there are various language IDs for
Roman script: English, French, German, Italian, Dutch, Swedish,
Spanish... Anybdoy had ever seen a TrueType font that has
non-zero language ID?

Regards,
mpsuzuki