[ft-devel] [FYI] MingLiU identifier

[mpsuzuki]

Hi all,

Since freetype-2.4.3, TrueType hinter is enabled for
the fonts without family name. It was a fallbacking
solution of MingLiU embedded in PDF, without family
name (according to Type42 spec, name table is optional,
so embedded TrueType in PDF may lack family name).

Recently, Gentoo people request to revert it to disable
the hinter by default, because it makes TimesNewRoman
embedded by Mac OS X Quartz ContextPDF (a generic
framework in Mac OS X to generate PDF document) ugly.

Thus, now I'm trying to identify problematic fonts
which cannot be readable if rendered without hinter,
by the checksum (or the pair of checksum & length?)
of required table for Type42. cvt, fpgm and prep are
the candidates because their content is tightly bound
to glyf programs, so they are usually preserved in
the TrueType subsetting process.

# the proof of idea was posted at:
# http://lists.nongnu.org/archive/html/freetype-devel/2010-08/msg00019.html

Here I collected the checksums of various versions
of MingLiU. During the check, I found that recent
MingLiU (post-Vista, and Microsoft Office for Mac)
don't cause broken shape issue anymore.

I checked various versions mentioned at:
  http://zh.wikipedia.org/zh/%E6%96%B0%E7%B4%B0%E6%98%8E%E9%AB%94
>From the result, I think, the checksum of cvt/fpgm/prep
can be classified into 2 groups, older & newer, I'm
happy to see that we (may) don't have to maintain
long list of the checksum for all versions of MingLiU.

Regards,
mpsuzuki

Microsoft Windows NT 4.0: ver 2.00 (1996-May-15, second release)
               tag cvt  offset 0x0023dc7c length 0x000002e4 checkSum 0x05bcf058
               tag fpgm offset 0x0023df60 length 0x000087c4 checkSum 0x28233bf1
               tag prep offset 0x005fb248 length 0x000001e1 checkSum 0xa344a1eb

Microsoft OfficeXP Proof Kit: ver 3.00
               tag cvt  offset 0x0038bb94 length 0x000002e4 checkSum 0x05bcf058
               tag fpgm offset 0x0038be78 length 0x000087c4 checkSum 0x28233bf1
               tag prep offset 0x0082fe78 length 0x000001e1 checkSum 0xa344a1eb

Microsoft Windows XP: ver 3.21
               tag cvt  offset 0x003a101c length 0x000002e4 checkSum 0x05bcf058
               tag fpgm offset 0x003a1300 length 0x000087c4 checkSum 0x28233bf1
               tag prep offset 0x0086a004 length 0x000001e1 checkSum 0xa344a1eb

(Microsoft Office for Mac v.X: MingLiU is not bundled)
Microsoft Office for Mac 2004: ver 4.55
Microsoft Office for Mac 2008: ver 4.55
Microsoft Office for Mac 2011: ver 4.55
               tag cvt  offset 0x0001cdf8 length 0x00000008 checkSum 0x00000000
               tag fpgm offset 0x0001cdd0 length 0x00000011 checkSum 0xf40ddf13
               tag prep offset 0x0001cde4 length 0x00000013 checkSum 0x6286ee0a

Microsoft Windows Vista: ver 6.02
               tag cvt  offset 0x004a437c length 0x00000008 checkSum 0x00000000
               tag fpgm offset 0x004a4384 length 0x00000011 checkSum 0xf40ddf13
               tag prep offset 0x019fc218 length 0x00000013 checkSum 0x6286ee0a

Microsoft Windows 7: ver 7.00
               tag cvt  offset 0x00499f78 length 0x00000008 checkSum 0x00000000
               tag fpgm offset 0x00499f80 length 0x00000011 checkSum 0xf40ddf13
               tag prep offset 0x019f4064 length 0x00000013 checkSum 0x6286ee0a