Re: [ft-devel] [Patch] CJK autofit/autohint blue zones

[mpsuzuki]

Dear Sir,

Thank you for quick reply. For fist, I comment about the
requirement of the vertical blue zone.

On Wed, 20 Apr 2011 20:34:52 +0800
Just Fill Bugs <address@hidden> wrote:

>On 04/20/2011 02:16 PM, address@hidden wrote:
>> Q1) The vertical bluezones are essential?
>> 
>> In vertical CJK typography, there would be the requirement
>> to align long center stems (of the glyphs like "十", "土",
>> "王"), to pretend the centerlines of the glyphs are aligned.
>> However, I'm questionable if there is a requirement to align
>> non-center stems to be aligned. Maybe the alignment of the
>> vertical stems of the radical-"enclosure" glyphs (like "回",
>> "囚", "困") or radical-"gate" glyphs (like "門", "開", "閉" )
>> may improve the quality. But I'm questionable if there is
>> the requirement to align the left vertical stems of radical
>> "mound" glyphs (like "阿", "防", "阻"), or radical "mouse"
>> glyphs (like "叫", "叩", "叱").
>> 
>> Maybe my impression about vertical bluezone is based on the
>> typography in Japanese market, so, I don't think this is
>> generic. Please let me know if there is such requirement in
>> Chinese or Korean typography.
>
>There is require to align side of glyph in vertical writing in Chinese.
>
>For the vertical blue zone. Partly because I kinda misunderstood the
>icfb tag describe by Adobe at
>
>http://partners.adobe.com/public/developer/opentype/index_tag4.html#ideoembox
>
>I guess it mostly talking about horizontal alignment using icfb, while I
>mistook it's also used for vertical layout.

Umm, I think, the requirement described in Adobe document
is talking about the alignment of the rectangle to store
the glyphs with reserved inter-glyph spaces (em-box, body
size) and without reserved inter-glyph spaces (something
like an integration of bounding box of the glyphs). It does
not mean that there is a vertical alignment of the vertical
stems. I will ask Adobe experts.

>Another reason I consider to add vertical blue zone is that I don't know
>how vertical layout looks like at small size on screen. Without blue
>zone, the width of glyphs will vary quite frequently at small points. I
>don't know how our eyes tolerant to that.

Indeed. In my impression, the customers who request the
vertical writing mode of digital text tend to prefer
the paper-like appearance, so they are not interested in
so much about the text with the small points at low
resolution device.

>Just better safe than sorry. Of course it can always be removed now and
>add back by request.

Although I'm going to disable the vertical alignment by
default (to reduce the time of blue zone calculation),
I appreciate that you included the code for vertical
alignment. It would be really useful to draft the autofitter
for the scripts using vertical alignment, like, Mongolian
or Phaspa.

Regards,
mpsuzuki