Re: A patch for enforcing double-width CJK character display

[Werner LEMBERG <wl@gnu.org>]

> [...] it looks like the issue is that the version of "Sazanami
> minchou" in Debian includes hand-tuned bitmaps.  These look much
> better in many cases, but because there's a limited number of them,
> and the font-rendering system prefers bitmaps, it chooses a slightly
> smaller size so it can use a bitmap.

This is not correct: Bitmap strikes are selected by PPEM only, no
other size is used.

What you are actually observing is a font bug: The bitmap strikes in
sazanami-mincho are buggy, specifying incorrect advance widths for
many PPEM values.

Try the ftview demo program, go to the kana and kanji ranges, then
toggle bitmap strike display with key `b'.  You will see `jumping
glyphs' for most PPEM values.  Now repeat the same with msmincho.ttc,
and you won't see this effect.

It's probably worth to send a bug report to the people who are
maintaining sazanami-mincho to fix this.  All in all, the font is of
really bad quality (I'm not talking of the glyph shapes itself); the
`name' table contains bizarre entries, the version field hasn't been
increased inspite of changes (as preserved in the `FFTM' table, the
`FontForge timestamp' which is not visible for other tools), the
glyphs are unnecessarily big because the outlines aren't properly
simplified, etc., etc.

Note that I've looked at the version which has been modified last at
10-Dec-2011.


    Werner