bug#10179: 24.0.91; enforcing double-width CJK character display

bug#10179: 24.0.91; enforcing double-width CJK character display

[Kan-Ru Chen]

Discussion was started by Werner LEMBERG in this thread:

https://lists.gnu.org/archive/html/emacs-devel/2011-07/msg00938.html

Currently Emacs chooses fonts that has width close to the width of
the default font. But the font may have smaller advance width so a
double width character will not be rendered as wide as twice of a latin
character.

I set `face-font-rescale-alist' for every font that might be used as a
workaround:

  (setq face-font-rescale-alist
        '(("WenQuanYi Micro Hei" . 1.2)
          ("cwTexYen" . 1.35)
          ("AR Heiti Light B5" . 1.2)))

Ideally this should be calculated and applied automatically (I believe
the information has been exported to lisp but haven't find a good way to
manipulate the font-object) or the display engine should add padding to
double-width font so they are rendered nicely.

-- 
Kanru

bug#10179: 24.0.91; enforcing double-width CJK character display

[Werner LEMBERG]

Just to have the wishes directly visible in this bug report:

Another important parameter to configure is glyph padding since
scaling makes Emacs display CJK characters very slowly on X11 (before
the glyphs get cached).  Additionally, lines with such scaled glyphs
become too high, causing irregular line spacing.


    Werner