[XeTeX] letter spacing

[Wlodek Bzyl]

Adam Twardoch napisał(a):
| The "cpsp" OpenType feature does not solve the task because it only
| offers a fixed tracking change for all caps settings. This is useful
| (provided the designer has included this information in
| the font anyway)
| but on top of that, the user ALWAYS needs to track. It can't be an
| "on/off" thing, you need to be able to specify both
| the positive and the
| negative amount. Of course, in most cases, the tracking changes are
| small (0.5-4% of the em).

   Letterspacing belongs to the Polish typographical tradition and
   text is letterspaced according to the data from the table below
   (ftp://ftp.gust.org.pl/pub/GUST/bulletin/05/06-mw.ps in Polish):

         | a 1 . ; ( )
       ---------------
       a | 2 2 0 1 2 0
       1 | 2 0 0 1 2 0
       . | 2 0 0 1 2 0
       ; | 2 2 0 1 2 0
       ( | 0 0 0 0 0 0
       ) | 2 2 0 1 2 0

   For point sizes 10, 12, 14 extra space equal to 2*1pt
   is added between letters, between letter and dot
   0*1pt extra space is added and between letter
   and semicolon 1*1pt extra space is added etc.
   For point sizes below 10 `1pt' extra space above
   should be replaced by `1/2pt'.
   For example, numbers in letterspaced text are *not*
   letterspaced.

   So OpenType tracking is not a replacement for letterspacing.


--Włodek Bzyl