Re: [ft-devel] a hidden gem: the autohint warper code

[Werner LEMBERG]

>> If the bottom line of the warped glyph is shifted away from a
>> bluezone, then the whole glyph should be shifted back a whole
>> 1 pixel back toward the bluezone after being warped.
> 
> This won't work.  If you shift one pixel back, all other optimized
> zones, would be at the wrong position.  Warping, as it is currently
> implemented, only works if the code has the absolute freedom to
> positions stems at any places.

To be more precise: The autohinter doesn't scale glyphs uniformly in
the main hinting direction.  Instead, it works similar to the TrueType
bytecode hinter: The glyph's local and global main features are
aligned to the pixel grid (as much as possible), then the remaining
points are scaled relatively to the already aligned features.  I think
this is the optimum you can achieve.  What is improvable, however, is
the algorithm to decide which stems are `main features', and which
features (e.g. serifs) must be handled specially.  In particular,
handling of diagonal stems might be improved.


    Werner