Re: [ft] weird hinting behavior

[Werner LEMBERG]

> This only happens when using the native TrueType hints.
> (Auto-hinting works fine.)  I suspect there may be a bug in the
> font's hints -- is there any way to verify that?
> 
> This is with FreeType 2.5.0.1 and ft2demos 2.5.0.

The font program of glyph `-' is indeed buggy since it contains

  PUSHW_2
  0
  -1
  MIRP

In other words, the MIRP instruction tries to access CVT entry -1,
which is invalid.  FreeType has obscure code (which is probably not
correct) to handle entry -1, however, Greg Hitchkock from Microsoft
told me some time ago that a negative CVT entry makes the MS hinting
engine abort immediately.

BTW, FontForge tells me that this font has an OS/2 table with
version 0, something which is not supported on Windows.  So maybe this
old font (from 1997) is specially tailored to the old Apple
rasterizer, relying on undocumented features.

Note that the abovementioned MIRP instruction belongs to the x axis
hints.  Before that, there are two MDAP instructions which round the
vertical point positions to the grid, without any further correction,
and at small sizes it can happen that the two vertical positions of
the hyphen are rounded to a single value, making the glyph disappear.

This font is crap.  For example, look at the broken outline of glyph
`a'.


    Werner