Re: [ft-devel] ttfautohint / Oxygen / infinality

[Werner LEMBERG]

> Not sure i understand 100%, but isn't it significant that the
> infinality patched freetype only renders ttfautohinted fonts in this
> way? An infinality patched freetype (bug or not) renders other
> instructed truetype fonts perfectly normally afaik.

Well, Erik tries to implement Greg's ClearType whitepaper which seems
to indicate that SHPIX instructions are to be ignored in ClearType
mode.  However, given that Windows ClearType (both GDI and DW) renders
ttfautohint output just fine, this assumption is not valid in general,
and obviously Erik's code does something wrong.

It is true that virtually no other fonts use the SHPIX bytecode
instruction, and if they do so, it is related to the adjustment of
single pixels, something which shouldn't be necessary in ClearType
mode.  The Windows rasterizer contains code to catch that, and here's
the difference: Windows doesn't handle ttfautohint output in backwards
compatibility mode, while Erik's patch does.  I consider the Windows
rasterizer the reference implementation of ClearType, so I conclude
that the infinality patches should be adjusted accordingly.


    Werner