Re: [ft-devel] Taming CFF_CONFIG_OPTION_DARKENING_PARAMETER_Y* for a gamma of ~2.2/sRGB?

[Werner LEMBERG]

> Ok, so I'm still trying to wrap my head around FT's internals and
> how it all works (anybody got some recommendations on how to explore
> an unknown codebase and getting a feeling for it?)

Unfortunately, FreeType's source code is not sufficiently documented.
It would be great if you could add comments while walking over the
various functions that I can then further massage and commit.

For the beginning I suggest that you start with file `ftobjs.c', which
holds the most important high-level functions (tagged with
`FT_EXPORT_DEF').

> ftview exposes different AA methods and they result in different
> metrics when using the autohinter? Look at some font with "ftview 16
> something.otf", use the autohinter with f and press A, B, C and look
> at how the glyphs shift around. Shouldn't they stay in place?

Mode `forced A' is strong auto-hinting, which hints horizontally also,
thus modifying the advance widths.  `forced B' (which is identical to
`B') is light auto-hinting that only hints along the vertical axis,
thus the advance widths are the same as if you render the font
unhinted.  `forced C' should have the same advance widths as `forced
A'.

> Interestingly, when Adobe's hinter is active with .otf fonts and you
> press B (-> autohinter), glyphs don't shift.

Yes, because Adobe's hinting engine doesn't hint along the horizontal
axis (contrary to FreeType's old CFF hinter).


    Werner