Re: [Devel] Kerning problem with capitals

[Werner LEMBERG]

> > This only exists for FreeType's autohinter.  What we've discussed
> > before is a problem with the native TrueType hinter which normally
> > doesn't handle sub-pixel rendering...
>
> I was under impression that the spacing problem has nothing to do
> with subpixel rendering.

Oops.  I meant sub-pixel position corrections.

> Are you saying that TT hinter won't be able to detect these
> distortions in terms or rsb_delta + lsb_delta?

Of course it does, but it doesn't expose this data to the
application.

> I thought that rsb_delta and lsb_delta are of not much use
> separately, while their sum actually means the spacing distortion,
> which is easy to correct by removing or adding just one pixel.  Why
> TT hinter doesn see it?

The concept of rsb_delta and lsb_delta is specific to FreeType's
autohinter (it is an invention of David Chester).  It simply doesn't
exist for TrueType, and it shouldn't be necessary at all for well
hinted fonts.  The very idea of TrueType's hinting instructions is to
have full control over all points.  In the specific case we've
discussed in previous mails it is the kerning between `R' and `e'
which must be handled more sensible.


    Werner