Re: [ft-devel] Issues due to commit "Fix metrics on size request for scalable fonts."

[Werner LEMBERG]

> This is not strictly a vertical line spacing problem. The primary
> impact of this fix is that the metrics are now integer-scaled rather
> than fractionally scaled. (Indeed, this appears to be the reason the
> TT driver overrides the default size_request.)

Yes.  This is what the TrueType standard mandates for bi-level and
grey-level glyphs.  Note that ClearType is *not* implemented in
FreeType yet!  As soon as this happens, the situation changes.  This
document

  http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx

writes the following about the GETINFO bytecode instruction:

  Compatible Width ClearType (Selector bit 7, Return bit 14)

    This flag is requested by setting selector bit seven.  If the
    return bit fourteen is set, this indicates that the glyphs for
    this font size will be adjusted post hinting in order to return
    advance widths that are exactly the same as bi-level rendering.
    If the return bit fourteen is not set, then the advanced widths
    will be either returned as integers rounded to the nearest pixel
    or rounded to the nearest sixteenth of a pixel.  The former is
    referred to as natural widths ClearType and the later as sub-pixel
    positioned ClearType.

> Integer scaling *may* have been the font designer's requirement.

If you develop non-ClearType TTFs, this *is* a requirement.

> However, it could be argued that if the font designer was using
> FreeType to proof the work, that the 'intention' was for the font to
> look as it did before this fix.

Hmm.  A font designer who relies only on FreeType for proofing a font?


    Werner