> > Note that freetype does not use the overlap flags to determine the path fill > rule (winding vs even-odd), it always uses winding for TT or CFF2 variable > fonts, as the spec mandates; the discussion here is about freetype using the > (TT glyf only) overlap flags to enable what Alexei calls "4x4 bilevel > oversampling" in order to mitigate the effects of increased pixel coverage > where paths overlap inside a glyph. I'm just summarizing the above linked > fonttools issue, but I don't fully understand the technical details of this > rendering technique. > CFF2 doesn't have an equivalent mechanism to say "this glyph may contain > overlaps", which prompted this specific email thread.
>> CFF was even-odd. CFF2 is non-zero winding. >> This is about the coverage calculation rather than the fill rule. Suppose two contours cover half-pixel each. The integral coverage depends on how they overlap over that pixel. The only way to reasonably deal with it is oversampling.
