Re: Progress update on adjustment database

I have an algorithm I'm testing for the tilde unflattening.  I went with
doing it before all steps, because it worked better with my idea, but the
function af_glyph_hints_align_weak_points is undoing my changes.
I can tell by measuring the height of the tilde after each step of the
latin hinting process.
Here's an example from one test:
before tilde unflattening: 109 units
after: 124 units
after af_latin_hint_edges: 124 units
after af_glyph_hints_align_edge_points: 146 units
after af_glyph_hints_align_strong_points: 146 units
after af_glyph_hints_align_weak_points: 59 units

Even setting oy = y for all the points doesn't stop it, or making
extreme changes like raising all points by 200.  How do I fix this?

On Mon, Jul 31, 2023 at 12:51 AM Werner LEMBERG <[email protected]> wrote:

> > > Just take the extrema of *all* points – for fonts this should be
> > > good enough, because it is standard to have points at the curve
> > > extrema, thus making the bounding box of the curve identical to
> > > the bounding box of the points (both on and off points).
> >
> > Ok, thanks.  This is exactly what I needed.  I was already trying
> > this, but I thought it was wrong because of off points.
>
> For your information, you might also look at FreeType's function
> `FT_Glyph_Get_CBox`, which handles the generic case.
>
> > What I mean is: my code allows the adjustment for i to be applied to
> > glyphs with more than 2 contours to also adjust accented o and a, so
> > the rules you suggested would reject around half of the characters
> > that are currently being adjusted this way.  I think your rules can
> > still be enforced by treating the contour to be moved as "A" and all
> > other contours collectively as "B".
>
> Yeah, I was especially referring to glyph 'i', since here the problem
> is most visible.
>
> >> [...] I ask you to have this in mind to find a solution that can be
> >> easily extended to cover this situation, too (for example, by using
> >> an extendable structure instead of a plain variable).
> >
> > In this case, do you mean that instead of making a codepoint a key
> > for the database directly, I should wrap it in a struct so that
> > other kind of keys can be added?
>
> Something like this, yes.  Just try to be generic, and think of
> possible extensions.
>
>
>    Werner
>