Re: Clean up and fix glyph contour generation nits. (issue 566080043 by address@hidden)

[lemzwerg]

> > I don't fully understand this code. 
> 
> that is an ominous comment to come from the Freetype
> author.  I had assumed you reviewed the existing code
> as well.

I have two difficulties: I'm not good at C++ and Guile stuff, and it's
not completely clear to me what the code wants to achieve.  It's not
your recent changes that I'm struggling with but the overall design.

What's definitely missing is handling the case where the first point of
an outline is a (second-order) off-curve point, making it necessary to
construct an on-curve point if the point before (i.e., the last point of
the current contour) is a (second order) off-curve point, too.

On the other hand, we talked about approximating the outlines by using
the hull polygon that is spanned by the control points: If you do this
the construction of the on-curve point wouldn't be necessary, right? 
Does your code change in commit 79ec62e6 do that already?  The comment
only says 'Substitute a line segment instead' but doesn't explain
whether this is a legitimate approximation.

> > A quite well documented routine to walk over a contour is function
> > `FT_Outline_Decompose` in file `src/base/ftoutln.c` of the FreeType
source
> code.
> 
> I'll have a look.

Thanks.  Note that the first point of a contour can never be a
third-order off-curve point, which means that you don't need to handle
wrapping in this case.


https://codereview.appspot.com/566080043/