Re: [ft-devel] [Rendering Regressions] Outlines vs. Bitmaps

[Werner LEMBERG]

> as suggested by Werner, I currently look into using outlines as a
> (considerably faster) means to detect rendering regressions.  I do
> understand that the outlines of glyphs should definitely be checked.
> However, I wonder if it is enough to guarantee "no rendering
> regressions" by just comparing the outlines and without checking the
> rendered bitmaps?

It depends.  If there are no changes to the rasterizer, it is
sufficient.  So maybe two targets, `check_outlines' and
`check_rasterization' (or something like that) will do.

> To get a feeling for that matter, it would help me to understand
> where most changes of FreeType happen and where versions differ the
> most.  Concretely: is the outline-to-bitmap algorithm definitive and
> final or is it subject to (probably subtle) changes every now and
> then?

Most changes happen to the outlines.  However, from time to time, both
the B/W and graymap rasterizers get modified; for such cases it is
necessary to run the whole test suite.


    Werner