Re: FT Performance Regression?

[Alexei Podtelezhnikov]

> > Does using clip_box solve it?
> Yes, using the clip_box logic from my earlier email. Once again, not 
> documented nor called out in a release note. I've not looked at the code for 
> 2.10.1, but if all you've done is fixed the crash when omitting 
> FT_RASTER_FLAG_CLIP so that it uses an unbounded clip_box without clamping it 
> later (like gray_compute_cbox used to) then you're still sitting on a 10x 
> performance regression.

FreeType always calculates and uses bounding box with
FT_RASTER_FLAG_DIRECT except one corner case when the clip_box is
*provided*. Indeed, FreeType assumes that the clip_box is actively
designed to cut parts of the glyph out, not some distant page margins.
You have to admit that ignoring out of bounds spans is quite easy in
direct mode, so passing this job on FreeType is lazy. The key concept
here is that FreeType is not a layout engine it is incorrect to pass
the page margins to FreeType. So in a nutshell, do not bother FreeType
with page margins use clip_box *only* to cut parts of a glyph out.

You welcome to argue otherwise.