[ft] OTF rendered strangely at large sizes (mono)

[Alex Taylor]

I've got my OS/2 font driver pretty much working now.  So OS/2 can now 
support OTF fonts, yay.  :)

There's one odd thing I'm seeing, though.  For some reason, with 
OpenType/CFF fonts specifically, the rendering of glyphs at very large 
sizes is weirdly distorted.  I see it on-screen at 144pt, or when printed 
(the print driver uses the font engine to rasterize text, in this case for 
600dpi output).

I use monochrome rendering, because that's all the OS/2 graphics engine 
supports for text.

An example:  http://altsan.org/programming/os2/brill_otf_rendering.png

This shows Brill (a high-quality free-for-non-commercial-use OTF) rendered 
through my driver at various sizes.  Notice how, at 144pt, all curves look 
'squared-off' -- compare especially the letter 'e' at 144pt versus the 
other sizes.

This phenomenon isn't specific to this font: it appears to occur with all 
OTF fonts.

Could I be doing something wrong?

My code uses FT_Load_Glyph with FT_LOAD_DEFAULT and then FT_Render_Glyph 
with FT_RENDER_MODE_MONO.  (I can provide more details about my code as 
needed but I don't really know where to look at this point.)


-- 
Alex Taylor <address@hidden>
http://www.altsan.org