Re: [ft-devel] Rendering problem with 'y' character

[David Turner]

>From the screenshot, I can tell that you enabled the bytecode interpreter
on your version of FreeType. There are great chances that the artefact is
caused by the bytecoded program of the Y, which creates a distorsion that
is normally not visible when rendering the 'straight' version of the
glyph outline.

this is the same kind of 'bug' which makes certain diagonals too thin,
or even disappear, when they're displayed with anti-aliasing with
FreeType. Windows by default doesn't anti-alias small text sizes, for
this specific reason (I'm not talking about ClearType here)

The only way to get rid of that is to change the way the LCD glyph outline
is computed. Instead of calling FT_Load_Glyph normally, then expand the outline
3x horizontally, we should render the glyph directly at 3 times the horizontal
resolution. The problem is that this introduces other problems when computing
the advance width; there are ways to overcome this, but they're all patented
by Microsoft. Also, this would also require specific patches to libXft, Cairo
and any other FreeType client, which only happens when you enable the
bytecode interpreter.

I'm a bit fed up with this, which mean that unless you can provide patches,
I think you'll have to stick with these bugs (and all the other bytecode+AA
bugs that already exist), or simply disable the bytecode interpreter.

Sorry,

- David Turner
- The FreeType Project  (www.freetype.org)

PS: Of course, the bug could be something different, in which case we could
    try to fix it.




On Mon, 2 Oct 2006 19:49:22 +0300, "Ismail Donmez" <address@hidden> said:
> Hi,
> 
> Attached patch shows a rendering problem with 'y' character with Tahoma
> font 
> (in "python" and "system" ). Notice that top-left part of y looks
> cropped. 
> Dpi is 96, and font size is 9 pts. I only see the problem when italic
> text is 
> used.
> 
> Does anyone know if this is a problem in KDE/Qt or a known problem? And
> how to 
> debug this better?
> 
> P.S: The screenshot is taken from python.org with Konqueror 3.5.4
> 
> Regards,
> ismail
> 
- David Turner
- The FreeType Project  (www.freetype.org)