[ft] Stray pixel from FT_Outline_Get_Bitmap()?

[Ian Britten]

Hi all,
I believe I'm seeing a regression between 2.3.9 and 2.3.11 when
rendering monochrome text, resulting in a stray pixel being
rendered - See the attached screenshots.  Note that I feel this
is a regression since the 2.3.11 version looks wrong, while the
older 2.3.9 looks correct.  This is on a 64-bit Mandriva 2010.0
system (GCC 4.4.1).  Note that no problems are seen when the
text is rendered using AA.  Also, hinting is disabled.

I had initially encountered this via Cairo, but after some
debugging and discussions with them, suspicion is on the
FT_Outline_Get_Bitmap() function that Cairo uses as part of its
rasterization of text.

Unfortunately, I'm not able to give out this custom font nor view
it in ftview, so I'm at a bit of a loss as to how to best pass this
problem over to someone for further investigation - Suggestions
welcome!

Meanwhile, I can provide the raw geometry of the problematic
diamond shape (from the font file), in the hopes that it can be
used somehow:
     -35, 368   (LL)
    -111, 444   (UL)
     -22, 444   (UR)
      54, 368   (LR)
     -35, 368   (LL)
My suspicion is on the 45-degree angle the lower-right corner forms,
with that angle triggering a problem somewhere in
freetype-2.3.11/raster/ftraster.c

As part of my testing, I switched back from 2.3.11 to 2.3.9, and my
failing tests then passed, reinforcing my suspicion that the problem
is in FT 2.3.11.

Any suggestions about how to proceed welcome!
Ian

ft_2.3.9.png
Description: PNG image

ft_2.3.11.png
Description: PNG image