[Devel] CFF problems

[Blinn, Eric W]

I'm seeing some problems with CFF fonts. I have some fixes
or workarounds that work reasonably with my application, 
but I've also been digging down into the FreeType code to 
understand what is going on and wanted to go ahead and 
bounce the problems off the FreeType and/or CFF gurus 
on the list.

I've attached a small CFF font file to demonstrate the 
problems. Load it into ftview with a ppem of 72 (note that 
the ftview from ft2demos-current fails to open a CFF file 
but the one from ft2demos-beta8 works). Once the font is 
brought up in ftview, the problems are as follows:

1) The glyphs are tiny. In T2_Init_Face() the units_per_EM
is being set extremely high, at 32768 grid units. Standard 
Type 1 Postscript fonts should be fixed at 1000 grid units, 
right? Setting units_per_EM to 1000 seems to get the CFF 
glyphs rendered at the proper size.

2) The glyphs are flipped (reflected over a horizontal 
midline). There is some disabled code in T2_Load_Glyph() 
where FT_Outline_Transform() would otherwise be called. 
Enabling that code and feeding it the appropriate transform 
matrix values flips the glyphs into the orientation I would 
expect.

3) The pen position is not always getting advanced correctly. 
Glyphs often sit on top of one another. This appears to be 
caused by incorrect glyph metrics, particularly a negative 
left side bearing (horiBearingX). The left side bearing 
should always be positive for a horizontal layout, right? I 
thought maybe this was happening because the metrics were 
being calculated using a control box. You might expect this
behavior if some control points lie far enough outside the 
glyph's bounding box. However, I've tried using the bounding 
box to calculate the metrics instead, but saw no improvement.

Thanks,
Eric Blinn

 <<example.cff>>

example.cff
Description: Binary data