[Devel] [SF BUG#473296] No support for MS composit glyphs

[Antoine Leca]

Hi guys,

I was reviewing SourceForge, and I noticed a looooooooong list of bugs
there, most if not all without any commitment.
I then decided to copy them here, to make them able to be handled.
Expect several messages from me, but please don't ask me to solve any
questions, nor flame me with bad description or bad assumptions, I made
NO attempts to check or validate anything, or whatever you may ask for
a proper bug report.

Since this bug seems to be signed, I cc:ed what seems to be the author,
"George Williams". To him, I should make clear that the SF bug tracker
system is NOT the place to report bugs (BTW, David, probably we should
close it).


Antoine


Category: FT2 truetype driver


I notice that truetype/ttgload.c only supports Apple's 
definition of offsets for composit glyphs. Apple and 
Microsoft behave differently if there is a scale 
factor. OpenType defines some bits to disambiguate. 

(a problem in both 2.0.4 and 2.0.5) 

Apple says 
(http://fonts.apple.com/TTRefMan/RM06/Chap6glyf.html) 
that if flags&ARGS_ARE_XY is set then the offsets 
should be scaled by the scale factors (as you have 
done), but they also say something very cryptic about 
what happens when the component is rotated at 45° 
(which you do not support)-- See the "Important" note 
at the bottom. 

The old truetype spec from Microsoft did not mention 
this. The OpenType spec 
(http://www.microsoft.com/typography/otspec/glyf.htm, 
http://partners.adobe.com/asn/developer/opentype/glyf.html)
efines two new bits to disambiguate: 
SCALED_COMPONENT_OFFSET 11 
Composite designed to have the component offset scaled 
(designed for Apple rasterizer) 
UNSCALED_COMPONENT_OFFSET 12 
Composite designed not to have the component offset 
scaled (designed for the Microsoft TrueType rasterizer) 

Perhaps you could add a load_flag to allow the user to 
define the default setting?