Re: [ft-devel] [GSoC] Extending the CF2 interpreter

[Ewald Hew]

Thanks all for the valuable info! Sorry for the lack of reply.

I had fixed hinting as I realised the interpreter was actually not
respecting mid-charstring hints due to the hintmask.

>> While I am not aware of any open source Type 1 fonts from Adobe, I'd
>> suggest looking into converting some CFF fonts to Type 1 for
>> testing.
>
> This sounds very sensible!  Ewald, can you do that?

Yes, I'd already tried converting one of the Source family fonts using
the `tx' utillity. Doing this I found that the placement of glyphs
seemed wrong, which I've been trying to figure out.

Refer to the attached gifs.

The first two are between hinting on and off for Type 1. Notice how
the base glyphs of accented characters shift about regardless.
The third is for CFF converted to Type 1. Notice how the line spacing
changes in discrete steps above a certain font size. For 26~29pt, it
shifts downwards one step, and for 30pt it seems to shift a little bit
more.

I compared the two code paths, especially the parts to do with
metrics, but could not find what changed between that would cause
this. My current guess is that some metric info is not being passed
properly from the interpreter out to the module loading the glyph, but
this is proving hard to debug via comparing printouts of numbers.

Ewald

type1-hinting-on.gif
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type1-hinting-off.gif
Description: GIF image

cff-type1.gif
Description: GIF image