[ft] CFF glyph height doubles with autohinting

[Derek B. Noonburg]

I'm seeing an odd case where glyph height in a CFF font doubles with
autohinting (relative to using the Adobe engine).

I'm attaching the font in question.  It's a subset that was embedded in
a PDF file -- the glyphs are various math symbols.

If I run "ftview 16 f1.cff", and then toggle autohinting on with the 'f'
key, the glyphs get taller.  Actually it doesn't seem to be 2x -- closer
to 1.5x taller.

I believe the shorter height is correct.  I.e., the Adobe CFF engine is
getting it right, and the autohinter is getting it wrong.

I have no idea where this font came from -- I received the PDF file from
a customer, and there's no useful info on how it was generated.  So it's
also possible that the font is broken.  But I'm not sure how a broken
font could trick the autohinter into increasing the height by that much.

I'm using FreeType 2.5.2.

Thanks for taking a look at this.

- Derek

f1.cff
Description: Binary data