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

[Ewald Hew]

> fontforge does output afm. But I did not include them in the tar ball
> as the intended purpose (TeX) of outcome does need them. If you use
> the fontforge script itself, or go a bit further later in that mail
> archive for the one about 'Combo script', and run the script itself
> with fontforge, it should generate afm also. It is the last line. You
> might be able to adapt that for non-CJK font too. It takes about 25
> minutes to run on my hardware to convert the 25M(?) of CJK font so be
> patient; and takes about 1.5GB of ram - fontforge is quite hungry but
> we are talking about loading a large cjk font . ascii fonts will be
> quicker and use less resources.

I see. I'll try converting a CJK font on my own once I get the Latin
glyphs looking right first.

So I tried converting SourceSansPro-Regular using fontforge. In the
process also fixing problems with the flex feature (which I've just
pushed)

Looking at the metrics, though...

Converted (AFM)
  StartFontMetrics 2.0
  Comment Generated by FontForge 20120731
  Comment Creation Date: Mon Jul 17 15:39:50 2017
  FontName SourceSansPro-Regular
  FullName Source Sans Pro
  FamilyName Source Sans Pro
  Weight Book
  Notice (Copyright 2010, 2012, 2014 Adobe Systems Incorporated
(http://www.adobe.com/), with Reserved Font Name 'Source'.)
  ItalicAngle 0
  IsFixedPitch false
  UnderlinePosition -50
  UnderlineThickness 50
  Version 2.0
  EncodingScheme AdobeStandardEncoding
  FontBBox -454 -293 2159 968
  CapHeight 656
  XHeight 486
  Ascender 712
  Descender -205

Original (OS/2)
  <OS_2>
    <!-- The fields 'usFirstCharIndex' and 'usLastCharIndex'
         will be recalculated by the compiler -->
    <version value="3"/>
    <sTypoAscender value="750"/>
    <sTypoDescender value="-250"/>
    <sTypoLineGap value="0"/>
  </OS_2>

The relevant fields in the AFM are, I believe, `Ascender' and
`Descender'. However, these do not match `sTypoAscender' and
`sTypoDescender', which is what `cffgload.c' uses to set the vertical
advance, and I can't find a way to combine the other values to make
these. I'm not sure why fontforge output those values...

Ewald