Re: hidden composites

["Melissa O'Neill" <oneill@cs.sfu.ca>]

I said:
>> I've been told for a long time that PFMs have almost all the information
>> you'll find in an AFM but some things are missing, but never known
>> exactly what.

... and Berthold K.P. Horn <bkph@ai.mit.edu> replied, saying:
> PFM's are rather anaemic.  They do not contain character bounding
> boxes.  They contain no information on unencoded characters.  They do
> not have the font encoding.

Eww...

I also said:
>> Similarly, I've never really understood why Adobe introduced PFMs
>> and MMM files when they had AFMs and AMFMs, it just seems to add
>> needless complexity and incompatibility to font issues.

... and Berthold replied:
> For the same reason TeX uses TFM's rather than say PL's: speed and
> compactness.  For many fonts the AFM file is almost as large as the
> actual font itself in PFB format and takes a long time to parse.  
> I don't know what platform you are on, but if you are on a Mac then you
> have another weirdness, which is the `screen font' suitcase the only real 
> use of which is the FOND resource that contains the font's metrics - 
> quite like the PFM file.
> 
> As for AMFM's, I have never seen one and am beginning to doubt whether
> they really exist.  I always make AFM or TFM files for my Multiple
> Master instances directly from the installed font.

Well, still I don't think it was such a good strategy. My AFMs seem to
average about 25% of the size of my PFA files, which I'm fine with,
compared to the other sources of bloat you find in computer systems --
especially since people doing serious work using fonts may find that
their software needs the AFMs anyway, meaning they get the bloat of having
AFMs and PFMs or AFMs and Font Suitcases. I use NEXTSTEP, which uses
AFMs directly, although it caches the information from parsing the AFMs
for better performance. Whether NEXTSTEP's successor, Rhapsody will do
the same remains to be seen; maybe by that time OpenType will have fixed
everything.

I have AMFMs (and the sets of design AFMs needed) for Nueva and Tekton,
my two Multiple Master fonts, so I can vouch for their reality. Getting
AMFMs for Nueva required a contact in Adobe. It certainly looks like
Adobe doesn't want to bother with them any more.

Best Regards,

    Melissa.