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From: rcd@ico.isc.com (Dick Dunn)
Newsgroups: comp.fonts
Subject: Re: Type 1 vs. Type 3
Message-ID: <1991Jun10.210023.7625@ico.isc.com>
Date: 10 Jun 91 21:00:23 GMT
References: <1991Jun9.035349.27813@thyme.jpl.nasa.gov> <91160.192807FLEGLEI@YaleVM.YCC.Yale.Edu>
Organization: Interactive Systems Corporation, Boulder, CO
Lines: 41

FLEGLEI@YaleVM.YCC.Yale.Edu writes:
> Type 3 is an unencrypted user reserved PostScript font specification...

Type 3 can be encrypted or not, as you wish.  The "eexec" operator (encryp-
ted exec) is a separate matter.

>...that allows filling and shading (not allowed in Type 1) & some different
> stroking specifications than Type 1...

Type 1 fonts are intended to produce an outline which can be filled.

The operators available in Type 3 fonts are just the normal PostScript
"red book" operators.

>...Type 3 was Adobe's sop to non-
> registered type developers and individuals...

C'mon now.  Type 3 gives you a way to create fonts using normal PostScript
operators, without all the hair of font hints, special operators and rules,
and limited error checking in Type 1.  While I do think Adobe took too long
to provide the info to let people create Type 1 fonts, there's still a use
for Type 3.  Main point is that it gives you access to the font cache.

>...Type 1 is encrypted & I
> think compressed in the same process allowing smaller and faster trans-
> mission & output...

While all the Type 1 fonts I've seen have been encrypted, I think that's
more a matter of protection than a requirement, and it would be a bizarre
requirement--eexec is really a separate concept from the font mechanism.
(I'm being cautious only because I've not tried an unencrypted Type 1 font.
I have created encrypted Type 3's, tho.)

Type 1 fonts aren't really "compressed" in the usual sense of the word
(where compression is applied uniformly after-the-fact), but the font
mechanism provides a set of shorthand codes for operators, so the effect
is that they're much more compact than if they were written in terms of
normal "moveto...lineto" operators.
-- 
Dick Dunn     rcd@ico.isc.com -or- ico!rcd       Boulder, CO   (303)449-2870
   ...Simpler is better.