Path: utzoo!attcan!uunet!tektronix!pogo!rgrove
From: rgrove@pogo.GPID.TEK.COM (Robert Grove)
Newsgroups: comp.lang.postscript
Subject: Re: composite characters
Message-ID: <6613@pogo.GPID.TEK.COM>
Date: 17 Jan 89 01:54:10 GMT
References: <8600@bloom-beacon.MIT.EDU>
Reply-To: rgrove@pogo.GPID.TEK.COM (Robert Grove)
Organization: Tektronix Inc., Wilsonville, Oregon
Lines: 41

In article <8600@bloom-beacon.MIT.EDU> noid@athena.mit.edu (Adam G. Mellis) writes:
>Could someone tell me the right way to create a composite
>character in a user-defined font.  Say I have two chars, z
>and caron, both defined in my CharacterDefs dict, and I want
>a new char, zcaron, that has a caron above the z: simply
>calling the caron procedure within zcaron fails as the caron
>procedure is apparently undefined.  Why?...

I sent mail but, I am not sure it got through.

I suspect the reason to be that you have set the current directory
to be your font directory within the BuildChar procedure. The character
definitions are in another dictionary, probably CharacterDefs, which is
a dictionary contained within your fontdict.

Usually, the procedure to draw your character is put on the stack and
executed by something like:
   CharacterDefs Charname get exec  % Charname is the name of the character
within BuildChar. If your CharacterDef entry for your combined character,
/zcaron, simply tries to execute the procedure for /z and /caron, it won't
find them in the current dictionary (Your font dict).

There are several solutions to the problem. One technique I have used 
sucessfully for combined user defined characters would have an entry for the
zcaron character in CharacterDefs something like the following:

/zcaron { CharacterDefs /z get exec
          CharacterDefs /caron get exec
        } def

Another solution which should work, although I have not tried it, would
be to make Characterdefs the currentdict with begin ... end within the
procedure for zcaron.

Don't forget to have a BBox entry for zcaron which will hold both of the
characters from which it is derived as well as an appropriate Metrics
entry.

-- 
Robert Grove
rgrove@pogo.gpid.tek.com | {anybackbone}!tektronix!pogo.gpid.tek.com!rgrove