Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!ames!umd5!uflorida!gatech!ncsuvx!ece-csc!rss
From: rss@ece-csc.UUCP (ML)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Font help needed
Message-ID: <3651@ece-csc.UUCP>
Date: 9 Jun 88 17:33:25 GMT
References: <62300001@hobbiton> <62300003@hobbiton>
Reply-To: rss@ece-csc.UUCP (ML)
Organization: the loony bin
Lines: 41

In a previous article tran@hobbiton.prime.com wrote:
>BEGIN
>   Gfx := OpenLibrary(ADR("graphics.library"),0);   (* Just in case *)
>   Intu := OpenLibrary(ADR("intuition.library"),0); (* Just in case *)
>   Dfon := OpenLibrary(ADR("diskfont.library"),0);  
...
>   ft := OpenDiskFont(ta);
>   SetFont(win^.RPort^,ft^);
>
>Now, the code drops dead at the OpenDiskFont call.  What am I doing wrong?
>As far as I can see, it should work.  I have added all your responses so far
>(diamond.font in lowercase, adding the diskfont.library, etc) but still this
>turkey refuses to fly.

I may be off base here, since I program in C and not Pascal, but ...

As I understand it, routines like OpenDiskFont et al are actually stubs
which use the library base pointers and apply offsets to these pointers
to get a jump vector to the real routine.  The library base pointer used
in these routines therefore must be a global variable which also must 
be named correctly:

     GfxBase
     IntuitionBase
     DiskfontBase

or whatever, rather than Gfx, Intu, and Dfon.  If you OpenLibary(x) and 
assign it to Dfon; then call OpenDiskFont; it does something like
"Jump to Subroutine @ address (DiskfontBase - 30)" -- but you haven't
set DiskfontBase, just your own variable "Dfon" & so you usually get a 
visit from the Guru.  I found (at least with Lattice C) that something
somewhere apparently declares these global variables, if not actually
setting them, so that the linker was NOT kind enough to tell me that
"DiskfontBase" or whatever was undefined.

Remember -- take this "explanation" with a grain of salt.  I'm guessing,
and playing footloose and fancy-free with my explanation to boot.
Hope it helps...

       Mark Lanzo
      ...!mcnc!ece-csc!rss