Xref: utzoo comp.sys.amiga:30870 comp.sys.amiga.tech:4243
Path: utzoo!attcan!telly!ziebmef!cks
From: cks@ziebmef.uucp (Chris Siebenmann)
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Subject: Supporting the clipboard (Re: Jerry declares the 2000 as 'the most improved computer')
Summary: note the Followup-To!
Message-ID: <1989Mar19.023257.20564@ziebmef.uucp>
Date: 19 Mar 89 07:32:54 GMT
References: <8903011852.AA16426@jade.berkeley.edu> <6193@columbia.edu> <10901@well.UUCP> <794@zehntel.UUCP> <10923@well.UUCP> <6206@cbmvax.UUCP>
Reply-To: cks@ziebmef.UUCP (Chris Siebenmann)
Followup-To: comp.sys.amiga.tech
Organization: ex Gold Disk Comicsetter programmer, now UofT student
Lines: 50

[hah. finally got around to commenting on this topic.]

In article <6206@cbmvax.UUCP> jesup@cbmvax.UUCP (Randell Jesup) writes:
...
| 	Part of this is the Mac's clipboard.  This makes integration of 
| artwork and text, and import of text, very easy.  We in theory have the same
| ability, but few people support the clipboard device (bad developers, bad! :-)
| (That's just a joke!)).

 I can't comment on why everyone seems to ignore the clipboard, though
I have a pretty good idea. I can tell you why ComicSetter doesn't use
it, and it's very simple.

 There's no IFF routines that will write to the clipboard, and it's
not at all obvious how to write them.
 
 You see, the clipboard requires you to put IFF data into it. Now IFF
is a perfectly good structure for data; it's nicely recursive 'cause
it's made up of things inside things (and so on..), includes a decent
amount of error checking, and is very nice overall. However, each
thing in an IFF data stream has to include its size (including the
sizes of all sub-things inside it) ... at the beginning of itself. And
the clipboard.device doesn't appear to support random seeking around
to write data (when writing to a file, the IFF routines seek back to
the start of a hunk and write the size once they know it).

 This makes it remarkably difficult to write a complicated recursive
data structure out in IFF chunks to the clipboard, of course. You
basically have to "write" it twice, once to find out the sizes of all
the hunks, and the second time to do the real writing with the real
sizes.

 Faced with this problem, we punted and decided that we didn't really
need to support the clipboard after all (it didn't help that we were
short for time). It only took me a couple of days to write the
cut-and-paste code that didn't use the clipboard. Using the clipboard
would have taken considerably longer, and we were short for time and
code space.

 So (to turn this into a comp.sys.amiga.tech topic), having listened
to my tale of woe, does anyone have any suggestions? Does the
clipboard.device support random seeks after all (the documentation is
remarkably opaque on this point)? Does anyone have a clever idea about
how to do this, or nifty code?

-- 
	"Though you may disappear, you're not forgotten here
	 And I will say to you, I will do what I can do"
Chris Siebenmann		uunet!{utgpu!moore,attcan!telly}!ziebmef!cks
cks@ziebmef.UUCP	     or	.....!utgpu!{,ontmoh!,ncrcan!brambo!}cks