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From: rosenber@ra.abo.fi (Robin Rosenberg INF)
Newsgroups: comp.sys.amiga
Subject: Re: Clipboard support, and why it hasn't happened.
Message-ID: <156@ra.abo.fi>
Date: 4 Oct 89 22:16:45 GMT
References: <8909250219.AA13930@jade.berkeley.edu> <899@madnix.UUCP> <4272@sugar.hackercorp.com>
Organization: Abo Academy, Finland
Lines: 63

In article <4272@sugar.hackercorp.com>, peter@sugar.hackercorp.com (Peter da Silva) writes:
> In article <PORTUESI.89Oct2102409@tweezers.esd.sgi.com>, portuesi@tweezers.esd.sgi.com (Michael Portuesi) writes:
> > This is not intended to be a flame against the Clipboard.  I would
> > like to see Clipboard support in all programs myself.  Though if the
> > Clipboard is to be truly successful, the following things must happen:
> 
> 	* It must be no harder to use the clipboard than it is to use
> 	  a file. The easiest way to do this is to provide a CLIPBOARD:
> 	  handler. That way you could open CLIPBOARD:0, write stuff,
> 	  and close it with no more difficulty than you have now creating
> 	  a file in RAM:.

MHO: 

It is no harder than writing/reading files, really. It looks different
and it's more flexible. For simple clipboard access the correspondence
is like this.

	fopen()	--> OpenDevice(), set id and io_Offset to zero
	fwrite() --> set data and length, CMD_WRITE
	fread() --> set data and length, CMD_READ, check io_actual
	fseek() --> fill in the io_Offset field before read or write
	fclose() --> CMD_UPDATE, CloseDevice()

Wha *IS* nasty is reading the thing. This is because one cannot know what is
in the clip other than it is an IFF file.
The special case is a CAT with id 'CLIP' or id '    ', (the docs are ambigous
on this). This kind of clip is for representing alternative forms of the data,
Lets say a spreatsheet supports the clipboard (Maxiplan does not, grrrrr...),
If it's correct and the authors have understood the philosophy of the clipboard
the would write a clipfile like this

	CAT CLIP
	    FORMSPSH	- 'SPSH' -> spreadsheet data
		whatever format the spreadsheet preferes it's data in
	    FORMFTXT	- 'FTXT' -> Formattet text. Can be simple text
				    if there is no need for formatting it.
	    FORMILBM	- 'ILBM' -> Graphical representation (seems a little
				    superflous in this case.

Now switch to a word processor and select 'paste'. The program sees that the
clip has alternative representations so it scans the clip for a representation
it understands and processes it. The rest is skipped since it is other 
representations of the same thing.

I know of no programs that handles the clipboard correctly. Most assume that
the clipboard contains a FORM-FTXT, otherwise it chokes. I think this must
be annoying for developers since thay cannot implement the clipboard fulle
(in most cases) without being incompatible with other programs.

What is needed is powerful and easy to use routines for manipulating iff-files
in a correct and consistent manner. C-A has only provided code and examples the
simple cases. The guidelines are very fuzzy.

> For 1.4. Pretty please?

Simple routines for the simple cases and more advanced routines for the nasty
ones. "Simple things should be simple and complex things should be possible"
should be the rule.

Another question: WIll there be a format for structured drawings in 1.4?

----------
Robin Rosenberg