[comp.sys.mac.misc] When is a GIF not a GIF?

schneide@parc.xerox.com (Kris A. Schneider) (03/31/91)

Hi folks,

Bear with me while I ramble a bit and tell you what's lead up to this question.

I finally gained access to a Sun Sparc2 that writes wonderfully formatted 1.44M
DOS disks.  Now, with AFS (Apple File Exchange) running on my IIsi at home,
the advice of a former teacher has come alive - "Never underestimate the
bandwidth of a truck."  Well, I've only got a dinky ole Mazda, but it still
beats tar out of a 1200b modem!  Anyway, one of the things I've downloaded from
the Sparc2 onto disks are GIF files.  They display without problem using a tool
called xv on the Sparc2, however only some of them display on my Mac.  When
AFS opens one of the DOS disks, the icons for the GIFs that will eventually
display have simulated writing on them (kinda like a MacWrite doc).  The ones
that won't display just have a blank doc icon.  This doesn't change after
the files have been installed on the Mac's hard-drive.  BTW, I'm using both
Giffer and GifWatch (I think that's right...), and when I say files will or
won't display, I mean that neither application recognizes them as GIFs so
the option isn't even there to open them.

Ok, hope ya'll are still reading.  What I'm wondering is, is there some
significant piece of info that tells either the applications or the Mac that
they/it are/is looking at a GIF?  Is there some way to change the files that
aren't recognized so that they are?  I've heard myths and legends surrounding
this wonderful tool known as ResEdit, will this help, where can I find it?
Guess that's enough...  Thanks for any leads!

-Kris
schneide@arisia.xerox.com

fadushin@rodan.acs.syr.edu (Fred Dushin) (03/31/91)

I've had a related problem responses you get.  My problem 
is that when I run gifConverter,
some of the documents I have downloaded are regognized by
gifConverter (in the std opon dialog box), but gifConverter
eventually claims it has run into an error when it tries
to read the files.

Now in itself, this isn't all that strange, but when I try to
peek into these files using QuickGif, I get a similar error
dialogue (except this time it complains about the file's not
being binary (which it is)).  The output to the screen gets all
garbled, so I quit.

Now, still this isn't all that strange, but lo and behold, gifConverter
can now read the files (and flawlessly, at that).  What I have
notoced is that the file type gets converted from document to
QuickGif document, which apparently makes all the difference
to GifConverter.

Fred Dushin  				Syracuse University, Syracuse, NY
Internet:				Bitnet:
fadushin@rodan.acs.syr.edu 		fadushin@sunrise.bitnet	
(FYI, RODAN is a Sun4 running SunOS Release 4.1_PSR_A.)

dewhirst@kuhub.cc.ukans.edu (04/03/91)

In article <1991Mar30.184820.7477@parc.xerox.com>, schneide@parc.xerox.com (Kris A. Schneider) writes:
> When
> AFS opens one of the DOS disks, the icons for the GIFs that will eventually
> display have simulated writing on them (kinda like a MacWrite doc).  The ones
> that won't display just have a blank doc icon.  This doesn't change after
> the files have been installed on the Mac's hard-drive.

You will never get a GIF icon for a file that is added to the desktop in the
manner you have described above.  When you transfer things over the DOS
machine, you lose the MacBinary "header" that describes such things as file
type, size, icon, etc.  This is not a problem.  

> What I'm wondering is, is there some
> significant piece of info that tells either the applications or the Mac that
> they/it are/is looking at a GIF?  Is there some way to change the files that
> aren't recognized so that they are?  I've heard myths and legends surrounding
> this wonderful tool known as ResEdit, will this help, where can I find it?

Yes and no. GIFfer 1.8 *should* recognize a GIF file regardless, but sometimes
it takes a little coaxing.  Try this--
Get ResEdit from an online service or sumex. (you own a Mac and you don't own
resedit? Does your Mazda have a steering wheel? <grin>)
Use ResEdit to"Get info" about the GIF file, and then modify the FILE TYPE and
CREATOR to "GIFf" and "Bozo" respectively (the creator change is not crucial).
Now giffer will recognize this as a giffer document. If you get a "Sorry buddy,
this isn't a GIF file" when you try to open it, you transferred the file
improperly on the dos machine or the GIF file is corrupt.  Make sure you used a
binary ftp mode for a binary file!

It takes a REALLY corrupt file for giffer to absolutely refuse to open it. 

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