Path: utzoo!mnetor!uunet!husc6!huma1!fry
From: fry@huma1.HARVARD.EDU (David Fry)
Newsgroups: comp.sys.mac
Subject: Re: Background screen on a Mac
Message-ID: <4242@husc6.harvard.edu>
Date: 17 Mar 88 21:14:42 GMT
References: <3841@cbterra.ATT.COM> <46100113@uxe.cso.uiuc.edu>
Sender: news@husc6.harvard.edu
Reply-To: fry@huma1.UUCP (David Fry)
Organization: Harvard Math Department
Lines: 29

In article <46100113@uxe.cso.uiuc.edu> leonardr@uxe.cso.uiuc.edu writes:
>
>tedj@hpcilzb.HP.COM(Ted Johnson) writes in comp.sys.mac
>
>>Does anyone know where can I find the definition of a StartupScreen file?  
>>I haven't come across it in any of the Technical Notes or Inside Macintosh bibles...
>>
>>I am interested in writing a little program that makes StartupScreens
>>from MacPaint files.  (Yes, I *know* it has been done before :-)
>>
>	If memory serves me correctly, the StartupScreen format that has been
>constant until the Mac ][ is basically a MacPaint document WITHOUT the 512byte
>header.

This isn't quite right.  In MacPaint files, each horizontal
line of pixels is compressed via PackBits().  In  a
StartupScreen the line is totally uncompressed, just a direct
image of the picture's bitmap, 512/8 = 64 bytes wide.  And the
screen is 342 pixels high, so each StartupScreen (in the old
format, that is) is 64*342 = 21888 bytes long.  

StartupScreens on Mac II's can be PICT resources, as
mentioned, and have unlimited dimensions (memory restraints
notwithstanding).

David Fry				fry@huma1.harvard.EDU
Department of Mathematics		fry@harvma1.bitnet
Harvard University			...!harvard!huma1!fry
Cambridge, MA  02138