Article View: comp.sys.mac
Article #26466Re: Background screen on a Mac
From: David Fry
Date: Thu, 17 Mar 1988 21:14
Date: Thu, 17 Mar 1988 21:14
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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
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Path: arc1-ca.pugleaf.net!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