Path: utzoo!mnetor!uunet!husc6!bloom-beacon!oberon!pollux.usc.edu!papa
From: papa@pollux.usc.edu (Marco Papa)
Newsgroups: comp.sys.amiga
Subject: Re: Scrolling SuperBitMaps
Message-ID: <6426@oberon.USC.EDU>
Date: 23 Jan 88 07:21:45 GMT
References: <8801230030.AA28130@jade.berkeley.edu>
Sender: nobody@oberon.USC.EDU
Reply-To: papa@pollux.usc.edu (Marco Papa)
Organization: Felsina Software, Los Angeles, CA
Lines: 22

In article <8801230030.AA28130@jade.berkeley.edu> FATXC@USU.BITNET writes:
>
>  I am trying to use either a ScrollLayer() or BltBitMap() function to
>scroll a superbitmap in a window.  The functions appear to work quite
>well, but there is always an annoying flicker when several calls are
>made to these functions in rapid succession.  Is theere a way to prevent
>the colors on the screen from flashing?

Yes.

> I have
>seen some very nice scrolling rastports without flicker, so I assume it can
>be done...

In A-Talk Plus I do that in the Zoom for the Tek4014 emulator.  I have two
horizontal and vertical scrolling gadgets that control a 1024 x 780 
superbitmap.  When I get a GADGETDOWN, I smooth-scroll until the gadget is 
released looping for INTUITICKS messages.  A little voodoo with ModifyIDCMP
is also needed.  I recall that the source code for the Lines Workbench demo
(probably by Bart) does just that.

-- Marco