Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!purdue!haven!udel!mmdf
From: rogers%iris.ucdavis.edu@cunyvm.cuny.edu
Newsgroups: comp.sys.amiga
Subject: Re: Fast Scrolling
Message-ID: <5473@nigel.udel.EDU>
Date: 6 Dec 89 16:11:36 GMT
Sender: mmdf@udel.EDU
Lines: 26

In article <13939@eerie.acsu.Buffalo.EDU> gbbrooks@sybil.cs.buffalo.edu (G.
 Brandon Brooks) writes:
>       I use Benchmark Modula-2, and to scroll a view, all I do is:
>
>ViewPort.DxOffset := 10;
>ViewPort.DyOffset := 5;
>ScrollVPort(ViewPort);
>
>       This moves a view IMMEDIATELY 10 pixels to the right, and 5 pixels
>down; effextively making (10,5) the origin of the screen (0,0).

ScrollVPort is actually pretty slow. Also, in the RKM's it is described
as having a slight bug where it may flicker periodically.
Doesn't ScrollVPort do a MergeCopList (or whatever its called)?
Basically, any system command is going to have to do some big data
moving to get the screen's new copperlist to work with the screen-dragging
the O.S. supports.

It depends on how much CPU time you want to spend scrolling your view.


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