Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!cbmvax!cbmehq!cbmger!peterk
From: peterk@cbmger.UUCP (Peter Kittel GERMANY)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Intuition graphics help wanted
Message-ID: <334@cbmger.UUCP>
Date: 28 Aug 90 14:40:18 GMT
References: <1237000014@uxa.cso.uiuc.edu>
Reply-To: peterk@cbmger.UUCP (Peter Kittel GERMANY)
Organization: Commodore Bueromaschinen GmbH, West Germany
Lines: 25

In article <1237000014@uxa.cso.uiuc.edu> ragg0270@uxa.cso.uiuc.edu writes:
>I have some points drawn on a black background in a window. While looking
>at this window, I am drawing into another and then using WindowToFront() when
>I want to view the other window. The only thing I don't like is that when I
>call WindowToFront(), the points flash a color that is loaded in a different
>register before they disappear.

This is not Intuition. What happens is that when you put a window in front
the layers library handles all the memory swapping involved. It uses the
Blitter heavily. If your window is not miniature then it can happen that
the Blitter already has worked on one of the bitplanes but has not yet
done the other(s). When you are "lucky" enough to catch this moment then
some area on the screen appears in different colors because one bitplane
is from one window contents and the others from the other window.

This is why double buffering animation techniques use always whole screens
and do not change windows. To flip from one screen to another, there is
not much memory blitting necessary, only a different copper list with
different pointers to the different bitplanes. So this can be done fast
as lightning. The same by flipping windows would lead to such intermediate
color corruptions as you experience.

-- 
Best regards, Dr. Peter Kittel      //     E-Mail to 
Commodore Frankfurt, Germany      \X/      rutgers!cbmvax!cbmger!peterk