Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!rpi!uupsi!sunic!dkuug!imada!micro
From: micro@imada.dk (Klaus Pedersen)
Newsgroups: comp.sys.atari.st.tech
Subject: Can VDI draw on a virtual screen?
Message-ID: <1991Mar3.233757.10358@imada.dk>
Date: 3 Mar 91 23:37:57 GMT
Sender: news@imada.dk (USENET News System)
Organization: Dept. of Math. & Computer Science, Odense University, Denmark
Lines: 17

Hi, 

Is it possible to use VDI operations to draw on a virtual screen? Possibly
on a screen which is bigger than the real screen.

Now, I am drawing in a window, copying the inner to a buffer, and copying
it back into the window when I get a redraw, or determining which part
of the buffer is valid when I get a scroll or size, and then copy the 
valid part into the window, drawing the other area(s), and then copying 
the new contents to the buffer... 
 - It would be easier to draw in a big buffer, and only copy the portion 
which is visible to the window. 

I think that AIM is using a virtual buffer to it's images, but I guess
that it is using custom drawing functions...

-Klaus