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From: ken@cbmvax.commodore.com (Ken Farinsky - CATS)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: Intuition Double Buffering
Message-ID: <20282@cbmvax.commodore.com>
Date: 2 Apr 91 16:51:28 GMT
References: <1991Mar24.170937.24081@watdragon.waterloo.edu>
Reply-To: ken@cbmvax.commodore.com (Ken Farinsky - CATS)
Distribution: na
Organization: Commodore, West Chester, PA
Lines: 26

In article <1991Mar24.170937.24081@watdragon.waterloo.edu> drpwilliams@tiger.uwaterloo.ca (Don Williams) writes:
>I am trying to double buffer LEGALLY under Intuition.  The code I
>have come up with works, however, alternate gadget images only show
>up in the original bitmap, and screen grab programs can only get the
>original bitmap regardless of whether the alternate bitmap is being
>displayed.  The code I am using follows.  Can anyone suggest a fix
>or a better way??? (The method must be Intuition compatible)

Intuition does not really support double-buffering.  If you want something
to appear in both buffers, then you have to copy the data to the second.
For instance, if you open a window and it is displayed into one of the buffers,
you must then copy the window into the second buffer for it to appear there.
If you do not copy the data, then the object will appear to flicker.

>void switch_bitmaps()
>void refresh_screen()

Look in the ROM Kernel Manual: Libraries and Devices for an example of a
double-buffered screen.  There is one in the Graphics: Sprites, Bobs and
Animation chapter, specifically look at the DrawGels() routine that begins
on page 501.
-- 
--
Ken Farinsky - CATS - (215) 431-9421 - Commodore Business Machines
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