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From: "Sascha Kimmel \(tricos Mediaservice\)" <kimmel@tricos.com>
Newsgroups: comp.lang.beta
Subject: How to copy a bitmap object (nti)?
Date: 8 Feb 2000 20:19:40 -0000
Organization: University of Aarhus, Department of Computer Science (DAIMI)
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Hi!

I want to copy a bitmap object (on Windows) to realize a simple image buffer
for animation.
(See http://msdn.microsoft.com/library/techart/msdn_anim32.htm and
http://msdn.microsoft.com/library/techart/msdn_flicker.htm for details)
This works as follows: you have a bitmap which is the background, a sprite
(also a bitmap) that you draw onto the background bitmap - and then copy the
resulting bitmap to the screen - this prevents flickering ("single buffer").

So I need to copy a bitmap (pixmap in beta):

....
screenBitmap,bg,sprite,buffer:^pixmap;
do
(** INIT **)
&pixmap[]->buffer[];
&pixmap[]->screenBitmap[];
'background.bmp'->screenBitmap.read;
&pixmap[]->bg[];
'background.bmp'->bg.read;
&pixmap[]->sprite[];
'sprite.bmp'->sprite.read;

....

(** Off-screen drawing **)
bg[]->buffer[]; (** well, here's the problem !! **)
(sprite[],(0,0),(5,5),sprite.width,sprite.height)->buffer.drawPixmap;


(** Copying buffer to screen bitmap **)
buffer[]->ScreenBitmap[]; (** another problem **)
....


Due to the use of references instead of objects (a->b, (a,b pixmaps) gives a
compiler error) when assigning bg[] to the buffer[] and the following
drawPixmap both buffer[] and bg[] point to the same pixmap, so *both* are
changed.

Any solution?

Regards,
Sascha Kimmel