Re: [AD] Fw: Acquire/Release speed issue

[Angelo Mottola <a.mottola@xxxxxxxxxx>]

> > What should I do? Should I remove the whole video bitmaps support from
> > OSX, as it's not really following the docs?
> No, I think you should keep it.  After all, the windowed drivers also 
> emulate
> page flipping.  But is it really not possible to return the screen for 
> the
> first video bitmap allocated with the same dimensions?
I investigated in the issue and found why I didn't reuse the screen on 
first create_video_bitmap() call. Since we're emulating page flipping, 
there is no real page flip at all, as the video bitmaps are copied onto 
the real screen.
In typical page flipping system, you request two pages, draw in one 
(clearing it and redrawing the entire frame) while the other is 
displayed, then you flip them. With emulation how I did it, you have 
the real "screen" BITMAP, and each time you call create_video_bitmap(), 
it returns a new BITMAP. You draw into one of these, then 
show_video_bitmap() copies onto "screen". If I reuse the screen, this 
doesn't work, as with emulation "screen" is always displayed, no matter 
if you call show_video_bitmap() to flip pages... So if one of the user 
pages is the actual screen (reused), when the program is drawing on it, 
drawings will appear on the screen in realtime, causing big bad 
flickering (this in a two pages configuration happens once every two 
frames).
--
Angelo Mottola
a.mottola@xxxxxxxxxx