Re: [iPAQ] double buffering

 --- Paulo Marques <pmarques_at_restinfor.pt> schrieb: >
> David Bannach wrote:
>
> > Does the iPAQ framebuffer device support double buffering? And how could this be
> > managed?
> >
> > I heard about ioctl() but never used it. Currently I work with open("/dev/fb0")
> and
> > mmap() and get flickering animations.
>
>
> Why are they flickering?
>
> This can only happen if you draw on the frame buffer "temporary" states
> (like drawing the background and then some sprites on top).

Yes, I draw directly on the frame buffer. First the background, then some points and
lines.

>
> You should use different techniques (like dirty blocks, etc.) to draw in
> memory and then only transfer to the framebuffer the relevant result.

You create a virtual framebuffer in memory. This means there is no double-buffering
support by the framebuffer driver?

>
> This way there is no flicker at all.
ok no more flickering, but you still draw on the framebuffer while it is displayed.
If your process gets interrupted or is slow for any reason then you can watch how
the screen gets updated.
>
>
> Hope this helps,
yes, thanks!
>
> --
> Paulo Marques
> Software Development Department - Restinfor, Lda.
> Phone: +351 252 290600, Fax: +351 252 290601
> Web: www.grupopie.com
>
> "In a world without walls and fences who needs windows and gates?"
>

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Received on Thu Oct 31 2002 - 14:11:36 EST