Re: Xlib problems (Lol. I've only been programming in it for 10days...)

[Pierre Phaneuf <pp@ludusdesign.com>]

TI95NEUK@de.ibm.com wrote:

> If you really need speed. Well, use DGA.

I'd like to set something straight once and for all: DGA isn't that
fast. It is "okay", but not fast. It gives you programmed I/O access to
the framebuffer, which doesn't accelerate anything (in fact, XCopyArea
of a largish Pixmap to a Window is WAY faster than DGA with XFree86
3.9.x).

If you don't believe me, here is is, right from Dave Taylor:

> The big value I saw from DGA (at the time) was being able to page flip
> and being able to set up the video memory organization. I was also under
> the delusion that direct framebuffer access would give me faster
> rasterization speed, but I'm better now.

The page flipping is one of the biggest incentive. The video memory
organization is useless if you can't use the hardware blitter to move
things around (which may or may not be possible using DGA, depending on
the version).

If all you want from DGA is fullscreen access and you don't use page
flipping, do everyone a service and use a large override_redirect Window
at +0+0 and use xf86vmode to switch mode (or just use WidthOfScreen()
and HeightOfScreen()).

-- 
Pierre Phaneuf
Ludus Design, http://ludusdesign.com/
"First they ignore you. Then they laugh at you.
Then they fight you. Then you win." -- Gandhi