EXA prepare/finish hooks & random X questions

[Keith Packard]

On Thu, 2005-09-01 at 16:12 +1000, Benjamin Herrenschmidt wrote:

>  - Have PrepareAccess allocate & return a full pixmap structure instead
> with a new pointer that we pass down as a drawable to fb()

That's already possible with the GetWindowPixmap screen function;
modifying fb to call through the pointer for that wouldn't be very hard.

Getting fb to call back into the system when it finishes drawing would
be more tedious.

> 
> That leads to my worry that we might wrap an fb call with
> PrepareAccess/FinishAccess, but the fbXXX call itself might call back
> through the GCOops,

It isn't supposed to; fb is supposed to be self-contained once you dive
in.

> Can somebody give me a quick overview of what are "fb" vs. "mi" layers ?
> fb seem to do actual drawing to the framebuffer. I haven't looked into
> too much details into "mi". We seem to use fb most of the time, but we
> fallback to mi in a couple of cases, sometimes, based on the value of
> pGC->lineWidth (wether it's 0 or not).

mi contains 'harder' algorithms, like wide lines and filled polygons and
eventually calls to the spans routines implemented by fb (or exa) to
draw stuff. mi never touches pixels directly.

-keith

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