[xserver patch v6 4/5] dri2: Support the DRI2InvalidateBuffers event.

[Keith Packard]

On Mon, 22 Feb 2010 23:56:59 +0100, Francisco Jerez <currojerez at riseup.net> wrote:

>  Discussed here [1], in short, the point of the PreConfigureWindow hook
>  is that it's executed before any ConfigureNotify events get queued up,
>  we want this to avoid a race condition.

If you want a specific event order to be required, then I'd suggest
putting that requirement into the DRI2 protocol spec as well. In
particular, it looks like you want the InvalidateBuffers event delivered
before the client receives any other notification that the buffers might
be invalid.

I note that the DRI2 protocol spec doesn't say when or how clients might
express interest in the events -- I assume you just get them when you
start using DRI2 requests on a drawable, but it would be nice to have
that nailed down.

> +    if (ds->PreConfigureWindow) {
> +	pScreen->PreConfigureWindow = ds->PreConfigureWindow;
> +	(*pScreen->PreConfigureWindow)(pWin, x, y, w, h, bw, pSib);
> +	ds->PreConfigureWindow = pScreen->PreConfigureWindow;
> +    }

You need to reset pScreen->PreConfigureWindow here, otherwise you've
just lost your hook...

Thinking about this a bit more, could you call this a ConfigNotify hook?
It seems like this is the desired semantic -- notification without any
option to change the operation or even cause it to
fail. PreConfigureWindow seems like a function which might need to do
something.

-- 
keith.packard at intel.com
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