[Intel-gfx] [RFC] DRI2 swapbuffers (yes yet again)

[Ian Romanick]

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Kristian Høgsberg wrote:
> On Tue, May 5, 2009 at 12:20 PM, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
>> On Mon, 04 May 2009 19:14:29 -0700
>> Ian Romanick <idr at freedesktop.org> wrote:
>>
>>> Having this ability would allow us to advertise some fbconfigs with
>>> GLX_SWAP_METHOD_OML = GLX_SWAP_COPY_OML.  We obviously don't have any
>>> apps that use that today, but I can think of a couple that should. :)
>> Yeah, ok.
> 
> It's not something that needs to be exposed in the protocol or dri2
> module.  If you want the copy behaviour, use DRI2CopyRegion().
> Another point about GLX_SWAP_METHOD_OML is that we can't really
> implement the "always swap" (GLX_SWAP_EXCHANGE_OML) behaviour without
> a fair bit of yucky code, and without that we can't really claim to
> support the extension.

I think you misunderstand the extension.  The fbconfig has an extra
value that says "this is how glXSwapBuffer happens."  The three possible
values are: flip, copy, unknown.  Right now we support this extension,
but we always say unknown.  As you point out, I doubt we'd ever be able
to say flip, but we might be able to say copy and unknown.  Telling the
application flip isn't terribly useful, but a lot of applications could
do something smart (i.e., partial screen updates) if they knew the swap
method was always copy.  Right?
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