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

[Kristian Høgsberg]

2009/5/5 Ian Romanick <idr at freedesktop.org>:
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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?

Ah, yes, that works.  I was thinking that it was a drawable attribute
you could specify at glx drawable creation time, but if it's a config
attribute, we can just expose the ones we support.  Cool.

Kristian