[PATCH 4/5] glx: Implement GLX_PRESERVED_CONTENTS drawable attribute

[Adam Jackson]

On Thu, 2013-02-28 at 13:55 -0800, Ian Romanick wrote:
> On 02/25/2013 02:04 PM, Adam Jackson wrote:
> > We back pixmaps with pbuffers so they're never actually clobbered, so
> > we're really just recording the value passed in at create time so that
> > you get the same thing when you query.
> 
> Is that actually right?  There are some cases where they query returns 
> the actual state, and there are some cases where the query returns the 
> apps setting.  I haven't checked to see which this is.  In Mesa, we've 
> taken to quoting the spec in cases like this.

If the spec had anything to say about the matter, I would happily quote
it.  Unfortunately GLX is much less rigorous about this than GL.  My
reply to Eric was based on a careful reading of GLX 1.4.  While it's
clearly within the law to treat all pbuffers as preserved, the spec is
silent on whether the queried attribute value reflects the value given
at pbuffer creation.

- ajax