Can't hook into the Double Buffer extension.

[Adam Jackson]

On Fri, 2014-09-12 at 14:59 -0400, Stirling Westrup wrote:
> I am writing a video driver for which I'd like to support the Double
> Buffer Extension. However I need to hook some of the calling functions
> described xorg/dbestruct.h, especially 'AllocateBackBuffer' and
> 'SwapBuffers'.

You found an app that uses it?  Impressive.

> However, the only way to access them is via the private key for dbe,
> and its not exported. Am I missing something, or is it really
> impossible to hook those functions?

At the moment, yeah.  Not so much out of malice as neglect, the
extension is not widely used and none of the open (or closed!) drivers
attempts to support it specially.  I wouldn't object to a patch,
although I'd at least like to see it done with accessor functions that
return the window/screen private pointer rather than by exporting the
private keys.

Ideally we'd do what the GLX spec says and unify the view of "the back
buffer" across extensions, which I guess could include DRI3 at this
point.

- ajax