VRetrace Sync

[Adam Jackson]

On Saturday 18 February 2006 05:23, James Wright wrote:
>    I hope this is the correct mailing list to post this question to, if not
> please advise where it should go!
>
>    Does anyone know if/when X11 will be extended to allow 2d drawing to be
> syncronised to the monitors vertical refresh. I already draw to a
> backbuffer first and use XShmPutImage() to copy to the window, so
> flickering is not a problem, but still get tearing/shearing which is
> especially noticable when scrolling large areas.  I understand that this
> also requires the event to be exposed in the kernel, but I thought i had
> read that had been done...?

The kernel notification basically already exists for drivers using the DRM.  
Exposing this to client applications is a Small Matter of hooking the 
vertical retrace up to a counter in the Sync extension.

Note that as we move towards using compositing managers everywhere, the 
question for all the other apps besides the compmgr is not "how do I get my 
bits on the screen during the retrace" but "how do I notify the compmgr that 
my front buffer contains a complete frame".  The Sync extension appears to be 
flexible enough to handle this, but no one has tried it yet.

- ajax
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