[cairo] [patch] gl: when using a surface as source/mask in drawing operation on GL surface target, we can avoid map_to_image()

[Henry (Yu) Song - SISA]

Hi, Chris

Is cairo_surface_map_to_image() calls _cairo_gl_surface_map_to_image() in which a new image surface is allocated and use glReadPixels() to read pixels from gl surface to image surface?  I could not see where PBO is allocated.

Thanks

Henry

-----Original Message-----
From: Chris Wilson [mailto:chris at chris-wilson.co.uk] 
Sent: Friday, March 30, 2012 8:09 AM
To: Henry (Yu) Song - SISA; cairo at cairographics.org
Subject: RE: [cairo] [patch] gl: when using a surface as source/mask in drawing operation on GL surface target, we can avoid map_to_image()

On Fri, 30 Mar 2012 15:05:44 +0000, "Henry (Yu) Song - SISA" <hsong at sisa.samsung.com> wrote:
> Hi, Chris
> 
> Do you mean the patch is OK?  I don't see a need to download image from a newly created GL surface, it is just like you create a new image surface.  Am I right?

No, the patch forces the use of system memory when we could be allocating a PBO. Also it is performing an optimization at a higher level which I think is more suitable in map-to-image.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre