Dri2 buffer format

[Jesse Barnes]

On Wed, 10 Nov 2010 12:30:11 +1100
Russell Shaw <rjshaw at netspace.net.au> wrote:

> On 10/11/10 09:28, Jerome Glisse wrote:
> > On Mon, Nov 8, 2010 at 6:55 PM, Russell Shaw<rjshaw at netspace.net.au>  wrote:
> >> On 09/11/10 04:53, Jerome Glisse wrote:
> >>>
> >>> On Mon, Nov 8, 2010 at 10:52 AM, Russell Shaw<rjshaw at netspace.net.au>
> >>>   wrote:
> >>>>
> >>>> Hi,
> >>>> How should the "format" of a DRI2 buffer be determined?
> >>>>
> >>>>
> >>>> http://www.x.org/releases/current/doc/dri2proto/dri2proto.txt
> >>>>
> >>>> DRI2ATTACH_FORMAT { attachment: CARD32
> >>>>             format:     CARD32 }
> >>>>
> >>>>     The DRI2ATTACH_FORMAT describes an attachment and the associated
> >>>>     format.  'attachment' describes the attachment point for the buffer,
> >>>>     'format' describes an opaque, device-dependent format for the buffer.
> >>>>
> >>>>
> >>>
> >>> As the spec says, it's opaque and only the driver understand it, intel,
> >>> radeon, nouveau all use different things i think. DRI2 is meant to be
> >>> use btw different driver of same hw which should all understand each
> >>> others.
> >>
> >> If it's opaque, how does one know what bytes are red/green/blue so that
> >> you can draw a line in the right colour?
> >
> > This format is intend to be exchanged btw Xorg DDX driver for a given
> > hw for instance the nouveau ddx and with the mesa or other dri2 driver
> > like for instance the nouveau gallium driver. Both of this component
> > understand each others.
> >
> > DRI2 is not mean to be use by end user application, it's only use by
> > Xorg to comunicate with library such as opengl that want to provide
> > direct rendering to X pixmap/window.
> 
> Ok. How do i plot a pixel in Wayland? I'm not using gtk/qt/OpenGL/OpenVG etc.

Allocate an shm buffer based on an mmap you've done in your client.
Then you can draw to it and notify wayland of the damage.

-- 
Jesse Barnes, Intel Open Source Technology Center