[Mesa-dev] [PATCH] gallium/swrast: fix front buffer blitting. (v2)

[Martin Peres]

On 09/10/15 08:55, Dave Airlie wrote:
> On 9 October 2015 at 13:30, Boyan Ding <boyan.j.ding at gmail.com> wrote:
>> 2015-10-09 8:38 GMT+08:00 Dave Airlie <airlied at gmail.com>:
>>> From: Dave Airlie <airlied at redhat.com>
>>>
>>> So I've known this was broken before, cogl has a workaround
>>> for it from what I know, but with the gallium based swrast
>>> drivers BlitFramebuffer from back to front or vice-versa
>>> was pretty broken.
>>>
>>> The legacy swrast driver tracks when a front buffer is used
>>> and does the get/put images when it is mapped/unmapped,
>>> so this patch attempts to add the same functionality to the
>>> gallium drivers.
>>>
>>> It creates a new context interface to denote when a front
>>> buffer is being created, and passes a private pointer to it,
>>> this pointer is then used to decide on map/unmap if the
>>> contents should be updated from the real frontbuffer using
>>> get/put image.
>>>
>>> This is primarily to make gtk's gl code work, the only
>>> thing I've tested so far is the glarea test from
>>> https://github.com/ebassi/glarea-example.git
>>>
>>> v2: bump extension version,
>>> check extension version before calling get image. (Ian)
>>>
>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91930
>>>
>>> Signed-off-by: Dave Airlie <airlied at redhat.com>
>> Hi Dave,
>>
>> I'm wondering if it is necessary to implement the new interface of
>> swrastLoader in egl. If you think so, I may try to work on it in a
>> few days. The X11 part of egl is somewhat funny since it uses pure
>> xcb. Maybe the code there will need xcb-utils-image.
>>
>> I came up with the question above after I tested glarea on GNOME
>> wayland with sw rendering, where it seems to work all right. It seems
>> GLArea in gtk is using EGL on wayland while using glx on X.
> EGL doesn't support front buffer rendering from what I know, so I don't
> think the interface is required there.
>
> So I don't think there is a requirement for this interface on egl.

There was an old discussion about it. Here is the relevant email from Chad:
http://lists.freedesktop.org/archives/mesa-dev/2013-June/040129.html

In any case, the series I am about to post does not implement support 
for it.