[PATCH weston] simple-shm: honour wl_buffer.release

[Bill Spitzak]

Pekka Paalanen wrote:
> On Mon, 19 Nov 2012 15:56:23 -0500
> Kristian Høgsberg <hoegsberg at gmail.com> wrote:
> 
>> On Mon, Nov 19, 2012 at 03:29:09PM +0200, Pekka Paalanen wrote:
>>> Change simple-shm to properly process the wl_buffer.release event, and
>>> not reuse a buffer until it is released by the server, as specified in
>>> the protocol.
>>>
>>> In case the server has not released the buffer, but signals that it has
>>> been shown (frame callback), allocate a second buffer. Simple-shm will
>>> now automatically do double-buffering if needed.
>> Looks fine, but simple-shm is less and less simple.
> 
> Yes, I know, but this is really required by the core protocol. Not
> just nice to have, nor optional.

It sounds like Wayland clients *must* do double buffering, is this correct?

I was under the impression that a client could draw over it's buffer at 
any time, with the caveat that what will get composited to the screen 
may be unpredictable.

Is it now illegal to write to the memory that the compositor is looking 
at? That makes sense but conflicts with the first few pages of the 
wayland documentation.

If it is ok to write over the memory (just not pretty) I would leave the 
"simple" program as simple as possible.