[PATCH wayland 4/4] protocol: elaborate on wl_buffer
ppaalanen at gmail.com
Wed Oct 10 02:47:50 PDT 2012
Spell out exactly when a client may re-use a wl_buffer or its backing
storage. Mention the optimization for GL-compositor with wl_shm-clients.
Signed-off-by: Pekka Paalanen <ppaalanen at gmail.com>
protocol/wayland.xml | 18 +++++++++++++++++-
1 files changed, 17 insertions(+), 1 deletions(-)
diff --git a/protocol/wayland.xml b/protocol/wayland.xml
index 740fb43..8214852 100644
@@ -231,12 +231,28 @@
<request name="destroy" type="destructor">
<description summary="destroy a buffer">
Destroy a buffer. This will invalidate the object id.
+ For possible side-effects to a surface, see wl_surface.attach.
<description summary="compositor releases buffer">
- Sent when an attached buffer is no longer used by the compositor.
+ Sent when this wl_buffer is no longer used by the compositor.
+ If a client does not get a release event before the frame callback
+ requested in the same wl_surface.commit that attaches this wl_buffer
+ to a surface, then the client may assume, that the compositor will
+ be using this wl_buffer until the client attaches another wl_buffer.
+ Therefore the client will need a second wl_buffer to update the
+ surface contents again.
+ Otherwise, if a release event arrives before the frame callback, the
+ client is immediately free to re-use the buffer and its backing
+ storage, and does not necessarily need a second buffer. Typically
+ this is possible, when the compositor maintains a copy of the
+ wl_surface contents, e.g. as a GL texture. This is an important
+ optimization for GL(ES) compositors with wl_shm clients.
More information about the wayland-devel