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authorPekka Paalanen <ppaalanen@gmail.com>2012-10-09 12:37:29 (GMT)
committerPekka Paalanen <ppaalanen@gmail.com>2012-10-10 09:39:47 (GMT)
commit3c323f5ee54780837b56abdf6e9b054e5252f6ee (patch)
treed300c34c3b211bb01c2e5fb3bfef57b4f180a1a3
parent4b615af6e370515ec6b00857de1081f09effab6c (diff)
downloadwayland-latched-2.tar.gz
wayland-latched-2.tar.xz
protocol: elaborate on wl_bufferlatched-2
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@gmail.com>
-rw-r--r--protocol/wayland.xml18
1 files changed, 17 insertions, 1 deletions
diff --git a/protocol/wayland.xml b/protocol/wayland.xml
index 740fb43..8214852 100644
--- a/protocol/wayland.xml
+++ b/protocol/wayland.xml
@@ -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>
</request>
<event name="release">
<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.
</description>
</event>
</interface>