Sorry for the confusion. Yes it's just a bug that needs fixing...
If one frame has been posted then you need to take it because you can
never predict how long before a second one arrives, if at all.
On 29/05/15 11:12, Christopher James Halse Rogers wrote:
On Fri, May 29, 2015 at 2:35 AM, Alan Griffiths
<alan.griffi...@canonical.com> wrote:
There's a comment in unity-system-compositor (src/window_manager.cpp)
// We need to wait for the second frame before marking the session
// as ready. The first frame posted from sessions is a blank frame.
// TODO: Solve this issue at its root and remove this workaround
that led me to do some experimenting. And what I discovered is that a
nested server posts a frame when the first surface is *created*.
That is...
1. start a host session: sudo mir_demo_server --vt 2 --arw-file
2. Start a nested session that will be obvious: mir_demo_server
--host-socket /tmp/mir_socket --background-color purple
--custom-compositor adorning --window-manager tiling
At this point vt2 will have a black display because the nested server
has yet to post a buffer. (Although there's a titlebar visible for
its window - which is wrong but not the issue I want to raise.)
3. Now create a surface but don't post a buffer: mir_demo_client_basic
At this point the purple background from the nested server appears.
(And yes, I checked it is the surface appearing that causes the post:
"tiling" doesn't paint titlebar surfaces and sticking a sleep() after
mir_surface_create() makes it clear this is the relevant call.)
This seems inconsistent. I could imagine it making sense to post a
frame when starting (but the above comment suggests this isn't
desirable).
Since we don't post on startup we really ought to wait until we
actually have content from a client.
A nested server should post a frame as soon as it's got something to
draw. For most servers that should happen at startup, because they're
drawing a shell. Presumably Unity8 falls into this category?
For mir_demo_server_basic we probably shouldn't draw anything before the
first client posts a buffer. For mir_demo_server we probably should at
least draw a background on startup.
--
Mir-devel mailing list
Mir-devel@lists.ubuntu.com
Modify settings or unsubscribe at:
https://lists.ubuntu.com/mailman/listinfo/mir-devel
