Since commit 972134abe4 a frame getting
drawn has three states (with the vendor nvidia driver at least):
1. drawn by gtk waiting on the GPU
2. drawn by GPU waiting on the compositor
3. drawn by compositor
Those three states are encoded in two flags: frame_pending and
frame_still_painting.
frame_pending means step 1 is done, but step 2 and 3 are still
in progress. frame_still_painting means step 2 is still in progress.
After step 1 is finished the surface is frozen until step 3 is finished.
When the compositor notifies gtk it's done with step 3, with a
_NET_WM_FRAME_DRAWN client message, the toolkit thaws the surface to
allow the next frame to proceed.
The compositor sometimes sends gtk a _NET_WM_FRAME_DRAWN client message
between steps 1 and 2. This message should be ignored because it's not
a reply to the current frame.
Unfortunately, gtk currently assumes if it gets a _NET_WM_FRAME_DRAWN
client message while waiting for step 2 that it's actually at step 3,
and proceeds to draw a new frame while the existing frame is still
pending, leading to a blown assertion.
This commit addresses the problem by ignoring _NET_WM_FRAME_DRAWN
client messages from the compositor unless actually expecting one.
Fixes: #2902
Since commit 972134abe4 we now call
glClientWaitSync for the vendor nvidia driver, to know when a frame
is ready for the compositor to process.
If a surface is hidden while a frame is still being rendered by the GPU,
the surface will never produce the damage event the code relies on to
trigger the call to glClientWaitSync. This leaves the fence dangling,
and the next time the surface is shown, it will start a fresh frame
and blow an assertion since the fence from the last frame is still
hanging around.
This commit ensures a frame gets fully wrapped up before hiding a
surface.
In particular, it will NULL-ified the current global context if this is
the finalized one, avoiding dangling invalid pointers.
Would have been a cherry-pick from branch gtk-3-24 of commit
b592ded80a, but files moved.
Add a Help item to the gear menu that opens the
node-format.md file in a new window. This could
be improved if we could parse markdown and apply
tags, similar to how we can load pango markup.
One of the widget-factory focus tests is flaky in ci,
perhaps due to font changes causing size computations
to go slightly differently.
Drop this for now.
Include docstrings and format the list of supported
values better.
Also, add the same warning we have for GTK_DEBUG when
the environment variable is ignored.
