This reverts commit 50e2259404.
Temporarily revert the removal until we have more information about this whole
thing.
Turns out a couple of drivers don't work properly without the sync fence,
including intel, llvmpipe and NVIDIA.
Although sync fence is needed, from the information I have gathered (looking
at old bug reports, protocol specifications, look at other compositors' code),
compton's usage of it is not proper. So we need to rewrite it in the future,
after we get more information from driver developers.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
This was a dubious "fix" for a Nvidia driver problem. The problem was
never fully understood, and the then developers took a shotgun approach
and implemented xsync fences as a fix. Which somehow fixed the problem.
Again, I don't see any indication that the developers understood why
this "fix" worked.
(for details, see chjj/compton#152 and chjj/compton#181)
The driver problem should have been fixed almost 5 years ago. So this
shouldn't be needed anymore. In addition the way compton uses xsync fences
is apparently wrong according to the xsync spec (fences are attached to
screen, but compton uses them as if they were attached to drawables).
So, I will try removing it and see if anyone will complain. If there are
real concrete reasons why fences are needed, it will be brought back.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
--dbe does not seem to have an effect on tearing, as noted in the old
manpage, and confirmed by my own testing.
So remove it, since it complicates the logic of painting.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
IANAL, but I think I am allowed to add missing copyright notices for
someone else. And I did my best job using git history to figure out who
wrote which functions. So I hope everything is fine.
Re-did the painting logic, and document it.
It is unclear to me what is the previous painting logic. But the current
one is basically this:
1. Go through all windows top to bottom, and put visible windows (not
unmapped, opacity > 0, etc) into a linked list, from bottom to top
2. Accumulate a region of ignore on each window, which is basically the
region of screen that is obscured by all the windows above current
one.
3. Paint all the visible windows from bottom to top. Subtract the region
of ignore from the painting region. If we need to paint shadow, we
subtract the body of the window from the shadow painting region too,
because we don't want shadow behind the window.
4. region of ignore is invalidated when window stack change, an
window on top moved or changed shape, when window changed between
opaque and transparent, etc.
Notes:
It is unclear whether all the different shapes of a window (extents,
noframe, border, bounding shape, etc) are calculated correctly or not.
It is unclear if window shape related events are handled correctly or
not. Need more testing.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
