Add multiple buffering to xwl_window

Xwayland takes care of not attaching a new buffer if a frame callback is pending.

Yet, the existing buffer (which was previously attached) may still be updated from the X11 side, causing unexpected visual glitches to the buffer.

Add multiple buffering to the xwl_window and alternate between buffers, to leave the Wayland buffer untouched between frame callbacks and avoid stuttering or tearing issues.

Closes: #835 (closed) Signed-off-by: Olivier Fourdan ofourdan@redhat.com

added Xwayland label

mentioned in commit ofourdan/xserver@a710a79b

added 1 commit

• a710a79b - xwayland: Add its own buffer pixmap to xwl_window

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It would be better to alternate between two different buffers for sending to the Wayland server. Otherwise there can still be artifacts, in particular if the Wayland server uses direct scanout of the Xwayland buffer.

mentioned in commit ofourdan/xserver@1c61c929

added 2 commits

• a1e3dfa5 - 1 commit from branch xorg:master
• 1c61c929 - xwayland: Add double buffering to xwl_window

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unmarked as a Work In Progress

changed title from WIP: xwayland: Add its own buffer pixmap to xwl_window to Add double buffering to xwl_window

changed the description

mentioned in commit ofourdan/xserver@a1e5c3fd

added 1 commit

• a1e5c3fd - xwayland: Add double buffering to xwl_window

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marked as a Work In Progress

Michel has different plans regarding this, so closing this MR.

closed

reopened

changed title from WIP: Add double buffering to xwl_window to WIP: Use “detached” wl_buffers for damage reporting

changed the description

mentioned in commit ofourdan/xserver@ce4465a8

added 2 commits

• 065c2c95 - xwayland: Add detached mode for `wl_buffer`
• ce4465a8 - xwayland: Use detached buffers for damage

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Ah crap, no... it works but it's using the same pixmap's bo so the buffer is still subject to change from the X11 side.

I think this is where I fail to understand, because there seems to be a 1:1 relationship between the Pixmap and its wl_buffer, trying to have multiple wl_buffers is like duplicating most of the xwl_pixmap, so using different backing pixmaps as initially made sense to me...