[PATCH weston 0/7] Initial Xwayland window positioning

[Pekka Paalanen]

On Tue, 29 Nov 2016 20:23:07 +0100
Quentin Glidic <sardemff7+wayland at sardemff7.net> wrote:

> On 29/11/2016 16:11, Pekka Paalanen wrote:
> > From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> >
> > Many old X11 applications provide -geometry command line option that can be
> > used to initially position the window. Some obscure applications even rely on
> > this to work properly. Currently it does not work in Weston, the shell will
> > unconditionally pick a place of its own.
> >
> > This series makes -geometry +x+y work.
> >
> > First it sets up the plumbing needed to deliver initial position from
> > xwayland.so through libweston-desktop to the desktop shell.
> >
> > However, shell using the initial position is not enough because Xwayland runs
> > wild with its wl_surface.commits. Commonly Xwayland does the first commit
> > before xwayland.so has set up the window geometry, causing the initial
> > placement to be wrong. It's a race. Xwayland also waits for frame callbacks so
> > the compositor cannot ignore the commit either, because Xwayland would never
> > commit again. Writing a completely separate path for Xwayland windows in Weston
> > core and the shell would be ugly the least and a maintenance nightmare. Hence
> > the race is suggested to be fixed with more X11 protocol, in the last patch, so
> > that the first commit from Xwayland happens when everything is actually ready.
> >
> > A band-aid fix is to handle geometry changes on an already mapped window
> > attempting to keep the content in place, but because of a related race the
> > decorations are already drawn, so the window appears to jump rather than just
> > grow decorations. But, arguably on-the-fly geometry changes should be handled.
> >
> > The jumping is fixed with the help of a new Xwayland feature:
> > _WAYLAND_ALLOW_COMMITS property. With that, we not only ensure the geometry is
> > set before the first commit, but also that the decorations are really fully
> > drawn.
> >
> > The last is WIP, because when we investigated the original race, Daniel came up
> > with a plan described in https://phabricator.freedesktop.org/T7622 . I have not
> > yet done the XWM reorganization it calls for.
> >
> > This patch series is also available at:
> > https://git.collabora.com/cgit/user/pq/weston.git/log/?h=x11-positioning-v1
> > with a couple more debug patches on top.
> >
> > The Xwayland patch series needed for _XWAYLAND_ALLOW_COMMITS is:
> > https://patchwork.freedesktop.org/series/15904/
> > https://lists.x.org/archives/xorg-devel/2016-November/051913.html
> >
> > A question was presented, how _XWAYLAND_ALLOW_COMMITS would interact with
> > _NET_WM_SYNC_REQUEST in both basic and extended forms:
> > https://lists.x.org/archives/xorg-devel/2016-November/051932.html
> >
> >
> > Thanks,
> > pq
> >
> > Pekka Paalanen (7):
> >   xwayland: WM debug prints
> >   xwayland: add set_toplevel_with_position to internal API
> >   libweston-desktop: add set_xwayland_position API
> >   xwayland: detect initially positioned X11 windows
> >   shell: implement set_xwayland_position
> >   libweston-desktop/xwayland: react to geometry changes
> >   WIP xwayland: poke _XWAYLAND_ALLOW_COMMITS  
> 
> Patches 3, 5 and 6 are:
> Reviewed-by: Quentin Glidic <sardemff7+git at sardemff7.net>
> 
> Same goes for 2 and 4 with the comment addressed.

Hi Quentin,

thank you for the extremely quick reply!

> 1 and 7 requires too much X11-enabled brain and xwayland.c knowledge for 
> now.

Ok, no problem.


Thanks,
pq


> >  desktop-shell/shell.c                  | 37 ++++++++++++++++
> >  libweston-desktop/internal.h           |  5 +++
> >  libweston-desktop/libweston-desktop.c  | 10 +++++
> >  libweston-desktop/libweston-desktop.h  | 33 +++++++++++++++
> >  libweston-desktop/xwayland.c           | 18 ++++++++
> >  xwayland/window-manager.c              | 77 +++++++++++++++++++++++++++++++++-
> >  xwayland/xwayland-internal-interface.h |  2 +
> >  xwayland/xwayland.h                    |  1 +
> >  8 files changed, 181 insertions(+), 2 deletions(-)
> >  
> 
> 

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