When running rootless as well as rootful, Xwayland gets its outputs
configuration from the Wayland compositor.
When running rootful, it means that we end up with a large black
surface the size of all monitors combined, that's not very convenient
and there is no way for set the desired size of the Xwayland window.
Add a new command line option "-geometry" to force a specific mode when
running rootful for the user to specify the root window size to use for
Xwayland.
That option has no effect when Xwayland is running rootless.
v2: Not using libxcvt as the mode may not be a valid CVT mode.
v3: Add a set of XRandR modes and the RR hooks to make that work.
Update the man page for Xwayland.
v4: Add RandR 1.0 support for older clients
v5: Fix XVidMode failing with a BadMatch
v6: Add a separate xwl_output specifically for fixed mode, instead of
using the existing output list - that will allow for further
improvements like a fullscreen mode eventually.
v7: Sort the RR modes
v8: Fix RandR 1.0
v9: Add physical size
v10: Cleanup
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Closes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1338
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