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Olivier Fourdan 6cbd6a09b9 xwayland: Use a fixed DPI value for core protocol
The way Xwayland works (like all Wayland clients), it first queries the
Wayland registry, set up all relevant protocols and then initializes its
own structures.

That means Xwayland will get the Wayland outputs from the Wayland
compositor, compute the physical size of the combined outputs and set
the corresponding Xwayland screen properties accordingly.

Then it creates the X11 screen using fbScreenInit() but does so by using
a default DPI value of 96. That value is used to set the physical size
of the X11 screen, hence overriding the value computed from the actual
physical size provided by the Wayland compositor.

As a result, the DPI computed by tools such as xdpyinfo will always be
96 regardless of the actual screen size and resolution.

However, if the Wayland outputs get reconfigured, or new outputs added,
or existing outputs removed, Xwayland will recompute and update the
physical size of the screen, leading to an unexpected change of DPI.

To avoid that discrepancy, use a fixed size DPI (defaults to 96, and can
be set using the standard command lime option "-dpi") and compute a
physical screen size to match that DPI setting.

Note that only affects legacy core protocols, X11 clients can still get
the actual physical output size as reported by the Wayland compositor
using the RandR protocol, which also allows for the size to be 0 if the
size is unknown or meaningless.

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
Closes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/731
(cherry picked from commit b0413b6e99)
2020-08-18 04:12:09 +00:00
.gitlab-ci gitlab-ci: Add ccache to docker image, and leave in autotools 2019-02-22 11:55:31 +01:00
Xext os: Don't crash in AttendClient if the client is gone 2019-11-20 11:18:28 -08:00
Xi Xi: return AlreadyGrabbed for key grabs > 255 2020-01-09 16:18:28 -05:00
composite Switch automatic composite update to WorkQueue 2018-10-05 09:14:18 +02:00
config meson: Fix install path for 10-quirks.conf 2018-03-27 10:28:33 -04:00
damageext Use ARRAY_SIZE all over the tree 2017-10-30 13:45:20 -04:00
dbe meson: Distribute more SDK headers 2018-04-02 13:42:08 -04:00
dix dix: do not send focus event when grab actually does not change 2020-04-15 13:29:19 +02:00
doc mi: Add a default no-op miSourceValidate 2019-11-18 14:23:15 -05:00
dri3 dri3: Fix XACE access mode for open and get_supported_modifiers 2019-02-20 14:25:58 -05:00
exa Restrict 1x1 pixmap filling optimization to GXcopy 2020-02-06 17:54:36 +01:00
fb fboverlay: move bpp checks above malloc 2018-10-04 17:26:09 +02:00
glamor xwayland: clear pixmaps after creation in rootless mode 2020-02-21 23:21:33 +00:00
glx Revert "dri2: Don't make reference to noClientException" 2020-02-06 18:01:55 +01:00
hw xwayland: Use a fixed DPI value for core protocol 2020-08-18 04:12:09 +00:00
include configure: Define GLAMOR_HAS_EGL_QUERY_DRIVER when available 2020-01-14 15:30:57 -08:00
m4 Add ax_pthread.m4 to m4/ 2016-05-29 19:20:51 -07:00
man man: s/__/@/g 2018-03-27 10:13:17 -04:00
mi mi: Add a default no-op miSourceValidate 2019-11-18 14:23:15 -05:00
miext miext/sync: Make struct _SyncObject::initialized fully ABI compatible 2019-09-26 18:26:45 +02:00
os os: Ignore dying client in ResetCurrentRequest 2020-02-06 18:02:01 +01:00
present present/wnmd: Free flip_queue entries in present_wnmd_clear_window_flip 2020-07-20 13:22:20 +00:00
pseudoramiX Unvalidated lengths 2017-10-10 23:33:34 +02:00
randr randr: Check rrPrivKey in RRHasScanoutPixmap() 2020-07-21 16:48:37 -05:00
record os: Don't crash in AttendClient if the client is gone 2019-11-20 11:18:28 -08:00
render dix: Call SourceValidate before GetImage 2019-11-18 14:23:38 -05:00
test Fix building with `-fno-common` 2020-03-07 11:58:57 -08:00
xfixes xfixes: Restore monitoring of animated cursors 2018-02-14 13:52:45 -05:00
xkb Fix crash on XkbSetMap 2019-10-14 15:36:17 +10:00
.appveyor.yml appveyor: use meson 2018-03-21 10:16:44 -04:00
.dir-locals.el Add .dir-locals.el 2013-08-17 12:17:36 +02:00
.gitignore .gitignore: Add new autotools file 'test-driver' 2014-04-21 13:41:42 -07:00
.gitlab-ci.yml Revert "gitlab-ci: Only run docker-image stage if relevant source files change" 2019-03-25 12:45:52 +01:00
.travis.yml Drop Travis Linux build in favour of GitLab CI 2019-02-22 11:52:42 +01:00
COPYING modesetting: Merge modesetting's COPYING into the xserver's. 2014-09-15 12:46:02 -07:00
Makefile.am Update README for gitlab migration 2019-02-20 14:22:02 -05:00
README.md Update README for gitlab migration 2019-02-20 14:22:02 -05:00
autogen.sh autogen: Set a default subject prefix for patches 2016-02-08 17:41:38 -05:00
configure.ac xserver 1.20.8 2020-03-29 13:02:03 -07:00
devbook.am doc: Create a script to filter xmlto output 2015-01-05 14:24:06 -08:00
docbook.am docbook.am: embed css styles inside the HTML HEAD element 2011-09-21 14:07:49 -07:00
fix-miregion Change region implementation names to eliminate the 'mi' prefix 2010-06-05 17:47:32 -07:00
fix-miregion-private Change region implementation names to eliminate the 'mi' prefix 2010-06-05 17:47:32 -07:00
fix-patch-whitespace Rename region macros to eliminate screen argument 2010-06-05 18:59:00 -07:00
fix-region Rename region macros to eliminate screen argument 2010-06-05 18:59:00 -07:00
manpages.am man: Fix automake seddery 2018-05-08 12:15:30 -04:00
meson.build xserver 1.20.8 2020-03-29 13:02:03 -07:00
meson_options.txt meson: Add configuration of listening on tcp, unix and local 2018-08-01 11:01:37 -04:00
xorg-server.m4 macros: clarify documentation 2012-11-05 13:24:57 -06:00
xorg-server.pc.in xfree86: link modules against Xorg symbols on Cygwin 2012-04-05 21:57:07 -05:00
xserver.ent.in doc: relocate xserver.ent in the package root directory 2011-05-14 11:22:26 -07:00

X Server

The X server accepts requests from client applications to create windows, which are (normally rectangular) "virtual screens" that the client program can draw into.

Windows are then composed on the actual screen by the X server (or by a separate composite manager) as directed by the window manager, which usually communicates with the user via graphical controls such as buttons and draggable titlebars and borders.

For a comprehensive overview of X Server and X Window System, consult the following article: https://en.wikipedia.org/wiki/X_server

All questions regarding this software should be directed at the Xorg mailing list:

https://lists.freedesktop.org/mailman/listinfo/xorg

The master development code repository can be found at:

https://gitlab.freedesktop.org/xorg/xserver

For patch submission instructions, see:

https://www.x.org/wiki/Development/Documentation/SubmittingPatches

As with other projects hosted on freedesktop.org, X.Org follows its Code of Conduct, based on the Contributor Covenant. Please conduct yourself in a respectful and civilized manner when using the above mailing lists, bug trackers, etc:

https://www.freedesktop.org/wiki/CodeOfConduct