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Olivier Fourdan b0413b6e99 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
2020-07-03 12:59:23 +00:00
.gitlab-ci gitlab-ci: Install libnvidia-egl-wayland-dev package 2020-01-06 15:52:33 +01:00
composite composite: Stop wrapping GetImage/GetSpans 2019-10-30 16:26:01 +00:00
config udev: Fixed NULL pointer argument of strcmp 2019-09-20 05:33:47 +00:00
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 os: Don't crash in AttendClient if the client is gone 2019-11-19 10:15:05 -08:00
doc mi: Add a default no-op miSourceValidate 2019-10-30 16:26:01 +00:00
dri3 dri3: Fix XACE access mode for open and get_supported_modifiers 2019-01-16 20:05:43 +00:00
exa Fix build with gcc 9.3.0's -Werror=alloc-size-larger-than= 2020-05-01 20:02:29 +00:00
fb fboverlay: move bpp checks above malloc 2018-09-12 12:26:48 +10:00
glamor glamor_egl: Reject OpenGL < 2.1 early on 2020-01-08 15:20:10 +00:00
glx glx: unbreak on Unix without /usr/include/drm 2020-05-27 07:15:07 +00:00
hw xwayland: Use a fixed DPI value for core protocol 2020-07-03 12:59:23 +00:00
include meson: split udev from udev_kms which requires systemd 2020-05-27 07:16:02 +00:00
m4 Add ax_pthread.m4 to m4/ 2016-05-29 19:20:51 -07:00
man dix: Remove -to option to set the default connection timeout 2019-10-30 16:17:04 +00:00
mi misprite: Stop wrapping GetImage/GetSpans 2019-10-30 16:26:01 +00:00
miext mi: Add a default no-op miSourceValidate 2019-10-30 16:26:01 +00:00
os os: unbreak xsha1 on FreeBSD 2020-05-27 07:15:07 +00:00
present present/wnmd: Free flip_queue entries in present_wnmd_clear_window_flip 2020-06-25 17:27:10 +02:00
pseudoramiX Unvalidated lengths 2017-10-10 23:33:34 +02:00
randr Fix build with gcc 9.3.0's -Werror=alloc-size-larger-than= 2020-05-01 20:02:29 +00:00
record os: Don't crash in AttendClient if the client is gone 2019-11-19 10:15:05 -08:00
render dix: Call SourceValidate before GetImage 2019-10-30 16:26:01 +00:00
test test: Fix struct initialization warning 2020-05-08 16:45:50 +02:00
Xext os: Don't crash in AttendClient if the client is gone 2019-11-19 10:15:05 -08:00
xfixes xfixes: Restore monitoring of animated cursors 2018-02-14 13:52:45 -05:00
Xi xinput: Remove PropagateMask 2020-03-30 21:48:11 +00:00
xkb xkb: fix key type index check in _XkbSetMapChecks 2020-02-25 12:12:55 -05:00
.appveyor.yml hw/xwin: Remove XSetAuthorization() for helper clients 2020-04-15 14:13:58 +00:00
.dir-locals.el .dir-locals.el: Add missing final newline 2019-10-01 17:05:28 +00:00
.gitignore .gitignore: Add new autotools file 'test-driver' 2014-04-21 13:41:42 -07:00
.gitlab-ci.yml gitlab CI: use the fdo ci-templates repository 2020-05-20 11:01:13 +10:00
.travis.yml travis: Add OSX meson build to matrix 2019-05-02 15:42:58 +00:00
autogen.sh autogen: Set a default subject prefix for patches 2016-02-08 17:41:38 -05:00
configure.ac Remove BSD APM support. 2020-06-03 17:33:10 +02:00
COPYING modesetting: Merge modesetting's COPYING into the xserver's. 2014-09-15 12:46:02 -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
Makefile.am xfree86: Merge vbe into int10 2019-10-02 10:03:26 -04:00
manpages.am man: Fix automake seddery 2018-05-08 12:15:30 -04:00
meson_options.txt meson: split udev from udev_kms which requires systemd 2020-05-27 07:16:02 +00:00
meson.build meson: split udev from udev_kms which requires systemd 2020-05-27 07:16:02 +00:00
README.md Update README for gitlab migration 2018-11-25 20:55:11 +00:00
xorg-server.m4 xorg-server.m4: just all cflags instead of just sdkdir 2018-09-20 20:12:24 +01:00
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