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Willem Jan Palenstijn 4348934f2e mi: fix rounding issues around zero in miPointerSetPosition
Fixes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/577

This patch replaces the instances of trunc in miPointerSetPosition by
floor, thereby removing the incorrect behaviour with subpixel pointer
locations between -1 and 0.

This is the relevant code fragment:

    /* In the event we actually change screen or we get confined, we just
     * drop the float component on the floor
     * FIXME: only drop remainder for ConstrainCursorHarder, not for screen
     * crossings */
    if (x != trunc(*screenx))
        *screenx = x;
    if (y != trunc(*screeny))
        *screeny = y;

The behaviour of this code does not match its comment for subpixel
coordinates between -1 and 0. For example, if *screenx is -0.5, the
preceding code would (correctly) clamp x to 0, but this would not be
detected by this condition, since 0 == trunc(-0.5), leaving *screenx
at -0.5, out of bounds.

This causes undesirable behaviour in GTK3 code using xi2, where negative
subpixel coordinates like this would (to all appearances randomly)
remove the focus from windows aligned with the zero boundary when the
mouse hits the left or top screen boundaries.

The other occurences of trunc in miPointerSetPosition have a more subtle
effect which would prevent proper clamping if there is a pointer limit
at a negative integer rather than at 0. This patch changes these to
floor for consistency.

Signed-off-by: Willem Jan Palenstijn <wjp@usecode.org>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1451>
(cherry picked from commit 0ee4ed286e)
2026-01-19 12:32:24 -08:00
.gitlab-ci CI: add a driver build stage to check for header breakage 2026-01-19 12:32:22 -08:00
composite composite: Expose CompositeIsImplicitRedirectException 2023-07-18 09:34:39 +00:00
config config: wscons: fix warning on discarded const 2026-01-19 12:32:24 -08:00
damageext Remove autotools support 2021-10-27 13:15:40 +03:00
dbe dbe: drop obsolete NEED_DBE_PROTOCOL 2026-01-19 12:32:19 -08:00
dix dix: drop now obsolete cursorScreenDevPriv 2026-01-19 12:32:21 -08:00
doc dix: dixutils: make workQueue pointer dix-private 2026-01-19 12:32:18 -08:00
dri3 randr: move private definitons from randrstr.h to randrstr_priv.h 2026-01-19 12:32:18 -08:00
exa replace _X_INLINE by inline in internal static functions 2024-02-05 19:26:14 +00:00
fb fb: Fix 1bpp Xservers on "whitePixel=0, blackPixel=1" VRAMs 2024-01-03 19:43:16 +00:00
glamor glamor: drop duplicate _X_EXPORT from .c source 2026-01-19 12:32:19 -08:00
glx glx: move private definitions from vndserver.h to vndserver_priv.h 2026-01-19 12:32:18 -08:00
hw Xquartz: ProcAppleDRICreatePixmap needs to use unswapped length to send reply 2026-01-19 12:32:24 -08:00
include xkb: make XkbUpdateKeyTypesFromCore() static 2026-01-19 12:32:24 -08:00
m4 Add ax_pthread.m4 to m4/ 2016-05-29 19:20:51 -07:00
man Xserver.man: Note that -byteswappedclients is the default in this release 2026-01-19 12:32:23 -08:00
mi mi: fix rounding issues around zero in miPointerSetPosition 2026-01-19 12:32:24 -08:00
miext os: move os_move_fd() out of public API 2026-01-19 12:32:20 -08:00
os os: move SELinux enforcement state to the extension 2026-01-19 12:32:24 -08:00
present randr: move private definitons from randrstr.h to randrstr_priv.h 2026-01-19 12:32:18 -08:00
pseudoramiX Remove autotools support 2021-10-27 13:15:40 +03:00
randr randr: drop duplicate _X_EXPORT from .c source 2026-01-19 12:32:19 -08:00
record record: Support architectures with sizeof(void*) > sizeof(long) 2023-12-17 19:30:52 +00:00
render render: fix refcounting of glyphs during ProcRenderAddGlyphs 2026-01-19 12:32:24 -08:00
test test: fix FTBS on missing xlib includes on NetBSD 2026-01-19 12:32:24 -08:00
Xext include: unpexport SELINUX_* consts from include/global.h 2026-01-19 12:32:24 -08:00
xfixes Remove "All rights reserved" from Oracle copyright notices 2023-02-25 09:40:41 -08:00
Xi Xi: ProcXIPassiveGrabDevice needs to use unswapped length to send reply 2026-01-19 12:32:24 -08:00
xkb xkb: make XkbUpdateKeyTypesFromCore() static 2026-01-19 12:32:24 -08:00
.appveyor.yml appveyor: Add libxcvt build dep 2021-11-04 13:03:25 +00:00
.dir-locals.el .dir-locals.el: Add missing final newline 2019-10-01 17:05:28 +00:00
.gitignore Clean up the .gitignore file 2024-01-12 00:50:24 +00:00
.gitlab-ci.yml CI: Only run the driver build job on Xorg changes 2026-01-19 12:32:22 -08:00
.mailmap Add a .mailmap file to canonicalize author names and emails 2023-03-15 18:10:51 +00:00
.travis.yml travis: Add OSX meson build to matrix 2019-05-02 15:42:58 +00:00
COPYING modesetting: Merge modesetting's COPYING into the xserver's. 2014-09-15 12:46:02 -07:00
meson.build test: fix FTBS on missing xlib includes on NetBSD 2026-01-19 12:32:24 -08:00
meson_options.txt xwayland/glamor: Drop the EGLStream backend 2026-01-19 12:32:21 -08:00
README.md Fix spelling/wording issues 2020-07-05 13:07:33 -07:00
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

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

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