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xcb: Drop libXi version check

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...because we cannot support it in a robust way. Querying the version
via pkg-config only works when xi2 is picked up via pkg-config. Also,
having a version at build time does not mean we'll have the same at
runtime.

Modern distros (e.g. Ubuntu 15.04 and newer) will have libXi 1.7.4 or
newer.

Task-number: QTBUG-56017
Change-Id: Ia4a3b0dc47f2b92bcc953f462c95602a8ea2efd6
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
This commit is contained in:
Laszlo Agocs 2016-10-07 14:56:29 +02:00 committed by Oswald Buddenhagen
parent b4085e56b9
commit 0a71cc111a
2 changed files with 11 additions and 20 deletions
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10
src/plugins/platforms/xcb/README
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@ -21,3 +21,13 @@ REDUCING RUNTIME DEPENDENCIES
The '-qt-xcb' configure option can be used to get rid of most xcb- dependencies. Only libxcb will
still be linked dynamically, since it will be most likely be pulled in via other dependencies anyway.
This should allow for binaries that are portable across most modern Linux distributions.
PACKAGE VERSION REQUIREMENTS
When using touch input via XInput 2.2 or higher, there is a potential issue on systems that ship with
a libXi older than 1.7.4. This is because XIAllowTouchEvents can deadlock with libXi 1.7.3 and earlier.
When touch events are never received, this is not an issue, so plain mouse/keyboard systems are not affected.
See http://lists.x.org/archives/xorg-devel/2014-July/043059.html for details on the libXi patch.
Qt versions before 5.8 attempted to recognize this scenario based on the pkg-config package version and skip
the call. This has been removed starting from 5.8 since relying on pkg-config package versions is unsafe given
that Qt must also support systems with limited or incomplete pkg-config setups.

21
src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
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@ -697,26 +697,7 @@ void QXcbConnection::xi2ProcessTouch(void *xiDevEvent, QXcbWindow *platformWindo
if (m_xiGrab) {
// XIAllowTouchEvents deadlocks with libXi < 1.7.4 (this has nothing to do with the XI2 versions like 2.2)
// http://lists.x.org/archives/xorg-devel/2014-July/043059.html
#ifndef XCB_USE_XINPUT2
static bool allowTouchWarningShown = false;
if (!allowTouchWarningShown) {
allowTouchWarningShown = true;
qWarning("Skipping XIAllowTouchEvents() because it was not possible to detect libXi version at build time."
" Minimum libXi version required is 1.7.4."
" Expect issues with touch behavior.");
}
#elif QT_LIBRARY_VERSION(xinput2) < QT_VERSION_CHECK(1, 7, 4)
static bool allowTouchWarningShown = false;
if (!allowTouchWarningShown) {
allowTouchWarningShown = true;
qWarning("Skipping XIAllowTouchEvents() due to not having libXi >= 1.7.4."
" libXi version at build time was %d.%d.%d."
" Expect issues with touch behavior.",
QT_LIBRARY_VERSION_MAJOR(xinput2),
QT_LIBRARY_VERSION_MINOR(xinput2),
QT_LIBRARY_VERSION_PATCH(xinput2));
}
#else
#ifdef XCB_USE_XINPUT2
XIAllowTouchEvents(static_cast<Display *>(m_xlib_display), xiDeviceEvent->deviceid,
xiDeviceEvent->detail, xiDeviceEvent->event, XIAcceptTouch);
#endif