xcb: Use XIGrabDevice instead of xcb_grab_pointer with XI 2.2

Switch to using the pointer events from XI2 when touch is available (i.e.
version is >= 2.2). This allows us to select and grab the button and motion
events together with the touch ones. This prevents the issue of not getting
touch events when grabbing via the plain xcb functions.

To prevent touch sequences from being replayed after ungrabbing (for example after
dismissing a popup that caused a grab), we try to accept touches via XIAllowTouchEvents.
Unfortunately this leads to a deadlock and therefore we can only do it when we know
we have a new enough libXi. This is a configure time check which is not ideal since
the system on which apps run can have a newer libXi than the machine that did the Qt
build, but seems like the best we can do.

The environment variable QT_XCB_NO_XI2_MOUSE can be set to 1 in order to prevent
processing mouse events through XInput. This restores the old behavior with broken
grabbing.

[ChangeLog][QtGui] Pointer event delivery on X11 is now done via XInput 2.2+ when available.

Done-with: Michal Klocek <michal.klocek@theqtcompany.com>
Done-with: Alexander Volkov <a.volkov@rusbitech.ru>
Task-number: QTBUG-43525
Task-number: QTBUG-45054
Task-number: QTBUG-30417
Change-Id: I7cb2002b31bef4cd527aa427549dcf2d5467968e
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbkeyboard.cpp b/src/plugins/platforms/xcb/qxcbkeyboard.cpp
index 6a9ef5869e..2d96ed1c21 100644
--- a/src/plugins/platforms/xcb/qxcbkeyboard.cpp
+++ b/src/plugins/platforms/xcb/qxcbkeyboard.cpp
@@ -47,6 +47,12 @@
 #include <stdio.h>
 #include <X11/keysym.h>
 
+#ifdef XCB_USE_XINPUT22
+#include <X11/extensions/XI2proto.h>
+#undef KeyPress
+#undef KeyRelease
+#endif
+
 #ifndef XK_ISO_Left_Tab
 #define XK_ISO_Left_Tab         0xFE20
 #endif
@@ -791,6 +797,31 @@ void QXcbKeyboard::updateXKBStateFromCore(quint16 state)
     }
 }
 
+void QXcbKeyboard::updateXKBStateFromXI(void *modInfo, void *groupInfo)
+{
+#ifdef XCB_USE_XINPUT22
+    if (m_config && !connection()->hasXKB()) {
+        xXIModifierInfo *mods = static_cast<xXIModifierInfo *>(modInfo);
+        xXIGroupInfo *group = static_cast<xXIGroupInfo *>(groupInfo);
+        const xkb_state_component newState = xkb_state_update_mask(xkb_state,
+                                                                   mods->base_mods,
+                                                                   mods->latched_mods,
+                                                                   mods->locked_mods,
+                                                                   group->base_group,
+                                                                   group->latched_group,
+                                                                   group->locked_group);
+
+        if ((newState & XKB_STATE_LAYOUT_EFFECTIVE) == XKB_STATE_LAYOUT_EFFECTIVE) {
+            //qWarning("TODO: Support KeyboardLayoutChange on QPA (QTBUG-27681)");
+        }
+    }
+#else
+    Q_UNUSED(modInfo);
+    Q_UNUSED(groupInfo);
+    Q_ASSERT(false); // this can't be
+#endif
+}
+
 quint32 QXcbKeyboard::xkbModMask(quint16 state)
 {
     quint32 xkb_mask = 0;