xcb: respect QEventLoop::ExcludeUserInputEvents in native event handlers

This was a regression from Qt 4.

Before this patch, we supported filtering events only at QWindowSystemInterface
level, but to properly support filtering in QAbstractEventDispatcher::filterNativeEvent,
we have to filter the events earlier. Now it is possible to enable/disable this
feature for platforms that support native event filtering.

The mapping of which events are user input events were taken from
QWindowSystemInterfacePrivate::EventType.

Task-number: QTBUG-69687
Change-Id: I9a5fb9f999451c47abcdc83fdcc129b5eeb55447
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

3 files changed, 27 insertions, 4 deletions

diff --git a/src/gui/kernel/qwindowsysteminterface.cpp b/src/gui/kernel/qwindowsysteminterface.cpp
index 07ece5689e..67e1283462 100644
--- a/src/gui/kernel/qwindowsysteminterface.cpp
+++ b/src/gui/kernel/qwindowsysteminterface.cpp
@@ -57,6 +57,7 @@ QT_BEGIN_NAMESPACE
 
 QElapsedTimer QWindowSystemInterfacePrivate::eventTime;
 bool QWindowSystemInterfacePrivate::synchronousWindowSystemEvents = false;
+bool QWindowSystemInterfacePrivate::platformFiltersEvents = false;
 bool QWindowSystemInterfacePrivate::TabletEvent::platformSynthesizesMouse = true;
 QWaitCondition QWindowSystemInterfacePrivate::eventsFlushed;
 QMutex QWindowSystemInterfacePrivate::flushEventMutex;
@@ -1047,10 +1048,15 @@ bool QWindowSystemInterface::sendWindowSystemEvents(QEventLoop::ProcessEventsFla
     int nevents = 0;
 
     while (QWindowSystemInterfacePrivate::windowSystemEventsQueued()) {
-        QWindowSystemInterfacePrivate::WindowSystemEvent *event =
-            (flags & QEventLoop::ExcludeUserInputEvents) ?
-                QWindowSystemInterfacePrivate::getNonUserInputWindowSystemEvent() :
-                QWindowSystemInterfacePrivate::getWindowSystemEvent();
+        QWindowSystemInterfacePrivate::WindowSystemEvent *event = nullptr;
+
+        if (QWindowSystemInterfacePrivate::platformFiltersEvents) {
+            event = QWindowSystemInterfacePrivate::getWindowSystemEvent();
+        } else {
+            event = flags & QEventLoop::ExcludeUserInputEvents ?
+                        QWindowSystemInterfacePrivate::getNonUserInputWindowSystemEvent() :
+                        QWindowSystemInterfacePrivate::getWindowSystemEvent();
+        }
         if (!event)
             break;
 
@@ -1089,6 +1095,21 @@ bool QWindowSystemInterface::nonUserInputEventsQueued()
     return QWindowSystemInterfacePrivate::nonUserInputEventsQueued();
 }
 
+/*!
+    Platforms that implement UserInputEvent filtering at native event level must
+    set this property to \c true. The default is \c false, which means that event
+    filtering logic is handled by QWindowSystemInterface. Doing the filtering in
+    platform plugins is necessary when supporting AbstractEventDispatcher::filterNativeEvent(),
+    which should respect flags that were passed to event dispatcher's processEvents()
+    call.
+
+    \since 5.12
+*/
+void QWindowSystemInterface::setPlatformFiltersEvents(bool enable)
+{
+    QWindowSystemInterfacePrivate::platformFiltersEvents = enable;
+}
+
 // --------------------- QtTestLib support ---------------------
 
 // The following functions are used by testlib, and need to be synchronous to avoid
diff --git a/src/gui/kernel/qwindowsysteminterface.h b/src/gui/kernel/qwindowsysteminterface.h
index 6bf6ee645c..1dde9130ac 100644
--- a/src/gui/kernel/qwindowsysteminterface.h
+++ b/src/gui/kernel/qwindowsysteminterface.h
@@ -292,6 +292,7 @@ public:
     static void deferredFlushWindowSystemEvents(QEventLoop::ProcessEventsFlags flags);
     static int windowSystemEventsQueued();
     static bool nonUserInputEventsQueued();
+    static void setPlatformFiltersEvents(bool enable);
 };
 
 #ifndef QT_NO_DEBUG_STREAM
diff --git a/src/gui/kernel/qwindowsysteminterface_p.h b/src/gui/kernel/qwindowsysteminterface_p.h
index 492f559f22..9cb4e191cc 100644
--- a/src/gui/kernel/qwindowsysteminterface_p.h
+++ b/src/gui/kernel/qwindowsysteminterface_p.h
@@ -525,6 +525,7 @@ public:
 public:
     static QElapsedTimer eventTime;
     static bool synchronousWindowSystemEvents;
+    static bool platformFiltersEvents;
 
     static QWaitCondition eventsFlushed;
     static QMutex flushEventMutex;