qpa: Teach handleApplicationStateChanged about sync/async delivery

Using QWindowSystemInterface::SynchronousDelivery reduces the chance
that we are flushing other events before delivering the application
state change. Those other events may conclude that the application
is still active, while in reality it is not, and do bad things.

Change-Id: I738c162fac22d2cd18de1e080bcd2cda78ec3f77
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

5 files changed, 9 insertions, 4 deletions

diff --git a/src/gui/kernel/qwindowsysteminterface.cpp b/src/gui/kernel/qwindowsysteminterface.cpp
index 34519cd91b..3f27094845 100644
--- a/src/gui/kernel/qwindowsysteminterface.cpp
+++ b/src/gui/kernel/qwindowsysteminterface.cpp
@@ -265,12 +265,12 @@ void QWindowSystemInterface::handleWindowScreenChanged(QWindow *window, QScreen
     QWindowSystemInterfacePrivate::handleWindowSystemEvent(e);
 }
 
-void QWindowSystemInterface::handleApplicationStateChanged(Qt::ApplicationState newState, bool forcePropagate)
+QT_DEFINE_QPA_EVENT_HANDLER(void, handleApplicationStateChanged, Qt::ApplicationState newState, bool forcePropagate)
 {
     Q_ASSERT(QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::ApplicationState));
     QWindowSystemInterfacePrivate::ApplicationStateChangedEvent *e =
         new QWindowSystemInterfacePrivate::ApplicationStateChangedEvent(newState, forcePropagate);
-    QWindowSystemInterfacePrivate::handleWindowSystemEvent(e);
+    QWindowSystemInterfacePrivate::handleWindowSystemEvent<Delivery>(e);
 }
 
 /*!
diff --git a/src/gui/kernel/qwindowsysteminterface.h b/src/gui/kernel/qwindowsysteminterface.h
index e582787dd9..e91c79749d 100644
--- a/src/gui/kernel/qwindowsysteminterface.h
+++ b/src/gui/kernel/qwindowsysteminterface.h
@@ -179,6 +179,7 @@ public:
     static void handleWindowStateChanged(QWindow *window, Qt::WindowState newState, int oldState = -1);
     static void handleWindowScreenChanged(QWindow *window, QScreen *newScreen);
 
+    template<typename Delivery = QWindowSystemInterface::DefaultDelivery>
     static void handleApplicationStateChanged(Qt::ApplicationState newState, bool forcePropagate = false);
 
 #ifndef QT_NO_DRAGANDDROP
diff --git a/src/plugins/platforms/ios/qiosapplicationstate.mm b/src/plugins/platforms/ios/qiosapplicationstate.mm
index 7b923e4692..13e7e1150f 100644
--- a/src/plugins/platforms/ios/qiosapplicationstate.mm
+++ b/src/plugins/platforms/ios/qiosapplicationstate.mm
@@ -39,6 +39,8 @@
 
 #include "qiosapplicationstate.h"
 
+#include "qiosglobal.h"
+
 #include <qpa/qwindowsysteminterface.h>
 #include <QtCore/qcoreapplication.h>
 
@@ -72,8 +74,8 @@ static Qt::ApplicationState qtApplicationState(UIApplicationState uiApplicationS
 static void handleApplicationStateChanged(UIApplicationState uiApplicationState)
 {
     Qt::ApplicationState state = qtApplicationState(uiApplicationState);
-    QWindowSystemInterface::handleApplicationStateChanged(state);
-    QWindowSystemInterface::flushWindowSystemEvents();
+    qCDebug(lcQpaApplication) << "moved to" << state;
+    QWindowSystemInterface::handleApplicationStateChanged<QWindowSystemInterface::SynchronousDelivery>(state);
 }
 
 QT_BEGIN_NAMESPACE
diff --git a/src/plugins/platforms/ios/qiosglobal.h b/src/plugins/platforms/ios/qiosglobal.h
index f74e3004cc..14e06aa37c 100644
--- a/src/plugins/platforms/ios/qiosglobal.h
+++ b/src/plugins/platforms/ios/qiosglobal.h
@@ -47,6 +47,7 @@
 
 QT_BEGIN_NAMESPACE
 
+Q_DECLARE_LOGGING_CATEGORY(lcQpaApplication);
 Q_DECLARE_LOGGING_CATEGORY(lcQpaInputMethods);
 
 #if !defined(QT_NO_DEBUG)
diff --git a/src/plugins/platforms/ios/qiosglobal.mm b/src/plugins/platforms/ios/qiosglobal.mm
index 1482ffc7af..8de6481444 100644
--- a/src/plugins/platforms/ios/qiosglobal.mm
+++ b/src/plugins/platforms/ios/qiosglobal.mm
@@ -44,6 +44,7 @@
 
 QT_BEGIN_NAMESPACE
 
+Q_LOGGING_CATEGORY(lcQpaApplication, "qt.qpa.application");
 Q_LOGGING_CATEGORY(lcQpaInputMethods, "qt.qpa.input.methods");
 
 bool isQtApplication()