Plumb application quit through platform plugin

If we have a platform plugin we ask the platform to quit, and if
not we fall back to the base implementation of QCoreApplication
that sends Quit events directly.

This allows the platform to involve the rest of the system in the
process. The platform will then come back with a spontaneous quit
via QWSI::handleApplicationTermination(), which will then send
the corresponding Quit even from QGuiApplication like normal.

Task-number: QTBUG-45262
Task-number: QTBUG-33235
Task-number: QTBUG-72013
Task-number: QTBUG-59782
Change-Id: I0000aaf7192e4b905933c5da0e53901c6c88f26a
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

4 files changed, 24 insertions, 0 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 37e8edb6f7..15955e2287 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -3641,6 +3641,14 @@ bool QGuiApplicationPrivate::shouldQuitInternal(const QWindowList &processedWind
     return true;
 }
 
+void QGuiApplicationPrivate::quit()
+{
+    if (auto *platformIntegration = QGuiApplicationPrivate::platformIntegration())
+        platformIntegration->quit();
+    else
+        QCoreApplicationPrivate::quit();
+}
+
 void QGuiApplicationPrivate::processApplicationTermination(QWindowSystemInterfacePrivate::WindowSystemEvent *windowSystemEvent)
 {
     QEvent event(QEvent::Quit);
diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index 2bbb5ae9a6..7e3c2931f3 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -105,6 +105,7 @@ public:
     void addQtOptions(QList<QCommandLineOption> *options) override;
 #endif
     virtual bool shouldQuit() override;
+    void quit() override;
 
     bool shouldQuitInternal(const QWindowList &processedWindows);
 
diff --git a/src/gui/kernel/qplatformintegration.cpp b/src/gui/kernel/qplatformintegration.cpp
index 1127ab43d2..634a04b791 100644
--- a/src/gui/kernel/qplatformintegration.cpp
+++ b/src/gui/kernel/qplatformintegration.cpp
@@ -529,6 +529,20 @@ void QPlatformIntegration::beep() const
 {
 }
 
+/*!
+   \since 6.0
+
+   Asks the platform to terminate the application.
+
+   Overrides should ensure there's a callback into the QWSI
+   function handleApplicationTermination so that the quit can
+   be propagated to QtGui and the application.
+*/
+void QPlatformIntegration::quit() const
+{
+    QWindowSystemInterface::handleApplicationTermination<QWindowSystemInterface::SynchronousDelivery>();
+}
+
 #ifndef QT_NO_OPENGL
 /*!
   Platform integration function for querying the OpenGL implementation type.
diff --git a/src/gui/kernel/qplatformintegration.h b/src/gui/kernel/qplatformintegration.h
index 638d373c3c..5083542e12 100644
--- a/src/gui/kernel/qplatformintegration.h
+++ b/src/gui/kernel/qplatformintegration.h
@@ -220,6 +220,7 @@ public:
     virtual void setApplicationIcon(const QIcon &icon) const;
 
     virtual void beep() const;
+    virtual void quit() const;
 
 #if QT_CONFIG(vulkan) || defined(Q_CLANG_QDOC)
     virtual QPlatformVulkanInstance *createPlatformVulkanInstance(QVulkanInstance *instance) const;