Fix ref counted window close handling.

Instead of refcounting QWindow visibility, we ask the Application
subclass whether quitting is appropriate.

Task-Id: QTBUG-24120
Change-Id: Idd19cc1a3e5742fddded89c7638aaaa5e47c568d
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>

8 files changed, 65 insertions, 23 deletions

diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
index cf3ae1b7c5..80e42336d6 100644
--- a/src/corelib/kernel/qcoreapplication.cpp
+++ b/src/corelib/kernel/qcoreapplication.cpp
@@ -1506,8 +1506,14 @@ void QCoreApplicationPrivate::ref()
 
 void QCoreApplicationPrivate::deref()
 {
-    if (!quitLockRef.deref() && in_exec && quitLockRefEnabled)
-        QCoreApplication::postEvent(qApp, new QEvent(QEvent::Quit));
+    if (!quitLockRef.deref())
+        maybeQuit();
+}
+
+void QCoreApplicationPrivate::maybeQuit()
+{
+    if (quitLockRef.load() == 0 && in_exec && quitLockRefEnabled && shouldQuit())
+        QCoreApplication::postEvent(QCoreApplication::instance(), new QEvent(QEvent::Quit));
 }
 
 /*!
diff --git a/src/corelib/kernel/qcoreapplication_p.h b/src/corelib/kernel/qcoreapplication_p.h
index 861a046f16..112b313129 100644
--- a/src/corelib/kernel/qcoreapplication_p.h
+++ b/src/corelib/kernel/qcoreapplication_p.h
@@ -92,6 +92,10 @@ public:
     QAtomicInt quitLockRef;
     void ref();
     void deref();
+    virtual bool shouldQuit() {
+      return true;
+    }
+    void maybeQuit();
 
     static QThread *theMainThread;
     static QThread *mainThread();
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 4d80aafea5..5f50fe343a 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -1477,6 +1477,17 @@ void QGuiApplicationPrivate::emitLastWindowClosed()
     }
 }
 
+bool QGuiApplicationPrivate::shouldQuit()
+{
+    /* if there is no visible top-level window left, we allow the quit */
+    QWindowList list = QGuiApplication::topLevelWindows();
+    for (int i = 0; i < list.size(); ++i) {
+        QWindow *w = list.at(i);
+        if (w->visible())
+            return false;
+    }
+    return true;
+}
 
 /*!
     \property QGuiApplication::layoutDirection
diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index 7fafe0336d..f86d8264fa 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -74,6 +74,8 @@ public:
     virtual void notifyLayoutDirectionChange();
     virtual void notifyActiveWindowChange(QWindow *previous);
 
+    virtual bool shouldQuit();
+
     static Qt::KeyboardModifiers modifier_buttons;
     static Qt::MouseButtons mouse_buttons;
 
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 61ae2a2438..d15198c505 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -165,14 +165,6 @@ void QWindow::setVisible(bool visible)
         return;
     d->visible = visible;
     emit visibleChanged(visible);
-    if (QCoreApplication::instance() && !transientParent()) {
-        QCoreApplicationPrivate *applicationPrivate = static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(QCoreApplication::instance()));
-        if (visible) {
-            applicationPrivate->ref();
-        } else {
-            applicationPrivate->deref();
-        }
-    }
 
     if (!d->platformWindow)
         create();
@@ -514,15 +506,6 @@ void QWindow::setTransientParent(QWindow *parent)
     QWindow *previousParent = d->transientParent;
 
     d->transientParent = parent;
-
-    if (QCoreApplication::instance() && d->visible) {
-        QCoreApplicationPrivate *applicationPrivate = static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(QCoreApplication::instance()));
-        if (parent && !previousParent) {
-            applicationPrivate->deref();
-        } else if (!parent && previousParent) {
-            applicationPrivate->ref();
-        }
-    }
 }
 
 QWindow *QWindow::transientParent() const
@@ -1116,13 +1099,16 @@ void QWindowPrivate::maybeQuitOnLastWindowClosed()
         bool lastWindowClosed = true;
         for (int i = 0; i < list.size(); ++i) {
             QWindow *w = list.at(i);
-            if (!w->visible() || w->parent())
+            if (!w->visible())
                 continue;
             lastWindowClosed = false;
             break;
         }
-        if (lastWindowClosed)
+        if (lastWindowClosed) {
             QGuiApplicationPrivate::emitLastWindowClosed();
+            QCoreApplicationPrivate *applicationPrivate = static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(QCoreApplication::instance()));
+            applicationPrivate->maybeQuit();
+        }
     }
 
 }
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index 4387d2a287..b04925d85d 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -67,6 +67,7 @@
 #include "private/qstylesheetstyle_p.h"
 #include "private/qstyle_p.h"
 #include "qmessagebox.h"
+#include "qwidgetwindow_qpa_p.h"
 #include <QtWidgets/qgraphicsproxywidget.h>
 #include <QtGui/qstylehints.h>
 #include <QtGui/qinputmethod.h>
@@ -3289,6 +3290,20 @@ int QApplication::exec()
     return QGuiApplication::exec();
 }
 
+bool QApplicationPrivate::shouldQuit()
+{
+    /* if there is no non-withdrawn primary window left (except
+        the ones without QuitOnClose), we emit the lastWindowClosed
+        signal */
+    QWidgetList list = QApplication::topLevelWidgets();
+    for (int i = 0; i < list.size(); ++i) {
+        QWidget *w = list.at(i);
+        if (w->isVisible() && !w->parentWidget() && w->testAttribute(Qt::WA_QuitOnClose))
+            return false;
+    }
+    return true;
+}
+
 /*! \reimp
  */
 bool QApplication::notify(QObject *receiver, QEvent *e)
diff --git a/src/widgets/kernel/qapplication_p.h b/src/widgets/kernel/qapplication_p.h
index 790176afe3..e728868182 100644
--- a/src/widgets/kernel/qapplication_p.h
+++ b/src/widgets/kernel/qapplication_p.h
@@ -178,6 +178,8 @@ public:
     virtual void notifyLayoutDirectionChange();
     virtual void notifyActiveWindowChange(QWindow *);
 
+    virtual bool shouldQuit();
+
 #if defined(Q_WS_X11)
 #ifndef QT_NO_SETTINGS
     static bool x11_apply_settings();
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index f98f7fbe66..f095e475af 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -7410,8 +7410,24 @@ bool QWidgetPrivate::close_helper(CloseMode mode)
     // Attempt to close the application only if this has WA_QuitOnClose set and a non-visible parent
     quitOnClose = quitOnClose && (parentWidget.isNull() || !parentWidget->isVisible());
 
-    if (quitOnClose && q->windowHandle()) {
-        static_cast<QWindowPrivate*>(QObjectPrivate::get(q->windowHandle()))->maybeQuitOnLastWindowClosed();
+    if (quitOnClose) {
+        /* if there is no non-withdrawn primary window left (except
+           the ones without QuitOnClose), we emit the lastWindowClosed
+           signal */
+        QWidgetList list = QApplication::topLevelWidgets();
+        bool lastWindowClosed = true;
+        for (int i = 0; i < list.size(); ++i) {
+            QWidget *w = list.at(i);
+            if (!w->isVisible() || w->parentWidget() || !w->testAttribute(Qt::WA_QuitOnClose))
+                continue;
+            lastWindowClosed = false;
+            break;
+        }
+        if (lastWindowClosed) {
+            QGuiApplicationPrivate::emitLastWindowClosed();
+            QCoreApplicationPrivate *applicationPrivate = static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(QCoreApplication::instance()));
+            applicationPrivate->maybeQuit();
+        }
     }