Add the event loop quitlock feature to QtCore.

A feature of a ref-counted quit (managed by a quit-lock class)
is added to both QEventLoop and QCoreApplication.

This allows, for example, an event loop to quit() when there is
no more work for it to do.

quitOnLastWindowClosed is implemented in terms of the refcount in
QCoreApplication so that jobs can be completed before the
application quits.

Change-Id: I14c8f4e7ee12bbf81a6e5849290d4c8ff37fa110
Reviewed-by: David Faure <faure@kde.org>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>

3 files changed, 22 insertions, 11 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index ea562c75b8..9f7bc24119 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -107,8 +107,6 @@ int QGuiApplicationPrivate::mousePressX = 0;
 int QGuiApplicationPrivate::mousePressY = 0;
 int QGuiApplicationPrivate::mouse_double_click_distance = 5;
 
-bool QGuiApplicationPrivate::quitOnLastWindowClosed = true;
-
 static Qt::LayoutDirection layout_direction = Qt::LeftToRight;
 static bool force_reverse = false;
 
@@ -1388,14 +1386,14 @@ void QGuiApplicationPrivate::notifyActiveWindowChange(QWindow *)
 
 void QGuiApplication::setQuitOnLastWindowClosed(bool quit)
 {
-    QGuiApplicationPrivate::quitOnLastWindowClosed = quit;
+    QCoreApplication::setQuitLockEnabled(quit);
 }
 
 
 
 bool QGuiApplication::quitOnLastWindowClosed()
 {
-    return QGuiApplicationPrivate::quitOnLastWindowClosed;
+    return QCoreApplication::isQuitLockEnabled();
 }
 
 
@@ -1403,11 +1401,6 @@ bool QGuiApplication::quitOnLastWindowClosed()
 void QGuiApplicationPrivate::emitLastWindowClosed()
 {
     if (qGuiApp && qGuiApp->d_func()->in_exec) {
-        if (QGuiApplicationPrivate::quitOnLastWindowClosed) {
-            // get ready to quit, this event might be removed if the
-            // event loop is re-entered, however
-            QGuiApplication::postEvent(qApp, new QEvent(QEvent::Quit));
-        }
         emit qGuiApp->lastWindowClosed();
     }
 }
diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index 6d3e650c32..2f1cfa509d 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -183,8 +183,6 @@ public:
     QStyleHints *styleHints;
     QInputPanel *inputPanel;
 
-    static bool quitOnLastWindowClosed;
-
     static QList<QObject *> generic_plugin_list;
 #ifndef QT_NO_SHORTCUT
     QShortcutMap shortcutMap;
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index e85d8379fa..4436884359 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -165,6 +165,14 @@ 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();
@@ -499,7 +507,19 @@ void QWindow::setWindowState(Qt::WindowState state)
 void QWindow::setTransientParent(QWindow *parent)
 {
     Q_D(QWindow);
+
+    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