From fc8adfea9f5e09e5f47ac4e592e5d9db471caede Mon Sep 17 00:00:00 2001
From: Simon Hausmann <simon.hausmann@digia.com>
Date: Fri, 29 Nov 2013 13:21:38 +0100
Subject: [PATCH] Introduce helper for QML to allow creating QWidget
 hierarchies
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Commit 1259c5768e410361bcd8b5cf0c2057a2ebabda83 in qtdeclarative removed the
ability to create QWidgets in QML by giving them the correct parent, which
requires calling QWidget::setParent instead of QObject::setParent. This patch
introduces a hook that will allow QtQml to give widgets a proper parent.

Change-Id: I84c57ca5032582c43e405219343d55ac9cf2ffa0
Reviewed-by: Jørgen Lind <jorgen.lind@theqtcompany.com>
---
 src/corelib/kernel/qobject.cpp                  |  1 +
 src/corelib/kernel/qobject_p.h                  |  1 +
 src/widgets/kernel/qapplication.cpp             |  3 +++
 src/widgets/kernel/qwidget.cpp                  |  8 ++++++++
 src/widgets/kernel/qwidget_p.h                  |  2 ++
 .../auto/widgets/kernel/qwidget/tst_qwidget.cpp | 17 +++++++++++++++++
 6 files changed, 32 insertions(+)

diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 223de0c8e0..2f9ef9ca4a 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -177,6 +177,7 @@ void (*QAbstractDeclarativeData::parentChanged)(QAbstractDeclarativeData *, QObj
 void (*QAbstractDeclarativeData::signalEmitted)(QAbstractDeclarativeData *, QObject *, int, void **) = 0;
 int  (*QAbstractDeclarativeData::receivers)(QAbstractDeclarativeData *, const QObject *, int) = 0;
 bool (*QAbstractDeclarativeData::isSignalConnected)(QAbstractDeclarativeData *, const QObject *, int) = 0;
+void (*QAbstractDeclarativeData::setWidgetParent)(QObject *, QObject *) = 0;
 
 QObjectData::~QObjectData() {}
 
diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index b663bc8d8c..dba5f0265f 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -87,6 +87,7 @@ public:
     static void (*signalEmitted)(QAbstractDeclarativeData *, QObject *, int, void **);
     static int  (*receivers)(QAbstractDeclarativeData *, const QObject *, int);
     static bool (*isSignalConnected)(QAbstractDeclarativeData *, const QObject *, int);
+    static void (*setWidgetParent)(QObject *, QObject *); // Used by the QML engine to specify parents for widgets. Set by QtWidgets.
 };
 
 // This is an implementation of QAbstractDeclarativeData that is identical with
diff --git a/src/widgets/kernel/qapplication.cpp b/src/widgets/kernel/qapplication.cpp
index bf05b2029b..392db60e2b 100644
--- a/src/widgets/kernel/qapplication.cpp
+++ b/src/widgets/kernel/qapplication.cpp
@@ -630,6 +630,9 @@ void QApplicationPrivate::initialize()
     // needed for a static build.
     qRegisterWidgetsVariant();
 
+    // needed for widgets in QML
+    QAbstractDeclarativeData::setWidgetParent = QWidgetPrivate::setWidgetParentHelper;
+
     if (application_type != QApplicationPrivate::Tty)
         (void) QApplication::style();  // trigger creation of application style
 #ifndef QT_NO_STATEMACHINE
diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 7b7600fdc3..403e64d1ba 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -12779,6 +12779,14 @@ void QWidget::clearMask()
     setMask(QRegion());
 }
 
+void QWidgetPrivate::setWidgetParentHelper(QObject *widgetAsObject, QObject *newParent)
+{
+    Q_ASSERT(widgetAsObject->isWidgetType());
+    Q_ASSERT(!newParent || newParent->isWidgetType());
+    QWidget *widget = static_cast<QWidget*>(widgetAsObject);
+    widget->setParent(static_cast<QWidget*>(newParent));
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qwidget.cpp"
diff --git a/src/widgets/kernel/qwidget_p.h b/src/widgets/kernel/qwidget_p.h
index 50a8066a41..afc2cfc06b 100644
--- a/src/widgets/kernel/qwidget_p.h
+++ b/src/widgets/kernel/qwidget_p.h
@@ -653,6 +653,8 @@ public:
     virtual void resolveSamples() { }
 #endif
 
+    static void setWidgetParentHelper(QObject *widgetAsObject, QObject *newParent);
+
     // Variables.
     // Regular pointers (keep them together to avoid gaps on 64 bit architectures).
     QWExtra *extra;
diff --git a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
index 000cefb524..8f3f12e7ff 100644
--- a/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
+++ b/tests/auto/widgets/kernel/qwidget/tst_qwidget.cpp
@@ -439,6 +439,8 @@ private slots:
 
     void resizeStaticContentsChildWidget_QTBUG35282();
 
+    void qmlSetParentHelper();
+
 private:
     bool ensureScreenSize(int width, int height);
     QWidget *testWidget;
@@ -10396,5 +10398,20 @@ void tst_QWidget::resizeStaticContentsChildWidget_QTBUG35282()
     QVERIFY(childWidget.numPaintEvents >= 1);
 }
 
+void tst_QWidget::qmlSetParentHelper()
+{
+#ifdef QT_BUILD_INTERNAL
+    QWidget parent;
+    QWidget child;
+    QVERIFY(QAbstractDeclarativeData::setWidgetParent);
+    QAbstractDeclarativeData::setWidgetParent(&child, &parent);
+    QVERIFY(child.parentWidget() == &parent);
+    QAbstractDeclarativeData::setWidgetParent(&child, 0);
+    QVERIFY(!child.parentWidget());
+#else
+    QSKIP("Needs QT_BUILD_INTERNAL");
+#endif
+}
+
 QTEST_MAIN(tst_QWidget)
 #include "tst_qwidget.moc"