Make QQuickRenderControl usable (still private)

QQuickRenderControl needs a QQuickWindow in order to function. This
required the use of a private QQuickWindow constructor, meaning that
only friend classes of QQuickWindow could use QQuickRenderControl.

This change adds a factory function, QQuickRenderControl::createOffscreenWindow().

Task-number: QTBUG-38996
Change-Id: I92f6f1f60045934f3dd33c300352247852463c73
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>

4 files changed, 22 insertions, 2 deletions

diff --git a/src/quick/items/qquickrendercontrol.cpp b/src/quick/items/qquickrendercontrol.cpp
index 87a60b5cce..2842d7e933 100644
--- a/src/quick/items/qquickrendercontrol.cpp
+++ b/src/quick/items/qquickrendercontrol.cpp
@@ -239,6 +239,10 @@ void QQuickRenderControl::setWindow(QQuickWindow *window)
     d->window = window;
 }
 
+/*!
+  Returns the offscreen window.
+ */
+
 QQuickWindow *QQuickRenderControl::window() const
 {
     Q_D(const QQuickRenderControl);
@@ -246,6 +250,21 @@ QQuickWindow *QQuickRenderControl::window() const
 }
 
 /*!
+  Create an offscreen QQuickWindow for this render control,
+  unless the render control already has a window().
+
+  Returns the offscreen window if one is created, otherwise returns null.
+  The caller takes ownership of the window, and is responsible for deleting it.
+ */
+QQuickWindow *QQuickRenderControl::createOffscreenWindow()
+{
+    Q_D(QQuickRenderControl);
+    if (!d->window)
+        return new QQuickWindow(this);
+    return 0;
+}
+
+/*!
   \fn QWindow *QQuickRenderControl::renderWindow(QPoint *offset)
 
   Reimplemented in subclasses to return the real window this render control
diff --git a/src/quick/items/qquickrendercontrol_p.h b/src/quick/items/qquickrendercontrol_p.h
index e7b7759afa..cc30e37724 100644
--- a/src/quick/items/qquickrendercontrol_p.h
+++ b/src/quick/items/qquickrendercontrol_p.h
@@ -63,6 +63,7 @@ public:
     ~QQuickRenderControl();
 
     QQuickWindow *window() const;
+    QQuickWindow *createOffscreenWindow();
     virtual QWindow *renderWindow(QPoint *offset) { Q_UNUSED(offset); return 0; }
     static QWindow *renderWindowFor(QQuickWindow *win, QPoint *offset = 0);
 
diff --git a/src/quick/items/qquickwindow.h b/src/quick/items/qquickwindow.h
index 2572f31375..0d1aaf64f0 100644
--- a/src/quick/items/qquickwindow.h
+++ b/src/quick/items/qquickwindow.h
@@ -191,7 +191,7 @@ private Q_SLOTS:
 private:
     friend class QQuickItem;
     friend class QQuickWidget;
-    friend class QQuickWidgetPrivate;
+    friend class QQuickRenderControl;
     friend class QQuickAnimatorController;
     explicit QQuickWindow(QQuickRenderControl*);
     Q_DISABLE_COPY(QQuickWindow)
diff --git a/src/quickwidgets/qquickwidget.cpp b/src/quickwidgets/qquickwidget.cpp
index ec5d0bf8df..e63b0cc3c7 100644
--- a/src/quickwidgets/qquickwidget.cpp
+++ b/src/quickwidgets/qquickwidget.cpp
@@ -86,7 +86,7 @@ void QQuickWidgetPrivate::init(QQmlEngine* e)
     Q_Q(QQuickWidget);
 
     renderControl = new QQuickWidgetRenderControl(q);
-    offscreenWindow = new QQuickWindow(renderControl);
+    offscreenWindow = renderControl->createOffscreenWindow();
     offscreenWindow->setTitle(QString::fromLatin1("Offscreen"));
     // Do not call create() on offscreenWindow.
     createOffscreenSurface();