QOffscreenSurface: add a constructor taking a parent object

Just like all QObject subclasses. Use a delegating constructor
call to share the code from the existing constructor.

Change-Id: Ia3c893ccc4c94883e61337f8952d80b665c17fbf
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

src/gui/kernel/qoffscreensurface.cpp

@@ -121,14 +121,16 @@ public:
 
 
 /*!
-    Creates an offscreen surface for the \a targetScreen.
+    \since 5.10
+
+    Creates an offscreen surface for the \a targetScreen with the given \a parent.
 
     The underlying platform surface is not created until create() is called.
 
     \sa setScreen(), create()
 */
-QOffscreenSurface::QOffscreenSurface(QScreen *targetScreen)
+QOffscreenSurface::QOffscreenSurface(QScreen *targetScreen, QObject *parent)
-    : QObject(*new QOffscreenSurfacePrivate(), 0)
+    : QObject(*new QOffscreenSurfacePrivate(), parent)
     , QSurface(Offscreen)
 {
     Q_D(QOffscreenSurface);
@@ -143,6 +145,18 @@ QOffscreenSurface::QOffscreenSurface(QScreen *targetScreen)
     connect(d->screen, SIGNAL(destroyed(QObject*)), this, SLOT(screenDestroyed(QObject*)));
 }
 
+/*!
+    Creates an offscreen surface for the \a targetScreen.
+
+    The underlying platform surface is not created until create() is called.
+
+    \sa setScreen(), create()
+*/
+QOffscreenSurface::QOffscreenSurface(QScreen *targetScreen)
+    : QOffscreenSurface(targetScreen, nullptr)
+{
+}
+
 
 /*!
     Destroys the offscreen surface.

src/gui/kernel/qoffscreensurface.h

@@ -57,7 +57,8 @@ class Q_GUI_EXPORT QOffscreenSurface : public QObject, public QSurface
     Q_DECLARE_PRIVATE(QOffscreenSurface)
 
 public:
-
+    // ### Qt 6: merge overloads
+    explicit QOffscreenSurface(QScreen *screen, QObject *parent = Q_NULLPTR);
     explicit QOffscreenSurface(QScreen *screen = Q_NULLPTR);
     virtual ~QOffscreenSurface();