Cleanup reference counting in QIcon class

It is better to use QSharedData and QExplicitlySharedDataPointer then
doing manual ref counting.

Change-Id: Icbb06d92102bcc906291238c5895a05e8d0e6de1
Reviewed-on: http://codereview.qt.nokia.com/1438
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Olivier Goffart <olivier.goffart@nokia.com>

src/gui/image/qicon.cpp

@@ -116,7 +116,7 @@ static void qt_cleanup_icon_cache()
 }
 
 QIconPrivate::QIconPrivate()
-    : engine(0), ref(1),
+    : engine(0),
     serialNum(serialNumCounter.fetchAndAddRelaxed(1)),
     detach_no(0),
     engine_version(2),
@@ -536,10 +536,7 @@ QIcon::QIcon(const QPixmap &pixmap)
 */
 QIcon::QIcon(const QIcon &other)
     :d(other.d)
-{
-    if (d)
-        d->ref.ref();
-}
+{}
 
 /*!
     Constructs an icon from the file with the given \a fileName. The
@@ -593,10 +590,7 @@ QIcon::QIcon(QIconEngineV2 *engine)
     Destroys the icon.
 */
 QIcon::~QIcon()
-{
-    if (d && !d->ref.deref())
-        delete d;
-}
+{}
 
 /*!
     Assigns the \a other icon to this icon and returns a reference to
@@ -604,10 +598,6 @@ QIcon::~QIcon()
 */
 QIcon &QIcon::operator=(const QIcon &other)
 {
-    if (other.d)
-        other.d->ref.ref();
-    if (d && !d->ref.deref())
-        delete d;
     d = other.d;
     return *this;
 }
@@ -775,8 +765,6 @@ void QIcon::detach()
                 x->v1RefCount->ref();
             }
             x->engine_version = d->engine_version;
-            if (!d->ref.deref())
-                delete d;
             d = x;
         }
         ++d->detach_no;

src/gui/image/qicon.h

@@ -132,14 +132,14 @@ public:
     Q_DUMMY_COMPARISON_OPERATOR(QIcon)
 
 private:
-    QIconPrivate *d;
+    QExplicitlySharedDataPointer<QIconPrivate> d;
 #if !defined(QT_NO_DATASTREAM)
     friend Q_GUI_EXPORT QDataStream &operator<<(QDataStream &, const QIcon &);
     friend Q_GUI_EXPORT QDataStream &operator>>(QDataStream &, QIcon &);
 #endif
 
 public:
-    typedef QIconPrivate * DataPtr;
+    typedef QExplicitlySharedDataPointer<QIconPrivate> DataPtr;
     inline DataPtr &data_ptr() { return d; }
 };
 

src/gui/image/qicon_p.h

@@ -63,7 +63,7 @@
 #ifndef QT_NO_ICON
 QT_BEGIN_NAMESPACE
 
-class QIconPrivate
+class QIconPrivate : public QSharedData
 {
 public:
     QIconPrivate();
@@ -81,7 +81,6 @@ public:
 
     QIconEngine *engine;
 
-    QAtomicInt ref;
     int serialNum;
     int detach_no;
     int engine_version;