Debug logging support for QNativeGestureEvent

The most useful information is what kind of gesture the event
represents, but it was missing until now.

Also added a line of documentation about the NativeGesture event type.

Change-Id: I1ba3c951dcc5751e937d762d9b647ab0bf8d93b8
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>

src/corelib/global/qnamespace.h

@@ -98,6 +98,7 @@ Qt {
 #ifndef QT_NO_GESTURES
     Q_ENUMS(GestureState)
     Q_ENUMS(GestureType)
+    Q_ENUMS(NativeGestureType)
 #endif
     Q_ENUMS(CursorMoveStyle)
     Q_ENUMS(TimerType)

src/corelib/kernel/qcoreevent.cpp

@@ -184,6 +184,7 @@ QT_BEGIN_NAMESPACE
     \value MouseMove                        Mouse move (QMouseEvent).
     \value MouseTrackingChange              The mouse tracking state has changed.
     \value Move                             Widget's position changed (QMoveEvent).
+    \value NativeGesture                    The system has detected a gesture (QNativeGestureEvent).
     \value OrientationChange                The screens orientation has changes (QScreenOrientationChangeEvent)
     \value Paint                            Screen update necessary (QPaintEvent).
     \value PaletteChange                    Palette of the widget changed.

src/gui/kernel/qevent.cpp

@@ -3595,6 +3595,12 @@ public:
         static const int enumIdx = QObject::staticQtMetaObject.indexOfEnumerator("FocusReason");
         return QObject::staticQtMetaObject.enumerator(enumIdx).valueToKey(reason);
     }
+
+    static const char *nativeGestureTypeToString(Qt::NativeGestureType type)
+    {
+        static const int enumIdx = QObject::staticQtMetaObject.indexOfEnumerator("NativeGestureType");
+        return QObject::staticQtMetaObject.enumerator(enumIdx).valueToKey(type);
+    }
 };
 } // namespace
 
@@ -3775,7 +3781,8 @@ QDebug operator<<(QDebug dbg, const QEvent *e)
 #  ifndef QT_NO_GESTURES
     case QEvent::NativeGesture: {
         const QNativeGestureEvent *ne = static_cast<const QNativeGestureEvent *>(e);
-        dbg << "QNativeGestureEvent(localPos=" << ne->localPos() << ", value=" << ne->value() << ')';
+        dbg << "QNativeGestureEvent(" << DebugHelper::nativeGestureTypeToString(ne->gestureType())
+            << "localPos=" << ne->localPos() << ", value=" << ne->value() << ')';
     }
          break;
 #  endif // !QT_NO_GESTURES