added necessary changes to enable ::region() slot for kcommondecoration

REVIEW: 107253

libkdecorations/kcommondecoration.cpp

@@ -334,6 +334,11 @@ void KCommonDecoration::objDestroyed(QObject *obj)
         m_previewWidget = 0;
 }
 
+QRegion KCommonDecoration::region(KDecorationDefines::Region r)
+{
+    return QRegion();
+}
+
 int KCommonDecoration::buttonsLeftWidth() const
 {
     return buttonContainerWidth(m_buttonsLeft);

libkdecorations/kcommondecoration.h

@@ -376,6 +376,16 @@ private Q_SLOTS:
     /* look out for buttons that have been destroyed. */
     void objDestroyed(QObject *obj);
 
+    /**
+     * This slot can be reimplemented to return the regions defined
+     * by KDecorationDefines::Region.
+     *
+     * The default implementation always returns an empty region.
+     *
+     * @since 4.10
+     */
+    QRegion region(KDecorationDefines::Region r);
+
 private:
     void resetLayout();
 

libkdecorations/kcommondecoration_p.cpp

@@ -126,3 +126,13 @@ void KCommonDecorationWrapper::wrapSetAlphaEnabled(bool enabled)
     setAlphaEnabled(enabled);
 }
 
+QRegion KCommonDecorationWrapper::region(KDecorationDefines::Region r)
+{
+    QRegion region;
+    QMetaObject::invokeMethod(decoration, "region",
+        Qt::DirectConnection,
+        Q_RETURN_ARG(QRegion, region),
+        Q_ARG(KDecorationDefines::Region,
+        KDecorationDefines::ExtendedBorderRegion));
+    return region;
+}

libkdecorations/kcommondecoration_p.h

@@ -62,6 +62,16 @@ public:
     virtual void padding(int &left, int &right, int &top, int &bottom) const;
 
     void wrapSetAlphaEnabled(bool enabled);
+
+public Q_SLOTS:
+    /**
+     * This slot can be reimplemented to return the regions defined
+     * by KDecorationDefines::Region.
+     *
+     * @since 4.10
+     */
+    QRegion region(KDecorationDefines::Region r);
+
 private:
     KCommonDecoration* decoration;
 };