DecorationPlugin becomes a QObject

This allows to move the slot to reset the decoration when compositing
got toggled from Workspace to DecorationPlugin and the custom cleanup
is no longer needed.

REVIEW: 109909

decorations.cpp

@@ -33,8 +33,9 @@ namespace KWin
 
 KWIN_SINGLETON_FACTORY(DecorationPlugin)
 
-DecorationPlugin::DecorationPlugin(QObject *)
-    : KDecorationPlugins(KGlobal::config())
+DecorationPlugin::DecorationPlugin(QObject *parent)
+    : QObject(parent)
+    , KDecorationPlugins(KGlobal::config())
     , m_disabled(false)
 {
     defaultPlugin = "kwin3_oxygen";
@@ -145,4 +146,12 @@ QList< int > DecorationPlugin::supportedColors() const
     return ret;
 }
 
+void DecorationPlugin::resetCompositing()
+{
+    if (m_disabled) {
+        return;
+    }
+    factory()->reset(SettingCompositing);
+}
+
 } // namespace

decorations.h

@@ -29,8 +29,9 @@ namespace KWin
 {
 
 class DecorationPlugin
-    : public KDecorationPlugins
+    : public QObject, public KDecorationPlugins
 {
+    Q_OBJECT
 public:
     virtual ~DecorationPlugin();
     virtual bool provides(Requirement);
@@ -53,6 +54,9 @@ public:
      * @todo: remove KDE5
      **/
     QList<int> supportedColors() const;
+
+public Q_SLOTS:
+    void resetCompositing();
 protected:
     virtual void error(const QString& error_msg);
 private:

workspace.cpp

@@ -208,7 +208,7 @@ Workspace::Workspace(bool restore)
 
     m_compositor = Compositor::create(this);
     connect(this, SIGNAL(currentDesktopChanged(int,KWin::Client*)), m_compositor, SLOT(addRepaintFull()));
-    connect(m_compositor, SIGNAL(compositingToggled(bool)), SLOT(slotCompositingToggled()));
+    connect(m_compositor, SIGNAL(compositingToggled(bool)), decorationPlugin(), SLOT(resetCompositing()));
 
     new DBusInterface(this);
 
@@ -537,7 +537,6 @@ Workspace::~Workspace()
 
     delete rootInfo;
     delete supportWindow;
-    delete decorationPlugin();
     delete startup;
     delete Placement::self();
     delete client_keys_dialog;
@@ -1811,15 +1810,6 @@ QString Workspace::supportInformation() const
     return support;
 }
 
-void Workspace::slotCompositingToggled()
-{
-    // notify decorations that composition state has changed
-    DecorationPlugin *deco = DecorationPlugin::self();
-    if (!deco->isDisabled()) {
-        deco->factory()->reset(SettingCompositing);
-    }
-}
-
 void Workspace::slotToggleCompositing()
 {
     if (m_compositor) {

workspace.h

@@ -402,7 +402,6 @@ public slots:
 
     void reconfigure();
     void slotReconfigure();
-    void slotCompositingToggled();
 
     void slotKillWindow();