Only call active effects in the effect chain

Each effect is able to declare itself as currently being active,
that is transforming windows or painting or screen or doing anything
during the current rendered frame.

This change eliminates the hottest path inside KWin identified by
callgrind.

REVIEW: 102449

effects.cpp

@@ -97,7 +97,6 @@ EffectsHandlerImpl::EffectsHandlerImpl(CompositingType type)
     , fullscreen_effect(0)
     , next_window_quad_type(EFFECT_QUAD_TYPE_START)
     , mouse_poll_ref_count(0)
-    , current_paint_effectframe(0)
 {
     Workspace *ws = Workspace::self();
     connect(ws, SIGNAL(currentDesktopChanged(int)), this, SLOT(slotDesktopChanged(int)));
@@ -203,54 +202,54 @@ void EffectsHandlerImpl::reconfigure()
 // the idea is that effects call this function again which calls the next one
 void EffectsHandlerImpl::prePaintScreen(ScreenPrePaintData& data, int time)
 {
-    if (current_paint_screen < loaded_effects.size()) {
-        loaded_effects[current_paint_screen++].second->prePaintScreen(data, time);
-        --current_paint_screen;
+    if (m_currentPaintScreenIterator != m_activeEffects.end()) {
+        (*m_currentPaintScreenIterator++)->prePaintScreen(data, time);
+        --m_currentPaintScreenIterator;
     }
     // no special final code
 }
 
 void EffectsHandlerImpl::paintScreen(int mask, QRegion region, ScreenPaintData& data)
 {
-    if (current_paint_screen < loaded_effects.size()) {
-        loaded_effects[current_paint_screen++].second->paintScreen(mask, region, data);
-        --current_paint_screen;
+    if (m_currentPaintScreenIterator != m_activeEffects.end()) {
+        (*m_currentPaintScreenIterator++)->paintScreen(mask, region, data);
+        --m_currentPaintScreenIterator;
     } else
         scene->finalPaintScreen(mask, region, data);
 }
 
 void EffectsHandlerImpl::postPaintScreen()
 {
-    if (current_paint_screen < loaded_effects.size()) {
-        loaded_effects[current_paint_screen++].second->postPaintScreen();
-        --current_paint_screen;
+    if (m_currentPaintScreenIterator != m_activeEffects.end()) {
+        (*m_currentPaintScreenIterator++)->postPaintScreen();
+        --m_currentPaintScreenIterator;
     }
     // no special final code
 }
 
 void EffectsHandlerImpl::prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time)
 {
-    if (current_paint_window < loaded_effects.size()) {
-        loaded_effects[current_paint_window++].second->prePaintWindow(w, data, time);
-        --current_paint_window;
+    if (m_currentPaintWindowIterator != m_activeEffects.end()) {
+        (*m_currentPaintWindowIterator++)->prePaintWindow(w, data, time);
+        --m_currentPaintWindowIterator;
     }
     // no special final code
 }
 
 void EffectsHandlerImpl::paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data)
 {
-    if (current_paint_window < loaded_effects.size()) {
-        loaded_effects[current_paint_window++].second->paintWindow(w, mask, region, data);
-        --current_paint_window;
+    if (m_currentPaintWindowIterator != m_activeEffects.end()) {
+        (*m_currentPaintWindowIterator++)->paintWindow(w, mask, region, data);
+        --m_currentPaintWindowIterator;
     } else
         scene->finalPaintWindow(static_cast<EffectWindowImpl*>(w), mask, region, data);
 }
 
 void EffectsHandlerImpl::paintEffectFrame(EffectFrame* frame, QRegion region, double opacity, double frameOpacity)
 {
-    if (current_paint_effectframe < loaded_effects.size()) {
-        loaded_effects[current_paint_effectframe++].second->paintEffectFrame(frame, region, opacity, frameOpacity);
-        --current_paint_effectframe;
+    if (m_currentPaintEffectFrameIterator != m_activeEffects.end()) {
+        (*m_currentPaintEffectFrameIterator++)->paintEffectFrame(frame, region, opacity, frameOpacity);
+        --m_currentPaintEffectFrameIterator;
     } else {
         const EffectFrameImpl* frameImpl = static_cast<const EffectFrameImpl*>(frame);
         frameImpl->finalRender(region, opacity, frameOpacity);
@@ -259,9 +258,9 @@ void EffectsHandlerImpl::paintEffectFrame(EffectFrame* frame, QRegion region, do
 
 void EffectsHandlerImpl::postPaintWindow(EffectWindow* w)
 {
-    if (current_paint_window < loaded_effects.size()) {
-        loaded_effects[current_paint_window++].second->postPaintWindow(w);
-        --current_paint_window;
+    if (m_currentPaintWindowIterator != m_activeEffects.end()) {
+        (*m_currentPaintWindowIterator++)->postPaintWindow(w);
+        --m_currentPaintWindowIterator;
     }
     // no special final code
 }
@@ -276,18 +275,18 @@ bool EffectsHandlerImpl::provides(Effect::Feature ef)
 
 void EffectsHandlerImpl::drawWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data)
 {
-    if (current_draw_window < loaded_effects.size()) {
-        loaded_effects[current_draw_window++].second->drawWindow(w, mask, region, data);
-        --current_draw_window;
+    if (m_currentDrawWindowIterator != m_activeEffects.end()) {
+        (*m_currentDrawWindowIterator++)->drawWindow(w, mask, region, data);
+        --m_currentDrawWindowIterator;
     } else
         scene->finalDrawWindow(static_cast<EffectWindowImpl*>(w), mask, region, data);
 }
 
 void EffectsHandlerImpl::buildQuads(EffectWindow* w, WindowQuadList& quadList)
 {
-    if (current_build_quads < loaded_effects.size()) {
-        loaded_effects[current_build_quads++].second->buildQuads(w, quadList);
-        --current_build_quads;
+    if (m_currentBuildQuadsIterator != m_activeEffects.end()) {
+        (*m_currentBuildQuadsIterator++)->buildQuads(w, quadList);
+        --m_currentBuildQuadsIterator;
     }
 }
 
@@ -309,10 +308,17 @@ bool EffectsHandlerImpl::decorationSupportsBlurBehind() const
 // start another painting pass
 void EffectsHandlerImpl::startPaint()
 {
-    assert(current_paint_screen == 0);
-    assert(current_paint_window == 0);
-    assert(current_draw_window == 0);
-    assert(current_build_quads == 0);
+    m_activeEffects.clear();
+    for(QVector< KWin::EffectPair >::iterator it = loaded_effects.begin(); it != loaded_effects.end(); ++it) {
+        if (it->second->isActive()) {
+            m_activeEffects << it->second;
+        }
+    }
+    m_currentDrawWindowIterator = m_activeEffects.begin();
+    m_currentPaintWindowIterator = m_activeEffects.begin();
+    m_currentPaintScreenIterator = m_activeEffects.begin();
+    m_currentPaintEffectFrameIterator = m_activeEffects.begin();
+    m_currentBuildQuadsIterator = m_activeEffects.begin();
 }
 
 void EffectsHandlerImpl::slotClientMaximized(KWin::Client *c, KDecorationDefines::MaximizeMode maxMode)
@@ -1087,10 +1093,6 @@ QStringList EffectsHandlerImpl::listOfEffects() const
 bool EffectsHandlerImpl::loadEffect(const QString& name, bool checkDefault)
 {
     Workspace::self()->addRepaintFull();
-    assert(current_paint_screen == 0);
-    assert(current_paint_window == 0);
-    assert(current_draw_window == 0);
-    assert(current_build_quads == 0);
 
     if (!name.startsWith(QLatin1String("kwin4_effect_")))
         kWarning(1212) << "Effect names usually have kwin4_effect_ prefix" ;
@@ -1201,10 +1203,6 @@ bool EffectsHandlerImpl::loadEffect(const QString& name, bool checkDefault)
 void EffectsHandlerImpl::unloadEffect(const QString& name)
 {
     Workspace::self()->addRepaintFull();
-    assert(current_paint_screen == 0);
-    assert(current_paint_window == 0);
-    assert(current_draw_window == 0);
-    assert(current_build_quads == 0);
 
     for (QMap< int, EffectPair >::iterator it = effect_order.begin(); it != effect_order.end(); ++it) {
         if (it.value().first == name) {

effects.h

@@ -208,7 +208,14 @@ protected:
     QHash< long, int > registered_atoms;
     int next_window_quad_type;
     int mouse_poll_ref_count;
-    int current_paint_effectframe;
+
+private:
+    QList< Effect* > m_activeEffects;
+    QList< Effect* >::iterator m_currentDrawWindowIterator;
+    QList< Effect* >::iterator m_currentPaintWindowIterator;
+    QList< Effect* >::iterator m_currentPaintEffectFrameIterator;
+    QList< Effect* >::iterator m_currentPaintScreenIterator;
+    QList< Effect* >::iterator m_currentBuildQuadsIterator;
 };
 
 class EffectWindowImpl : public EffectWindow

effects/boxswitch/boxswitch.cpp

@@ -947,6 +947,11 @@ void BoxSwitchEffect::activateFromProxy(int mode, bool animate, bool showText, f
     }
 }
 
+bool BoxSwitchEffect::isActive() const
+{
+    return mActivated;
+}
+
 BoxSwitchEffect::ItemInfo::ItemInfo()
     : iconFrame(NULL)
 {

effects/boxswitch/boxswitch.h

@@ -55,6 +55,7 @@ public:
 
     virtual void windowInputMouseEvent(Window w, QEvent* e);
     virtual void* proxy();
+    virtual bool isActive() const;
     void activateFromProxy(int mode, bool animate, bool showText, float positioningFactor);
     void paintWindowsBox(const QRegion& region);
 

effects/coverswitch/coverswitch.cpp

@@ -995,4 +995,9 @@ void CoverSwitchEffect::slotWindowClosed(EffectWindow* c)
     }
 }
 
+bool CoverSwitchEffect::isActive() const
+{
+    return mActivated || stop || stopRequested;
+}
+
 } // namespace

effects/coverswitch/coverswitch.h

@@ -48,6 +48,7 @@ public:
     virtual void postPaintScreen();
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void windowInputMouseEvent(Window w, QEvent* e);
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/cube/cube.cpp

@@ -2087,4 +2087,9 @@ void CubeEffect::unregisterCubeInsideEffect(CubeInsideEffect* effect)
     m_cubeInsideEffects.removeAll(effect);
 }
 
+bool CubeEffect::isActive() const
+{
+    return activated;
+}
+
 } // namespace

effects/cube/cube.h

@@ -50,6 +50,7 @@ public:
     virtual bool borderActivated(ElectricBorder border);
     virtual void grabbedKeyboardEvent(QKeyEvent* e);
     virtual void windowInputMouseEvent(Window w, QEvent* e);
+    virtual bool isActive() const;
 
     // proxy functions
     virtual void* proxy();

effects/cube/cubeslide.cpp

@@ -617,4 +617,9 @@ void CubeSlideEffect::windowMovingChanged(float progress, RotationDirection dire
     effects->addRepaintFull();
 }
 
+bool CubeSlideEffect::isActive() const
+{
+    return !slideRotations.isEmpty();
+}
+
 } // namespace

effects/cube/cubeslide.h

@@ -42,6 +42,7 @@ public:
     virtual void postPaintScreen();
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/dashboard/dashboard.cpp

@@ -199,4 +199,9 @@ void DashboardEffect::slotWindowClosed(EffectWindow* w)
     }
 }
 
+bool DashboardEffect::isActive() const
+{
+    return transformWindow;
+}
+
 } // namespace

effects/dashboard/dashboard.h

@@ -43,6 +43,7 @@ public:
     virtual void propagate();
     virtual void reconfigure(ReconfigureFlags);
     virtual void unpropagate();
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowAdded(EffectWindow* c);

effects/desktopgrid/desktopgrid.cpp

@@ -1221,10 +1221,10 @@ void DesktopGridEffect::globalShortcutChanged(const QKeySequence& seq)
     shortcut = KShortcut(seq);
 }
 
-bool DesktopGridEffect::isMotionManagerMovingWindows()
+bool DesktopGridEffect::isMotionManagerMovingWindows() const
 {
     if (isUsingPresentWindows()) {
-        QList<WindowMotionManager>::iterator it;
+        QList<WindowMotionManager>::const_iterator it;
         for (it = m_managers.begin(); it != m_managers.end(); ++it) {
             if ((*it).areWindowsMoving())
                 return true;
@@ -1372,6 +1372,11 @@ void DesktopGridEffect::desktopsRemoved(int old)
     effects->addRepaintFull();
 }
 
+bool DesktopGridEffect::isActive() const
+{
+    return timeline.currentValue() != 0 || (isUsingPresentWindows() && isMotionManagerMovingWindows());
+}
+
 /************************************************
 * DesktopButtonView
 ************************************************/

effects/desktopgrid/desktopgrid.h

@@ -75,6 +75,7 @@ public:
     virtual void windowInputMouseEvent(Window w, QEvent* e);
     virtual void grabbedKeyboardEvent(QKeyEvent* e);
     virtual bool borderActivated(ElectricBorder border);
+    virtual bool isActive() const;
 
     enum { LayoutPager, LayoutAutomatic, LayoutCustom }; // Layout modes
 
@@ -106,7 +107,7 @@ private:
     void setup();
     void setupGrid();
     void finish();
-    bool isMotionManagerMovingWindows();
+    bool isMotionManagerMovingWindows() const;
     bool isUsingPresentWindows() const;
     QRectF moveGeometryToDesktop(int desktop) const;
     void desktopsAdded(int old);

effects/dialogparent/dialogparent.cpp

@@ -95,4 +95,9 @@ void DialogParentEffect::slotWindowClosed(EffectWindow* w)
     effectStrength.remove(w);
 }
 
+bool DialogParentEffect::isActive() const
+{
+    return !effectStrength.isEmpty();
+}
+
 } // namespace

effects/dialogparent/dialogparent.h

@@ -46,6 +46,8 @@ public:
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintWindow(EffectWindow* w);
 
+    virtual bool isActive() const;
+
 public Q_SLOTS:
     void slotWindowClosed(EffectWindow *c);
     void slotWindowActivated(EffectWindow *c);

effects/dimscreen/dimscreen.cpp

@@ -108,4 +108,10 @@ void DimScreenEffect::slotWindowActivated(EffectWindow *w)
         }
     }
 }
+
+bool DimScreenEffect::isActive() const
+{
+    return mActivated;
+}
+
 } // namespace

effects/dimscreen/dimscreen.h

@@ -39,6 +39,7 @@ public:
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void postPaintScreen();
     virtual void paintWindow(EffectWindow *w, int mask, QRegion region, WindowPaintData &data);
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowActivated(EffectWindow *w);

effects/explosion/explosion.cpp

@@ -202,5 +202,10 @@ void ExplosionEffect::slotWindowDeleted(EffectWindow* c)
     mWindows.remove(c);
 }
 
+bool ExplosionEffect::isActive() const
+{
+    return mActiveAnimations > 0;
+}
+
 } // namespace
 

effects/explosion/explosion.h

@@ -47,6 +47,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/fade/fade.cpp

@@ -199,4 +199,9 @@ bool FadeEffect::isFadeWindow(EffectWindow* w)
     return (!w->isDesktop() && !w->isUtility());
 }
 
+bool FadeEffect::isActive() const
+{
+    return !windows.isEmpty();
+}
+
 } // namespace

effects/fade/fade.h

@@ -36,6 +36,7 @@ public:
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
+    virtual bool isActive() const;
 
     // TODO react also on virtual desktop changes
 

effects/fadedesktop/fadedesktop.cpp

@@ -107,6 +107,11 @@ void FadeDesktopEffect::slotDesktopChanged(int old)
     effects->addRepaintFull();
 }
 
+bool FadeDesktopEffect::isActive() const
+{
+    return m_fading;
+}
+
 } // namespace
 
 #include "fadedesktop.moc"

effects/fadedesktop/fadedesktop.h

@@ -39,6 +39,7 @@ public:
     virtual void postPaintScreen();
     virtual void prePaintWindow(EffectWindow *w, WindowPrePaintData &data, int time);
     virtual void paintWindow(EffectWindow *w, int mask, QRegion region, WindowPaintData &data);
+    virtual bool isActive() const;
 
 private Q_SLOTS:
     void slotDesktopChanged(int old);

effects/fallapart/fallapart.cpp

@@ -160,4 +160,9 @@ void FallApartEffect::slotWindowDeleted(EffectWindow* c)
     windows.remove(c);
 }
 
+bool FallApartEffect::isActive() const
+{
+    return !windows.isEmpty();
+}
+
 } // namespace

effects/fallapart/fallapart.h

@@ -37,6 +37,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowClosed(EffectWindow *c);

effects/flipswitch/flipswitch.cpp

@@ -934,6 +934,11 @@ void FlipSwitchEffect::grabbedKeyboardEvent(QKeyEvent* e)
     }
 }
 
+bool FlipSwitchEffect::isActive() const
+{
+    return m_active;
+}
+
 //*************************************************************
 // Item Info
 //*************************************************************

effects/flipswitch/flipswitch.h

@@ -47,6 +47,7 @@ public:
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual bool borderActivated(ElectricBorder border);
     virtual void grabbedKeyboardEvent(QKeyEvent* e);
+    virtual bool isActive() const;
 
     static bool supported();
 private Q_SLOTS:

effects/glide/glide.cpp

@@ -226,6 +226,11 @@ bool GlideEffect::isGlideWindow(EffectWindow* w)
     return true;
 }
 
+bool GlideEffect::isActive() const
+{
+    return !windows.isEmpty();
+}
+
 GlideEffect::WindowInfo::WindowInfo()
     : deleted(false)
     , added(false)

effects/glide/glide.h

@@ -41,6 +41,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintWindow(EffectWindow* w);
+    virtual bool isActive() const;
 
     static bool supported();
 public Q_SLOTS:

effects/highlightwindow/highlightwindow.cpp

@@ -257,4 +257,9 @@ void HighlightWindowEffect::finishHighlighting()
         m_windowOpacity.constBegin().key()->addRepaintFull();
 }
 
+bool HighlightWindowEffect::isActive() const
+{
+    return !m_windowOpacity.isEmpty();
+}
+
 } // namespace

effects/highlightwindow/highlightwindow.h

@@ -36,6 +36,7 @@ public:
 
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowAdded(EffectWindow* w);

effects/invert/invert.cpp

@@ -161,6 +161,11 @@ void InvertEffect::toggleWindow()
     effects->activeWindow()->addRepaintFull();
 }
 
+bool InvertEffect::isActive() const
+{
+    return m_valid && (m_allWindows || !m_windows.isEmpty());
+}
+
 } // namespace
 
 #include "invert.moc"

effects/invert/invert.h

@@ -44,6 +44,7 @@ public:
     virtual void prePaintScreen(ScreenPrePaintData &data, int time);
     virtual void prePaintWindow(EffectWindow *w, WindowPrePaintData &data, int time);
     virtual void paintEffectFrame(KWin::EffectFrame* frame, QRegion region, double opacity, double frameOpacity);
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/login/login.cpp

@@ -117,4 +117,9 @@ bool LoginEffect::isLoginSplash(EffectWindow* w)
     return false;
 }
 
+bool LoginEffect::isActive() const
+{
+    return login_window != NULL;
+}
+
 } // namespace

effects/login/login.h

@@ -38,6 +38,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void reconfigure(ReconfigureFlags);
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowClosed(EffectWindow *w);

effects/logout/logout.cpp

@@ -400,4 +400,9 @@ void LogoutEffect::slotPropertyNotify(EffectWindow* w, long a)
     canDoPersistent = true;
 }
 
+bool LogoutEffect::isActive() const
+{
+    return progress != 0;
+}
+
 } // namespace

effects/logout/logout.h

@@ -44,6 +44,7 @@ public:
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
     virtual void postPaintScreen();
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
+    virtual bool isActive() const;
 public Q_SLOTS:
     void slotWindowAdded(EffectWindow* w);
     void slotWindowClosed(EffectWindow *w);

effects/lookingglass/lookingglass.cpp

@@ -247,6 +247,11 @@ void LookingGlassEffect::postPaintScreen()
     }
 }
 
+bool LookingGlassEffect::isActive() const
+{
+    return m_valid && m_enabled;
+}
+
 } // namespace
 
 #include "lookingglass.moc"

effects/lookingglass/lookingglass.h

@@ -48,6 +48,7 @@ public:
 
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/magiclamp/magiclamp.cpp

@@ -353,4 +353,9 @@ void MagicLampEffect::slotWindowUnminimized(EffectWindow* w)
     mTimeLineWindows[w]->setCurrentTime(mAnimationDuration);
 }
 
+bool MagicLampEffect::isActive() const
+{
+    return !mTimeLineWindows.isEmpty();
+}
+
 } // namespace

effects/magiclamp/magiclamp.h

@@ -40,6 +40,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/magnifier/magnifier.cpp

@@ -232,6 +232,11 @@ void MagnifierEffect::slotMouseChanged(const QPoint& pos, const QPoint& old,
         effects->addRepaintFull();
 }
 
+bool MagnifierEffect::isActive() const
+{
+    return zoom != 1.0 || zoom != target_zoom;
+}
+
 } // namespace
 
 #include "magnifier.moc"

effects/magnifier/magnifier.h

@@ -41,6 +41,7 @@ public:
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
     static bool supported();
 private slots:
     void zoomIn();

effects/minimizeanimation/minimizeanimation.cpp

@@ -148,5 +148,10 @@ void MinimizeAnimationEffect::slotWindowUnminimized(EffectWindow* w)
     timeline->setCurrentTime(timeline->duration());
 }
 
+bool MinimizeAnimationEffect::isActive() const
+{
+    return !mTimeLineWindows.isEmpty();
+}
+
 } // namespace
 

effects/minimizeanimation/minimizeanimation.h

@@ -43,6 +43,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowDeleted(EffectWindow *w);

effects/mousemark/mousemark.cpp

@@ -186,6 +186,12 @@ MouseMarkEffect::Mark MouseMarkEffect::createArrow(QPoint arrow_start, QPoint ar
     return ret;
 }
 
+bool MouseMarkEffect::isActive() const
+{
+    return !marks.isEmpty() || !drawing.isEmpty();
+}
+
+
 } // namespace
 
 #include "mousemark.moc"

effects/mousemark/mousemark.h

@@ -36,6 +36,7 @@ public:
     ~MouseMarkEffect();
     virtual void reconfigure(ReconfigureFlags);
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
+    virtual bool isActive() const;
 private slots:
     void clear();
     void clearLast();

effects/outline/outline.cpp

@@ -75,4 +75,9 @@ void OutlineEffect::slotShowOutline(const QRect& geometry)
     effects->addRepaint(geometry);
 }
 
+bool OutlineEffect::isActive() const
+{
+    return m_active;
+}
+
 } // namespace

effects/outline/outline.h

@@ -35,6 +35,7 @@ public:
 
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
     virtual bool provides(Feature feature);
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotShowOutline(const QRect &geometry);

effects/presentwindows/presentwindows.cpp

@@ -2043,6 +2043,11 @@ void PresentWindowsEffect::globalShortcutChangedClass(const QKeySequence& seq)
     shortcutClass = KShortcut(seq);
 }
 
+bool PresentWindowsEffect::isActive() const
+{
+    return m_activated || m_motionManager.managingWindows();
+}
+
 /************************************************
 * CloseWindowView
 ************************************************/

effects/presentwindows/presentwindows.h

@@ -104,6 +104,7 @@ public:
     virtual bool borderActivated(ElectricBorder border);
     virtual void windowInputMouseEvent(Window w, QEvent *e);
     virtual void grabbedKeyboardEvent(QKeyEvent *e);
+    virtual bool isActive() const;
 
     enum { LayoutNatural, LayoutRegularGrid, LayoutFlexibleGrid }; // Layout modes
     enum PresentWindowsMode {

effects/scalein/scalein.cpp

@@ -95,4 +95,9 @@ void ScaleInEffect::slotWindowClosed(EffectWindow* c)
     delete mTimeLineWindows.take(c);
 }
 
+bool ScaleInEffect::isActive() const
+{
+    return !mTimeLineWindows.isEmpty();
+}
+
 } // namespace

effects/scalein/scalein.h

@@ -38,6 +38,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintWindow(EffectWindow* w);
+    virtual bool isActive() const;
     // TODO react also on virtual desktop changes
 public Q_SLOTS:
     void slotWindowAdded(EffectWindow* c);

effects/screenshot/screenshot.cpp

@@ -258,4 +258,9 @@ void ScreenShotEffect::convertFromGLImage(QImage &img, int w, int h)
     img = img.mirrored();
 }
 
+bool ScreenShotEffect::isActive() const
+{
+    return m_scheduledScreenshot != NULL;
+}
+
 } // namespace

effects/screenshot/screenshot.h

@@ -40,6 +40,7 @@ public:
     ScreenShotEffect();
     virtual ~ScreenShotEffect();
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
     static bool supported();
     static void convertFromGLImage(QImage &img, int w, int h);

effects/sheet/sheet.cpp

@@ -186,6 +186,11 @@ bool SheetEffect::isSheetWindow(EffectWindow* w)
     return (w->isModal() || w->data(IsSheetWindow).toBool());
 }
 
+bool SheetEffect::isActive() const
+{
+    return !windows.isEmpty();
+}
+
 SheetEffect::WindowInfo::WindowInfo()
     : deleted(false)
     , added(false)

effects/sheet/sheet.h

@@ -40,6 +40,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintWindow(EffectWindow* w);
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/slide/slide.cpp

@@ -230,6 +230,11 @@ void SlideEffect::slotDesktopChanged(int old, int current)
     effects->addRepaintFull();
 }
 
+bool SlideEffect::isActive() const
+{
+    return slide;
+}
+
 } // namespace
 
 #include "slide.moc"

effects/slide/slide.h

@@ -41,6 +41,7 @@ public:
     virtual void postPaintScreen();
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
+    virtual bool isActive() const;
 
 private Q_SLOTS:
     void slotDesktopChanged(int old, int current);

effects/slideback/slideback.cpp

@@ -376,4 +376,9 @@ QRect SlideBackEffect::getModalGroupGeometry(EffectWindow *w)
     return modalGroupGeometry;
 }
 
+bool SlideBackEffect::isActive() const
+{
+    return motionManager.managingWindows();
+}
+
 } //Namespace

effects/slideback/slideback.h

@@ -40,6 +40,7 @@ public:
 
     virtual void prePaintScreen(ScreenPrePaintData &data, int time);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowAdded(EffectWindow *w);

effects/slidingpopups/slidingpopups.cpp

@@ -246,4 +246,10 @@ void SlidingPopupsEffect::slotPropertyNotify(EffectWindow* w, long a)
     }
     mWindowsData[ w ] = animData;
 }
+
+bool SlidingPopupsEffect::isActive() const
+{
+    return !mAppearingWindows.isEmpty() || !mDisappearingWindows.isEmpty();
+}
+
 } // namespace

effects/slidingpopups/slidingpopups.h

@@ -41,6 +41,7 @@ public:
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintWindow(EffectWindow* w);
     virtual void reconfigure(ReconfigureFlags flags);
+    virtual bool isActive() const;
     // TODO react also on virtual desktop changes
 
 public Q_SLOTS:

effects/snaphelper/snaphelper.cpp

@@ -216,4 +216,9 @@ void SnapHelperEffect::slotWindowFinishUserMovedResized(EffectWindow *w)
     }
 }
 
+bool SnapHelperEffect::isActive() const
+{
+    return m_timeline.currentValue() != 0.0;
+}
+
 } // namespace

effects/snaphelper/snaphelper.h

@@ -39,6 +39,7 @@ public:
 
     virtual void prePaintScreen(ScreenPrePaintData &data, int time);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/startupfeedback/startupfeedback.cpp

@@ -417,4 +417,9 @@ QRect StartupFeedbackEffect::feedbackRect() const
     return rect;
 }
 
+bool StartupFeedbackEffect::isActive() const
+{
+    return m_active;
+}
+
 } // namespace

effects/startupfeedback/startupfeedback.h

@@ -41,6 +41,7 @@ public:
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
     static bool supported();
 

effects/taskbarthumbnail/taskbarthumbnail.cpp

@@ -154,4 +154,9 @@ void TaskbarThumbnailEffect::slotPropertyNotify(EffectWindow* w, long a)
     }
 }
 
+bool TaskbarThumbnailEffect::isActive() const
+{
+    return !thumbnails.isEmpty();
+}
+
 } // namespace

effects/taskbarthumbnail/taskbarthumbnail.h

@@ -38,6 +38,7 @@ public:
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
+    virtual bool isActive() const;
 
 public Q_SLOTS:
     void slotWindowAdded(EffectWindow *w);

effects/thumbnailaside/thumbnailaside.cpp

@@ -172,6 +172,11 @@ void ThumbnailAsideEffect::repaintAll()
     effects->addRepaint(d.rect);
 }
 
+bool ThumbnailAsideEffect::isActive() const
+{
+    return !windows.isEmpty();
+}
+
 } // namespace
 
 #include "thumbnailaside.moc"

effects/thumbnailaside/thumbnailaside.h

@@ -48,6 +48,7 @@ private slots:
     void slotWindowClosed(EffectWindow *w);
     void slotWindowGeometryShapeChanged(EffectWindow *w, const QRect &old);
     void slotWindowDamaged(EffectWindow* w, const QRect& damage);
+    virtual bool isActive() const;
 private:
     void addThumbnail(EffectWindow* w);
     void removeThumbnail(EffectWindow* w);

effects/trackmouse/trackmouse.cpp

@@ -209,4 +209,9 @@ void TrackMouseEffect::loadTexture()
     textureSize = im.size();
 }
 
+bool TrackMouseEffect::isActive() const
+{
+    return active;
+}
+
 } // namespace

effects/trackmouse/trackmouse.h

@@ -41,6 +41,7 @@ public:
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
     virtual void postPaintScreen();
     virtual void reconfigure(ReconfigureFlags);
+    virtual bool isActive() const;
 private slots:
     void toggle();
     void slotMouseChanged(const QPoint& pos, const QPoint& old,

effects/windowgeometry/windowgeometry.cpp

@@ -178,3 +178,7 @@ void WindowGeometry::slotWindowStepUserMovedResized(EffectWindow *w, const QRect
     }
 }
 
+bool WindowGeometry::isActive() const
+{
+    return iAmActive;
+}

effects/windowgeometry/windowgeometry.h

@@ -38,6 +38,7 @@ public:
     }
     void reconfigure(ReconfigureFlags);
     void paintScreen(int mask, QRegion region, ScreenPaintData &data);
+    virtual bool isActive() const;
 
 private slots:
     void toggle();

effects/wobblywindows/wobblywindows.cpp

@@ -1218,6 +1218,10 @@ void WobblyWindowsEffect::heightRingLinearMean(Pair** data_pointer, WindowWobbly
     wwi.buffer = tmp;
 }
 
+bool WobblyWindowsEffect::isActive() const
+{
+    return !windows.isEmpty();
+}
 
 } // namespace KWin
 

effects/wobblywindows/wobblywindows.h

@@ -35,6 +35,7 @@ public:
     virtual void prePaintWindow(EffectWindow* w, WindowPrePaintData& data, int time);
     virtual void paintWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 
     // Wobbly model parameters
     void setStiffness(qreal stiffness);

effects/zoom/zoom.cpp

@@ -492,6 +492,11 @@ void ZoomEffect::focusChanged(int px, int py, int rx, int ry, int rwidth, int rh
     }
 }
 
+bool ZoomEffect::isActive() const
+{
+    return zoom != 1.0 || zoom != target_zoom;
+}
+
 } // namespace
 
 #include "zoom.moc"

effects/zoom/zoom.h

@@ -43,6 +43,7 @@ public:
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
     virtual void postPaintScreen();
+    virtual bool isActive() const;
 private slots:
     void zoomIn();
     void zoomOut();

libkwineffects/kwineffects.cpp

@@ -171,6 +171,11 @@ bool Effect::provides(Feature)
     return false;
 }
 
+bool Effect::isActive() const
+{
+    return true;
+}
+
 void Effect::drawWindow(EffectWindow* w, int mask, QRegion region, WindowPaintData& data)
 {
     effects->drawWindow(w, mask, region, data);
@@ -229,11 +234,7 @@ double Effect::animationTime(int defaultTime)
 //****************************************
 
 EffectsHandler::EffectsHandler(CompositingType type)
-    : current_paint_screen(0)
-    , current_paint_window(0)
-    , current_draw_window(0)
-    , current_build_quads(0)
-    , compositing_type(type)
+    : compositing_type(type)
 {
     if (compositing_type == NoCompositing)
         return;

libkwineffects/kwineffects.h

@@ -447,6 +447,23 @@ public:
 
     virtual bool borderActivated(ElectricBorder border);
 
+    /**
+     * Overwrite this method to indicate whether your effect will be doing something in
+     * the next frame to be rendered. If the method returns @c false the effect will be
+     * excluded from the chained methods in the next rendered frame.
+     *
+     * This method is called always directly before the paint loop begins. So it is totally
+     * fine to e.g. react on a window event, issue a repaint to trigger an animation and
+     * change a flag to indicate that this method returns @c true.
+     *
+     * As the method is called each frame, you should not perform complex calculations.
+     * Best use just a boolean flag.
+     *
+     * The default implementation of this method returns @c true.
+     * @since 4.8
+     **/
+    virtual bool isActive() const;
+
     static int displayWidth();
     static int displayHeight();
     static QPoint cursorPos();
@@ -1023,10 +1040,6 @@ protected:
     QHash< QString, KLibrary* > effect_libraries;
     QList< InputWindowPair > input_windows;
     //QHash< QString, EffectFactory* > effect_factories;
-    int current_paint_screen;
-    int current_paint_window;
-    int current_draw_window;
-    int current_build_quads;
     CompositingType compositing_type;
 };