2 files changed, 17 insertions, 4 deletions
diff --git a/src/gui/effects/qgraphicseffect.cpp b/src/gui/effects/qgraphicseffect.cpp
index 4f7ffc8..dafea52 100644
--- a/src/gui/effects/qgraphicseffect.cpp
+++ b/src/gui/effects/qgraphicseffect.cpp
@@ -374,10 +374,14 @@ QGraphicsEffectSourcePrivate::~QGraphicsEffectSourcePrivate()
     invalidateCache();
 }
 
-void QGraphicsEffectSourcePrivate::invalidateCache(bool effectRectChanged) const
+void QGraphicsEffectSourcePrivate::invalidateCache(InvalidateReason reason) const
 {
-    if (effectRectChanged && m_cachedMode != QGraphicsEffect::PadToEffectiveBoundingRect)
+    if (m_cachedMode != QGraphicsEffect::PadToEffectiveBoundingRect
+        && (reason == EffectRectChanged
+            || reason == TransformChanged
+               && m_cachedSystem == Qt::LogicalCoordinates))
         return;
+
     QPixmapCache::remove(m_cacheKey);
 }
 
@@ -523,7 +527,7 @@ void QGraphicsEffect::updateBoundingRect()
     Q_D(QGraphicsEffect);
     if (d->source) {
         d->source->d_func()->effectBoundingRectChanged();
-        d->source->d_func()->invalidateCache(true);
+        d->source->d_func()->invalidateCache(QGraphicsEffectSourcePrivate::EffectRectChanged);
     }
 }
 
diff --git a/src/gui/effects/qgraphicseffect_p.h b/src/gui/effects/qgraphicseffect_p.h
index 0011eef..cab7a48 100644
--- a/src/gui/effects/qgraphicseffect_p.h
+++ b/src/gui/effects/qgraphicseffect_p.h
@@ -108,6 +108,13 @@ public:
         , m_cachedMode(QGraphicsEffect::PadToTransparentBorder)
     {}
 
+    enum InvalidateReason
+    {
+        TransformChanged,
+        EffectRectChanged,
+        SourceChanged
+    };
+
     virtual ~QGraphicsEffectSourcePrivate();
     virtual void detach() = 0;
     virtual QRectF boundingRect(Qt::CoordinateSystem system) const = 0;
@@ -121,7 +128,9 @@ public:
     virtual QPixmap pixmap(Qt::CoordinateSystem system, QPoint *offset = 0,
                            QGraphicsEffect::PixmapPadMode mode = QGraphicsEffect::PadToTransparentBorder) const = 0;
     virtual void effectBoundingRectChanged() = 0;
-    void invalidateCache(bool effectRectChanged = false) const;
+
+    void invalidateCache(InvalidateReason reason = SourceChanged) const;
+    Qt::CoordinateSystem currentCachedSystem() const { return m_cachedSystem; }
 
     friend class QGraphicsScenePrivate;
     friend class QGraphicsItem;