5 files changed, 41 insertions, 2 deletions
diff --git a/src/gui/graphicsview/qgraphicseffect.cpp b/src/gui/graphicsview/qgraphicseffect.cpp
index f9a99fc..76a3feb 100644
--- a/src/gui/graphicsview/qgraphicseffect.cpp
+++ b/src/gui/graphicsview/qgraphicseffect.cpp
@@ -108,6 +108,9 @@ QGraphicsEffectSource::QGraphicsEffectSource(QGraphicsEffectSourcePrivate &dd, Q
 QGraphicsEffectSource::~QGraphicsEffectSource()
 {}
 
+QRect QGraphicsEffectSource::deviceRect() const
+{ return d_func()->deviceRect(); }
+
 QRectF QGraphicsEffectSource::boundingRect(Qt::CoordinateSystem system) const
 { return d_func()->boundingRect(system); }
 
@@ -709,7 +712,8 @@ void QGraphicsShadowEffect::draw(QPainter *painter, QGraphicsEffectSource *sourc
     qreal delta = d->radius * 3;
     blurRect.adjust(-delta, -delta, delta, delta);
     blurRect |= sourceRect;
-    const QRect effectRect = blurRect.toAlignedRect();
+    QRect effectRect = blurRect.toAlignedRect();
+    effectRect &= source->deviceRect();
 
     QPixmap pixmap(effectRect.size());
     pixmap.fill(Qt::transparent);
diff --git a/src/gui/graphicsview/qgraphicseffect.h b/src/gui/graphicsview/qgraphicseffect.h
index 8cf80b9..0125ebc 100644
--- a/src/gui/graphicsview/qgraphicseffect.h
+++ b/src/gui/graphicsview/qgraphicseffect.h
@@ -74,6 +74,7 @@ public:
     void update();
 
     QRectF boundingRect(Qt::CoordinateSystem coordinateSystem = Qt::LogicalCoordinates) const;
+    QRect deviceRect() const;
     QPixmap pixmap(Qt::CoordinateSystem system = Qt::LogicalCoordinates, QPoint *offset = 0) const;
 
 protected:
diff --git a/src/gui/graphicsview/qgraphicseffect_p.h b/src/gui/graphicsview/qgraphicseffect_p.h
index 5348ae9..9e6e2a1 100644
--- a/src/gui/graphicsview/qgraphicseffect_p.h
+++ b/src/gui/graphicsview/qgraphicseffect_p.h
@@ -74,6 +74,7 @@ public:
     virtual ~QGraphicsEffectSourcePrivate() {}
     virtual void detach() = 0;
     virtual QRectF boundingRect(Qt::CoordinateSystem system) const = 0;
+    virtual QRect deviceRect() const = 0;
     virtual const QGraphicsItem *graphicsItem() const = 0;
     virtual const QStyleOption *styleOption() const = 0;
     virtual void draw(QPainter *p) = 0;
diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 9d9c3af..976ffa3 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -10048,10 +10048,34 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
     QGraphicsScenePrivate *scened = item->d_ptr->scene->d_func();
 
     const QRectF sourceRect = boundingRect(system);
-    const QRect effectRect = item->graphicsEffect()->boundingRectFor(sourceRect).toAlignedRect();
+    QRect effectRect = item->graphicsEffect()->boundingRectFor(sourceRect).toAlignedRect();
     if (offset)
         *offset = sourceRect.toAlignedRect().topLeft();
 
+    if (deviceCoordinates) {
+        // Clip to viewport rect.
+        int left, top, right, bottom;
+        effectRect.getCoords(&left, &top, &right, &bottom);
+        if (left < 0) {
+            if (offset)
+                offset->rx() += -left;
+            effectRect.setX(0);
+        }
+        if (top < 0) {
+            if (offset)
+                offset->ry() += -top;
+            effectRect.setY(0);
+        }
+        // NB! We use +-1 for historical reasons (see QRect documentation).
+        if (right + 1 > info->widget->width())
+            effectRect.setRight(info->widget->width() - 1);
+        if (bottom + 1 > info->widget->height())
+            effectRect.setBottom(info->widget->height() -1);
+    }
+
+    if (effectRect.isEmpty())
+        return QPixmap();
+
     QPixmap pixmap(effectRect.size());
     pixmap.fill(Qt::transparent);
     QPainter pixmapPainter(&pixmap);
diff --git a/src/gui/graphicsview/qgraphicsitem_p.h b/src/gui/graphicsview/qgraphicsitem_p.h
index 69d8b5f..8b7f5b5 100644
--- a/src/gui/graphicsview/qgraphicsitem_p.h
+++ b/src/gui/graphicsview/qgraphicsitem_p.h
@@ -557,6 +557,15 @@ public:
     inline const QStyleOption *styleOption() const
     { return info ? info->option : 0; }
 
+    inline QRect deviceRect() const
+    {
+        if (!info || !info->widget) {
+            qWarning("QGraphicsEffectSource::deviceRect: Not yet implemented, lacking device context");
+            return QRect();
+        }
+        return info->widget->rect();
+    }
+
     QRectF boundingRect(Qt::CoordinateSystem system) const;
     void draw(QPainter *);
     QPixmap pixmap(Qt::CoordinateSystem system, QPoint *offset) const;