3 files changed, 31 insertions, 43 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index bd214e11f7..368af582be 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -10810,6 +10810,7 @@ void QGraphicsItemEffectSourcePrivate::draw(QPainter *painter)
     }
 }
 
+// sourceRect must be in the given coordinate system
 QRect QGraphicsItemEffectSourcePrivate::paddedEffectRect(Qt::CoordinateSystem system, QGraphicsEffect::PixmapPadMode mode, const QRectF &sourceRect, bool *unpadded) const
 {
     QRectF effectRectF;
@@ -10819,7 +10820,8 @@ QRect QGraphicsItemEffectSourcePrivate::paddedEffectRect(Qt::CoordinateSystem sy
 
     if (mode == QGraphicsEffect::PadToEffectiveBoundingRect) {
         if (info) {
-            effectRectF = item->graphicsEffect()->boundingRectFor(boundingRect(Qt::DeviceCoordinates));
+            QRectF deviceRect = system == Qt::DeviceCoordinates ? sourceRect : info->painter->worldTransform().mapRect(sourceRect);
+            effectRectF = item->graphicsEffect()->boundingRectFor(deviceRect);
             if (unpadded)
                 *unpadded = (effectRectF.size() == sourceRect.size());
             if (info && system == Qt::LogicalCoordinates)
@@ -10868,30 +10870,6 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
         return static_cast<QGraphicsPixmapItem *>(item)->pixmap();
     }
 
-    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).
-        QPaintDevice *device = info->painter->device();
-        const int deviceWidth = device->width();
-        const int deviceHeight = device->height();
-        if (right + 1 > deviceWidth)
-            effectRect.setRight(deviceWidth - 1);
-        if (bottom + 1 > deviceHeight)
-            effectRect.setBottom(deviceHeight -1);
-
-    }
     if (effectRect.isEmpty())
         return QPixmap();
 
diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index afea082386..4ee2301806 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -4714,31 +4714,18 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
         if (sourced->currentCachedSystem() != Qt::LogicalCoordinates
             && sourced->lastEffectTransform != painter->worldTransform())
         {
-            bool unclipped = false;
             if (sourced->lastEffectTransform.type() <= QTransform::TxTranslate
                 && painter->worldTransform().type() <= QTransform::TxTranslate)
             {
-                QRectF itemRect = item->boundingRect();
-                if (!item->d_ptr->children.isEmpty())
-                    itemRect |= item->childrenBoundingRect();
+                QRectF sourceRect = sourced->boundingRect(Qt::DeviceCoordinates);
+                QRect effectRect = sourced->paddedEffectRect(Qt::DeviceCoordinates, sourced->currentCachedMode(), sourceRect);
 
-                QRectF oldSourceRect = sourced->lastEffectTransform.mapRect(itemRect);
-                QRectF newSourceRect = painter->worldTransform().mapRect(itemRect);
-
-                QRect oldEffectRect = sourced->paddedEffectRect(sourced->currentCachedSystem(), sourced->currentCachedMode(), oldSourceRect);
-                QRect newEffectRect = sourced->paddedEffectRect(sourced->currentCachedSystem(), sourced->currentCachedMode(), newSourceRect);
-
-                QRect deviceRect(0, 0, painter->device()->width(), painter->device()->height());
-                if (deviceRect.contains(oldEffectRect) && deviceRect.contains(newEffectRect)) {
-                    sourced->setCachedOffset(newEffectRect.topLeft());
-                    unclipped = true;
-                }
+                sourced->setCachedOffset(effectRect.topLeft());
+            } else {
+                sourced->invalidateCache(QGraphicsEffectSourcePrivate::TransformChanged);
             }
 
             sourced->lastEffectTransform = painter->worldTransform();
-
-            if (!unclipped)
-                sourced->invalidateCache(QGraphicsEffectSourcePrivate::TransformChanged);
         }
 
         item->d_ptr->graphicsEffect->draw(painter);
diff --git a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
index 795431bd4e..1007d618c2 100644
--- a/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
+++ b/tests/auto/qgraphicseffect/tst_qgraphicseffect.cpp
@@ -72,6 +72,7 @@ private slots:
     void drawPixmapItem();
     void deviceCoordinateTranslateCaching();
     void inheritOpacity();
+    void dropShadowClipping();
 };
 
 void tst_QGraphicsEffect::initTestCase()
@@ -590,6 +591,28 @@ void tst_QGraphicsEffect::inheritOpacity()
     QTRY_VERIFY(item->numRepaints > numRepaints);
 }
 
+void tst_QGraphicsEffect::dropShadowClipping()
+{
+    QImage img(128, 128, QImage::Format_ARGB32_Premultiplied);
+    img.fill(0xffffffff);
+
+    QGraphicsScene scene;
+    QGraphicsRectItem *item = new QGraphicsRectItem(-5, -500, 10, 1000);
+    item->setGraphicsEffect(new QGraphicsDropShadowEffect);
+    item->setPen(Qt::NoPen);
+    item->setBrush(Qt::red);
+
+    scene.addItem(item);
+
+    QPainter p(&img);
+    scene.render(&p, img.rect(), QRect(-64, -64, 128, 128));
+    p.end();
+
+    for (int y = 1; y < img.height(); ++y)
+        for (int x = 0; x < img.width(); ++x)
+            QCOMPARE(img.pixel(x, y), img.pixel(x, y-1));
+}
+
 QTEST_MAIN(tst_QGraphicsEffect)
 #include "tst_qgraphicseffect.moc"