Fix redraw bugs when using graphics effects in device coordinate mode.

QGraphicsEffect::boundingRectFor() needs the source bounding rect in
device coordinates. This patch fixes the documentation to reflect this,
and fixes some internal usage of boundingRectFor() to ensure it always
gets the device rect of the source.

Task-number: QTBUG-5918
Reviewed-by: Bjørn Erik Nilsen

5 files changed, 77 insertions, 9 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 90cc132..8bbe929 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -2584,6 +2584,35 @@ void QGraphicsItem::setGraphicsEffect(QGraphicsEffect *effect)
 /*!
     \internal
     \since 4.6
+    Returns the effective bounding rect of the given item space rect.
+    If the item has no effect, the rect is returned unmodified.
+    If the item has an effect, the effective rect can be extend beyond the
+    item's bounding rect, depending on the effect.
+
+    \sa boundingRect()
+*/
+QRectF QGraphicsItemPrivate::effectiveBoundingRect(const QRectF &rect) const
+{
+#ifndef QT_NO_GRAPHICSEFFECT
+    Q_Q(const QGraphicsItem);
+    QGraphicsEffect *effect = graphicsEffect;
+    if (scene && effect && effect->isEnabled()) {
+        QRectF sceneRect = q->mapRectToScene(rect);
+        QRectF sceneEffectRect;
+        foreach (QGraphicsView *view, scene->views()) {
+            QRectF deviceRect = view->d_func()->mapRectFromScene(sceneRect);
+            QRect deviceEffectRect = effect->boundingRectFor(deviceRect).toAlignedRect();
+            sceneEffectRect |= view->d_func()->mapRectToScene(deviceEffectRect);
+        }
+        return q->mapRectFromScene(sceneEffectRect);
+    }
+#endif //QT_NO_GRAPHICSEFFECT
+    return rect;
+}
+
+/*!
+    \internal
+    \since 4.6
     Returns the effective bounding rect of the item.
     If the item has no effect, this is the same as the item's bounding rect.
     If the item has an effect, the effective rect can be larger than the item's
@@ -2594,16 +2623,19 @@ void QGraphicsItem::setGraphicsEffect(QGraphicsEffect *effect)
 QRectF QGraphicsItemPrivate::effectiveBoundingRect() const
 {
 #ifndef QT_NO_GRAPHICSEFFECT
-    QGraphicsEffect *effect = graphicsEffect;
-    QRectF brect = effect && effect->isEnabled() ? effect->boundingRect() : q_ptr->boundingRect();
+    Q_Q(const QGraphicsItem);
+    QRectF brect = effectiveBoundingRect(q_ptr->boundingRect());
     if (ancestorFlags & QGraphicsItemPrivate::AncestorClipsChildren)
         return brect;
 
     const QGraphicsItem *effectParent = parent;
     while (effectParent) {
-        effect = effectParent->d_ptr->graphicsEffect;
-        if (effect && effect->isEnabled())
-            brect = effect->boundingRectFor(brect);
+        QGraphicsEffect *effect = effectParent->d_ptr->graphicsEffect;
+        if (scene && effect && effect->isEnabled()) {
+            const QRectF brectInParentSpace = q->mapRectToItem(effectParent, brect);
+            const QRectF effectRectInParentSpace = effectParent->d_ptr->effectiveBoundingRect(brectInParentSpace);
+            brect = effectParent->mapRectToItem(q, effectRectInParentSpace);
+        }
         if (effectParent->d_ptr->ancestorFlags & QGraphicsItemPrivate::AncestorClipsChildren)
             return brect;
         effectParent = effectParent->d_ptr->parent;
@@ -10649,17 +10681,21 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
     QGraphicsScenePrivate *scened = item->d_ptr->scene->d_func();
 
     const QRectF sourceRect = boundingRect(system);
-    QRect effectRect;
+    QRectF effectRectF;
 
     if (mode == QGraphicsEffect::PadToEffectiveBoundingRect) {
-        effectRect = item->graphicsEffect()->boundingRectFor(sourceRect).toAlignedRect();
+        effectRectF = item->graphicsEffect()->boundingRectFor(boundingRect(Qt::DeviceCoordinates));
+        if (system == Qt::LogicalCoordinates)
+            effectRectF = info->painter->worldTransform().inverted().mapRect(effectRectF);
     } else if (mode == QGraphicsEffect::PadToTransparentBorder) {
         // adjust by 1.5 to account for cosmetic pens
-        effectRect = sourceRect.adjusted(-1.5, -1.5, 1.5, 1.5).toAlignedRect();
+        effectRectF = sourceRect.adjusted(-1.5, -1.5, 1.5, 1.5);
     } else {
-        effectRect = sourceRect.toAlignedRect();
+        effectRectF = sourceRect;
     }
 
+    QRect effectRect = effectRectF.toAlignedRect();
+
     if (offset)
         *offset = effectRect.topLeft();
 
diff --git a/src/gui/graphicsview/qgraphicsitem_p.h b/src/gui/graphicsview/qgraphicsitem_p.h
index 8f9fe54..2d8de65 100644
--- a/src/gui/graphicsview/qgraphicsitem_p.h
+++ b/src/gui/graphicsview/qgraphicsitem_p.h
@@ -236,6 +236,8 @@ public:
     QRectF effectiveBoundingRect() const;
     QRectF sceneEffectiveBoundingRect() const;
 
+    QRectF effectiveBoundingRect(const QRectF &rect) const;
+
     virtual void resolveFont(uint inheritedMask)
     {
         for (int i = 0; i < children.size(); ++i)
diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index 3f9f443..ffe64aa 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -545,6 +545,32 @@ qint64 QGraphicsViewPrivate::verticalScroll() const
 
 /*!
     \internal
+
+    Maps the given rectangle to the scene using QTransform::mapRect()
+*/
+QRectF QGraphicsViewPrivate::mapRectToScene(const QRect &rect) const
+{
+    if (dirtyScroll)
+        const_cast<QGraphicsViewPrivate *>(this)->updateScroll();
+    QRectF scrolled = QRectF(rect.translated(scrollX, scrollY));
+    return identityMatrix ? scrolled : matrix.inverted().mapRect(scrolled);
+}
+
+
+/*!
+    \internal
+
+    Maps the given rectangle from the scene using QTransform::mapRect()
+*/
+QRectF QGraphicsViewPrivate::mapRectFromScene(const QRectF &rect) const
+{
+    if (dirtyScroll)
+        const_cast<QGraphicsViewPrivate *>(this)->updateScroll();
+    return (identityMatrix ? rect : matrix.mapRect(rect)).translated(-scrollX, -scrollY);
+}
+
+/*!
+    \internal
 */
 void QGraphicsViewPrivate::updateScroll()
 {
diff --git a/src/gui/graphicsview/qgraphicsview.h b/src/gui/graphicsview/qgraphicsview.h
index 2aed0e6..90576e5 100644
--- a/src/gui/graphicsview/qgraphicsview.h
+++ b/src/gui/graphicsview/qgraphicsview.h
@@ -278,6 +278,7 @@ private:
     friend class QGraphicsSceneWidget;
     friend class QGraphicsScene;
     friend class QGraphicsScenePrivate;
+    friend class QGraphicsItemPrivate;
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QGraphicsView::CacheMode)
diff --git a/src/gui/graphicsview/qgraphicsview_p.h b/src/gui/graphicsview/qgraphicsview_p.h
index cd161ad..d4b718e 100644
--- a/src/gui/graphicsview/qgraphicsview_p.h
+++ b/src/gui/graphicsview/qgraphicsview_p.h
@@ -86,6 +86,9 @@ public:
     qint64 horizontalScroll() const;
     qint64 verticalScroll() const;
 
+    QRectF mapRectToScene(const QRect &rect) const;
+    QRectF mapRectFromScene(const QRectF &rect) const;
+
     QPointF mousePressItemPoint;
     QPointF mousePressScenePoint;
     QPoint mousePressViewPoint;