Delete existing graphics effect when setting a new one.

Before we had to delete the existing effect before setting a new one
(in the same fashion as QLayout behaves). This feels wrong and we should
automatically delete it instead.

2 files changed, 18 insertions, 10 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index 5fa1748..b8187e7 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -2240,9 +2240,8 @@ QGraphicsEffect *QGraphicsItem::graphicsEffect() const
 
 /*!
     Sets \a effect as the item's effect. If there already is an effect installed
-    on this item, QGraphicsItem won't let you install another. You must first
-    delete the existing effect (returned by graphicsEffect()) before you can call
-    setGraphicsEffect() with the new effect.
+    on this item, QGraphicsItem will delete the existing effect before installing
+    the new \a effect.
 
     If \a effect is the installed on a different item, setGraphicsEffect() will remove
     the effect from the item and install it on this item.
@@ -2257,10 +2256,8 @@ void QGraphicsItem::setGraphicsEffect(QGraphicsEffect *effect)
         return;
 
     if (d_ptr->graphicsEffect && effect) {
-        // ### This seems wrong - the effect should automatically be deleted.
-        qWarning("QGraphicsItem::setGraphicsEffect: Attempting to set QGraphicsEffect "
-                 "%p on %p, which already has an effect installed", effect, this);
-        return;
+        delete d_ptr->graphicsEffect;
+        d_ptr->graphicsEffect = 0;
     }
 
     if (!effect) {
diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index a9ef6aa..6928761 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -4870,6 +4870,18 @@ QGraphicsEffect *QWidget::graphicsEffect() const
     return d->graphicsEffect;
 }
 
+/*!
+    Sets \a effect as the widget's effect. If there already is an effect installed
+    on this widget, QWidget will delete the existing effect before installing
+    the new \a effect.
+
+    If \a effect is the installed on a different widget, setGraphicsEffect() will remove
+    the effect from the widget and install it on this widget.
+
+    \note This function will apply the effect on itself and all its children.
+
+    \since 4.6
+*/
 void QWidget::setGraphicsEffect(QGraphicsEffect *effect)
 {
     Q_D(QWidget);
@@ -4877,9 +4889,8 @@ void QWidget::setGraphicsEffect(QGraphicsEffect *effect)
         return;
 
     if (d->graphicsEffect && effect) {
-        // ### This seems wrong - the effect should automatically be deleted.
-        qWarning("already set");
-        return;
+        delete d->graphicsEffect;
+        d->graphicsEffect = 0;
     }
 
     if (!effect) {