Optimization. Avoid calling prepareGeometryChange() if the new and old geometry have the same size. Added a graphicsItem() method to LayoutItem which returns the associated graphics item (if any). Needed for effects during layouting.

svn path=/trunk/KDE/kdebase/workspace/libs/plasma/; revision=699494

widgets/layoutitem.cpp

@@ -56,6 +56,11 @@ LayoutItem::~LayoutItem()
     delete d;
 }
 
+QGraphicsItem* LayoutItem::graphicsItem() 
+{
+    return 0;
+}
+
 bool LayoutItem::hasHeightForWidth() const
 {
 	return false;

widgets/layoutitem.h

@@ -24,6 +24,8 @@
 
 #include <plasma/plasma_export.h>
 
+class QGraphicsItem;
+
 namespace Plasma
 {
 
@@ -137,6 +139,14 @@ class PLASMA_EXPORT LayoutItem
          **/
         Layout* managingLayout() const;
 
+        /**
+         * Returns the graphics item associated with this layout item or 0
+         * if there is no associated graphics item.
+         *
+         * The default implementation returns 0.
+         */
+        virtual QGraphicsItem* graphicsItem();
+
     private:
         class Private;
         Private *const d;

widgets/widget.cpp

@@ -39,6 +39,7 @@ class Widget::Private
     public:
         Private()
             : parent(0)
+            , opacity(1.0)
         { }
         ~Private() { }
 
@@ -49,9 +50,16 @@ class Widget::Private
         Widget *parent;
         QList<Widget *> childList;
 
+        qreal opacity;
+
         bool shouldPaint(QPainter *painter, const QTransform &transform);
 };
 
+QGraphicsItem* Widget::graphicsItem()
+{
+    return this;
+}
+
 bool Widget::Private::shouldPaint(QPainter *painter, const QTransform &transform)
 {
     qreal zoomLevel = painter->transform().m11() / transform.m11();
@@ -77,6 +85,11 @@ Widget::~Widget()
     delete d;
 }
 
+void Widget::setOpacity(qreal opacity)
+{
+    d->opacity = opacity;
+}
+
 Qt::Orientations Widget::expandingDirections() const
 {
     return 0;
@@ -138,12 +151,14 @@ QRectF Widget::localGeometry() const
 
 void Widget::setGeometry(const QRectF& geometry)
 {
-    prepareGeometryChange();
+    bool sizeChange = d->size != geometry.size();
 
+    if ( sizeChange ) {
+        prepareGeometryChange();
+        d->size = geometry.size();
+    }
     setPos(geometry.topLeft());
-    d->size = geometry.size();
 
-    updateGeometry();
     update();
 }
 
@@ -152,7 +167,7 @@ void Widget::updateGeometry()
     prepareGeometryChange();
 
     if (layout()) {
-        kDebug() << (void *) this << " updating geometry to " << size();
+     //   kDebug() << (void *) this << " updating geometry to " << size();
         layout()->setGeometry(geometry());
     }
 }
@@ -227,6 +242,8 @@ void Widget::addChild(Widget *w)
 
 void Widget::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
 {
+    painter->setOpacity(d->opacity);
+
     if (d->shouldPaint(painter, transform())) {
         paintWidget(painter, option, widget);
     }

widgets/widget.h

@@ -218,6 +218,10 @@ public:
      */
     Q_INVOKABLE void addChild(Widget *widget);
 
+    void setOpacity(qreal opacity);
+
+    virtual QGraphicsItem* graphicsItem();
+
 protected:
     /**
      * Paints the widget