--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/graphicsview/elasticnodes/node.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,186 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QGraphicsScene>
+#include <QGraphicsSceneMouseEvent>
+#include <QPainter>
+#include <QStyleOption>
+
+#include "edge.h"
+#include "node.h"
+#include "graphwidget.h"
+
+Node::Node(GraphWidget *graphWidget)
+    : graph(graphWidget)
+{
+    setFlag(ItemIsMovable);
+    setFlag(ItemSendsGeometryChanges);
+    setCacheMode(DeviceCoordinateCache);
+    setZValue(-1);
+}
+
+void Node::addEdge(Edge *edge)
+{
+    edgeList << edge;
+    edge->adjust();
+}
+
+QList<Edge *> Node::edges() const
+{
+    return edgeList;
+}
+
+void Node::calculateForces()
+{
+    if (!scene() || scene()->mouseGrabberItem() == this) {
+        newPos = pos();
+        return;
+    }
+    
+    // Sum up all forces pushing this item away
+    qreal xvel = 0;
+    qreal yvel = 0;
+    foreach (QGraphicsItem *item, scene()->items()) {
+        Node *node = qgraphicsitem_cast<Node *>(item);
+        if (!node)
+            continue;
+
+        QLineF line(mapFromItem(node, 0, 0), QPointF(0, 0));
+        qreal dx = line.dx();
+        qreal dy = line.dy();
+        double l = 2.0 * (dx * dx + dy * dy);
+        if (l > 0) {
+            xvel += (dx * 150.0) / l;
+            yvel += (dy * 150.0) / l;
+        }
+    }
+
+    // Now subtract all forces pulling items together
+    double weight = (edgeList.size() + 1) * 10;
+    foreach (Edge *edge, edgeList) {
+        QPointF pos;
+        if (edge->sourceNode() == this)
+            pos = mapFromItem(edge->destNode(), 0, 0);
+        else
+            pos = mapFromItem(edge->sourceNode(), 0, 0);
+        xvel += pos.x() / weight;
+        yvel += pos.y() / weight;
+    }
+    
+    if (qAbs(xvel) < 0.1 && qAbs(yvel) < 0.1)
+        xvel = yvel = 0;
+
+    QRectF sceneRect = scene()->sceneRect();
+    newPos = pos() + QPointF(xvel, yvel);
+    newPos.setX(qMin(qMax(newPos.x(), sceneRect.left() + 10), sceneRect.right() - 10));
+    newPos.setY(qMin(qMax(newPos.y(), sceneRect.top() + 10), sceneRect.bottom() - 10));
+}
+
+bool Node::advance()
+{
+    if (newPos == pos())
+        return false;
+
+    setPos(newPos);
+    return true;
+}
+
+QRectF Node::boundingRect() const
+{
+    qreal adjust = 2;
+    return QRectF(-10 - adjust, -10 - adjust,
+                  23 + adjust, 23 + adjust);
+}
+
+QPainterPath Node::shape() const
+{
+    QPainterPath path;
+    path.addEllipse(-10, -10, 20, 20);
+    return path;
+}
+
+void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *)
+{
+    painter->setPen(Qt::NoPen);
+    painter->setBrush(Qt::darkGray);
+    painter->drawEllipse(-7, -7, 20, 20);
+
+    QRadialGradient gradient(-3, -3, 10);
+    if (option->state & QStyle::State_Sunken) {
+        gradient.setCenter(3, 3);
+        gradient.setFocalPoint(3, 3);
+        gradient.setColorAt(1, QColor(Qt::yellow).light(120));
+        gradient.setColorAt(0, QColor(Qt::darkYellow).light(120));
+    } else {
+        gradient.setColorAt(0, Qt::yellow);
+        gradient.setColorAt(1, Qt::darkYellow);
+    }
+    painter->setBrush(gradient);
+    painter->setPen(QPen(Qt::black, 0));
+    painter->drawEllipse(-10, -10, 20, 20);
+}
+
+QVariant Node::itemChange(GraphicsItemChange change, const QVariant &value)
+{
+    switch (change) {
+    case ItemPositionHasChanged:
+        foreach (Edge *edge, edgeList)
+            edge->adjust();
+        graph->itemMoved();
+        break;
+    default:
+        break;
+    };
+
+    return QGraphicsItem::itemChange(change, value);
+}
+
+void Node::mousePressEvent(QGraphicsSceneMouseEvent *event)
+{
+    update();
+    QGraphicsItem::mousePressEvent(event);
+}
+
+void Node::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
+{
+    update();
+    QGraphicsItem::mouseReleaseEvent(event);
+}