--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/graphicsview/elasticnodes/edge.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,152 @@
+/****************************************************************************
+**
+** 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 <QPainter>
+
+#include "edge.h"
+#include "node.h"
+
+#include <math.h>
+
+static const double Pi = 3.14159265358979323846264338327950288419717;
+static double TwoPi = 2.0 * Pi;
+
+Edge::Edge(Node *sourceNode, Node *destNode)
+    : arrowSize(10)
+{
+    setAcceptedMouseButtons(0);
+    source = sourceNode;
+    dest = destNode;
+    source->addEdge(this);
+    dest->addEdge(this);
+    adjust();
+}
+
+Edge::~Edge()
+{
+}
+
+Node *Edge::sourceNode() const
+{
+    return source;
+}
+
+void Edge::setSourceNode(Node *node)
+{
+    source = node;
+    adjust();
+}
+
+Node *Edge::destNode() const
+{
+    return dest;
+}
+
+void Edge::setDestNode(Node *node)
+{
+    dest = node;
+    adjust();
+}
+
+void Edge::adjust()
+{
+    if (!source || !dest)
+        return;
+
+    QLineF line(mapFromItem(source, 0, 0), mapFromItem(dest, 0, 0));
+    qreal length = line.length();
+
+    prepareGeometryChange();
+
+    if (length > qreal(20.)) {
+        QPointF edgeOffset((line.dx() * 10) / length, (line.dy() * 10) / length);
+        sourcePoint = line.p1() + edgeOffset;
+        destPoint = line.p2() - edgeOffset;
+    } else {
+        sourcePoint = destPoint = line.p1();
+    }
+}
+
+QRectF Edge::boundingRect() const
+{
+    if (!source || !dest)
+        return QRectF();
+
+    qreal penWidth = 1;
+    qreal extra = (penWidth + arrowSize) / 2.0;
+
+    return QRectF(sourcePoint, QSizeF(destPoint.x() - sourcePoint.x(),
+                                      destPoint.y() - sourcePoint.y()))
+        .normalized()
+        .adjusted(-extra, -extra, extra, extra);
+}
+
+void Edge::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
+{
+    if (!source || !dest)
+        return;
+
+    QLineF line(sourcePoint, destPoint);
+    if (qFuzzyCompare(line.length(), qreal(0.)))
+        return;
+
+    // Draw the line itself
+    painter->setPen(QPen(Qt::black, 1, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin));
+    painter->drawLine(line);
+
+    // Draw the arrows
+    double angle = ::acos(line.dx() / line.length());
+    if (line.dy() >= 0)
+        angle = TwoPi - angle;
+
+    QPointF sourceArrowP1 = sourcePoint + QPointF(sin(angle + Pi / 3) * arrowSize,
+                                                  cos(angle + Pi / 3) * arrowSize);
+    QPointF sourceArrowP2 = sourcePoint + QPointF(sin(angle + Pi - Pi / 3) * arrowSize,
+                                                  cos(angle + Pi - Pi / 3) * arrowSize);   
+    QPointF destArrowP1 = destPoint + QPointF(sin(angle - Pi / 3) * arrowSize,
+                                              cos(angle - Pi / 3) * arrowSize);
+    QPointF destArrowP2 = destPoint + QPointF(sin(angle - Pi + Pi / 3) * arrowSize,
+                                              cos(angle - Pi + Pi / 3) * arrowSize);
+
+    painter->setBrush(Qt::black);
+    painter->drawPolygon(QPolygonF() << line.p1() << sourceArrowP1 << sourceArrowP2);
+    painter->drawPolygon(QPolygonF() << line.p2() << destArrowP1 << destArrowP2);        
+}