--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/graphicsview/elasticnodes/edge.d	Wed Jul 07 22:54:12 2010 +0100
@@ -0,0 +1,171 @@
+/****************************************************************************
+**
+** Copyright (C) 2010 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.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial Usage
+** Licensees holding valid Qt Commercial licenses may use this file in
+** accordance with the Qt Commercial License Agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Nokia.
+**
+** 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.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+module edge;
+
+import std.math;
+import qt.gui.QGraphicsItem;
+
+import node;
+
+static const double Pi = 3.14159265358979323846264338327950288419717;
+static double TwoPi = 2.0 * Pi;
+
+class Edge : QGraphicsItem
+{
+public:
+    this(Node sourceNode, Node destNode)
+    {
+        arrowSize = 10;
+        setAcceptedMouseButtons(0);
+        source = sourceNode;
+        dest = destNode;
+        source.addEdge(this);
+        dest.addEdge(this);
+        adjust();
+    }
+
+    Node sourceNode() const
+    {
+        return cast(Node)source;
+    }
+    
+    void setSourceNode(Node node)
+    {
+        source = node;
+        adjust();
+    }
+
+    Node destNode() const
+    {
+        return cast(Node)dest;
+    }
+    
+    void setDestNode(Node node)
+    {
+        dest = node;
+        adjust();
+    }
+
+    void adjust()
+    {
+        if (!source || !dest)
+            return;
+
+        auto line = QLineF(mapFromItem(source, 0, 0), mapFromItem(dest, 0, 0));
+        qreal length = line.length();
+
+        prepareGeometryChange();
+
+        if (length > 20.) {
+            auto edgeOffset = QPointF((line.dx() * 10) / length, (line.dy() * 10) / length);
+            sourcePoint = line.p1() + edgeOffset;
+            destPoint = line.p2() - edgeOffset;
+        } else {
+            sourcePoint = destPoint = line.p1();
+        }
+    }
+
+    enum { Type = UserType + 2 };
+    int type() const { return Type; }
+    
+protected:
+    override QRectF 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);
+    }
+    
+    override void paint(QPainter painter, QStyleOptionGraphicsItem option, QWidget widget)
+    {
+        if (!source || !dest)
+            return;
+
+        auto line = QLineF(sourcePoint, destPoint);
+        if (qFuzzyCompare(line.length(), 0.))
+            return;
+
+        // Draw the line itself
+        painter.setPen(new QPen(new QBrush(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(new QBrush(Qt.black));
+        auto p1 = new QPolygonF();
+        p1.append(line.p1());
+        p1.append(sourceArrowP1);
+        p1.append(sourceArrowP2);
+        painter.drawPolygon(p1);
+        auto p2 = new QPolygonF();
+        p2.append(line.p2());
+        p2.append(destArrowP1);
+        p2.append(destArrowP2);
+        painter.drawPolygon(p2);        
+    }
+    
+private:
+    Node source, dest;
+
+    QPointF sourcePoint;
+    QPointF destPoint;
+    qreal arrowSize;
+};
+