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