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#include <QGraphicsScene>

#include <QGraphicsSceneMouseEvent>

#include <QPainter>

#include <QStyleOption>

#include "edge.h"

#include "node.h"

#include "graphwidget.h"

//! [0]

Node::Node(GraphWidget *graphWidget)

    : graph(graphWidget)

{

    setFlag(ItemIsMovable);

    setFlag(ItemSendsGeometryChanges);

    setCacheMode(DeviceCoordinateCache);

    setZValue(-1);

}

//! [0]

//! [1]

void Node::addEdge(Edge *edge)

{

    edgeList << edge;

    edge->adjust();

}

QList<Edge *> Node::edges() const

{

    return edgeList;

}

//! [1]

//! [2]

void Node::calculateForces()

{

    if (!scene() || scene()->mouseGrabberItem() == this) {

        newPos = pos();

        return;

    }

//! [2]

//! [3]

    // 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;

        QPointF vec = mapToItem(node, 0, 0);

        qreal dx = vec.x();

        qreal dy = vec.y();

        double l = 2.0 * (dx * dx + dy * dy);

        if (l > 0) {

            xvel += (dx * 150.0) / l;

            yvel += (dy * 150.0) / l;

        }

    }

//! [3]

//! [4]

    // Now subtract all forces pulling items together

    double weight = (edgeList.size() + 1) * 10;

    foreach (Edge *edge, edgeList) {

        QPointF vec;

        if (edge->sourceNode() == this)

            vec = mapToItem(edge->destNode(), 0, 0);

        else

            vec = mapToItem(edge->sourceNode(), 0, 0);

        xvel -= vec.x() / weight;

        yvel -= vec.y() / weight;

    }

//! [4]

//! [5]

    if (qAbs(xvel) < 0.1 && qAbs(yvel) < 0.1)

        xvel = yvel = 0;

//! [5]

//! [6]

    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));

}

//! [6]

//! [7]

bool Node::advance()

{

    if (newPos == pos())

        return false;

    setPos(newPos);

    return true;

}

//! [7]

//! [8]

QRectF Node::boundingRect() const

{

    qreal adjust = 2;

    return QRectF(-10 - adjust, -10 - adjust,

                  23 + adjust, 23 + adjust);

}

//! [8]

//! [9]

QPainterPath Node::shape() const

{

    QPainterPath path;

    path.addEllipse(-10, -10, 20, 20);

    return path;

}

//! [9]

//! [10]

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);

}

//! [10]

//! [11]

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);

}

//! [11]

//! [12]

void Node::mousePressEvent(QGraphicsSceneMouseEvent *event)

{

    update();

    QGraphicsItem::mousePressEvent(event);

}

void Node::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)

{

    update();

    QGraphicsItem::mouseReleaseEvent(event);

}

//! [12]