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#include <QtGui>

#include "arrow.h"

#include <math.h>

const qreal Pi = 3.14;

//! [0]

Arrow::Arrow(DiagramItem *startItem, DiagramItem *endItem,

         QGraphicsItem *parent, QGraphicsScene *scene)

    : QGraphicsLineItem(parent, scene)

{

    myStartItem = startItem;

    myEndItem = endItem;

    setFlag(QGraphicsItem::ItemIsSelectable, true);

    myColor = Qt::black;

    setPen(QPen(myColor, 2, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin));

}

//! [0]

//! [1]

QRectF Arrow::boundingRect() const

{

    qreal extra = (pen().width() + 20) / 2.0;

    return QRectF(line().p1(), QSizeF(line().p2().x() - line().p1().x(),

                                      line().p2().y() - line().p1().y()))

        .normalized()

        .adjusted(-extra, -extra, extra, extra);

}

//! [1]

//! [2]

QPainterPath Arrow::shape() const

{

    QPainterPath path = QGraphicsLineItem::shape();

    path.addPolygon(arrowHead);

    return path;

}

//! [2]

//! [3]

void Arrow::updatePosition()

{

    QLineF line(mapFromItem(myStartItem, 0, 0), mapFromItem(myEndItem, 0, 0));

    setLine(line);

}

//! [3]

//! [4]

void Arrow::paint(QPainter *painter, const QStyleOptionGraphicsItem *,

          QWidget *)

{

    if (myStartItem->collidesWithItem(myEndItem))

        return;

    QPen myPen = pen();

    myPen.setColor(myColor);

    qreal arrowSize = 20;

    painter->setPen(myPen);

    painter->setBrush(myColor);

//! [4] //! [5]

    QLineF centerLine(myStartItem->pos(), myEndItem->pos());

    QPolygonF endPolygon = myEndItem->polygon();

    QPointF p1 = endPolygon.first() + myEndItem->pos();

    QPointF p2;

    QPointF intersectPoint;

    QLineF polyLine;

    for (int i = 1; i < endPolygon.count(); ++i) {

    p2 = endPolygon.at(i) + myEndItem->pos();

    polyLine = QLineF(p1, p2);

    QLineF::IntersectType intersectType =

        polyLine.intersect(centerLine, &intersectPoint);

    if (intersectType == QLineF::BoundedIntersection)

        break;

        p1 = p2;

    }

    setLine(QLineF(intersectPoint, myStartItem->pos()));

//! [5] //! [6]

    double angle = ::acos(line().dx() / line().length());

    if (line().dy() >= 0)

        angle = (Pi * 2) - angle;

        QPointF arrowP1 = line().p1() + QPointF(sin(angle + Pi / 3) * arrowSize,

                                        cos(angle + Pi / 3) * arrowSize);

        QPointF arrowP2 = line().p1() + QPointF(sin(angle + Pi - Pi / 3) * arrowSize,

                                        cos(angle + Pi - Pi / 3) * arrowSize);

        arrowHead.clear();

        arrowHead << line().p1() << arrowP1 << arrowP2;

//! [6] //! [7]

        painter->drawLine(line());

        painter->drawPolygon(arrowHead);

        if (isSelected()) {

            painter->setPen(QPen(myColor, 1, Qt::DashLine));

        QLineF myLine = line();

        myLine.translate(0, 4.0);

        painter->drawLine(myLine);

        myLine.translate(0,-8.0);

        painter->drawLine(myLine);

    }

}

//! [7]