edge.cpp

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#include "edge.h"
#include "node.h"
 
#include <QPainter>
#include <QtMath>
 
Edge::Edge(Node *sourceNode, Node *destNode)
    : source(sourceNode), dest(destNode)
{
    setAcceptedMouseButtons(Qt::NoButton);
    source->addEdge(this);
    dest->addEdge(this);
    adjust();
}
 
Node *Edge::sourceNode() const
{
    return source;
}
 
Node *Edge::destNode() const
{
    return dest;
}
 
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 = std::atan2(-line.dy(), line.dx());
 
    QPointF sourceArrowP1 = sourcePoint + QPointF(sin(angle + M_PI / 3) * arrowSize,
                                                  cos(angle + M_PI / 3) * arrowSize);
    QPointF sourceArrowP2 = sourcePoint + QPointF(sin(angle + M_PI - M_PI / 3) * arrowSize,
                                                  cos(angle + M_PI - M_PI / 3) * arrowSize);
    QPointF destArrowP1 = destPoint + QPointF(sin(angle - M_PI / 3) * arrowSize,
                                              cos(angle - M_PI / 3) * arrowSize);
    QPointF destArrowP2 = destPoint + QPointF(sin(angle - M_PI + M_PI / 3) * arrowSize,
                                              cos(angle - M_PI + M_PI / 3) * arrowSize);
 
    painter->setBrush(Qt::black);
    painter->drawPolygon(QPolygonF() << line.p1() << sourceArrowP1 << sourceArrowP2);
    painter->drawPolygon(QPolygonF() << line.p2() << destArrowP1 << destArrowP2);
}