edge.cpp Example File

graphicsview/elasticnodes/edge.cpp
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#include "edge.h" #include "node.h" #include <math.h> #include <QPainter> static const double Pi = 3.14159265358979323846264338327950288419717; static double TwoPi = 2.0 * Pi; Edge::Edge(Node *sourceNode, Node *destNode) : arrowSize(10) { setAcceptedMouseButtons(0); source = sourceNode; dest = destNode; 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 = ::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(Qt::black); painter->drawPolygon(QPolygonF() << line.p1() << sourceArrowP1 << sourceArrowP2); painter->drawPolygon(QPolygonF() << line.p2() << destArrowP1 << destArrowP2); }