arrow.cpp Example File

graphicsview/diagramscene/arrow.cpp
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#include "arrow.h" #include <math.h> #include <QPen> #include <QPainter> const qreal Pi = 3.14; Arrow::Arrow(DiagramItem *startItem, DiagramItem *endItem, QGraphicsItem *parent) : QGraphicsLineItem(parent) { myStartItem = startItem; myEndItem = endItem; setFlag(QGraphicsItem::ItemIsSelectable, true); myColor = Qt::black; setPen(QPen(myColor, 2, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin)); } 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); } QPainterPath Arrow::shape() const { QPainterPath path = QGraphicsLineItem::shape(); path.addPolygon(arrowHead); return path; } void Arrow::updatePosition() { QLineF line(mapFromItem(myStartItem, 0, 0), mapFromItem(myEndItem, 0, 0)); setLine(line); } 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); 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())); 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; 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); } }