examples/graphicsview/elasticnodes/edge.cpp

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  41
  42 #include <QPainter>
  43
  44 #include "edge.h"
  45 #include "node.h"
  46
  47 #include <math.h>
  48
  49 static const double Pi = 3.14159265358979323846264338327950288419717;
  50 static double TwoPi = 2.0 * Pi;
  51
  52 Edge::Edge(Node *sourceNode, Node *destNode)
  53     : arrowSize(10)
  54 {
  55     setAcceptedMouseButtons(0);
  56     source = sourceNode;
  57     dest = destNode;
  58     source->addEdge(this);
  59     dest->addEdge(this);
  60     adjust();
  61 }
  62
  63 Edge::~Edge()
  64 {
  65 }
  66
  67 Node *Edge::sourceNode() const
  68 {
  69     return source;
  70 }
  71
  72 void Edge::setSourceNode(Node *node)
  73 {
  74     source = node;
  75     adjust();
  76 }
  77
  78 Node *Edge::destNode() const
  79 {
  80     return dest;
  81 }
  82
  83 void Edge::setDestNode(Node *node)
  84 {
  85     dest = node;
  86     adjust();
  87 }
  88
  89 void Edge::adjust()
  90 {
  91     if (!source || !dest)
  92         return;
  93
  94     QLineF line(mapFromItem(source, 0, 0), mapFromItem(dest, 0, 0));
  95     qreal length = line.length();
  96
  97     prepareGeometryChange();
  98
  99     if (length > qreal(20.)) {
 100         QPointF edgeOffset((line.dx() * 10) / length, (line.dy() * 10) / length);
 101         sourcePoint = line.p1() + edgeOffset;
 102         destPoint = line.p2() - edgeOffset;
 103     } else {
 104         sourcePoint = destPoint = line.p1();
 105     }
 106 }
 107
 108 QRectF Edge::boundingRect() const
 109 {
 110     if (!source || !dest)
 111         return QRectF();
 112
 113     qreal penWidth = 1;
 114     qreal extra = (penWidth + arrowSize) / 2.0;
 115
 116     return QRectF(sourcePoint, QSizeF(destPoint.x() - sourcePoint.x(),
 117                                       destPoint.y() - sourcePoint.y()))
 118         .normalized()
 119         .adjusted(-extra, -extra, extra, extra);
 120 }
 121
 122 void Edge::paint(QPainter *painter, const QStyleOptionGraphicsItem *, QWidget *)
 123 {
 124     if (!source || !dest)
 125         return;
 126
 127     QLineF line(sourcePoint, destPoint);
 128     if (qFuzzyCompare(line.length(), qreal(0.)))
 129         return;
 130
 131     // Draw the line itself
 132     painter->setPen(QPen(Qt::black, 1, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin));
 133     painter->drawLine(line);
 134
 135     // Draw the arrows
 136     double angle = ::acos(line.dx() / line.length());
 137     if (line.dy() >= 0)
 138         angle = TwoPi - angle;
 139
 140     QPointF sourceArrowP1 = sourcePoint + QPointF(sin(angle + Pi / 3) * arrowSize,
 141                                                   cos(angle + Pi / 3) * arrowSize);
 142     QPointF sourceArrowP2 = sourcePoint + QPointF(sin(angle + Pi - Pi / 3) * arrowSize,
 143                                                   cos(angle + Pi - Pi / 3) * arrowSize);
 144     QPointF destArrowP1 = destPoint + QPointF(sin(angle - Pi / 3) * arrowSize,
 145                                               cos(angle - Pi / 3) * arrowSize);
 146     QPointF destArrowP2 = destPoint + QPointF(sin(angle - Pi + Pi / 3) * arrowSize,
 147                                               cos(angle - Pi + Pi / 3) * arrowSize);
 148
 149     painter->setBrush(Qt::black);
 150     painter->drawPolygon(QPolygonF() << line.p1() << sourceArrowP1 << sourceArrowP2);
 151     painter->drawPolygon(QPolygonF() << line.p2() << destArrowP1 << destArrowP2);
 152 }