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#include <QPainter>

#include "edge.h"
#include "node.h"

#include <math.h>

//lint -e1535 member function '' exposes lower access pointer member ''
//lint -e1536 member function '' exposes lower access member ''
//lint -e1537 const member function '' exposes pointer member '' as pointer to non-const
//lint -e1540 non-static pointer data member '' not deallocated nor zeroed by destructor
//lint -e2466 '' was used despite being marked as 'unused'

static const double Pi = 3.14159265358979323846264338327950288419717;
static const 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();
}

Edge::~Edge()
{
}

Node *Edge::sourceNode() const
{
  return source;
}

void Edge::setSourceNode(Node *node)
{
  source = node;
  adjust();
}

Node *Edge::destNode() const
{
  return dest;
}

void Edge::setDestNode(Node *node)
{
  dest = node;
  adjust();
}

void Edge::adjust()
{
  if ( !source || !dest )
    return;

  QRectF srect = source->boundingRect();
  QRectF drect = dest->boundingRect();

  QLineF line(mapFromItem(source, srect.width() / 2, srect.height() / 2),
              mapFromItem(dest, drect.width() / 2, drect.height() / 2));
  qreal length = line.length();

  prepareGeometryChange();

  if ( length > qreal(40.) )
  {
    qreal line_angle = line.angle();
    qreal angle = line_angle > 90. ? fmod(line_angle, 90.0) : line_angle;
    qreal dist = qMax(angle, 45.0) - qMin(angle, 45.0);
    dist += 80.0 - dist;
    QPointF edgeOffset((line.dx() * dist) / length, (line.dy() * dist) / length);
    sourcePoint = line.p1() + edgeOffset;
    destPoint = line.p2() - edgeOffset;
    qreal new_angle = QLineF(sourcePoint, destPoint).angle();
    if ( qAbs(new_angle - line_angle) > 90. )
      sourcePoint = destPoint = line.p1();
  }
  else
  {
    sourcePoint = destPoint = line.p1();
  }
}

QRectF Edge::boundingRect() const
{
  if ( !source || !dest )
    return QRectF();

  qreal penWidth = 1;
  qreal extra = (penWidth + arrowSize) / 2.0;

  QRectF r(sourcePoint, QSizeF(destPoint.x() - sourcePoint.x(),
                               destPoint.y() - sourcePoint.y()));

  return r.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 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.p2() << destArrowP1 << destArrowP2);
}