Method mousePressEvent

QtNodeEditor/src/NodeGraphicsObject.cpp:189–263

void
NodeGraphicsObject::
mousePressEvent(QGraphicsSceneMouseEvent * event)
{
  if(_locked) return;

  // deselect all other items after this one is selected
  if (!isSelected() && event->modifiers() != Qt::ControlModifier)
  {
    _scene.clearSelection();
  }

  for(PortType portToCheck: {PortType::In, PortType::Out})
  {
    NodeGeometry & nodeGeometry = _node.nodeGeometry();

    // TODO do not pass sceneTransform
    int portIndex = nodeGeometry.checkHitScenePoint(portToCheck,
                                                    event->scenePos(),
                                                    sceneTransform());

    if (portIndex != INVALID)
    {
      NodeState const & nodeState = _node.nodeState();

      std::unordered_map<QUuid, Connection*> connections =
          nodeState.connections(portToCheck, portIndex);

      // start dragging existing connection
      if (!connections.empty() && portToCheck == PortType::In)
      {
        auto con = connections.begin()->second;

        NodeConnectionInteraction interaction(_node, *con, _scene);

        interaction.disconnect(portToCheck);
      }
      else // initialize new Connection
      {
        if (portToCheck == PortType::Out)
        {
          const auto outPolicy = _node.nodeDataModel()->portOutConnectionPolicy(portIndex);
          if (!connections.empty() &&
              outPolicy == NodeDataModel::ConnectionPolicy::One)
          {
            _scene.deleteConnection( *connections.begin()->second );
          }

          // todo add to FlowScene
          auto connection = _scene.createConnection(portToCheck,
                                                    _node,
                                                    portIndex);

          _node.nodeState().setConnection(portToCheck,
                                          portIndex,
                                          *connection);

          connection->connectionGraphicsObject().grabMouse();