nodeeditor/QtNodes.md

Plans

1. Model-view approach. A specific graph representation is wrapped in a model that delivers the information to the framework. The graph could be stored as a set of pointers, table etc.
2. Headless mode. Graph Model works on its own without GUI rendering.
3. Optional data propagation (data flow).
4. QML frontend.

Graph Model

Graph Model references all the nodes and their interconnections. Nodes have input and output ports. We model directed graph.

Graph Visualization

A simple Graph Model could be visualized. It does not support any data types or data transferring. We simply show nodes and connections and enable simple editing:

• Moving nodes around,
• Dis- and Re-connecting nodes,

FlowGraphicsScene stores the maps:

• map<Node, NodeGraphicsObject>,
• map<pair<Node1, Node2>, Connection>

each NodeGraphicsObject gets all the relevant information from the GraphModel (node position, colors etc).

class FlowGraphicsScene : public QGraphicsScene
{
public:
  explicit NodeGraphicsScene(GraphModel * graphModel) {}

  ...

};

class GraphModel
{
public:

  std::vector<Node> const &
  allNodes() const = 0;

  unsigned int
  nPorts(Node const & node, PortType portType) const = 0;

  std::vector<Node>
  connections(Node const & node, PortType portType) const = 0;

  QVariant
  data(Node const & node, NodeRole role);

  void
  setData(Node const, NodeRole role);
};


enum class NodeRole
{
  Data     = 0,
  DataType = 1,
  ConnectionPolicy = 2,

  Position = 3,
  CaptionVisible = 4,
  Caption = 5,


}: