/// <summary>Default ctor</summary>
public Graph()
{
_NodeRegistry = 0;
_Nodes = new List<Node>();
_Edges = new List<Edge>();
DragNode = null;
}
/// <summary>Creates a new node and adds it to the graph </summary>
/// <param name="label">Label of the new node</param>
/// <param name="magnet">Movement speed</param>
/// <returns>the newly created node</returns>
public Node AddNode(string label, double magnet = 60.0)
{
Node result = FindNode(label);
if (result != null) // already existing
return result;
result = new Node(++_NodeRegistry, label, magnet);
_Nodes.Add(result);
return result;
}
/// <summary>Initialization ctor</summary>
/// <param name="from">Node where this edge begins</param>
/// <param name="to">Node where this edge ends</param>
/// <param name="len">Virtual length of this edge</param>
public Edge(Node from, Node to, double len = 40.0)
{
From = from;
To = to;
Length = len;
}
/// <summary>Creates a new egde and adds it to the graph</summary>
/// <param name="from">Starting node</param>
/// <param name="to">Ending node</param>
/// <returns>the newly created edge</returns>
public Edge AddEdge(Node from, Node to)
{
Edge result = new Edge(from, to);
_Edges.Add(result);
return result;
}
private void ForAllNodePairs(Node n1, Node n2)
{
double dx = 0;
double dy = 0;
double vx = n1.x - n2.x;
double vy = n1.y - n2.y;
double len = vx * vx + vy * vy; //so it's length squared
if (len == 0)
{
Random rand = new Random();
dx = rand.NextDouble(); //If two nodes are right on top of each other, randomly separate
dy = rand.NextDouble();
}
else if (len < 600 * 600)
{ // 600, because we don't want deleted nodes to fly too far away
dx = vx / len; // If it was sqrt(len) then a single node surrounded by many others will
dy = vy / len; // always look like a circle. This might look good at first, but I think
// it makes large graphs look ugly + it contributes to oscillation. A
// linear function does not fall off fast enough, so you get rough edges
// in the 'force field'
}
double repSum = n1.repulsion * n2.repulsion / 100;
n1.dx += dx * repSum * rigidity;
n1.dy += dy * repSum * rigidity;
n2.dx -= dx * repSum * rigidity;
n2.dy -= dy * repSum * rigidity;
}
private void ForAllNodes(Node node)
{
double dx = node.dx;
double dy = node.dy;
dx *= damper; //The damper slows things down. It cuts down jiggling at the last moment, and optimizes
dy *= damper; //layout. As an experiment, get rid of the damper in these lines, and make a
//long straight line of nodes. It wiggles too much and doesn't straighten out.
node.dx = dx / 2; //Slow down, but don't stop. Nodes in motion store momentum. This helps when the force
node.dy = dy / 2; //on a node is very low, but you still want to get optimal layout.
double distMoved = Math.Sqrt(dx * dx + dy * dy); //how far did the node actually move?
if (!node.IsFixed)
{
node.x += Math.Max(-30, Math.Min(30, dx)); //don't move faster then 30 units at a time.
node.y += Math.Max(-30, Math.Min(30, dy)); //I forget when this is important. Stopping severed nodes from
//flying away?
}
maxMotionA = Math.Max(distMoved, maxMotionA);
}