/// <summary>
/// Get the <see cref="Edge"/> representing the original edge on the graph.
/// </summary>
/// <remarks>
/// As the core layout algorithm creates temporary edges for example for same-layer edges and edges spanning
/// multiple layers, we need to lookup the original edge of the graph for example as key in data providers.
/// </remarks>
private Edge GetOriginalEdge(Edge edge, ILayoutDataProvider ldp)
{
var originalEdge = sameLayerData.GetOriginalEdge(edge.Source) ??
(sameLayerData.GetOriginalEdge(edge.Target) ?? edge);
var edgeData = ldp.GetEdgeData(originalEdge);
return(edgeData.AssociatedEdge ?? originalEdge);
}
/// <summary>
/// Returns the best suited edge in <paramref name="edges"/> for use as in-flow edge or <see langword="null"/>
/// if no such edge could be found.
/// </summary>
private Edge GetBestFlowEdge(IEnumerable <Edge> edges, ILayoutDataProvider ldp, LayoutGraph graph)
{
List <Edge> weakCandidates = new List <Edge>();
List <Edge> candidates = new List <Edge>();
foreach (var edge in edges)
{
var originalEdge = GetOriginalEdge(edge, ldp);
if ((LaneCrossing)edge2LaneCrossing.Get(edge) != LaneCrossing.None ||
BpmnLayout.IsBoundaryInterrupting(originalEdge, graph) ||
IsSameLayerEdge(originalEdge, ldp) ||
edge.SelfLoop)
{
// an edge should not be aligned if:
// - it crosses stripe borders
// - it is boundary interrupting
// - it is a same-layer edge
// - it is a self-loop
continue;
}
if (ldp.GetEdgeData(edge).Reversed ||
!BpmnLayout.IsSequenceFlow(originalEdge, graph))
{
// it is only a weak candidate if:
// - it is reversed
// - it is no sequence flow
weakCandidates.Add(edge);
}
else
{
candidates.Add(edge);
}
}
if (candidates.Count > 0)
{
// if there are several candidates, choose the one that would keep the LaneAlignment
// of its source and target node consistent
candidates.Sort((edge1, edge2) => {
var ac1 = GetAlignmentConsistency(edge1);
var ac2 = GetAlignmentConsistency(edge2);
return(ac2 - ac1);
});
return(candidates[0]);
}
if (weakCandidates.Count > 0)
{
return(weakCandidates[(int)Math.Floor(weakCandidates.Count / 2.0)]);
}
return(null);
}