/// <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);
}
protected override void OptimizeAfterSequencing(IComparer <object> inEdgeOrder, IComparer <object> outEdgeOrder, LayoutGraph graph, ILayers layers,
ILayoutDataProvider ldp, IItemFactory itemFactory)
{
edge2LaneCrossing = Maps.CreateHashedEdgeMap();
node2LaneAlignment = Maps.CreateHashedNodeMap();
var criticalEdges = Maps.CreateHashedEdgeMap();
// determine whether an edge crosses a swim lane border and if so in which direction
foreach (var edge in graph.Edges)
{
var originalEdge = GetOriginalEdge(edge, ldp);
// now we have a 'real' edge with valid valid source and target nodes
var originalSourceId = GetLaneId(originalEdge.Source, ldp);
var originalTargetId = GetLaneId(originalEdge.Target, ldp);
LaneCrossing crossing = LaneCrossing.None;
if (originalSourceId != originalTargetId)
{
// check if we need to flip the sides because edge and original edge have different directions
var flipSides = edge.Source != originalEdge.Source;
var sourceId = flipSides ? originalTargetId : originalSourceId;
var targetId = flipSides ? originalSourceId : originalTargetId;
crossing = sourceId > targetId ? LaneCrossing.ToWest : LaneCrossing.ToEast;
}
edge2LaneCrossing.Set(edge, crossing);
}
// determine basic node alignment
foreach (var n in graph.Nodes)
{
LaneAlignment alignment = CalculateLaneAlignment(n);
node2LaneAlignment.Set(n, alignment);
}
foreach (var n in graph.Nodes)
{
// sort the edges with the provided comparer
n.SortInEdges(inEdgeOrder);
n.SortOutEdges(outEdgeOrder);
// calculate 'critical' in and out-edges whose nodes should be aligned in flow
var bestInEdge = n.InDegree > 0 ? GetBestFlowEdge(n.InEdges, ldp, graph) : null;
var bestOutEdge = n.OutDegree > 0 ? GetBestFlowEdge(n.OutEdges, ldp, graph) : null;
if (bestInEdge != null)
{
criticalEdges.SetDouble(bestInEdge, criticalEdges.GetDouble(bestInEdge) + 0.5);
}
if (bestOutEdge != null)
{
criticalEdges.SetDouble(bestOutEdge, criticalEdges.GetDouble(bestOutEdge) + 0.5);
}
if (n.Degree <= 4)
{
// should usually be the case and we can distribute each edge to its own side
// remember which node side is already taken by an in- or out-edge
bool westTakenByInEdge = false;
bool eastTakenByInEdge = false;
bool westTakenByOutEdge = false;
bool eastTakenByOutEdge = false;
if (n.InDegree > 0 && n.OutDegree < 3)
{
// if there are at least three out-edges, we distribute those first, otherwise we start with the in-edges
var firstInEdge = n.FirstInEdge;
var lastInEdge = n.LastInEdge;
if (GetLaneCrossing(firstInEdge) == LaneCrossing.ToEast &&
(n.InDegree > 1 || IsSameLayerEdge(firstInEdge, ldp)))
{
// the first in-edge comes from west and is either a same layer edge or there are other in-edges
ConstrainWest(firstInEdge, false, itemFactory);
westTakenByInEdge = true;
}
if (!westTakenByInEdge || n.OutDegree < 2)
{
// don't use west and east side for in-edges if there are at least 2 out-edges
if (GetLaneCrossing(lastInEdge) == LaneCrossing.ToWest &&
(n.InDegree > 1 || IsSameLayerEdge(lastInEdge, ldp)))
{
// the last in-edge comes from east and is either
// a same-layer edge or there are other in-edges
ConstrainEast(lastInEdge, false, itemFactory);
eastTakenByInEdge = true;
}
}
}
if (n.OutDegree > 0)
{
var firstOutEdge = n.FirstOutEdge;
var lastOutEdge = n.LastOutEdge;
if (!westTakenByInEdge)
{
// the west side is still free
if (BpmnLayout.IsBoundaryInterrupting(firstOutEdge, graph) ||
(GetLaneCrossing(firstOutEdge) == LaneCrossing.ToWest) &&
(n.OutDegree > 1 || IsSameLayerEdge(firstOutEdge, ldp)))
{
// the first out-edge is either boundary interrupting or goes to west and
// is either a same layer edge or there are other out-edges
ConstrainWest(firstOutEdge, true, itemFactory);
westTakenByOutEdge = true;
}
else if (eastTakenByInEdge && n.OutDegree >= 2 && !IsSameLayerEdge(firstOutEdge.NextOutEdge, ldp))
{
// the east side is already taken but we have more then one out edge.
// if the second out edge is a same layer edge, constraining the firstOutEdge could lead to
// no in-flow edge
ConstrainWest(firstOutEdge, true, itemFactory);
westTakenByOutEdge = true;
}
}
if (!eastTakenByInEdge)
{
// the east side is still free
if (GetLaneCrossing(lastOutEdge) == LaneCrossing.ToEast &&
(n.OutDegree > 1 || IsSameLayerEdge(lastOutEdge, ldp)))
{
// the last out-edge goes to east and
// is either a same layer edge or there are other out-edges
ConstrainEast(lastOutEdge, true, itemFactory);
eastTakenByOutEdge = true;
}
else if (westTakenByInEdge && n.OutDegree >= 2 && !IsSameLayerEdge(lastOutEdge.PrevOutEdge, ldp))
{
// the west side is already taken but we have more then one out edge.
// if the second last out edge is a same layer edge, constraining the lastOutEdge could lead to
// no in-flow edge
ConstrainEast(lastOutEdge, true, itemFactory);
eastTakenByOutEdge = true;
}
}
}
// distribute remaining in-edges
if (n.InDegree == 2 &&
!(eastTakenByInEdge || westTakenByInEdge))
{
// two in-edges but none distributed, yet
if (bestInEdge == n.FirstInEdge && !eastTakenByOutEdge)
{
// first in-edge is in-flow edge and east side is still free
ConstrainEast(n.LastInEdge, false, itemFactory);
eastTakenByInEdge = true;
}
else if (bestInEdge == n.LastInEdge && !westTakenByOutEdge)
{
// last in-edge is in-flow edge and west side is still free
ConstrainWest(n.FirstInEdge, false, itemFactory);
westTakenByInEdge = true;
}
}
else if (n.InDegree == 3 &&
!(eastTakenByInEdge && westTakenByInEdge) &&
!(IsSameLayerEdge(n.FirstInEdge.NextInEdge, ldp)))
{
// three in-edges but not both sides taken, yet and the middle edge is no same layer edge
if (!eastTakenByOutEdge)
{
// if not already taken, constraint the last in-edge to east
ConstrainEast(n.LastInEdge, false, itemFactory);
eastTakenByInEdge = true;
}
if (!westTakenByOutEdge)
{
// if not already taken, constraint the first in-edge to west
ConstrainWest(n.FirstInEdge, false, itemFactory);
westTakenByInEdge = true;
}
}
// distribute remaining out-edges
if (n.OutDegree == 2 && !(eastTakenByOutEdge || westTakenByOutEdge))
{
// two out-edges but none distributed, yet
if (bestOutEdge == n.FirstOutEdge && !eastTakenByInEdge)
{
// first out-edge is in-flow edge and east side is still free
ConstrainEast(n.LastOutEdge, true, itemFactory);
eastTakenByOutEdge = true;
}
else if (bestOutEdge == n.LastOutEdge && !westTakenByInEdge)
{
// last out-edge is in-flow edge and west side is still free
ConstrainWest(n.FirstOutEdge, true, itemFactory);
westTakenByOutEdge = true;
}
}
else if (n.OutDegree == 3 &&
!(eastTakenByOutEdge && westTakenByOutEdge) &&
!(IsSameLayerEdge(n.FirstOutEdge.NextOutEdge, ldp)))
{
// three out-edges but not both sides taken, yet and the middle edge is no same layer edge
if (!eastTakenByInEdge)
{
// if not already taken, constraint the last out-edge to east
ConstrainEast(n.LastOutEdge, true, itemFactory);
eastTakenByOutEdge = true;
}
if (!westTakenByInEdge)
{
// if not already taken, constraint the first out-edge to west
ConstrainWest(n.FirstOutEdge, true, itemFactory);
westTakenByOutEdge = true;
}
}
}
}
// register the data provider for critical edge paths. It is deregistered again by BpmnLayout itself
graph.AddDataProvider(HierarchicLayout.CriticalEdgePriorityDpKey, criticalEdges);
sameLayerData = null;
edge2LaneCrossing = null;
node2LaneAlignment = null;
}
