/*
* Copyright (c) 2005, David Benson
*
* All rights reserved.
*
* This file is licensed under the JGraph software license, a copy of which
* will have been provided to you in the file LICENSE at the root of your
* installation directory. If you are unable to locate this file please
* contact JGraph sales for another copy.
*/
package com.mxgraph.layout.hierarchical.stage;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import com.mxgraph.layout.hierarchical.mxHierarchicalLayout;
import com.mxgraph.layout.hierarchical.model.mxGraphHierarchyEdge;
import com.mxgraph.layout.hierarchical.model.mxGraphHierarchyModel;
import com.mxgraph.layout.hierarchical.model.mxGraphHierarchyNode;
import com.mxgraph.view.mxGraph;
/**
* An implementation of the first stage of the Sugiyama layout. Straightforward
* longest path calculation of layer assignment
*/
public class mxMinimumCycleRemover implements mxHierarchicalLayoutStage
{
/**
* Reference to the enclosing layout algorithm
*/
protected mxHierarchicalLayout layout;
/**
* Constructor that has the roots specified
*/
public mxMinimumCycleRemover(mxHierarchicalLayout layout)
{
this.layout = layout;
}
/**
* Produces the layer assignmment using the graph information specified
*/
public void execute(Object parent)
{
mxGraphHierarchyModel model = layout.getModel();
final Set<mxGraphHierarchyNode> seenNodes = new HashSet<mxGraphHierarchyNode>();
final Set<mxGraphHierarchyNode> unseenNodes = new HashSet<mxGraphHierarchyNode>(
model.getVertexMapper().values());
// Perform a dfs through the internal model. If a cycle is found,
// reverse it.
mxGraphHierarchyNode[] rootsArray = null;
if (model.roots != null)
{
Object[] modelRoots = model.roots.toArray();
rootsArray = new mxGraphHierarchyNode[modelRoots.length];
for (int i = 0; i < modelRoots.length; i++)
{
Object node = modelRoots[i];
mxGraphHierarchyNode internalNode = model
.getVertexMapper().get(node);
rootsArray[i] = internalNode;
}
}
model.visit(new mxGraphHierarchyModel.CellVisitor()
{
public void visit(mxGraphHierarchyNode parent,
mxGraphHierarchyNode cell,
mxGraphHierarchyEdge connectingEdge, int layer, int seen)
{
// Check if the cell is in it's own ancestor list, if so
// invert the connecting edge and reverse the target/source
// relationship to that edge in the parent and the cell
if ((cell)
.isAncestor(parent))
{
connectingEdge.invert();
parent.connectsAsSource.remove(connectingEdge);
parent.connectsAsTarget.add(connectingEdge);
cell.connectsAsTarget.remove(connectingEdge);
cell.connectsAsSource.add(connectingEdge);
}
seenNodes.add(cell);
unseenNodes.remove(cell);
}
}, rootsArray, true, null);
Set<Object> possibleNewRoots = null;
if (unseenNodes.size() > 0)
{
possibleNewRoots = new HashSet<Object>(unseenNodes);
}
// If there are any nodes that should be nodes that the dfs can miss
// these need to be processed with the dfs and the roots assigned
// correctly to form a correct internal model
Set<mxGraphHierarchyNode> seenNodesCopy = new HashSet<mxGraphHierarchyNode>(
seenNodes);
// Pick a random cell and dfs from it
mxGraphHierarchyNode[] unseenNodesArray = new mxGraphHierarchyNode[1];
unseenNodes.toArray(unseenNodesArray);
model.visit(new mxGraphHierarchyModel.CellVisitor()
{
public void visit(mxGraphHierarchyNode parent,
mxGraphHierarchyNode cell,
mxGraphHierarchyEdge connectingEdge, int layer, int seen)
{
// Check if the cell is in it's own ancestor list, if so
// invert the connecting edge and reverse the target/source
// relationship to that edge in the parent and the cell
if ((cell)
.isAncestor(parent))
{
connectingEdge.invert();
parent.connectsAsSource.remove(connectingEdge);
parent.connectsAsTarget.add(connectingEdge);
cell.connectsAsTarget.remove(connectingEdge);
cell.connectsAsSource.add(connectingEdge);
}
seenNodes.add(cell);
unseenNodes.remove(cell);
}
}, unseenNodesArray, true, seenNodesCopy);
mxGraph graph = layout.getGraph();
if (possibleNewRoots != null && possibleNewRoots.size() > 0)
{
Iterator<Object> iter = possibleNewRoots.iterator();
List<Object> roots = model.roots;
while (iter.hasNext())
{
mxGraphHierarchyNode node = (mxGraphHierarchyNode) iter.next();
Object realNode = node.cell;
int numIncomingEdges = graph.getIncomingEdges(realNode).length;
if (numIncomingEdges == 0)
{
roots.add(realNode);
}
}
}
}
}