private IList CreateSubgraphs(PlanarGraph graph)
{
ArrayList subgraphList = new ArrayList();
foreach (object obj in graph.Nodes)
{
Node node = (Node)obj;
if (!node.IsVisited)
{
BufferSubgraph subgraph = new BufferSubgraph();
subgraph.Create(node);
subgraphList.Add(subgraph);
}
}
/*
* Sort the subgraphs in descending order of their rightmost coordinate.
* This ensures that when the Polygons for the subgraphs are built,
* subgraphs for shells will have been built before the subgraphs for
* any holes they contain.
*/
subgraphList.Sort();
subgraphList.Reverse();
return(subgraphList);
}
/// <summary>
/// Finds all non-horizontal segments intersecting the stabbing line.
/// The stabbing line is the ray to the right of stabbingRayLeftPt.
/// </summary>
/// <param name="stabbingRayLeftPt">The left-hand origin of the stabbing line.</param>
/// <returns>A List of {DepthSegments} intersecting the stabbing line.</returns>
private IList FindStabbedSegments(ICoordinate stabbingRayLeftPt)
{
IList stabbedSegments = new ArrayList();
IEnumerator i = subgraphs.GetEnumerator();
while (i.MoveNext())
{
BufferSubgraph bsg = (BufferSubgraph)i.Current;
FindStabbedSegments(stabbingRayLeftPt, bsg.DirectedEdges, stabbedSegments);
}
return(stabbedSegments);
}
/// <summary>
/// BufferSubgraphs are compared on the x-value of their rightmost Coordinate.
/// This defines a partial ordering on the graphs such that:
/// g1 >= g2 - Ring(g2) does not contain Ring(g1)
/// where Polygon(g) is the buffer polygon that is built from g.
/// This relationship is used to sort the BufferSubgraphs so that shells are guaranteed to
/// be built before holes.
/// </summary>
public virtual int CompareTo(Object o)
{
BufferSubgraph graph = (BufferSubgraph)o;
if (this.RightMostCoordinate.X < graph.RightMostCoordinate.X)
{
return(-1);
}
if (this.RightMostCoordinate.X > graph.RightMostCoordinate.X)
{
return(1);
}
return(0);
}
/// <summary>
/// Completes the building of the input subgraphs by depth-labelling them,
/// and adds them to the <see cref="PolygonBuilder" />.
/// The subgraph list must be sorted in rightmost-coordinate order.
/// </summary>
/// <param name="subgraphList">The subgraphs to build.</param>
/// <param name="polyBuilder">The PolygonBuilder which will build the final polygons.</param>
private void BuildSubgraphs(IList subgraphList, PolygonBuilder polyBuilder)
{
IList processedGraphs = new ArrayList();
foreach (object obj in subgraphList)
{
BufferSubgraph subgraph = (BufferSubgraph)obj;
ICoordinate p = subgraph.RightMostCoordinate;
SubgraphDepthLocater locater = new SubgraphDepthLocater(processedGraphs);
int outsideDepth = locater.GetDepth(p);
subgraph.ComputeDepth(outsideDepth);
subgraph.FindResultEdges();
processedGraphs.Add(subgraph);
polyBuilder.Add(subgraph.DirectedEdges, subgraph.Nodes);
}
}