/// <summary>
/// <see cref="BufferSubgraphs"/> are compared on the x-value of their
/// rightmost Coordinate. This defines a partial ordering on the graphs such that:
/// <para>
/// g1 >= g2 <==> Ring(g2) does not contain Ring(g1)
/// </para>
/// <para>
/// where Polygon(g) is the buffer polygon that is built from g.
/// </para>
/// This relationship is used to sort the BufferSubgraphs so that shells
/// are guaranteed to be built before holes.
/// </summary>
public int CompareTo(object o)
{
BufferSubgraph graph = (BufferSubgraph)o;
if (this.rightMostCoord.X < graph.rightMostCoord.X)
{
return(-1);
}
if (this.rightMostCoord.X > graph.rightMostCoord.X)
{
return(1);
}
return(0);
}
/// <summary>
/// Completes the building of the input subgraphs by depth-labelling them,
/// and adds them to the 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)
{
ArrayList processedGraphs = new ArrayList();
int nCount = subgraphList.Count;
for (int i = 0; i < nCount; i++)
{
BufferSubgraph subgraph = (BufferSubgraph)subgraphList[i];
Coordinate 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);
}
}
/// <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 {@link DepthSegments} intersecting the stabbing line
/// </returns>
private ArrayList FindStabbedSegments(Coordinate stabbingRayLeftPt)
{
ArrayList stabbedSegments = new ArrayList();
for (IEnumerator i = subgraphs.GetEnumerator(); i.MoveNext();)
{
BufferSubgraph bsg = (BufferSubgraph)i.Current;
// optimization - don't bother checking subgraphs which the ray does not intersect
Envelope env = bsg.Envelope;
if (stabbingRayLeftPt.Y < env.MinY ||
stabbingRayLeftPt.Y > env.MaxY)
{
continue;
}
FindStabbedSegments(stabbingRayLeftPt,
bsg.DirectedEdges, stabbedSegments);
}
return(stabbedSegments);
}
private IList CreateSubgraphs(PlanarGraph graph)
{
ArrayList subgraphList = new ArrayList();
for (IEnumerator i = graph.Nodes.GetEnumerator(); i.MoveNext(); )
{
Node node = (Node) i.Current;
if (!node.Visited)
{
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(new ReverseComparator());
return subgraphList;
}
