private ISpatialIndexNode <TBounds, TItem> doSplit(ISpatialIndexNode <TBounds, TItem> node, DynamicRTreeBalanceHeuristic heuristic)
{
Boolean isLeaf = node.IsLeaf;
IEnumerable <IBoundable <TBounds> > boundables =
isLeaf
? Caster.Upcast <IBoundable <TBounds>, TItem>(node.Items)
: Caster.Upcast <IBoundable <TBounds>, ISpatialIndexNode <TBounds, TItem> >(node.SubNodes);
Int32 boundablesCount = isLeaf ? node.ItemCount : node.SubNodeCount;
List <IBoundable <TBounds> > entries = new List <IBoundable <TBounds> >(boundablesCount);
entries.AddRange(boundables);
IList <IBoundable <TBounds> > group1 = new List <IBoundable <TBounds> >();
IList <IBoundable <TBounds> > group2 = new List <IBoundable <TBounds> >();
pickSeeds(entries, group1, group2);
Int32 group1Count = 1, group2Count = 1;
distribute(entries, group1, group2, heuristic, ref group1Count, ref group2Count);
if (entries.Count > 0)
{
if (group1Count < heuristic.NodeItemMinimumCount)
{
fillShortGroup(entries, group1, ref group1Count);
}
else // group2Count < heuristic.NodeItemMinimumCount
{
fillShortGroup(entries, group2, ref group2Count);
}
}
node.Clear();
ISpatialIndexNode <TBounds, TItem> sibling = NodeFactory.CreateNode(node.Level);
IEnumerable <IBoundable <TBounds> > g1Sized = Enumerable.Take(group1, group1Count);
IEnumerable <IBoundable <TBounds> > g2Sized = Enumerable.Take(group2, group2Count);
if (isLeaf)
{
//IEnumerable<TItem> g1Cast = Caster.Downcast<TItem, IBoundable<TBounds>>(g1Sized);
node.AddRange(g1Sized);
//IEnumerable<TItem> g2Cast = Caster.Downcast<TItem, IBoundable<IExtents>>(g2Sized);
sibling.AddRange(g2Sized);
}
else
{
//IEnumerable<ISpatialIndexNode<IExtents, TItem>> g1Cast
// = Caster.Downcast<ISpatialIndexNode<IExtents, TItem>, IBoundable<IExtents>>(g1Sized);
node.AddRange(g1Sized);
//IEnumerable<ISpatialIndexNode<IExtents, TItem>> g2Cast
// = Caster.Downcast<ISpatialIndexNode<IExtents, TItem>, IBoundable<IExtents>>(g2Sized);
sibling.AddRange(g2Sized);
}
return(sibling);
}