/// <summary>
///
/// </summary>
/// <param name="node"></param>
/// <param name="addEnv"></param>
/// <returns></returns>
public static Node CreateExpanded(Node node, IEnvelope addEnv)
{
IEnvelope expandEnv = new Envelope(addEnv);
if (node != null)
expandEnv.ExpandToInclude(node.env);
Node largerNode = CreateNode(expandEnv);
if (node != null)
largerNode.InsertNode(node);
return largerNode;
}
/// <summary>
/// Insert an item which is known to be contained in the tree rooted at
/// the given QuadNode root. Lower levels of the tree will be created
/// if necessary to hold the item.
/// </summary>
private void InsertContained(Node tree, IEnvelope itemEnv, object item)
{
Assert.IsTrue(tree.Envelope.Contains(itemEnv));
/*
* Do NOT create a new quad for zero-area envelopes - this would lead
* to infinite recursion. Instead, use a heuristic of simply returning
* the smallest existing quad containing the query
*/
bool isZeroX = IntervalSize.IsZeroWidth(itemEnv.MinX, itemEnv.MaxX);
bool isZeroY = IntervalSize.IsZeroWidth(itemEnv.MinY, itemEnv.MaxY);
NodeBase node;
if (isZeroX || isZeroY)
node = tree.Find(itemEnv);
else node = tree.GetNode(itemEnv);
node.Add(item);
}
/// <summary>
///
/// </summary>
/// <param name="env"></param>
/// <returns></returns>
public static Node CreateNode(IEnvelope env)
{
Key key = new Key(env);
Node node = new Node(key.Envelope, key.Level);
return node;
}
/// <summary>
///
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
private Node CreateSubnode(int index)
{
// create a new subquad in the appropriate quadrant
double minx = 0.0;
double maxx = 0.0;
double miny = 0.0;
double maxy = 0.0;
switch (index)
{
case 0:
minx = env.MinX;
maxx = centre.X;
miny = env.MinY;
maxy = centre.Y;
break;
case 1:
minx = centre.X;
maxx = env.MaxX;
miny = env.MinY;
maxy = centre.Y;
break;
case 2:
minx = env.MinX;
maxx = centre.X;
miny = centre.Y;
maxy = env.MaxY;
break;
case 3:
minx = centre.X;
maxx = env.MaxX;
miny = centre.Y;
maxy = env.MaxY;
break;
default:
break;
}
IEnvelope sqEnv = new Envelope(minx, maxx, miny, maxy);
Node node = new Node(sqEnv, level - 1);
return node;
}
/// <summary>
///
/// </summary>
/// <param name="node"></param>
public void InsertNode(Node node)
{
Assert.IsTrue(env == null || env.Contains(node.Envelope));
int index = GetSubnodeIndex(node.env, centre);
if (node.level == level - 1)
subnode[index] = node;
else
{
// the quad is not a direct child, so make a new child quad to contain it
// and recursively insert the quad
Node childNode = CreateSubnode(index);
childNode.InsertNode(node);
subnode[index] = childNode;
}
}
