/// <summary>
/// Insert an item into the tree this is the root of.
/// </summary>
/// <param name="itemInterval"></param>
/// <param name="item"></param>
public virtual void Insert(Interval itemInterval, object item)
{
int index = GetSubnodeIndex(itemInterval, ORIGIN);
// if index is -1, itemEnv must contain the origin.
if (index == -1)
{
Add(item);
return;
}
/*
* the item must be contained in one interval, so insert it into the
* tree for that interval (which may not yet exist)
*/
Node node = Nodes[index];
/*
* If the subnode doesn't exist or this item is not contained in it,
* have to expand the tree upward to contain the item.
*/
if (node == null || !node.Interval.Contains(itemInterval))
{
Node largerNode = Node.CreateExpanded(node, itemInterval);
Nodes[index] = largerNode;
}
/*
* At this point we have a subnode which exists and must contain
* contains the env for the item. Insert the item into the tree.
*/
InsertContained(Nodes[index], itemInterval, item);
}
/// <summary>
///
/// </summary>
/// <param name="itemInterval"></param>
/// <returns></returns>
public static Node CreateNode(Interval itemInterval)
{
Key key = new Key(itemInterval);
Node node = new Node(key.Interval, key.Level);
return node;
}
/// <summary>
///
/// </summary>
/// <param name="node"></param>
/// <param name="addInterval"></param>
/// <returns></returns>
public static Node CreateExpanded(Node node, Interval addInterval)
{
Interval expandInt = new Interval(addInterval);
if (node != null) expandInt.ExpandToInclude(node._interval);
Node largerNode = CreateNode(expandInt);
if (node != null) largerNode.Insert(node);
return largerNode;
}
/// <summary>
///
/// </summary>
/// <param name="interval"></param>
/// <param name="resultItems"></param>
/// <returns></returns>
public virtual IList AddAllItemsFromOverlapping(Interval interval, IList resultItems)
{
if (!IsSearchMatch(interval))
return _items;
// resultItems.addAll(items);
foreach (object o in _items)
resultItems.Add(o);
for (int i = 0; i < 2; i++)
if (_subnode[i] != null)
_subnode[i].AddAllItemsFromOverlapping(interval, resultItems);
return _items;
}
/// <summary>
/// Insert an item which is known to be contained in the tree rooted at
/// the given Node. Lower levels of the tree will be created
/// if necessary to hold the item.
/// </summary>
/// <param name="tree"></param>
/// <param name="itemInterval"></param>
/// <param name="item"></param>
private static void InsertContained(Node tree, Interval itemInterval, object item)
{
Assert.IsTrue(tree.Interval.Contains(itemInterval));
/*
* Do NOT create a new node for zero-area intervals - this would lead
* to infinite recursion. Instead, use a heuristic of simply returning
* the smallest existing node containing the query
*/
bool isZeroArea = IntervalSize.IsZeroWidth(itemInterval.Min, itemInterval.Max);
NodeBase node;
if (isZeroArea)
node = tree.Find(itemInterval);
else node = tree.GetNode(itemInterval);
node.Add(item);
}
/// <summary>
///
/// </summary>
/// <param name="interval"></param>
/// <param name="level"></param>
public Node(Interval interval, int level)
{
_interval = interval;
_level = level;
_centre = (interval.Min + interval.Max) / 2;
}
/// <summary>
///
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
private Node CreateSubnode(int index)
{
// create a new subnode in the appropriate interval
double min = 0.0;
double max = 0.0;
switch (index)
{
case 0:
min = _interval.Min;
max = _centre;
break;
case 1:
min = _centre;
max = _interval.Max;
break;
default:
break;
}
Interval subInt = new Interval(min, max);
Node node = new Node(subInt, _level - 1);
return node;
}
/// <summary>
/// Returns the index of the subnode that wholely contains the given interval.
/// If none does, returns -1.
/// </summary>
/// <param name="interval"></param>
/// <param name="centre"></param>
public static int GetSubnodeIndex(Interval interval, double centre)
{
int subnodeIndex = -1;
if (interval.Min >= centre)
subnodeIndex = 1;
if (interval.Max <= centre)
subnodeIndex = 0;
return subnodeIndex;
}
/// <summary>
///
/// </summary>
/// <param name="interval"></param>
/// <param name="foundItems"></param>
public virtual void Query(Interval interval, IList foundItems)
{
_root.AddAllItemsFromOverlapping(interval, foundItems);
}
/// <summary>
///
/// </summary>
/// <param name="itemInterval"></param>
/// <param name="item"></param>
public virtual void Insert(Interval itemInterval, object item)
{
CollectStats(itemInterval);
Interval insertInterval = EnsureExtent(itemInterval, _minExtent);
_root.Insert(insertInterval, item);
}
/// <summary>
///
/// </summary>
/// <param name="interval"></param>
public Key(Interval interval)
{
ComputeKey(interval);
}
/// <summary>
///
/// </summary>
/// <param name="level"></param>
/// <param name="itemInterval"></param>
private void ComputeInterval(int level, Interval itemInterval)
{
double size = DoubleBits.PowerOf2(level);
_pt = Math.Floor(itemInterval.Min / size) * size;
_interval.Init(_pt, _pt + size);
}
/// <summary>
/// Return a square envelope containing the argument envelope,
/// whose extent is a power of two and which is based at a power of 2.
/// </summary>
/// <param name="itemInterval"></param>
public void ComputeKey(Interval itemInterval)
{
_level = ComputeLevel(itemInterval);
_interval = new Interval();
ComputeInterval(_level, itemInterval);
// MD - would be nice to have a non-iterative form of this algorithm
while (!_interval.Contains(itemInterval))
{
_level += 1;
ComputeInterval(_level, itemInterval);
}
}
/// <summary>
/// The root node matches all searches.
/// </summary>
/// <param name="interval"></param>
protected override bool IsSearchMatch(Interval interval)
{
return true;
}
/// <summary>
///
/// </summary>
/// <param name="itemInterval"></param>
/// <returns></returns>
protected override bool IsSearchMatch(Interval itemInterval)
{
return itemInterval.Overlaps(_interval);
}
/// <summary>
///
/// </summary>
/// <param name="interval"></param>
/// <returns></returns>
public static int ComputeLevel(Interval interval)
{
double dx = interval.Width;
int level = DoubleBits.GetExponent(dx) + 1;
return level;
}
/// <summary>
/// Ensure that the Interval for the inserted item has non-zero extents.
/// Use the current minExtent to pad it, if necessary.
/// </summary>
public static Interval EnsureExtent(Interval itemInterval, double minExtent)
{
double min = itemInterval.Min;
double max = itemInterval.Max;
// has a non-zero extent
if (min != max)
return itemInterval;
// pad extent
if (min == max)
{
min = min - minExtent / 2.0;
max = min + minExtent / 2.0;
}
return new Interval(min, max);
}
/// <summary>
/// Returns the subnode containing the envelope.
/// Creates the node if
/// it does not already exist.
/// </summary>
/// <param name="searchInterval"></param>
public virtual Node GetNode(Interval searchInterval)
{
int subnodeIndex = GetSubnodeIndex(searchInterval, _centre);
// if index is -1 searchEnv is not contained in a subnode
if (subnodeIndex != -1)
{
// create the node if it does not exist
Node node = GetSubnode(subnodeIndex);
// recursively search the found/created node
return node.GetNode(searchInterval);
}
return this;
}
/// <summary>
/// min and max may be the same value.
/// </summary>
/// <param name="interval"></param>
public virtual IList Query(Interval interval)
{
/*
* the items that are matched are all items in intervals
* which overlap the query interval
*/
IList foundItems = new ArrayList();
Query(interval, foundItems);
return foundItems;
}
/// <summary>
/// Returns the smallest existing
/// node containing the envelope.
/// </summary>
/// <param name="searchInterval"></param>
public virtual NodeBase Find(Interval searchInterval)
{
int subnodeIndex = GetSubnodeIndex(searchInterval, _centre);
if (subnodeIndex == -1)
return this;
if (Nodes[subnodeIndex] != null)
{
// query lies in subnode, so search it
Node node = Nodes[subnodeIndex];
return node.Find(searchInterval);
}
// no existing subnode, so return this one anyway
return this;
}
/// <summary>
///
/// </summary>
/// <param name="interval"></param>
private void CollectStats(Interval interval)
{
double del = interval.Width;
if (del < _minExtent && del > 0.0)
_minExtent = del;
}
/// <summary> /// /// </summary> /// <param name="interval"></param> /// <returns></returns> protected abstract bool IsSearchMatch(Interval interval);