/// <summary>
/// Insert an item into the tree this is the root of.
/// </summary>
/// <param name="itemInterval"></param>
/// <param name="item"></param>
public 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 = _subnode[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 );
_subnode[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( _subnode[index], itemInterval, item );
}
/// <summary>
/// Return a square envelope containing the argement 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 = Key.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 );
}
}
public ArrayList AddAllItemsFromOverlapping( Interval interval, ArrayList resultItems )
{
if ( !IsSearchMatch( interval ) )
{
return _items;
}
resultItems.AddRange( _items );
for (int i = 0; i < 2; i++)
{
if ( _subnode[i] != null )
{
_subnode[i].AddAllItemsFromOverlapping( interval, resultItems );
}
}
return _items;
}
/// <summary>
/// Returns the subnode containing the envelope. Creates the node if it does not already exist.
/// </summary>
/// <param name="searchInterval"></param>
/// <returns></returns>
public 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 );
}
else
{
return this;
}
}
/// <summary>
/// Returns the smallest existing node containing the envelope.
/// </summary>
/// <param name="searchInterval"></param>
/// <returns></returns>
public NodeBase Find( Interval searchInterval )
{
int subnodeIndex = GetSubnodeIndex( searchInterval, _centre );
if ( subnodeIndex == -1 )
{
return this;
}
if ( _subnode[subnodeIndex] != null )
{
// query lies in subnode, so search it
Node node = _subnode[subnodeIndex];
return node.Find( searchInterval );
}
// no existing subnode, so return this one anyway
return this;
}
/// <summary>
/// Initializes a new instance of the Key class.
/// </summary>
public Key( Interval interval )
{
ComputeKey( interval );
}
public Interval(Interval interval)
{
Initialize( interval.Min, interval.Max );
}
public bool Overlaps( Interval interval )
{
return Overlaps( interval.Min, interval.Max );
}
protected override bool IsSearchMatch( Interval itemInterval )
{
return itemInterval.Overlaps( _interval );
}
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;
}
public void Query(Interval interval, ArrayList foundItems)
{
_root.AddAllItemsFromOverlapping( interval, foundItems );
}
/// <summary>
/// Min and max may be the same value.
/// </summary>
/// <param name="interval"></param>
/// <returns></returns>
public ArrayList Query( Interval interval )
{
// the items that are matched are all items in intervals
// which overlap the query interval
ArrayList foundItems = new ArrayList();
Query( interval, foundItems );
return foundItems;
}
/// <summary>
/// Insert an item which is known to be contained in the tree rooted at the given Noed.
/// Lower levels of the tree will be created it necessary to hold the item.
/// </summary>
/// <param name="tree"></param>
/// <param name="itemInterval"></param>
/// <param name="item"></param>
private void InsertContained( Node tree, Interval itemInterval, object item )
{
Debug.Assert( 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>
/// The root node matches all searches.
/// </summary>
/// <param name="interval"></param>
/// <returns></returns>
protected override bool IsSearchMatch( Interval interval )
{
return true;
}
private void ComputeInterval( int level, Interval itemInterval )
{
double size = DoubleBits.PowerOf2( level );
//double size = pow2.power(level);
_pt = Math.Floor( itemInterval.Min / size) * size;
_interval.Initialize( _pt, _pt + size );
}
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;
}
Interval subInt = new Interval( min, max );
Node node = new Node (subInt, _level - 1);
return node;
}
public static Node CreateNode( Interval itemInterval )
{
Key key = new Key( itemInterval );
//System.out.println("input: " + env + " binaryEnv: " + key.getEnvelope());
Node node = new Node( key.Interval, key.Level );
return node;
}
private void CollectStats( Interval interval )
{
double del = interval.GetWidth();
if (del < _minExtent && del > 0.0)
{
_minExtent = del;
}
}
/// <summary>
/// Initializes a new instance of the Node class.
/// </summary>
public Node( Interval interval, int level )
{
_interval = interval;
_level = level;
_centre = ( interval.Min + interval.Max ) / 2;
}
/// <summary>
/// Ensure that the Interval for the inserted item has non-zero extents.
/// Use the current minExtent to pad it, if necessary.
/// </summary>
/// <param name="itemInterval"></param>
/// <param name="minExtent"></param>
/// <returns></returns>
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);
}
public void Insert( Interval itemInterval, object item )
{
CollectStats( itemInterval );
Interval insertInterval = EnsureExtent( itemInterval, _minExtent );
_root.Insert( insertInterval, item );
/* DEBUG
int newSize = size();
System.out.println("BinTree: size = " + newSize + " node size = " + nodeSize());
if (newSize <= oldSize)
{
System.out.println("Lost item!");
root.insert(insertInterval, item);
System.out.println("reinsertion size = " + size());
}*/
}
/// <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>
/// <returns></returns>
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;
}
public bool Contains( Interval interval )
{
return Contains( interval.Min, interval.Max );
}
protected abstract bool IsSearchMatch( Interval interval );
public void ExpandToInclude( Interval interval )
{
if ( interval.Max > _max ) _max = interval.Max;
if ( interval.Min < _min ) _min = interval.Min;
}
public static int ComputeLevel( Interval interval )
{
double dx = interval.GetWidth();
//int level = BinaryPower.exponent(dx) + 1;
int level = DoubleBits.Exponent(dx) + 1;
return level;
}
