private void Relocate(QuadTreeObject <T> item)
{
// Are we still inside our parent?
if (this.QuadRect.Contains(item.Data.Bounds))
{
// Good, have we moved inside any of our children?
if (this.TopLeftChild != null)
{
var dest = this.GetDestinationTree(item);
if (item.Owner != dest)
{
// Delete the item from this quad and add it to our child
// Note: Do NOT clean during this call, it can potentially delete our destination quad
var formerOwner = item.Owner;
this.Delete(item, false);
dest.Insert(item);
// Clean up ourselves
formerOwner.CleanUpwards();
}
}
}
else
{
// We don't fit here anymore, move up, if we can
this.Parent?.Relocate(item);
}
}
///<summary>
/// Adds an item to the QuadTree
///</summary>
///
///<param name="item">The object to add to the <see cref="T:System.Collections.Generic.ICollection`1" />.</param>
///<exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection`1" /> is read-only.</exception>
public void Add(T item)
{
var wrappedObject = new QuadTreeObject <T>(item);
this.wrappedDictionary.Add(item, wrappedObject);
this.QuadTreeRoot.Insert(wrappedObject);
}
/// <summary>
/// Add an item to the object list.
/// </summary>
/// <param name="item">The item to add.</param>
private void Add(QuadTreeObject <T> item)
{
if (this.objects == null)
{
this.objects = new List <QuadTreeObject <T> >();
}
item.Owner = this;
this.objects.Add(item);
}
/// <summary>
/// Moves the QuadTree object in the tree
/// </summary>
/// <param name="item">The item that has moved</param>
internal void Move(QuadTreeObject <T> item)
{
if (item.Owner != null)
{
item.Owner.Relocate(item);
}
else
{
this.Relocate(item);
}
}
/// <summary>
/// Remove an item from the object list.
/// </summary>
/// <param name="item">The object to remove.</param>
private void Remove(QuadTreeObject <T> item)
{
if (this.objects != null)
{
var removeIndex = this.objects.IndexOf(item);
if (removeIndex >= 0)
{
this.objects[removeIndex] = this.objects[this.objects.Count - 1];
this.objects.RemoveAt(this.objects.Count - 1);
}
}
}
/// <summary>
/// Deletes an item from this QuadTree. If the object is removed causes this Quad to have no objects in its children,
/// it's children will be removed as well.
/// </summary>
/// <param name="item">The item to remove.</param>
/// <param name="clean">Whether or not to clean the tree</param>
internal void Delete(QuadTreeObject <T> item, bool clean)
{
if (item.Owner != null)
{
if (item.Owner == this)
{
this.Remove(item);
if (clean)
{
this.CleanUpwards();
}
}
else
{
item.Owner.Delete(item, clean);
}
}
}
/// <summary>
/// Insert an item into this QuadTree object.
/// </summary>
/// <param name="item">The item to insert.</param>
internal void Insert(QuadTreeObject <T> item)
{
// If this quad doesn't contain the items rectangle, do nothing, unless we are the root
if (!this.QuadRect.Contains(item.Data.Bounds))
{
if (this.Parent == null)
{
// This object is outside of the QuadTree bounds, we should add it at the root level
this.Add(item);
}
else
{
return;
}
}
if (this.objects == null || this.TopLeftChild == null && this.objects.Count + 1 <= MaxObjectsPerNode)
{
// If there's room to add the object, just add it
this.Add(item);
}
else
{
// No quads, create them and bump objects down where appropriate
if (this.TopLeftChild == null)
{
this.Subdivide();
}
// Find out which tree this object should go in and add it there
var destTree = this.GetDestinationTree(item);
if (destTree == this)
{
this.Add(item);
}
else
{
destTree.Insert(item);
}
}
}
/// <summary>
/// Get the child Quad that would contain an object.
/// </summary>
/// <param name="item">The object to get a child for.</param>
/// <returns></returns>
private QuadTreeNode <T> GetDestinationTree(QuadTreeObject <T> item)
{
// If a child can't contain an object, it will live in this Quad
var destTree = this;
if (this.TopLeftChild.QuadRect.Contains(item.Data.Bounds))
{
destTree = this.TopLeftChild;
}
else if (this.TopRightChild.QuadRect.Contains(item.Data.Bounds))
{
destTree = this.TopRightChild;
}
else if (this.BottomLeftChild.QuadRect.Contains(item.Data.Bounds))
{
destTree = this.BottomLeftChild;
}
else if (this.BottomRightChild.QuadRect.Contains(item.Data.Bounds))
{
destTree = this.BottomRightChild;
}
return(destTree);
}
