Editing Quadtree (section)

===Insertion===
The following method inserts a point into the appropriate quad of a quadtree, splitting if necessary.

<syntaxhighlight lang="c++">
 class QuadTree
 {
     ...
   
     // Insert a point into the QuadTree
     function insert(XY p)
     {
         // Ignore objects that do not belong in this quad tree
         if (!boundary.containsPoint(p))
             return false; // object cannot be added
     
         // If there is space in this quad tree and if it doesn't have subdivisions, add the object here
         if (points.size < QT_NODE_CAPACITY && northWest == null)
         {
             points.append(p);
             return true;
         }
     
         // Otherwise, subdivide and then add the point to whichever node will accept it
         if (northWest == null)
             subdivide();
         // We have to add the points/data contained in this quad array to the new quads if we only want
         // the last node to hold the data
     
         if (northWest->insert(p)) return true;
         if (northEast->insert(p)) return true;
         if (southWest->insert(p)) return true;
         if (southEast->insert(p)) return true;
     
         // Otherwise, the point cannot be inserted for some unknown reason (this should never happen)
         return false;
     }
 }
</syntaxhighlight>