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Handful shortcuts for Java programming, Java 7 compatible.
/*
* Copyright (C) 2010-2014, Danilo Pianini and contributors
* listed in the project's pom.xml file.
*
* This file is part of Alchemist, and is distributed under the terms of
* the GNU General Public License, with a linking exception, as described
* in the file LICENSE in the Alchemist distribution's top directory.
*/
package org.danilopianini.lang;
import java.awt.geom.Rectangle2D;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
/**
*
* @author matheusdev
* @author Danilo Pianini
*
* @param
*/
public class QuadTree implements Serializable {
private static final long serialVersionUID = -8765593946059102012L;
private QuadTree botLeft;
private QuadTree botRight;
private final Rectangle2D bounds;
private final List> elements;
private final int elems;
private final double maxX;
private final double maxY;
private final double minX;
private final double minY;
private QuadTree topLeft;
private QuadTree topRight;
private static class QuadTreeEntry implements Serializable {
private static final long serialVersionUID = 9021533648086596986L;
private final E element;
private double x, y;
public QuadTreeEntry(final E el, final double xp, final double yp) {
element = el;
x = xp;
y = yp;
}
public String toString() {
return element.toString();
}
}
/**
* @param x
* minimum x
* @param y
* minimum y
* @param mx
* maximum x
* @param my
* maximum y
* @param elemPerQuad
* maximum number of elements per quad
*/
public QuadTree(final double x, final double y, final double mx, final double my, final int elemPerQuad) {
bounds = new Rectangle2D.Double();
minX = x;
maxX = mx;
minY = y;
maxY = my;
bounds.setFrameFromDiagonal(minX, minY, maxX, maxY);
elements = new ArrayList<>(elemPerQuad);
elems = elemPerQuad;
}
private boolean contains(final double x, final double y) {
return y >= minY && y <= maxY && x >= minX && x <= maxX;
}
/**
* Deletes an element from the QuadTree.
*
* @param e
* The element to delete
* @param x
* the x position of the element
* @param y
* the y position of the element
* @return true if the element is found and removed
*/
public boolean delete(final E e, final double x, final double y) {
if (!contains(x, y)) {
return false;
}
if (remove(e, x, y)) {
return true;
} else {
if (topRight.delete(e, x, y)) {
return true;
}
if (topLeft.delete(e, x, y)) {
return true;
}
if (botRight.delete(e, x, y)) {
return true;
}
if (botLeft.delete(e, x, y)) {
return true;
}
}
return false;
}
private boolean hasChildren() {
return topLeft != null;
}
/**
* Inserts an element in the QuadTree.
*
* @param e
* The element to add
* @param x
* the x position of the element
* @param y
* the y position of the element
* @return true if the element is correctly inserted, false otherwise (e.g.
* because the element is out of the indexed space)
*/
public boolean insert(final E e, final double x, final double y) {
return insert(new QuadTreeEntry(e, x, y));
}
private boolean insert(final QuadTreeEntry e) {
if (!contains(e.x, e.y)) {
return false;
}
if (set(e)) {
return true;
} else {
subdivide();
if (topRight.insert(e)) {
return true;
}
if (topLeft.insert(e)) {
return true;
}
if (botRight.insert(e)) {
return true;
}
if (botLeft.insert(e)) {
return true;
}
/*
* Point on the bounds of the subsets. Force inclusion here.
*/
elements.add(e);
return true;
}
}
/**
* @return the maximum number of elements per node
*/
public int getMaxElementsNumber() {
return elems;
}
/**
* If an element is moved, updates the QuadTree accordingly.
*
* @param e
* the element
* @param sx
* the start x
* @param sy
* the start y
* @param fx
* the final x
* @param fy
* the final y
* @return true if the element is found and no error occurred
*/
public boolean move(final E e, final double sx, final double sy, final double fx, final double fy) {
if (sx == fx && sy == fy) {
return true;
}
if (!contains(sx, sy)) {
return false;
}
final QuadTree currentContainer = searchForEntry(e, sx, sy);
final int pos = currentContainer.searchAtThisLevel(e, sx, sy);
final QuadTreeEntry entry = currentContainer.elements.get(pos);
entry.x = fx;
entry.y = fy;
if (!currentContainer.contains(fx, fy)) {
/*
* TODO: improve this.
*/
currentContainer.elements.remove(pos);
insert(entry);
}
return true;
}
/**
* @param range
* the range where to retrieve the objects
* @return a list of the objects in the range
*/
public List query(final Rectangle2D range) {
final List result = new ArrayList<>();
query(range, result);
return result;
}
private void query(final Rectangle2D range, final List results) {
if (bounds.intersects(range)) {
for (final QuadTreeEntry entry : elements) {
if (range.contains(entry.x, entry.y)) {
results.add(entry.element);
}
}
if (hasChildren()) {
topLeft.query(range, results);
topRight.query(range, results);
botLeft.query(range, results);
botRight.query(range, results);
}
}
}
private boolean remove(final E e, final double x, final double y) {
for (int i = 0; i < elements.size(); i++) {
final QuadTreeEntry entry = elements.get(i);
if (entry.x == x && entry.y == y && entry.element.equals(e)) {
elements.remove(i);
return true;
}
}
return false;
}
private int searchAtThisLevel(final E e, final double x, final double y) {
for (int i = 0; i < elements.size(); i++) {
final QuadTreeEntry entry = elements.get(i);
if (entry.x == x && entry.y == y && entry.element.equals(e)) {
return i;
}
}
return -1;
}
private QuadTree searchForEntry(final E e, final double sx, final double sy) {
if (!contains(sx, sy)) {
return null;
}
final int index = searchAtThisLevel(e, sx, sy);
if (index >= 0) {
return this;
} else {
if (hasChildren()) {
QuadTree result = topRight.searchForEntry(e, sx, sy);
if (result == null) {
result = topLeft.searchForEntry(e, sx, sy);
if (result == null) {
result = botRight.searchForEntry(e, sx, sy);
if (result == null) {
result = botLeft.searchForEntry(e, sx, sy);
}
}
}
return result;
}
return null;
}
}
private boolean set(final QuadTreeEntry e) {
if (elements.size() >= elems) {
return false;
}
elements.add(e);
return true;
}
/**
*
* Subdivides this Quadtree into 4 other quadtrees.
*
*
* This is usually used, when this Quadtree already has an Element.
*
*
* @return whether this Quadtree was subdivided, or didn't subdivide,
* because it was already subdivided.
*/
protected boolean subdivide() {
if (hasChildren()) {
return false;
}
final double cx = bounds.getCenterX();
final double cy = bounds.getCenterY();
topLeft = new QuadTree(minX, cy, cx, maxY, getMaxElementsNumber());
topRight = new QuadTree(cx, cy, maxX, maxY, getMaxElementsNumber());
botLeft = new QuadTree(minX, minY, cx, cy, getMaxElementsNumber());
botRight = new QuadTree(cx, minY, maxX, cy, getMaxElementsNumber());
return true;
}
@Override
public String toString() {
return bounds.toString() + ' ' + elements.toString();
}
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