add generic quadtree index for tile cache

src/org/oscim/utils/quadtree/QuadTree.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2013 Hannes Janetzek
+ *
+ * This program is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.oscim.utils.quadtree;
+
+public class QuadTree<T> {
+	public QuadTree<T> parent;
+	public QuadTree<T> child00;
+	public QuadTree<T> child10;
+	public QuadTree<T> child01;
+	public QuadTree<T> child11;
+
+	public T item;
+
+	// id of this child relative to parent
+	byte id;
+
+	// number of children and grandchildren
+	int refs = 0;
+
+	public T get(int i){
+		switch (i) {
+			case 0:
+				return (child00 != null) ? child00.item : null;
+			case 1:
+				return (child01 != null) ? child01.item : null;
+			case 2:
+				return (child10 != null) ? child10.item : null;
+			case 3:
+				return (child11 != null) ? child11.item : null;
+		}
+		return null;
+	}
+}

src/org/oscim/utils/quadtree/QuadTreeIndex.java

@@ -0,0 +1,193 @@
+/*
+ * Copyright 2013 Hannes Janetzek
+ *
+ * This program is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.oscim.utils.quadtree;
+
+public abstract class QuadTreeIndex<T>  {
+
+
+	QuadTree<T> pool;
+
+	QuadTree<T> root;
+
+	public QuadTreeIndex() {
+		root = new QuadTree<T>();
+		root.parent = root;
+	}
+
+	static boolean checkIndex(int x, int y, int z) {
+		if (x < 0 || x >= 1 << z) {
+			//Log.d(TAG, "invalid position");
+			return false;
+		}
+		if (y < 0 || y >= 1 << z) {
+			//Log.d(TAG, "invalid position");
+			return false;
+		}
+		return true;
+	}
+
+	public abstract T create(int x, int y, int z);
+
+	public abstract void remove(T item);
+
+	public QuadTree<T> add(int x, int y, int z) {
+
+		if (!checkIndex(x, y, z))
+			return null;
+
+		QuadTree<T> leaf = root;
+
+		for (int level = z - 1; level >= 0; level--) {
+
+			int id = ((x >> level) & 1) | ((y >> level) & 1) << 1;
+
+			leaf.refs++;
+
+			QuadTree<T> cur = null;
+
+			switch (id) {
+				case 0:
+					cur = leaf.child00;
+					break;
+				case 1:
+					cur = leaf.child01;
+					break;
+				case 2:
+					cur = leaf.child10;
+					break;
+				case 3:
+					cur = leaf.child11;
+					break;
+			}
+
+			if (cur != null) {
+				leaf = cur;
+				continue;
+			}
+
+			if (pool != null) {
+				cur = pool;
+				pool = pool.parent;
+			} else {
+				cur = new QuadTree<T>();
+			}
+
+			cur.refs = 0;
+			cur.id = (byte) id;
+			cur.parent = leaf;
+
+			switch (id) {
+				case 0:
+					cur.parent.child00 = cur;
+					break;
+				case 1:
+					cur.parent.child01 = cur;
+					break;
+				case 2:
+					cur.parent.child10 = cur;
+					break;
+				case 3:
+					cur.parent.child11 = cur;
+					break;
+			}
+
+			leaf = cur;
+		}
+
+		leaf.refs++;
+
+		return leaf;
+	}
+
+	public T getTile(int x, int y, int z) {
+
+		if (!checkIndex(x, y, z))
+			return null;
+
+		QuadTree<T> leaf = root;
+
+		for (int level = z - 1; level >= 0; level--) {
+
+			int id = ((x >> level) & 1) | ((y >> level) & 1) << 1;
+
+			switch (id) {
+				case 0:
+					leaf = leaf.child00;
+					break;
+				case 1:
+					leaf = leaf.child01;
+					break;
+				case 2:
+					leaf = leaf.child10;
+					break;
+				case 3:
+					leaf = leaf.child11;
+					break;
+			}
+
+			if (leaf == null)
+				return null;
+
+			if (level == 0) {
+				return leaf.item;
+			}
+		}
+		return null;
+	}
+
+	public boolean remove(QuadTree<T> item) {
+
+		QuadTree<T> cur = item;
+		QuadTree<T> next;
+
+		for (; cur != root;) {
+			if (cur == null)
+				throw new IllegalArgumentException("QuadTree.remove: item not in index");
+
+			// keep pointer to parent
+			next = cur.parent;
+			cur.refs--;
+
+			// if current node has no children
+			if (cur.refs == 0) {
+				// unhook from parent
+
+				switch (cur.id) {
+					case 0:
+						next.child00 = null;
+						break;
+					case 1:
+						next.child01 = null;
+						break;
+					case 2:
+						next.child10 = null;
+						break;
+					case 3:
+						next.child11 = null;
+						break;
+				}
+
+				// add item back to pool
+				cur.parent = pool;
+				pool = cur;
+			}
+			cur = next;
+		}
+
+		root.refs--;
+
+		return true;
+	}
+}