Files
openlayers/src/ol/structs/rtree.js
2013-07-22 17:42:47 +02:00

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20 KiB
JavaScript

// rtree.js - General-Purpose Non-Recursive Javascript R-Tree Library
// Version 0.6.2, December 5st 2009
//
// Copyright (c) 2009 Jon-Carlos Rivera
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
// Jon-Carlos Rivera - imbcmdth@hotmail.com
goog.provide('ol.structs.RTree');
goog.require('goog.array');
goog.require('ol.extent');
/**
* @typedef {{extent: ol.Extent,
* leaf: (Object|undefined),
* nodes: (Array.<ol.structs.RTreeNode>|undefined),
* target: (Object|undefined),
* type: (string|undefined)}}
*/
ol.structs.RTreeNode;
/**
* @constructor
* @param {number=} opt_maxWidth Width before a node is split. Default is 6.
*/
ol.structs.RTree = function(opt_maxWidth) {
/**
* Maximum width of any node before a split.
* @private
* @type {number}
*/
this.maxWidth_ = goog.isDef(opt_maxWidth) ? opt_maxWidth : 6;
/**
* Minimum width of any node before a merge.
* @private
* @type {number}
*/
this.minWidth_ = Math.floor(this.maxWidth_ / 2);
/**
* Start with an empty root-tree.
* @private
* @type {ol.structs.RTreeNode}
*/
this.rootTree_ = /** @type {ol.structs.RTreeNode} */
({extent: ol.extent.createEmpty(), nodes: []});
};
/**
* @param {ol.structs.RTreeNode} node Node.
* @private
*/
ol.structs.RTree.recalculateExtent_ = function(node) {
var n = node.nodes.length;
var extent = node.extent;
if (n === 0) {
ol.extent.empty(extent);
} else {
var firstNodeExtent = node.nodes[0].extent;
extent[0] = firstNodeExtent[0];
extent[1] = firstNodeExtent[1];
extent[2] = firstNodeExtent[2];
extent[3] = firstNodeExtent[3];
var i;
for (i = 1; i < n; ++i) {
ol.extent.extend(extent, node.nodes[i].extent);
}
}
};
/**
* This is Jon-Carlos Rivera's special addition to the world of r-trees.
* Every other (simple) method he found produced poor trees.
* This skews insertions to prefering squarer and emptier nodes.
*
* @param {number} l L.
* @param {number} w W.
* @param {number} fill Fill.
* @private
* @return {number} Squarified ratio.
*/
ol.structs.RTree.squarifiedRatio_ = function(l, w, fill) {
// Area of new enlarged rectangle
var peri = (l + w) / 2; // Average size of a side of the new rectangle
var area = l * w; // Area of new rectangle
// return the ratio of the perimeter to the area - the closer to 1 we are,
// the more "square" a rectangle is. conversly, when approaching zero the
// more elongated a rectangle is
var geo = area / (peri * peri);
return area * fill / geo;
};
/**
* Choose the best for rectangle to be inserted into.
*
* @param {ol.structs.RTreeNode} rect Rectangle.
* @param {ol.structs.RTreeNode} root Root to start search.
* @private
* @return {Array} Leaf node parent.
*/
ol.structs.RTree.prototype.chooseLeafSubtree_ = function(rect, root) {
var bestChoiceIndex = -1;
var bestChoiceStack = [];
var bestChoiceArea;
bestChoiceStack.push(root);
var nodes = root.nodes;
do {
if (bestChoiceIndex != -1) {
bestChoiceStack.push(nodes[bestChoiceIndex]);
nodes = nodes[bestChoiceIndex].nodes;
bestChoiceIndex = -1;
}
for (var i = nodes.length - 1; i >= 0; --i) {
var lTree = nodes[i];
if (goog.isDef(lTree.leaf)) {
// Bail out of everything and start inserting
bestChoiceIndex = -1;
break;
}
// Area of new enlarged rectangle
var oldLRatio = ol.structs.RTree.squarifiedRatio_(
lTree.extent[1] - lTree.extent[0],
lTree.extent[3] - lTree.extent[2],
lTree.nodes.length + 1);
// Enlarge rectangle to fit new rectangle
var nw = (lTree.extent[1] > rect.extent[1] ?
lTree.extent[1] : rect.extent[1]) -
(lTree.extent[0] < rect.extent[0] ?
lTree.extent[0] : rect.extent[0]);
var nh = (lTree.extent[3] > rect.extent[3] ?
lTree.extent[3] : rect.extent[3]) -
(lTree.extent[2] < rect.extent[2] ?
lTree.extent[2] : rect.extent[2]);
// Area of new enlarged rectangle
var lRatio = ol.structs.RTree.squarifiedRatio_(
nw, nh, lTree.nodes.length + 2);
if (bestChoiceIndex < 0 ||
Math.abs(lRatio - oldLRatio) < bestChoiceArea) {
bestChoiceArea = Math.abs(lRatio - oldLRatio);
bestChoiceIndex = i;
}
}
} while (bestChoiceIndex != -1);
return bestChoiceStack;
};
/**
* Non-recursive insert function.
*
* @param {ol.Extent} extent Extent.
* @param {Object} obj Object to insert.
* @param {string=} opt_type Optional type to store along with the object.
*/
ol.structs.RTree.prototype.insert = function(extent, obj, opt_type) {
var node = /** @type {ol.structs.RTreeNode} */
({extent: extent, leaf: obj});
if (goog.isDef(opt_type)) {
node.type = opt_type;
}
this.insertSubtree_(node, this.rootTree_);
};
/**
* Non-recursive internal insert function.
*
* @param {ol.structs.RTreeNode} node Node to insert.
* @param {ol.structs.RTreeNode} root Root to begin insertion at.
* @private
*/
ol.structs.RTree.prototype.insertSubtree_ = function(node, root) {
var bc; // Best Current node
// Initial insertion is special because we resize the Tree and we don't
// care about any overflow (seriously, how can the first object overflow?)
if (root.nodes.length === 0) {
root.extent = node.extent.concat();
root.nodes.push(node);
return;
}
// Find the best fitting leaf node
// chooseLeaf returns an array of all tree levels (including root)
// that were traversed while trying to find the leaf
var treeStack = this.chooseLeafSubtree_(node, root);
var workingObject = node;
// Walk back up the tree resizing and inserting as needed
do {
//handle the case of an empty node (from a split)
if (bc && goog.isDef(bc.nodes) && bc.nodes.length === 0) {
var pbc = bc; // Past bc
bc = treeStack.pop();
for (var t = 0, tt = bc.nodes.length; t < tt; ++t) {
if (bc.nodes[t] === pbc || bc.nodes[t].nodes.length === 0) {
bc.nodes.splice(t, 1);
break;
}
}
} else {
bc = treeStack.pop();
}
// If there is data attached to this workingObject
var isArray = goog.isArray(workingObject);
if (goog.isDef(workingObject.leaf) ||
goog.isDef(workingObject.nodes) || isArray) {
// Do Insert
if (isArray) {
for (var ai = 0, aii = workingObject.length; ai < aii; ++ai) {
ol.extent.extend(bc.extent, workingObject[ai].extent);
}
bc.nodes = bc.nodes.concat(workingObject);
} else {
ol.extent.extend(bc.extent, workingObject.extent);
bc.nodes.push(workingObject); // Do Insert
}
if (bc.nodes.length <= this.maxWidth_) { // Start Resizeing Up the Tree
workingObject = {extent: bc.extent.concat()};
} else { // Otherwise Split this Node
// linearSplit_() returns an array containing two new nodes
// formed from the split of the previous node's overflow
var a = this.linearSplit_(bc.nodes);
workingObject = a;//[1];
if (treeStack.length < 1) { // If are splitting the root..
bc.nodes.push(a[0]);
treeStack.push(bc); // Reconsider the root element
workingObject = a[1];
}
}
} else { // Otherwise Do Resize
//Just keep applying the new bounding rectangle to the parents..
ol.extent.extend(bc.extent, workingObject.extent);
workingObject = ({extent: bc.extent.concat()});
}
} while (treeStack.length > 0);
};
/**
* Split a set of nodes into two roughly equally-filled nodes.
*
* @param {Array.<ol.structs.RTreeNode>} nodes Array of nodes.
* @private
* @return {Array.<ol.structs.RTreeNode>} An array of two nodes.
*/
ol.structs.RTree.prototype.linearSplit_ = function(nodes) {
var n = this.pickLinear_(nodes);
while (nodes.length > 0) {
this.pickNext_(nodes, n[0], n[1]);
}
return n;
};
/**
* Pick the "best" two starter nodes to use as seeds using the "linear"
* criteria.
*
* @param {Array.<ol.structs.RTreeNode>} nodes Array of source nodes.
* @private
* @return {Array.<ol.structs.RTreeNode>} An array of two nodes.
*/
ol.structs.RTree.prototype.pickLinear_ = function(nodes) {
var lowestHighX = nodes.length - 1;
var highestLowX = 0;
var lowestHighY = nodes.length - 1;
var highestLowY = 0;
var t1, t2;
for (var i = nodes.length - 2; i >= 0; --i) {
var l = nodes[i];
if (l.extent[0] > nodes[highestLowX].extent[0]) {
highestLowX = i;
} else if (l.extent[1] < nodes[lowestHighX].extent[2]) {
lowestHighX = i;
}
if (l.extent[2] > nodes[highestLowY].extent[2]) {
highestLowY = i;
} else if (l.extent[3] < nodes[lowestHighY].extent[3]) {
lowestHighY = i;
}
}
var dx = Math.abs(nodes[lowestHighX].extent[1] -
nodes[highestLowX].extent[0]);
var dy = Math.abs(nodes[lowestHighY].extent[3] -
nodes[highestLowY].extent[2]);
if (dx > dy) {
if (lowestHighX > highestLowX) {
t1 = nodes.splice(lowestHighX, 1)[0];
t2 = nodes.splice(highestLowX, 1)[0];
} else {
t2 = nodes.splice(highestLowX, 1)[0];
t1 = nodes.splice(lowestHighX, 1)[0];
}
} else {
if (lowestHighY > highestLowY) {
t1 = nodes.splice(lowestHighY, 1)[0];
t2 = nodes.splice(highestLowY, 1)[0];
} else {
t2 = nodes.splice(highestLowY, 1)[0];
t1 = nodes.splice(lowestHighY, 1)[0];
}
}
return [
/** @type {ol.structs.RTreeNode} */
({extent: t1.extent.concat(), nodes: [t1]}),
/** @type {ol.structs.RTreeNode} */
({extent: t2.extent.concat(), nodes: [t2]})
];
};
/**
* Insert the best source rectangle into the best fitting parent node: a or b.
*
* @param {Array.<ol.structs.RTreeNode>} nodes Source node array.
* @param {ol.structs.RTreeNode} a Target node array a.
* @param {ol.structs.RTreeNode} b Target node array b.
* @private
*/
ol.structs.RTree.prototype.pickNext_ = function(nodes, a, b) {
// Area of new enlarged rectangle
var areaA = ol.structs.RTree.squarifiedRatio_(a.extent[1] - a.extent[0],
a.extent[3] - a.extent[2], a.nodes.length + 1);
var areaB = ol.structs.RTree.squarifiedRatio_(b.extent[1] - b.extent[0],
b.extent[3] - b.extent[2], b.nodes.length + 1);
var highAreaDelta;
var highAreaNode;
var lowestGrowthGroup;
for (var i = nodes.length - 1; i >= 0; --i) {
var l = nodes[i];
var newAreaA = [
a.extent[0] < l.extent[0] ? a.extent[0] : l.extent[0],
a.extent[1] > l.extent[1] ? a.extent[1] : l.extent[1],
a.extent[2] < l.extent[2] ? a.extent[2] : l.extent[2],
a.extent[3] > l.extent[3] ? a.extent[3] : l.extent[3]
];
var changeNewAreaA = Math.abs(ol.structs.RTree.squarifiedRatio_(
newAreaA[1] - newAreaA[0],
newAreaA[3] - newAreaA[2], a.nodes.length + 2) - areaA);
var newAreaB = [
b.extent[0] < l.extent[0] ? b.extent[0] : l.extent[0],
b.extent[1] > l.extent[1] ? b.extent[1] : l.extent[1],
b.extent[2] < l.extent[2] ? b.extent[2] : l.extent[2],
b.extent[3] > l.extent[3] ? b.extent[3] : l.extent[3]
];
var changeNewAreaB = Math.abs(ol.structs.RTree.squarifiedRatio_(
newAreaB[1] - newAreaB[0], newAreaB[3] - newAreaB[2],
b.nodes.length + 2) - areaB);
var changeNewAreaDelta = Math.abs(changeNewAreaB - changeNewAreaA);
if (!highAreaNode || !highAreaDelta ||
changeNewAreaDelta < highAreaDelta) {
highAreaNode = i;
highAreaDelta = changeNewAreaDelta;
lowestGrowthGroup = changeNewAreaB < changeNewAreaA ? b : a;
}
}
var tempNode = nodes.splice(highAreaNode, 1)[0];
if (a.nodes.length + nodes.length + 1 <= this.minWidth_) {
a.nodes.push(tempNode);
ol.extent.extend(a.extent, tempNode.extent);
} else if (b.nodes.length + nodes.length + 1 <= this.minWidth_) {
b.nodes.push(tempNode);
ol.extent.extend(b.extent, tempNode.extent);
}
else {
lowestGrowthGroup.nodes.push(tempNode);
ol.extent.extend(lowestGrowthGroup.extent, tempNode.extent);
}
};
/**
* Non-recursive function that deletes a specific region.
*
* @param {ol.Extent} extent Extent.
* @param {Object=} opt_obj Object.
* @return {Array} Result.
* @this {ol.structs.RTree}
*/
ol.structs.RTree.prototype.remove = function(extent, opt_obj) {
arguments[0] = /** @type {ol.structs.RTreeNode} */ ({extent: extent});
switch (arguments.length) {
case 1:
arguments[1] = false; // opt_obj == false for conditionals
case 2:
arguments[2] = this.rootTree_; // Add root node to end of argument list
default:
arguments.length = 3;
}
if (arguments[1] === false) { // Do area-wide †
var numberDeleted = 0;
var result = [];
do {
numberDeleted = result.length;
result = result.concat(this.removeSubtree_.apply(this, arguments));
} while (numberDeleted != result.length);
return result;
} else { // Delete a specific item
return this.removeSubtree_.apply(this, arguments);
}
};
/**
* Find the best specific node(s) for object to be deleted from.
*
* @param {ol.structs.RTreeNode} rect Rectangle.
* @param {Object} obj Object.
* @param {ol.structs.RTreeNode} root Root to start search.
* @private
* @return {Array} Leaf node parent.
*/
ol.structs.RTree.prototype.removeSubtree_ = function(rect, obj, root) {
var hitStack = []; // Contains the elements that overlap
var countStack = []; // Contains the elements that overlap
var returnArray = [];
var currentDepth = 1;
if (!rect || !ol.extent.intersects(rect.extent, root.extent)) {
return returnArray;
}
/** @type {ol.structs.RTreeNode} */
var workingObject = /** @type {ol.structs.RTreeNode} */
({extent: rect.extent.concat(), target: obj});
countStack.push(root.nodes.length);
hitStack.push(root);
do {
var tree = hitStack.pop();
var i = countStack.pop() - 1;
if (goog.isDef(workingObject.target)) {
// We are searching for a target
while (i >= 0) {
var lTree = tree.nodes[i];
if (ol.extent.intersects(workingObject.extent, lTree.extent)) {
if ((workingObject.target && goog.isDef(lTree.leaf) &&
lTree.leaf === workingObject.target) ||
(!workingObject.target && (goog.isDef(lTree.leaf) ||
ol.extent.containsExtent(workingObject.extent, lTree.extent))))
{ // A Match !!
// Yup we found a match...
// we can cancel search and start walking up the list
if (goog.isDef(lTree.nodes)) {
// If we are deleting a node not a leaf...
returnArray = this.searchSubtree_(lTree, true, [], lTree);
tree.nodes.splice(i, 1);
} else {
returnArray = tree.nodes.splice(i, 1);
}
// Resize MBR down...
ol.structs.RTree.recalculateExtent_(tree);
workingObject.target = undefined;
if (tree.nodes.length < this.minWidth_) { // Underflow
workingObject.nodes = /** @type {Array} */
(this.searchSubtree_(tree, true, [], tree));
}
break;
} else if (goog.isDef(lTree.nodes)) {
// Not a Leaf
currentDepth += 1;
countStack.push(i);
hitStack.push(tree);
tree = lTree;
i = lTree.nodes.length;
}
}
i -= 1;
}
} else if (goog.isDef(workingObject.nodes)) {
// We are unsplitting
tree.nodes.splice(i + 1, 1); // Remove unsplit node
// workingObject.nodes contains a list of elements removed from the
// tree so far
if (tree.nodes.length > 0) {
ol.structs.RTree.recalculateExtent_(tree);
}
for (var t = 0, tt = workingObject.nodes.length; t < tt; ++t) {
this.insertSubtree_(workingObject.nodes[t], tree);
}
workingObject.nodes.length = 0;
if (hitStack.length === 0 && tree.nodes.length <= 1) {
// Underflow..on root!
workingObject.nodes = /** @type {Array} */
(this.searchSubtree_(tree, true, workingObject.nodes, tree));
tree.nodes.length = 0;
hitStack.push(tree);
countStack.push(1);
} else if (hitStack.length > 0 && tree.nodes.length < this.minWidth_) {
// Underflow..AGAIN!
workingObject.nodes = /** @type {Array} */
(this.searchSubtree_(tree, true, workingObject.nodes, tree));
tree.nodes.length = 0;
} else {
workingObject.nodes = undefined; // Just start resizing
}
} else { // we are just resizing
ol.structs.RTree.recalculateExtent_(tree);
}
currentDepth -= 1;
} while (hitStack.length > 0);
return returnArray;
};
/**
* Non-recursive search function
*
* @param {ol.Extent} extent Extent.
* @param {string=} opt_type Optional type of the objects we want to find.
* @return {Array} Result.
* @this {ol.structs.RTree}
*/
ol.structs.RTree.prototype.search = function(extent, opt_type) {
var rect = /** @type {ol.structs.RTreeNode} */ ({extent: extent});
return /** @type {Array} */ (
this.searchSubtree_(rect, false, [], this.rootTree_, opt_type));
};
/**
* Non-recursive search function
*
* @param {ol.Extent} extent Extent.
* @param {string=} opt_type Optional type of the objects we want to find.
* @return {Object} Result. Keys are UIDs of the values.
* @this {ol.structs.RTree}
*/
ol.structs.RTree.prototype.searchReturningObject = function(extent, opt_type) {
var rect = /** @type {ol.structs.RTreeNode} */ ({extent: extent});
return /** @type {Object} */ (
this.searchSubtree_(rect, false, [], this.rootTree_, opt_type, true));
};
/**
* Non-recursive internal search function
*
* @param {ol.structs.RTreeNode} rect Rectangle.
* @param {boolean} returnNode Do we return nodes?
* @param {Array|Object} result Result.
* @param {ol.structs.RTreeNode} root Root.
* @param {string=} opt_type Optional type to search for.
* @param {boolean=} opt_resultAsObject If set, result will be an object keyed
* by UID.
* @private
* @return {Array|Object} Result.
*/
ol.structs.RTree.prototype.searchSubtree_ = function(
rect, returnNode, result, root, opt_type, opt_resultAsObject) {
var resultObject = {};
var hitStack = []; // Contains the elements that overlap
if (!ol.extent.intersects(rect.extent, root.extent)) {
return result;
}
hitStack.push(root.nodes);
do {
var nodes = hitStack.pop();
for (var i = nodes.length - 1; i >= 0; --i) {
var lTree = nodes[i];
if (ol.extent.intersects(rect.extent, lTree.extent)) {
if (goog.isDef(lTree.nodes)) { // Not a Leaf
hitStack.push(lTree.nodes);
} else if (goog.isDef(lTree.leaf)) { // A Leaf !!
if (!returnNode) {
// TODO keep track of type on all nodes so we don't have to
// walk all the way in to the leaf to know that we don't need it
if (!goog.isDef(opt_type) || lTree.type == opt_type) {
var obj = lTree.leaf;
if (goog.isDef(opt_resultAsObject)) {
resultObject[goog.getUid(obj).toString()] = obj;
} else {
result.push(obj);
}
}
} else {
result.push(lTree);
}
}
}
}
} while (hitStack.length > 0);
if (goog.isDef(opt_resultAsObject)) {
return resultObject;
} else {
return result;
}
};