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Move squarifiedRatio into private static function

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This commit is contained in:
Tom Payne
2013-05-25 18:12:09 -05:00
parent e63423eafe
commit 7f22455eed
1 changed files with 34 additions and 28 deletions
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62
src/ol/structs/rtree.js
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@@ -59,27 +59,6 @@ ol.structs.RTree = function(opt_width) {
var rootTree = /** @type {ol.structs.RTreeNode} */
({extent: [0, 0, 0, 0], nodes: []});
/**
* 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.
* @return {number} Squarified ratio.
*/
var 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;
};
/**
* Generates a minimally bounding rectangle for all rectangles in
* array "nodes". `rect` is modified into the MBR.
@@ -234,8 +213,10 @@ ol.structs.RTree = function(opt_width) {
break;
}
// Area of new enlarged rectangle
var oldLRatio = squarifiedRatio(lTree.extent[1] - lTree.extent[0],
lTree.extent[3] - lTree.extent[2], lTree.nodes.length + 1);
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] ?
@@ -248,7 +229,8 @@ ol.structs.RTree = function(opt_width) {
lTree.extent[2] : rect.extent[2]);
// Area of new enlarged rectangle
var lRatio = squarifiedRatio(nw, nh, lTree.nodes.length + 2);
var lRatio = ol.structs.RTree.squarifiedRatio_(
nw, nh, lTree.nodes.length + 2);
if (bestChoiceIndex < 0 ||
Math.abs(lRatio - oldLRatio) < bestChoiceArea) {
@@ -285,9 +267,9 @@ ol.structs.RTree = function(opt_width) {
*/
var pickNext = function(nodes, a, b) {
// Area of new enlarged rectangle
var areaA = squarifiedRatio(a.extent[1] - a.extent[0],
var areaA = ol.structs.RTree.squarifiedRatio_(a.extent[1] - a.extent[0],
a.extent[3] - a.extent[2], a.nodes.length + 1);
var areaB = squarifiedRatio(b.extent[1] - b.extent[0],
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;
@@ -302,7 +284,8 @@ ol.structs.RTree = function(opt_width) {
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(squarifiedRatio(newAreaA[1] - newAreaA[0],
var changeNewAreaA = Math.abs(ol.structs.RTree.squarifiedRatio_(
newAreaA[1] - newAreaA[0],
newAreaA[3] - newAreaA[2], a.nodes.length + 2) - areaA);
var newAreaB = [
@@ -311,7 +294,7 @@ ol.structs.RTree = function(opt_width) {
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(squarifiedRatio(
var changeNewAreaB = Math.abs(ol.structs.RTree.squarifiedRatio_(
newAreaB[1] - newAreaB[0], newAreaB[3] - newAreaB[2],
b.nodes.length + 2) - areaB);
@@ -605,3 +588,26 @@ ol.structs.RTree = function(opt_width) {
//End of RTree
};
/**
* 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;
};